Difference Between Robotics Technician And PLC Technician

If you’re studying towards or considering a career in industrial automation, you may be wondering about the difference between “robotics” and “automation”. Some other industrial automation words that sound suspiciously similar are “mechatronics”, “controls”, and “motion control”. Many of these terms are synonymous, or at least describe greatly overlapping domains. With that said, there is a distinction to be made between a Robotics Technician and a PLC Technician or PLC Programmer.

Recently, a reader left the following comment on our So, You Want To Be An Industrial Automation Engineer article:

Your article on Industrial Automation was very insightful. I am a manufacturing engineering technician student from London, ON. I am interested in becoming a Robotics Technician. So, I would like to know the similarities and differences of a PLC technician and a Robotics technician and what do I need to do to reach my career interest.

Eric’s Comment

Thanks for the question, Eric! It’s always awesome to hear from someone who’s getting involved in industrial automation. It’s hard work, but a lot of fun, and the opportunities to learn are endless. Let me do my best below to answer your questions.


Contents


What Do Robotics Technicians Do?

Robotics technicians generally do robot setup and programming. As far as I see it, there are three worlds to robotics:

  1. Robot setup
  2. Writing and debugging robot programs
  3. Teaching robot positions

Robot Setup

Robot setup involves getting a new robot out of the box ready to be programmed. This consists of any custom loads for your shop, IP and comm setup, etc. Sort of like getting a new device to talk on your Wi-Fi at home, but more complicated. 🙂

Someone who’s spending their time setting up robots will have to connect power and communications to the robot. You’ll need the right cables for the application. When someone says “application” in this context, they mean: the particular thing that the robot is intended to do.

For instance, if the robot is a “material handler”, its purpose is to move parts around. You would say the robot is, or has, a “material handling application”.

Material handling robots will often have end effectors with sensors and clamps. (You can read a bit about end effectors near the bottom of this article on sensors.) The robot will need power and communication cables to pass through its arm to the end effector. It will need these to provide power to the clamps and to receive feedback from the sensors. This may result in different cabling to the bottom of the robot. The person doing the setup will need to make sure they select and hook up the right cables.

Anyone working robot setup will also need to be very familiar with the robot’s setup menus. There may be a lot of little settings to change to get everything configured correctly. Additionally, you will likely need to understand the process for flashing images or firmware into the robot’s memory.

Writing And Debugging Robot Programs

Once initial setup is complete, the robot’s programming tells the robot when to go. The robot program also dictates what inputs and outputs to set along the way. Robot programming is reminiscent of high-level computer programming. Once you get involved in reading and understanding robot programs, I think it’s fairly easy to start building some skills as a programmer.

Robot programs often employ somewhat straightforward and easy-to-read logic. Usually, you’ll be evaluating some input from the PLC or the End Of Arm Tool (the “IF” condition). The robot then takes some action or sets some output as a result (the “THEN” result).

For example, a robot may enter a program and first check to see if it’s already holding a part. If it doesn’t have the part, it enters a branch of the program that sends it to the pickup location. From there, it may close its clamps (to secure the part in its grasp), and then check to see that its sensors indicate that it has a grip on the part.

If, instead, the robot already has the part, it will jump to a different branch of the program. In this branch, a different set of motion commands will move the robot to the drop-off location. Once there, it will release its clamps, then check its sensors to make sure that it no longer has the part.

If you’ve ever done any programming in BASIC, that’s what robot programming reminds me of. I’ve only ever worked with Fanuc robots, though, so other platforms may be different.

Teaching Robot Positions

Once robot programs are loaded, you have to tell the robot where to go to do its job. Different robot applications (robots that weld, robots that move parts around) require different tactics in terms of the motion necessary to accomplish the task.

For the most part, teaching robot positions is a lot of “jogging” the robot. To “jog” a robot is to drive it manually using the buttons on the teach pendant. Depending on the reference frame, these buttons either move an axis independently or move the End Of Arm Tool in one particular direction.

A Fanuc Teach Pendant. The teach pendant is used to view and control the robot's setup and programming. This image is part of an article describing the difference between robotics technician and plc technician jobs.
A Fanuc Teach Pendant. The jog buttons are the blue buttons on the right.

With that said, simply wiggling the robot around is only scratching the surface of position programming. Each position taught can be setup in a variety of different ways. Good programmers understand how the robot will move depending on the settings that they select when they teach a position. Skillful position programming can improve the performance of the robot (by reducing cycle time) and extend the life of the robot’s mechanical components.

Position programmers will also need to understand how motion is programmed for different applications. Material handler motion may be programmed differently from weld gun motion. Large, heavy robots with payloads of several hundred pounds may be taught differently than small robots that carry only a few pounds.

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Being A Well-Rounded Robotics Technician

Each of these elements is a bit of a world unto itself. If you get into robotics, then depending on where you work, you may specialize in one or two of these domains. Or, maybe your shop’s policy is that you own each robot for the complete process, from setup through customer acceptance.

Robot gods – guys or gals who are really, really knowledgeable – are likely to be proficient in both setup and programming.

What About PLC Programming?

A little snippet of ladder logic. Click for full-size image

The Programmable Logic Controller, or PLC, is the brains of the operation in many modern factories and processes. PLC’s tell the robots, valves, actuators, conveyors, and other systems when it is their turn to move. For instance, the PLC will tell the robot which program it should execute:

Run your program to…

  • …pick up a part and set it down somewhere else
  • …move to a maintenance position so a cable can be repaired
  • …drop off your end effector and return home
  • …etc.

The PLC will send several bits to the robot telling it that it is safe to move and that it wants it to run a program. It will also typically send a combination of bits that represent “program select”. In other words, the PLC will send the robot a code telling it which program to run, and other bits telling it it is safe to run that program.

This is just one example of what the PLC does. The PLC is the mastermind of the operation, evaluating all of its inputs, processing those inputs according to its programming, and setting all of its outputs on every “scan”. A scan is one complete execution of all of the PLC’s programmed logic.

What Does A PLC Do?

Think about some decent-to-high-end electronics purchase you’ve made recently. For instance, consider a smart home hub.

That smart home hub comes out of the box, ready to do its job of controlling your smart home devices. In order to do so, it uses its microprocessor, which is equipped with a set of programming instructions that were loaded at the factory. If you and your friend have the same smart home hub, both hubs will have the same programming.

Now, consider an automation line in a factory. An automation line in a factory is analogous, in some ways, to a smart home hub. It accepts inputs from many sensors. It processes those inputs, and depending on the inputs it receives, turns on outputs.

In the case of the home automation hub, it might be accepting voice commands, time of day, and RF signals as inputs, and it might be setting outputs such as locking the front door, turning on a light, or closing a set of motorized blinds.

What Does This Have To Do With PLC’s?

In the case of a PLC, it might be accepting proximity sensors, motor temperatures, and operator pushbuttons as inputs, and it might be setting outputs such as telling motors to turn, flashing lights on panels, or moving an actuator to position a part.

The PLC even shares the trait of using a microprocessor to perform its functions. Where the PLC differs from the smart home hub is that whereas manufactured devices like smart home hubs all have the same programming, each PLC running an automation line or process typically has custom programming.

In other words, two automation lines that connect with each other may have the same foundational “template” of logic loaded. Even if they start out similarly, however, they will both have many small differences in their programming to reflect different processes or equipment that are used on each line.

What Do PLC Programmers Do?

It is the PLC Programmer’s job to create and maintain the logic that drives automation lines or processes. PLC programmers are generally either developing and implementing new logic, or supporting and debugging existing systems.

Developing New Logic

A ladder logic sample with FAL instructions. FAL's are very efficient, and allow you to perform operations on every index in an array with one instruction. They are, however, very hard to read when you go back through to debug your logic.
FAL’s are a powerful – but cryptic – instruction. Click for full-size image

One of the most fun aspects of PLC programming is developing new logic. You might work with ladder logic, function block diagrams, structured text, or other programming methods. Whatever you’re using to program the PLC, developing new logic allows you, as the programmer, to bring an automated process to life.

This is where your creativity and programming skills will come in. A good PLC programmer has read and debugged a lot of logic and is able to bring solutions to bear in new applications. Knowing how you or other people have solved certain problems in the past gives you a “library” of solutions to reference to overcome new problems.

A good programmer is also resourceful. If you come across a problem you haven’t solved before, it’s important to know where to look and to have other smart people you can call upon to get the information you need.

Another key skill when writing new logic for the PLC is “being able to see the logic running in your head”, as one of my PLC mentors once said to me. It’s important to learn how the various PLC programming instructions work and how they respond on their first and future scans after input conditions become true or false. Understanding how your logic will behave while you’re working offline will help your implementation to go more smoothly and minimize debug time and issues.

Maintaining And Debugging Existing Systems

The other side of the coin is maintaining and debugging existing systems. Many organizations keep PLC programmers, or “Controls Guys” (or Gals), on for the sole purpose of getting the equipment back up and running when it breaks down. If you’re in a production support role of this type, you’ll need to learn the equipment in the area and the PLC logic that drives the process.

The best-case scenario is when you get to own a process from birth and throughout its lifecycle. If you’re trying to troubleshoot something, it sure is nice to have the person that wrote the logic available on site.

If you’re going to support existing equipment, it helps to be able to work well under pressure. Managers will be standing around tapping their feet and looking at you to get the equipment running. You’ll need to keep a cool head and work through the issue to get the line moving.

Other Functions Of A PLC Programmer Or Automation Engineer

There can be a lot more to it than the ladder logic (or other programming method). For instance, the PLC is the ultimate controller for the process, and thus many devices will need to be setup within the PLC software so that the PLC can talk to them. This may require you to obtain specific configuration values from the device’s manufacturer, or to load an EDS for the device. An EDS is a file that helps the PLC understand how to talk to a certain type of device.

Further, PLC Programmers (or Controls Engineers, etc.) often setup and maintain software and backups for any drives that are part of the system. Modern factories commonly employ Variable Frequency Drives, or VFD’s, to control motors. VFD’s allow you to set motor speed dynamically through the logic. This programmatic control enables the programmer to set up high and low speed settings, sync up speeds between neighboring motors, and more.

Another area of responsibility for PLC programmers is HMI development. The Human-Machine Interface, or HMI, is typically an LCD or touchscreen interface through which operators can control the system. As a PLC programmer, you may find yourself designing and debugging custom HMI screens to support your process. A well-designed HMI will provide users with:

  • Information they need to understand what’s going on in the process
  • Buttons and other input methods that allow them to control the process
An example of a  Human-Machine Interface screen. This is an example of something a PLC programmer might have to design. This image was used to illustrate some of the differences between PLC technicians and robot technicians.
An HMI interface for a pump. Image credit. Click for full-size image

Similarities Between Robotics Technician And PLC Technician Positions

Now that we’ve covered many of the differences between robotics and PLC technician roles, let’s discuss some of the similarities.

Programming Skills

To start with the obvious, both roles require you to be a decent programmer. You’ll need to have the patience and curiosity to learn the basic syntax and instructions with which the equipment is programmed. As you are exposed to new situations, it helps to remember programming solutions you’ve used or seen in the past. You never know when you might want to reuse something in the future to overcome a similar challenge.

Programmers working in the industrial automation field must take care in what they do. A single bit in the wrong state or a single number in the wrong register can bring your process to a halt, or worse – cause a robot or other equipment crash. You’ll need to be careful and pay attention to detail as you program and debug your logic.

Troubleshooting Skills

Another aspect of working as either a Robotics Technician or PLC Technician is troubleshooting. Troubleshooting is the process of identifying and correcting a problem to get equipment working.

To be a good troubleshooter, you need to learn your automation and the equipment and software that you’ll use to get the job done. If my factory uses Rockwell Automation PLC’s, for instance, I’ll need to be familiar with RSLogix 5000 and how to use it to quickly debug any issues. In a facility that employs Kawasaki robots, I’ll need to know my way around the Kawasaki pendant and understand generally how the robot functions. If I’m supporting a line with automated weld processes, I’ll need to become familiar with the weld equipment and controller.

Depending on the process, this most likely means you’ll need a good mechanical or electrical background. When you have knowledge of how equipment and components are supposed to work, it can help you to understand why they’re not working. Many PLC and robot programmers first work as industrial electricians or automation technicians. A strong electrical background can be very helpful in figuring out what’s going wrong in your process.

People Skills

Believe it or not, you still need to have decent people skills as a programmer. You’ll need to keep people informed of the work you have going on and often solicit their help in getting the job done. Managers and supervisors will need you to get a task accomplished or to get equipment back up and running, and you’ll need to be able to set expectations appropriately.

Salary Comparison Between PLC Technicians And Robot Technicians

The good news is that both pay pretty decently and both are very comparable. As you’ll see below, there appears to be a wide range of potential salaries within these fields, and I’m sure it depends greatly on the location, years of experience, and contract status. Here are some aggregated salary numbers from some reputable sites:

Robotics TechnicianPLC Technician
ZipRecruiter.com$56,875$58,090
PayScale.com$66,000$51,959
glassdoor.com$83,241$79,157

How To Get A Job As A Robot Programmer Or PLC Programmer

Within the field of industrial automation, I think there’s a bit of a chicken-and-the-egg thing with breaking into a programming job. This is something that I think is similar between robotics technicians and PLC technicians. When it comes to hiring into these fields, my personal perception is that employers would prefer experience to education.

What I mean to say is that for a technician position, an employer may be likely to choose a robot programmer with 4 years of pendant time over an Electrical Engineer with 4 years of education. The same may or may not be true for an engineering position.

I’m not trying to downplay education, which I think is important regardless of the position held. Experience, however, is a critical element when working with highly specialized platforms like robots and PLC’s.

The Importance Of Hands-On Experience

If you’re looking to get into the industry as a Robotics Technician or PLC Technician, hands-on time is very important to employers. I believe an employer would very strongly consider a candidate for either a technician or engineering position if the candidate had several years of relevant experience doing PLC or robotics work – even if that candidate didn’t have a degree.

I think that employers may even prefer experience over education for certain engineering positions. Because PLC and robotics work requires very specialized skills and knowledge, you just can’t trade time at the terminal or on the pendant. Becoming a proficient PLC programmer using Rockwell Automation’s RSLogix 5000, for instance, can be a life-long pursuit.

Please note that this is just my personal take on it; I’m sure every employer has different policies and expectations.

What If I Don’t Have Any Experience, Yet?

This is where the chicken-and-the-egg thing comes into play. If you’re trying to get your foot in the door somewhere to try to build that foundational experience with PLC’s or robotics, I’d say there are two common paths:

  • Earn a two-year (or even four-year) degree in a field like Mechatronics, Industrial Automation, Electrical Engineering, etc. This will help you to get an interview and hire on as a technician
  • With experience in a related field, get a position where you can start dabbling in PLC programming or robotics so that you can qualify for a more focused position later

A Couple Of Examples

I’ll give you two examples:

  • I know a very talented PLC programmer who works as a Controls Engineer
    • He got a two-year degree in Mechatronics and then worked for an automotive manufacturer as an Industrial Electrician. He transitioned into another Industrial Electrician position with another automotive manufacturer
    • His two-year degree plus the experience he’d built doing PLC debug along the way allowed him to interview for (and be offered) a position as a Controls Engineer
  • I know another very talented PLC programmer who works as an Industrial Electrician. Although Industrial Electricians perform a wide range of tasks within my facility, he is primarily doing PLC programming and troubleshooting
    • He worked as an Industrial Electrician at a government facility. During that time, he made sure to learn as much as he could about PLC’s, drives, and electrical troubleshooting. After several years, he hired on at my facility
    • He has the same job title as others at my facility who are doing less technical work. Because of his knowledge and experience, however, he has been able to specialize in PLC programming. His supervisor has identified him as a Subject Matter Expert for PLC’s and drives, and he primarily works as a PLC programmer and troubleshooter

Additional Information On The Differences Between PLC Technicians and Robotics Technicians

I hope that this article has given you a bit of perspective on the difference between PLC technician and robotics technician jobs in the field of industrial automation. If this was helpful for you, make sure to sign up for our email list below:

Once you’re on the list, we’ll keep you posted whenever we have something new for you related to industrial automation.

Further Reading

For further reading on the differences between robotics technician and plc programmer roles, here are some other resources from around the web:

Difference Between Inductive And Capacitive Proximity Sensors

Have you recently found yourself staring at two seemingly identical proximity switches? Have you wondered, what the heck is the difference between these two? Or maybe you’re getting ready to buy some sensors. You want to make sure you pick up the right device for the right application. Below, we’ll illustrate the differences between capacitive and inductive proximity sensors. We’ll look at how inductive proximity sensors work, how capacitive proximity sensors work, and compare these two types of proximity sensors.

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Inductive Proximity Sensor Working Principle

An inductive proximity sensor available for purchase on Amazon. The sensor has a chrome finish with a green face.
An inductive prox in a “barrel” form factor

Inductive proximity sensors are perhaps the most common type of prox switch in industrial automation. These sensors generate electromagnetic fields to detect their target. This field is strongest when no target is present in front of the sensor.

An inductive proximity sensor emitting its electromagnetic field at full strength, because no target is present in front of the sensor. This image is being used to illustrate the difference between capacitive and inductive proximity switches.
Inductive proximity sensor with no part present

When a target passes in front of the sensor, eddy currents form in the electromagnetic field, lowering the amplitude of the field as measured at the sensor.

When a metallic target is presented to an inductive prox sensor, the amplitude of the sensor's electromagnetic field is dampened.
When sufficient dampening takes place, the sensor's output changes state.
Inductive proximity sensor with a part present

Applications For Inductive Prox Switches

Because inductive proxes use electromagnetism, they are only able to detect metallic objects. Some inductive prox switches have a harder time detecting non-ferrous metals. Non-ferrous metal are metals that don’t contain very much iron. If you want to detect a metallic object, there are a variety of inductive proxes on the market. Depending on the iron content of your target, you can find inductive sensors to fit any of the following applications:

  • Inductive proximity sensors that primarily respond to ferrous metals (such as steel and iron)
  • Inductive proximity sensors that primarily respond to non-ferrous metals (such as aluminum)
  • Also, inductive proximity sensors that respond to varying metals equally

Because inductive proxes only sense metal objects, they have some advantages for certain applications:

  • Inductive proxes can detect metal objects through plastic (or other non-metallic) containers
  • Because they only sense metals, inductive proximity sensors are tolerant to dust build-up on the face of the prox

Inductive proxes can come with either Normally Open or Normally Closed outputs, or as analog sensors. You can hook up the sensor’s output to a PLC, robot, or other controller to detect machine motion.


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Capacitive Proximity Sensor Working Principle

A capacitive proximity sensor available for purchase on Amazon. The sensor has a chrome finish with a green face. I deliberately selected a prox that looked the same in its capacitive and inductive forms.
A capacitive proximity sensor. Look familiar?

Capacitive proximity sensors are another type of prox switch that are commonly used in industrial automation. Compare the picture of this capacitive prox to the inductive prox in the section above. Note that you wouldn’t be able to tell which sensor was inductive or capacitive just by looking at them. Always check your prox’s part number to determine its specs.

You saw above that inductive proxes generate electromagnetic fields. Capacitive proxes, on the other hand, generate electrostatic fields. Capacitive proxes house a capacitive plate behind the face of the prox. This plate generates an electrostatic field in front of the prox. Whereas inductive prox fields are highest with no target present, capacitive sensors detect very low capacitance when no target is present.

A capacitive proximity sensor with no part present in front of it. With no part present, the capacitance measured by the sensor is low.
A capacitive prox switch with no part present

When a target passes in front of a capacitive prox, the target acts as a second capacitive plate. For this reason, the presence of a target increases the capacitance measured by the prox. When a certain threshold of capacitance is met, the sensor’s output state will change.

A capacitive proximity sensor being made by its target. The difference between capacitive and inductive proximity sensors is the presence of an electrostatic versus an electromagnetic detection field, respectively.
A capacitive proximity sensor being “made” by its target

Unlike inductive sensors, many capacitive sensors are adjustable. This allows you to set the sensitivity of the prox to ensure accurate detection. With adjustable sensitivity, capacitive proxes have a few tricks up their sleeve. Adjustable capacitive proxes can differentiate between material thickness in certain cases. They can even detect liquids inside of containers.

Applications For Capacitive Prox Switches

Nearly any material presented to a capacitive prox will increase the capacitance that the sensor measures. For this reason, capacitive proxes are able to detect both metallic and non-metallic targets. Some applications for which capacitive prox sensors are well-suited include:

  • Sensing of non-metallic materials. This can include plastic, glass, liquids, biological matter, and more
  • Detection of a certain quantity or thickness of material
  • Liquid detection from the outside of the container

Like inductive sensors, capacitive sensor outputs can be NO, NC, or analog.

Comparison Between Inductive and Capacitive Proximity Sensors

While there are clear differences between the two types of sensors, there are similarities, as well. To start with what’s similar, let’s talk about the internals of inductive and capacitive prox switches:

Similarities Between Capacitive And Inductive Proxes

Many of the internal working principles of capacitive and inductive proxes are similar. Capacitive and inductive proxes are both typically fed by DC power. Because they need AC power for the sensor circuit, both types of proxes typically have “oscillators”. Oscillators are electronic circuits that generate AC power from a DC input. You can read more about oscillators in this write-up on Wikipedia.

Additionally, both types of sensors typically have a trigger circuit. Depending on the type of sensor, this circuit activates when the sensed signal passes either above or below a certain threshold.

Lastly, both types of sensors have an output circuit. This circuit switches the sensor’s output when the signal threshold is met. If the sensor is Normally Open, the sensor’s output will turn ON when it sees a part.

For Normally Closed sensors, the opposite is true. In other words, the output for Normally Closed sensors is on by default. When the prox sees a target, the output is turned off.

Other sensors on the market have analog outputs. Analog sensors provide a varying voltage or current output. For example, a sensor may provide an output ranging from 2 to 10 volts, DC. The output varies with how much of the sensor’s field is disturbed. In other words, the more the sensor detects the part, the greater its output value will be.

Form Factors

Another manner in which inductive and capacitive proxes are similar is the form factors in which they’re available. By “form factor”, I mean the physical shape and characteristics of the sensor. Among the sensors I see in use, the three most common form factors are shown below. (Images from Turck website):

  • “Barrel”:   A "barrel" prox that can be threaded into a tapped hole. Both inductive and capacitive sensors come in this and other form factors.
  • “Pancake”:   A "pancake" proximity sensor.
  • “Ice Cube”:   An "ice cube" prox form factor.

Among these, the “barrel” form factor is extremely common. In most cases, it won’t be possible to tell whether a sensor is inductive or capacitive just by looking at it. To determine which type of sensor you’re looking at, you will typically need to find the sensor’s part number and look it up online.

Difference Between Capacitive And Inductive Proximity Switches

The primary difference between inductive and capacitive proximity sensors is the sensing method:

  • Inductive sensors use a coil to generate an electromagnetic field
    • With no target present, the field is at its strongest amplitude
    • When a target is present, the electromagnetic field weakens. This weakening is caused by Eddy currents induced in the target
  • Capacitive sensors use a capacitive plate to generate an electrostatic field
    • With no target present, the field is at its lowest capacitance
    • When a target is present, the target acts as a second capacitive plate. The sensor will measure a higher capacitance when a target is present

Summary Of Capacitive And Inductive Prox Sensor Characteristics

For quick reference, here’s everything above, summed up in one place:

Inductive SensorsCapacitive Sensors
Sensing FieldElectromagneticElectrostatic
Sensing MechanismCoilPlate
Materials DetectedMetalsAlmost Any
(Commonly) Adjustable?NoYes
Resilient To Contaminants?YesNo
Sense Through Materials?Metallic Through Non-MetallicMany Through Non-Metallic
Liquid Level-SensingNoYes

More Information

For additional information, here are some further resources. These resources cover inductive, capacitive, and other proximity sensors:

Thank you for reading!

Thanks for reading this! I hope it helped you to gain a bit of an understanding on the difference between inductive and capacitive proxes. If you have any questions, feel free to ask in the comments at the bottom of this page. Is there anything in the industrial automation world that you’re struggling to understand? Something you’d just like a little bit more info on?

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Types Of Proximity Sensors Used In Industrial Automation

When you write logic in a PLC that initiates motion, you want to be certain that the motion you are expecting actually occurs. This is where sensors come into play. Sensors provide indication to the PLC, robot, or other controller that some physical event has taken place. As examples, sensors may detect that a part is present, that a part is not present, that an actuator is in a certain position, that a lift is lowered or raised, that a door is open or closed, or that a spring-returned component is a certain distance away. Proximity sensors are a specific subset of sensors in general. In this article, we’ll look at some of the many different types of proximity sensors that are used in industrial automation.

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Contents of this post:

What Is A Proximity Sensor?

An image of a "barrel prox", a type of proximity sensor that threads into a tapped hole. The sensor is triggered when an object of a certain material (depending on the sensor type) is placed or passes nearby the sensor. This is one type of proximity sensor utilized in industrial automation.
A “barrel prox“; a type of proximity sensor that threads into a tapped hole. Sensors of this type are triggered when an object of a certain material (depending on the sensor’s detection mechanism) is nearby the sensor. The sensor shown is an inductive barrel prox, which is a common type of proximity sensor utilized in industrial automation.

Proximity sensors – sometimes referred to as proximity switches – are sensors that are used in industrial automation and other applications. What distinguishes them from other sensors is that they can sense objects without having to touch them. Because they don’t have to physically interact with the objects they detect, proximity sensors often have no moving parts. Solid-state devices – devices that have no moving parts – often last much longer than devices which have to move to do their job. Wikipedia sums this up as follows:

A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact.

Proximity sensors can have a high reliability and long functional life because of the absence of mechanical parts and lack of physical contact between the sensor and the sensed object.

Wikipedia article on Proximity sensors

Advantages Of Solid-State Proximity Sensors

For the reasons above, proximity sensors are very popular in industrial automation. Other types of sensors, such as limit switches, require contact with the part.

Because they have to contact the part, limit switches require moving components. Because they have moving components, they may fail much sooner than a non-contact proximity sensor. For this reason, limit switches and other sensors that require internal motion are becoming less and less common.

An Allen Bradley limit switch. This switch is an example of a sensor that requires contact with the part and thus is subject to failure modes resulting from its internal motion.
An Allen Bradley limit switch. This switch is an example of a sensor that requires contact with the part and is thus subject to failure modes resulting from its own internal motion.

Proximity Sensor Types

The zoo of sensors on the market is quite diverse. Although there are other, more obscure sensors out there, I want to go over the types of proximity switches that are most commonly used in industrial automation:

Inductive Proximity Sensors

An inductive proximity sensor manufactured by Turck. This flat, rectangular form factor lends this sensor the moniker, "pancake prox."
An inductive proximity sensor manufactured by Turck. The flat, rectangular form factor lends this style the moniker: “pancake prox.” This is one example of an inductive proximity sensor. The barrel prox shown at the top of this article is another.

In industrial automation, inductive proximity sensors are one of the most common types of proxes. Inductive proximity sensors have a coil inside of them. The coil and body of the prox are designed to generate an electromagnetic field at the face of the prox. When a target is presented within the prox’s sensing range, the electromagnetic field is dampened. Once this dampening exceeds a certain threshold, the state of the output changes.

I felt a great disturbance in the force

Obi-Wan Kenobi, and inductive proximity sensors

The state of the output changes based on whether you’re using a “Normally Open” or “Normally Closed” sensor. Normally Open (or “NO”, or “N.O.”) sensors have outputs that are normally OFF (“open”). A NO sensor’s output turns ON when the sensor detects its target.

Similarly, Normally Closed sensor outputs are normally ON (“closed”). When an NC sensor sees a target, its output turns OFF. You can read much more about the concepts of NO and NC here.

Digital And Analog Proximity Sensors

The sensors above (NO and NC) are referred to as digital sensors. Digital, in this context, refers to the fact that the sensor’s output is either ON or OFF. In addition to digital sensors, there are analog sensors.

Analog sensors provide feedback as a variable voltage or current output. As the sensor’s target moves closer or further, the output signal increases or decreases. Using an analog sensor, you’re able to tell not just that the part is present, but also how far away the part is.

Click the following link for an in-depth look at the difference between analog and digital sensors.

Inductive Prox Applications

Because inductive proximity sensors utilize electromagnetic fields, they can only detect metallic objects. Within the domain of metallic objects, inductive proximity sensors respond differently to different metals. As sensors in this family have evolved, you can now purchase sensors that respond more sensitively to ferrous metals (such as iron and steel), nonferrous metals (such as aluminum), or sensors that respond to a variety of metals approximately equally.

Turck’s uprox factor 1 sensor has been the standard in the automotive sector for twenty years. The same large switching distances for all metals, weld field immunity and a large degree of mounting flexibility are the key benefits of these inductive sensors without a ferrite core.

From “Smart Switches“, a Turck publication describing their family of inductive proxes that sense different metals equally

The fact that inductive sensors only sense metal objects can be of benefit in many applications. As non-metallic contaminants will be less likely to trigger an inductive sensor, sensors of this type are tolerant of dirt and moisture build-up. For this reason, they’re the go-to choice for detection of metallic components.

Learn More About Inductive Proximity Sensors

Capacitive Proximity Sensors

An image of a capacitive proximity sensor. This sensor's threads and face are blue, but the coloring is branding; it's not indicative of whether the prox is inductive or capacitive. You would need to look up the part number to know for sure.
A capacitive proximity sensor. Note that this prox has the same “barrel” form factor as the inductive sensor shown at the very top of this page. This capacitive sensor’s threads and face are blue, but the coloring is not indicative of whether the prox is inductive or capacitive. You would need to look up the sensor’s part number to determine its sensing type.

Outwardly, capacitive proxes can be quite similar to inductive proxes. The two types are often available in the same form factors. Where capacitive proximity sensors differ from inductive proxes is in the sensing mechanism.

Capacitive proxes work as capacitors. There is an energized metallic plate in the face of a capacitive prox. This plate serves as one side of the capacitor, with the prox’s target serving as the other side.

When a capacitive sensor is exposed to open air, the measured capacitance is low. As an object approaches the prox’s sensing area, the capacitance increases until a threshold is met and the output is set. Like inductive sensors, many capacitive sensors are wired as NO or NC digital sensors, or alternatively as analog sensors.

Capacitive Prox Applications

Whereas inductive sensors generate electromagnetic fields, capacitive sensors generate electrostatic fields. Capacitive sensors are an interesting type of proximity sensor used in manufacturing.

Because capacitive sensors detect changes in the capacitance of the field they generate, they have the special property of being able to detect non-conductive materials. Due to this attribute, capacitive proxes can detect plastic, glass, water or other liquids, biological materials, and more.

In fact, capacitive proxes are often used as liquid or solid level detection sensors. Because the sensitivity of many capacitive proxes is adjustable, these sensors can be set up to read the presence or absence of a material through the material’s container.

Learn More About Capacitive Proximity Sensors

Magnetic (Hall Effect) Proximity Sensors

An image of a magnetic (Hall Effect) proximity sensor. This sensor's face is blue, but the coloring is branding; it's not indicative of whether the prox is inductive, capacitive, or magnetic. You would need to look up the part number to know for sure.

A magnetic (Hall Effect) proximity sensor. Note that, like inductive and capacitive sensors, magnetic sensors are also available in the barrel form factor, and that the color of the face or threads is no indication of whether the prox is inductive, capacitive, or magnetic. You would need to look up the part number to determine the prox’s detection mechanism.

Magnetic, or “Hall Effect,” proximity sensors are triggered by magnets. As illustrated in the image above, magnetic sensors are available in the barrel form factor, among others. Hopefully you have seen by now that you cannot assume a sensor’s type by its form factor. When buying or “spec’ing” a prox for your company or application, you have to research the part number to be sure of what you’re buying.

Humanity has known of the Hall Effect since the 19th century. Hall Effect switches have been in use since at least the 1970’s. Modern Hall Effect sensors detect the presence and distance of a permanent magnet. With the right setup, magnetic sensors can also detect ferrous metals.

Like inductive and capacitive proxes, magnetic sensors can provide either digital or analog outputs. Digital outputs are either on or off, whereas analog outputs provide a variable voltage or current based on how far the part is from the sensor.

“Reed sensors” bear mentioning in this space. Reed sensors are in many ways equivalent to the solid-state Hall Effect sensor, except that reed sensors have tiny parts inside that move. Because reed switches function very similarly, but have moving parts, I’ve chosen to limit the conversation to Hall Effect sensors.

Magnetic Sensor Applications In Industrial Automation

Magnetic sensors are very common and have many applications across industries – from automotive to aerospace engineering. Within industrial automation specifically, there are several prominent applications for magnetic sensors.

An image of a magnetic cylinder sensor. This sensor would be mounted on the side of a pneumatic cylinder with T-Slots, and would be used to indicate the position of the cylinder. Generally, one sensor of this type would be located to indicate when the cylinder is in its retracted ("Home") position, and one sensor would be located to indicate when the cylinder is in its extended ("Work") position.
An image of a magnetic cylinder sensor. This sensor would be mounted in a slot in the side of a pneumatic cylinder, and would be used to indicate the position of the cylinder. Generally, one sensor of this type would be positioned to indicate when the cylinder is in its retracted (“Home”) position, and one sensor would be positioned to indicate when the cylinder is in its extended (“Work”) position.

A very common application for magnetic proximity sensors is cylinder indication. Pneumatic cylinders are a common means of linear actuation. A linear actuator is a device that moves something from one position to another in a straight line. Pneumatic cylinders that are designed to be used with magnetic sensors have pistons with ring magnets.

An image depicting a pneumatic cylinder with a ring magnet inside. The purpose of the ring magnet is to provide a target for magnetic sensors mounted on the exterior of the cylinder. The image shows two sensors mounted on the cylinders. One sensor indicates the "Home" position of the cylinder, while the other sensor indicates the "Work" position.
An image from Wikipedia of a pneumatic cylinder with a ring magnet mounted on its piston. The purpose of the ring magnet is to provide a target for magnetic sensors installed on the exterior of the cylinder. In the application shown, one sensor provides indication when the cylinder is in its “Home”, or “Retracted” position, while the other sensor indicates the “Work”, or “Advanced” position.

When the piston moves within sensing range, the ring magnet’s magnetic field triggers the sensor. This provides indication back to the controller as to whether your requested actuation actually occurred.

A pneumatic cylinder with two magnetic cylinder sensors installed. The cylinder sensors are triggered when the ring magnet attached to the cylinder's piston is in a certain position.
A pneumatic cylinder with two magnetic sensors installed (the two slim rectangular devices facing each other in the upper slot).

Magnetic Position Sensors With Analog Outputs

A pneumatic cylinder with an analog magnetic sensor from the Sick MPS family of sensors. These sensors provide allow you to observe the position of the cylinder very precisely.
A pneumatic cylinder with an analog magnetic sensor from the Sick MPS family of sensors. These sensors provide very precise feedback on the position of the cylinder’s piston.

Magnetic sensors with analog outputs (like this Sick MPS-T) can indicate precise positions of pneumatic actuators. Sensors of this type act like LVDT’s, providing high-resolution feedback on the position of the magnet within the sensor’s sensing range. With many of these sensors, you can observe the position of a cylinder within tenths of a millimeter. That type of resolution allows very precise control of industrial processes.

Another Application For Magnetic Proximity Sensors

There is another application in which you might find this type of proximity sensor used in industrial automation. In certain situations that are difficult for inductive sensors, magnetic proximity sensors can thrive.

The sensing range for inductive sensors is dependent on the size of the sensor. The smaller the face of an inductive proximity sensor, the smaller its sensing range. With small inductive proxes, sensing ranges are in the single digit millimeter and sub-millimeter distances.

Even small magnetic proximity sensors often have sensing ranges much greater than many inductive proximity sensors. For this reason, magnetic sensors are sometimes used where a small sensor is needed, but the target is not very close. If this is the case, a magnet may need to be mounted on the target.

Learn More About Magnetic Proximity Sensors

Photoelectric Proximity Sensors

Photoelectric sensors, or “photo eyes,” are triggered by the presence or absence of electromagnetic radiation. Most commonly, this electromagnetic radiation would be infrared or visible light.

Depending on the type of sensor and application, photoelectric sensors may require some setup. This is due to the many ways in which photoelectric sensors can be utilized and the versatility offered by many sensors in when the sensor will turn on or off its output.

When discussing photo eyes, the concepts of Normally Open and Normally Closed often translate to Dark On and Light On. Depending on how your sensor is configured, Light On generally means that the sensor’s output will only be ON when the emitter’s beam is detected at the receiver. Dark On is the opposite condition.

There are three broad types of photoelectric sensors:

Through-Beam Photoelectric Sensors

Through-beam photo eyes consist of two separate electronic components: an emitter and a receiver. The emitter shines a beam of infrared or visible light. The receiver detects this light and the sensor’s output changes when a certain level of light is seen.

An illustration of a through-beam photoelectric sensor application. The image shows a can on a pallet on a conveyor. On either side of the conveyor are the two through-beam photo eye modules: one emitter and one receiver. The "effective beam" of light is shown transmitting from the emitter to the receiver.
A through-beam photoelectric sensor application. When the effective beam between the emitter and receiver is blocked, the sensor’s output state will change. Click the image to view full size.

Opposed (through-beam) photo eyes are often used to detect small parts. As long as the part is big enough to interrupt the effective beam, the sensor will change its output state.

Sensors of this type can look across a conveyor or feed track to count parts or to trigger an event when a part is seen. Through-beam sensors are very accurate and have a long sensing range. One of their chief drawbacks is that they require the purchase and installation of two costly components: an emitter and a receiver.

An example of a through-beam photoelectric sensor that you’re likely to be familiar with is your garage door safety sensor. If the beam between the two photo eye components at the bottom of your garage door is broken, your garage door will not close. This type of sensor setup – meaning a sensor with the two separate emitter and receiver photo eye components – is the type of through-beam photo eye most commonly seen in industrial automation.

A Second Style Of Through-Beam Photo Eyes

When using opposed photoelectric sensors, aligning the emitter and receiver can be a potentially painful element of the setup process. To combat this, sensor manufacturers have developed products that eliminate the need to align the emitter and receiver for certain applications.

Photoelectric “fork” sensors integrate the emitter and receiver on opposing posts on the same frame. The fork sensor’s design eliminates the need to install and align separate emitter and receiver modules. For certain applications, this design eliminates many of the drawbacks of traditional through-beam photo eyes.

Retro-Reflective Photoelectric Sensors

Retro-reflective photo eyes contain both the emitter and receiver in the same module. They rely on a reflector to bounce the emitter’s beam back to the receiver. Because they require a reflector, they share one of the drawbacks of through-beam photo eyes (installation and alignment of two separate components), but do improve in another area (reduced cost as they don’t require a separate receiver module).

An illustration of a retro-reflective photoelectric sensor application. The image shows a can on a pallet on a conveyor. On either side of the conveyor are the retro-reflector and the combined emitter/receiver photo eye module. The "effective beam" of light is shown transmitting from the emitter, bouncing off the retro-reflector, and then traveling back to the receiver.
A retro-reflective photoelectric sensor application. The effective beam is bounced off of the reflector in order to return to the receiver. Click the image to view full size.

Photo eyes of this variety are subject to one distinct weakness: if the light emitted by the emitter bounces off a shiny object and enters the receiver (referred to as “proxing”), it can fool the receiver into thinking that the beam is unbroken. Retro-reflective photo eyes with polarized filters are able to defeat this issue.

An illustration of a non-polarized retro-reflective photoelectric sensor application. The image shows a can on a pallet on a conveyor. On either side of the conveyor are the retro-reflector and the combined emitter/receiver photo eye module. The "effective beam" of light is shown transmitting from the emitter, bouncing off the can, and then traveling back to the receiver. Non-polarized photo eyes of this type can sometimes be fooled by objects with reflective surfaces.
A non-polarized retro-reflective photoelectric sensor application. Non-polarized sensors have a longer sensing range than polarized versions. One issue with non-polarized sensors, however, is “proxing.” The sensor can be fooled by objects with highly reflective surfaces. Click the image to view full size.
Polarized Retro-Reflective Photo Eyes

Some retro-reflective photoelectric sensors use polarized filters. When combined with specialized reflectors, polarization allows the retro-reflective sensor to differentiate between light that bounced off of the reflector and light that bounced off of a shiny object. This can be particularly helpful when the parts that you are trying to sense are made of a shiny metal (or otherwise have a highly reflective surface).

Polarized retro-reflective photo eyes have a polarizing filter at the output of the emitter. This filter allows only light that is oscillating on a certain axis to pass through. The receiver, which is mounted next to the emitter in the same module, also has a polarizing filter, which only permits light oscillating on the axis perpendicular to that of the emitter.

An illustration of a polarized retro-reflective photoelectric sensor application. The image shows a can on a pallet on a conveyor. On either side of the conveyor are the retro-reflector and the combined emitter/receiver photo eye module. The "effective beam" of light is shown transmitting from the emitter, bouncing off the reflector, and then traveling back to the receiver. A polarizing filter on the emitter only permits light oscillating in a certain direction to be emitted. The retro-reflector causes the polarization of the beam to be rotated by 90° before bouncing back towards the receiver. The receiver also has a polarized filter which only permits light oscillating opposite to the emitter's filter. This ensures that the light received bounced off of the retro-reflector.
A polarized retro-reflective photoelectric sensor application. Polarized sensors use polarizing filters to limit the orientation of light that is emitted and that can trigger the receiver. The reflector causes the orientation of the light to rotate by 90° before bouncing back towards the sensor’s receiver. The polarization properties of this type of setup allow the sensor to determine whether the light received bounced off of the retro-reflector (and not some other reflective surface). Click the image to view full size.

With these polarizing filters, light only enters the receiver if its polarization axis was rotated 90° from what the emitter initially put out. This change in polarization indicates to the sensor that the light it’s seeing has bounced off of the retro-reflector, and not off of some other shiny object.

An illustration of a polarized retro-reflective photoelectric sensor application. The image shows a can on a pallet on a conveyor. On either side of the conveyor are the retro-reflector and the combined emitter/receiver photo eye module. The "effective beam" of light is shown transmitting from the emitter, bouncing off the can, and then traveling back to the receiver. A polarizing filter on the emitter only permits light oscillating in a certain direction to be emitted. Because the light received did not bounce off of the retro-reflector, it was not rotated 90°. The receiver's polarized filter blocks any light that is oscillating in the same orientation as the emitter's filter. This ensures that the sensor is not fooled by the light that reflected off of a shiny surface other than the retro-reflector.
When an object with a reflective surface breaks the beam, light is reflected back to the receiver. The receiver’s polarizing filter blocks this light because it is the same orientation as the light emitted. This ensures that the sensor will only be triggered by light that bounced off of the reflector. Click the image to view full size.

Polarizing filters exclude some of the light that would otherwise enter the receiver. For this reason, polarized retro-reflective photo eyes have a shorter range than non-polarized versions.

Corner-Cube Retro-Reflectors

Some of the magic taking place with polarization is in the retro-reflector. Innocent looking (but secretly really cool) corner-cube reflectors are used with retro-reflective photoelectric sensors to cause the shift in polarization. Corner-cube reflectors accomplish two things to assist in retro-reflective photoelectric sensing:

  • The polarization (“phase”) of the light is shifted by 90°
  • Unlike a mirror, which reflects light away from its source as a function of the angle of incidence, the geometry of corner-cube reflectors causes light to be reflected back to its origin

With these special optical properties, corner-cube retro-reflectors are an ideal solution for ensuring that the light reaching the receiver actually bounced off of the reflector, and not some other shiny surface. Due to their high reflectivity and the fact that they direct light back to its source, corner-cube reflectors are the same types of reflectors that we trust for bicycle and highway safety. In fact, these devices are the same reflectors that we left on the moon to be able to measure its distance from the earth.

Diffuse Photoelectric Sensors

The third common type of photoelectric proximity sensor employed in industrial automation is the “diffuse” photo eye. Diffuse photo eyes only require the installation of one module in one location. For this reason, of the three types of photoelectric sensors at which we’ve looked, diffuse sensors are the easiest, cheapest, and quickest to install.

Like retro-reflective sensors, diffuse photoelectric sensors house both the emitter and receiver in the same module. While through-beam and retro-reflective sensors maintain sight of the beam until it is broken, diffuse sensors can’t see their beam until the sensor’s target is present.

Click the image to view full size.
A diffuse photoelectric sensor application. By default, a diffuse sensor’s emitted beam shines off to infinity, with no light reflecting back to the sensor’s receiver. The emitted light only reflects back to the receiver when the sensor’s target blocks the emitted beam. Click the image to view full size.

With diffuse sensors, the sensor’s target actually acts as the reflector. When the emitter’s light bounces off of the target, the light “diffuses” in many directions, with some portion of the emitted light striking the receiver.

An illustration of a diffuse photoelectric sensor application. The image shows a can on a pallet on a conveyor. The diffuse photo eye (combined emitter and receiver module) is mounted on one side of the conveyor and its beam can be seen shining and bouncing off of the can, which is positioned on the conveyor in front of the sensor. Because the target is present, the emitted beam scatters off of the surface of the target. Some of this light will bounce back towards the sensor and enter the receiver.
A diffuse photoelectric sensor application. When a part is present in front of the sensor, the emitted beam reflects off of the part’s surface. Some of this light will reflect back towards the sensor and enter the receiver, causing the sensor to change its output state. Click the image to view full size.

Because diffuse sensors rely on the detected object to scatter the emitted light, these photo eyes are more sensitive to:

  • The distance between the sensor and the target
  • The reflectivity of the target
  • The curvature and other topological properties of the target’s surface
Learn More About Photoelectric Proximity Sensors

Ultrasonic Proximity Sensors

A final common category of proximity sensor utilized in manufacturing is the ultrasonic sensor. Ultrasonic proximity sensors are similar in many ways to photoelectric sensors, except that they use high frequency sound instead of light. The use of sound can be an advantage in certain cases, as the sensor’s performance will be unaffected by smoke, dust, lighting, or the reflectivity of the target’s surface.

Like photo eyes, ultrasonic sensors can be purchased in an either an “opposed” (through-beam) configuration, or in a “diffuse” (reflective) configuration. The comparison with photo eyes is directly analogous.

Through-Beam Ultrasonic Proximity Sensors

By that, I mean that through-beam ultrasonic proxes use a separate transmitter and receiver module, just as through-beam photo eyes do. Through-beam ultrasonic modules would be mounted across a conveyor or other monitored area.

The “beam” of high frequency sound that is output from the transmitter would be detected continuously by the receiver. The sensor’s output changes state when the signal between transmitter and receiver is blocked by the sensor’s target.

Diffuse Ultrasonic Proximity Sensors

Similarly, diffuse ultrasonic proxes house the receiver and transmitter in the same module. Just like diffuse photoelectric sensors, the sensor’s target reflects sound waves back to the receiver as it passes in front of the sensor. With diffuse sensors, the signal is not detected at the receiver by default. The sensor’s output changes when a target moves in front of the sensor, reflecting the signal back towards the receiver. In my experience, this is the more common ultrasonic sensor.

Diffuse ultrasonic sensors utilize “time of flight” to determine the presence of an object. Because the speed of sound in air is known, the sensor is able to determine how far away an object is. It does so by monitoring the time that it takes for an ultrasonic signal to bounce back to the receiver after being emitted.

Sensors of this type can be purchased with analog or digital outputs. Diffuse ultrasonic proximity sensors with digital outputs indicate to the controller only that an object is present or not present. Ultrasonic proxes with analog outputs typically provide distance feedback. In other words, they can tell you not only that a part is present, but how far away that part is.

Ultrasonic Sensor Advantages and Disadvantages

As mentioned above, the use of sound can give ultrasonic sensors an advantage over photoelectric sensors in certain cases. Ambient lighting and the presence of smoke or dust have the potential to affect the performance of photo eyes. These factors are largely irrelevant to ultrasonic sensors. Ultrasonic sensors are also able to detect irregularly shaped objects, such as meshes and springs, that may be difficult for photo eyes to detect reliably.

While ultrasonic proximity sensors are very reliable in many cases, there are some factors that can affect performance. For instance, certain soft targets absorb sound waves and so may be difficult for ultrasonic sensors to detect. Temperature changes can also affect reliability. To combat this, many modern ultrasonic sensors have integrated temperature detection and calibration.

Learn More About Ultrasonic Proximity Sensors

Comparing Proximity Sensor Types

There are many different types of proximity sensors on the market. Depending on your application, there may be only one prox that is appropriate, or you may have a choice. Let’s take a last look at the different types of proximity sensors commonly implemented in factory automation:

InductiveCapacitiveMagneticPhotoelectricUltrasonic
Install ComplexitySimpleSimpleCan be trickyCan be trickyCan be tricky
Setup ComplexitySimpleSensitivity adjustableSimpleCan be trickyCan be tricky
Max RangeVery Short (a few CM)Very ShortShort (several CM)Very Long (many meters)Long (10-20 meters)
Materials DetectedMetalsAlmost anyMagnets, ferrous metalsAlmost any, shiny can be troubleAlmost any, soft can be trouble
Sense Through Container?Metal inside of non-metalSometimes possible with adjustmentMagnet/ferrous inside of non-ferrousCertain sensors, certain conditionsCertain sensors, certain conditions
Affected by Lighting/Color?NoNoNoYesNo
Close-Range Detection?YesYesYesYesDead zone
Liquid Level Sensing?NoYesNoYesYes

I hope that this post has been helpful for you in sorting out the various types of proximity sensors used in manufacturing. If you would like to see more content like this, enter your email for more in-depth industrial automation articles:

Thanks for reading, and make sure to leave a comment below with any thoughts!

5 Ways To Know If You Should Be A PLC Programmer

Are you considering a career in PLC programming? Awesome! Learning how to program PLC’s (and how to debug under pressure) is an incredibly fun and rewarding experience. Maybe you’ve been considering attending a tech school, or have been talking to a friend who is a licensed electrician or who works for an automation integrator. Maybe you’ve developed an interest in industrial automation on your own and want to know more about becoming a controls engineer or PLC programmer.

Where are you in your journey? We want to hear from you in the comments!

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Should You Become A PLC Programmer?

Whatever your background and level of interest, here are five suggestions for what might make PLC programming the right job for you!

1. You Think Automation Is Cool

But, I mean, who doesn’t, right? If the thought of setting up new systems, developing algorithms and sequences of operation, and programming robots and Programmable Logic Controllers sounds like it’s up your alley, then why not go for it?

Not everyone gets to do what they love, but if you have a true interest in automation, becoming a PLC programmer will allow you to learn how to establish and control automated processes. What could be cooler than that?!

An automated assembly line where orange Kuka robots are performing a joining operation on an automotive body as it proceeds down the assembly line.
How could you not think automated manufacturing is cool?

2. You Love To Learn

Being a good programmer means treating every situation as an opportunity to learn more about the PLC, the programming template, the production line, and the equipment you’re controlling.  As the “controller of the controller,” if you will, it’s not enough to be knowledgeable about just programming. The whole point of the PLC is to accept inputs and set outputs to and from alllllll the many field devices – conveyors, robots, I/O blocks, fixtures, actuators, sensors, servos, … , the list goes on forever.

Industrial automation is home to a thriving ecosystem of devices, equipment, and communications protocols. For instance, every imaginable flavor of communication can be found out there, from modern 10/100 (and faster) Ethernet to 9600 baud serial connections. As someone who designs and debugs PLC logic, you will need to work to grow your understanding at every layer of your production equipment. 

With so many different systems to learn, you must strive to build your knowledge of everything in the plant.  From physical cabling to vendor-specific camera solutions used on your vision systems, eventually, it’s going to break! When it does, people will be looking to you to come up with solutions to highly technical issues.

Long story short, as an industrial electrician, electrical engineer, or anyone else who does PLC programming, you should be learning something new every day. Don’t worry – what you don’t learn on your own, the breakdowns will teach you.  😀

3. You Love Solving Puzzles

Often times, as an automation engineer, you will find recurring issues with the equipment that no one knows how to fix.  As such, it will be your job to figure out what’s wrong.

Maybe…

  • … a bug in the original programming is allowing 1 in every 100 units to go through without a certain part being installed
  • … ten times a day a certain fault occurs and stops production, and there doesn’t seem to be any discernible pattern as to what’s causing the issue
  • … you’re having trouble with a complicated sequence of events that occurs within milliseconds
  • … you have to debug an exchange of data between two PLC’s that takes place over your industrial network

As a PLC or robotics programmer or engineer, people will often look to you to “deep dive” the tough, troublesome, technical issues that evade understanding. When you are working in that role, it’s likely that you will be presented with difficult troubleshooting situations that will require a deep understanding of the equipment and technology in question.

A 2x2 Rubik's Cube showing an orange, yellow, and blue face
A 2×2 Rubik’s Cube is more my speed

4. You Work Well In Challenging Situations

The first rule of PLC programming is: all logic requires debug. Whether you’re setting up a new process or troubleshooting an issue with an existing system, as a “controls guy” (or “controls gal” 🙂 ), people will be looking to you to get the equipment working again.

You know what they say – no guts, no glory. When the equipment isn’t working, excellent programmers or controls engineers are able to enter challenging situations with a cool head.  Once you’ve quickly gained an understanding of the problem, it’s time to work with your teammates to determine and correct the issue.

Adept PLC programmers who work in production (manufacturing) environments will likely be called to the toughest breakdowns. As your skills and knowledge grow, you will become more and more comfortable working in tense, time-sensitive situations. Wherever you are in your journey, the key is to always strive to learn more.

5. You Love To Think Creatively, Logically, And Analytically

Lastly, PLC programmers need to be able to:

  • Analyze a situation or a problem to be solved
  • Think of a possible solution
  • Come up with a way to turn that solution into logic
  • Then, write that logic and debug, debug, debug!

When you’re striving to make equipment run, it’s sometimes easy to get tunnel vision and hone in on one possible solution.  As such, PLC programmers need to be aware of the logic and the equipment with which they’re working, so they can pull the right programming “tool” out of their “tool bag” and put it to work to solve the problem.  Sometimes, you have to step back and think, “is this the only way I could attack this issue, or could there be an easier way?”  This may be the best way to jar yourself out of the tunnel and start thinking creatively. 

What Do You Think?

Do you fit the bill? Tell us what you think in the comments below! We want to know where you’re at in your own journey towards becoming a world-class PLC programmer.

If you want to know more about PLC programming and industrial automation, take just a moment to sign up for our newsletter. You’ll receive only a few emails a month, at most. 🙂

Thanks for reading!

What Is An Automated Systems Integrator?

If you’ve become involved in the world of industrial automation, you may have heard the terms “integrator,” “automation integrator,” or “automated systems integrator.” The term “systems integrator” exists in both the fields of industrial automation and information systems. There are some blurred lines between those fields, as both involve networking, computers, and programming. In this article, we’ll go over the concept of automated systems integration within the fields of industrial automation and manufacturing.

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What Is An Automation Integrator?

Let’s say you’ve just opened a new business. You want to manufacture pencils.

Several colored pencils.

Your company has a solid business plan, funding, a building, your management team, and employees. You know the colors that you want to manufacture and even how you want to market your products. There’s just one little problem… You don’t know anything about how to actually manufacture pencils. That is where a systems integrator comes in.

An integrator is a company that specializes in bringing systems, equipment, and machinery together to create a manufacturing solution. Thus, an integrator “integrates” whatever types of equipment and controls are required to turn separate machines into an assembly line (or other automated solution). The machines that are integrated may or may not be designed to work together easily. To do the job, the integrator must overcome any technical challenges to build a complete solution.

In this sense, an integrator transforms unrelated machinery and electronics into a factory. You can think of a factory as a sort of monstrous Rube Goldberg machine that converts raw materials into marketable products.

A view of the Frame line in the Tesla Model S factory. Many robots can be seen working on or prepared to work on the frame of the vehicle as it travels down a conveyor system in the center of the automation line. It's likely that Tesla designed this assembly line and then commissioned an automated systems integrator to purchase, setup, and program the manufacturing equipment.
The Tesla Model S Framer

What Kinds of Equipment Does An Automated Systems Integrator Have to Bring Together?

Consider everything going on in the image above (view full size here).

Conveyor Systems

Conveyor Beds

The red and grey assemblies in the center of the image are “conveyor beds.” Conveyors are custom-built fixtures that transport units to each “station” on the assembly line. Integrators fabricate the frames of the conveyor beds from stock steel. Industrial motors and roller systems built into the conveyor do the job of getting the units to physically move down the line.

This is just one example of a conveyance system. Conveyance comes in all shapes and sizes, depending on what is being manufactured. The conveyor beds shown above likely weigh around a ton. At the other end of the spectrum, you have smaller components like circuit boards. Conveyor systems of this size weigh only a few pounds.

Pallets

The production units themselves ride through the conveyor system on “pallets.” Like a conveyor bed, a pallet is custom-built to hold and carry each unit down the line. Pallets ride through the automation, passing from conveyor bed to conveyor bed.

Additionally, pallets are built to precise tolerances. When a unit arrives in a station, the robots will need to do their work in as close to the exact same physical location on the unit each time. For this reason, pallets must all be almost exactly the same, so that each unit will sit in a very specific position at each station.

Pallets hold each unit in place with carefully sized pins, or by other mechanical means. This helps to ensure proper positioning. In industrial automation, “repeatability” is the name of the game. Repeatability is the idea that, in automation, the same exact thing should happen in the same exact place every time.

Systems Integrator Roles

What is an automated systems integrator responsible for in regards to conveyance? Integrators will likely build, position, level, and program the conveyor systems. Systems integrators must take great care in many details to ensure that the conveyors will run smoothly. As examples, beds must be precisely assembled and leveled, and many parameters must be programmed into each motor and drive system.

Robotics

You can see many robots in the image above. Each robot is ready to go in and work on the next vehicle.

How does each robot know where to go to do its job? Integrators must carefully plan, teach, and test motion for each robot. Also, each robot must be programmed to control and receive feedback from its End Of Arm Tool, or “EOAT”.

The robot is just a means of moving the EOAT to where it needs to be. What is an EOAT? The EOAT is what actually gets the work done in a robotic factory. There are many different types of End Of Arm Tools. Some examples include:

  • Material Handlers: move parts from one place to another
  • Machine Vision: records data, locates parts, or provides error-prevention
  • Joining: welders, riveters, or other equipment that fastens parts together

The robots above look like they’re carrying weld guns. Weld guns are used to “spot weld” the frame of the vehicle together. Welders work by touching the top and bottom of a part of the vehicle. Then, they pass a high current from one side of the gun to the other. The heat generated by this current flow welds the metal of the vehicle together.

For this reason, each weld gun needs a weld controller. Each weld controller has to be setup to output a certain amount of power. Further, this power setting has to be carefully tested to ensure that the gun generates the right amount of heat to form a good weld.

Safety, Sensors, Feedback, And Motion

  • Gates, fencing, light curtains, E-Stop buttons, and other safety devices exist throughout the automation equipment to protect the people that work in the area
  • Also, sensors, switches, operator buttons, and other input devices inform the PLC on the status and position of various equipment
  • Lights, buzzers, displays, valves, motors, actuators, and other output devices move parts and help humans understand what the equipment is doing

Imagine the variety of these components present on a large automation line. There may be several sensors on one machine. Further, each sensor may work differently and come from a different manufacturer. An automated systems integrator must be able to install and configure all of these many, many different industrial automation devices.

Programmable Logic Controllers (PLC’s)

A “PLC” (Programmable Logic Controller) is the brains of the operation. PLC’s accept inputs from the equipment and sensors. The PLC then performs processing, and sets outputs based on its programming. These outputs then control the actions that take place in the automation.

For example, an air supply line has an analog pressure sensor. Our pressure sensor sends a signal to the PLC that represents the pressure read at the sensor. The PLC has been programmed to interpret the signal sent from the sensor. In the PLC’s logic, the signal’s value is converted back to a pressure reading.

Then, integrators have programmed the PLC to check this pressure reading against a minimum pressure. If the pressure reading is lower than the minimum pressure, the PLC turns on a pump. In this case, the PLC sets outputs to the pump that command it to turn on. This is an example of how integrators might program a PLC to manage air pressure in a supply line.

PLC’s must be carefully programmed for each application. This programming must take into consideration concerns for safety, quality, efficiency, ease of use, and repair.

Human-Machine Interfaces (HMI’s)

To allow operators to interact with the machinery without having to know how to program a PLC, there needs to be one or more “HMI” (Human-Machine Interface) panels. An HMI is a programmable display; it’s basically a fancy computer monitor. Using an HMI, someone can interact with the PLC through buttons and other input devices on the screen. Many modern HMI’s are rugged touchscreen interfaces, built to withstand the industrial environment.

An example of a custom Human-Machine Interface screen. This screen shows several feedback and control points for a well control system. HMI's are an example of what an automated systems integrator might be responsible for.
An example of a custom HMI screen used to control a well

What Jobs Are Available In Automated Systems Integration?

Often, a manufacturer will approach a systems integration company with a system it wants built. The integrator then designs and builds a complete automation solution that will assemble the manufacturer’s product. Building an automation line from scratch requires a variety of skills and talents.

  • Managers oversee the business side of the operation
  • Mechanical Engineers, Electrical Engineers, Automation Engineers, and engineers from other specialties will design the systems. Engineers will ensure that the equipment and programming meets the customer’s specifications and any appropriate codes and regulations. In this regard, engineers must dig into the little details to understand, for instance, what type of sensor will fit a particular application. Engineers may perform PLC programming, HMI design, and development of “templates” of logic for use in the PLC and robotics
  • Millwrights cut and weld large assemblies, operate lifting equipment, and fasten components to the building’s structure. Also, millwrights are often responsible for servicing and repairing large motors, gearboxes, and other heavy-duty mechanical devices
  • Toolmakers fabricate detailed components to tight tolerances
  • Robot Technicians set up and program robotic systems
  • Similarly, PLC Technicians set up and program the controllers
  • Industrial Electricians wire and install a wide range of electrical components, and may also program PLC’s, robots, and other electronic controllers

These are the core positions that automation integration shops employ. That is, at least in terms of building the automated systems. There may also be any number of other administrative positions in marketing, sales, finance, and other fields. On the technical side of the house, integrators may also employ Software Engineers, IT Technicians, and Facilities Engineers.

What Is It Like Working For An Automated Systems Integrator?

A typical work flow for an integration project might be as follows:

  • Firstly, project planning and materials acquisition
  • Machine assembly and programming at the integration facility
  • Transportation to the customer
  • Once on-site, machine installation, debug, and trials at the customer facility
  • On-site support as the customer takes on ownership of the equipment
  • Lastly, project wrap-up

Work Life As An Automation Integrator

Given that many integration projects consist of building an automated assembly line from scratch, integration work often occurs at the customer location. Depending on the size of the integration shop and the size of the project to which you’re assigned, very high travel percentages may be required. In other words, automated systems integrators may spend as much as 90-100% of their time away from home.

Customers who have purchased large or complicated automation solutions may require support well in to the launch of the project. Because of this, on-site support requirements can range from days to years. If you are a competent member of the team or have done a lot of the programming on a certain line, the company may ask you to stay on the road for months. In this case, many companies allow for you to travel home every couple of weeks.

Providing support for the customer can be stressful. The automation equipment that your company has built is what the customer uses to make money. For this reason, they may not be very happy when it breaks down.

On the other hand, you may be able to land a design or commissioning position that does not require any travel. Those performing “machine assembly” at the shop may be able to enjoy a similar lifestyle to other 9-to-5 positions. Even so, many shops will have “surges” in the pace of work. There may be slow periods followed by stretches where your boss wants you working overtime every day of the week.

Pay And Benefits For Automation Integrators

The good news is that many integration shops offer very competitive wages and benefits. While on the road, many shops pay both overtime and “Per Diem.” Per Diem is extra money the integration shop will pay you for each day away from home. This additional pay covers food and other costs.

There can be other perks of travelling. For example, opportunities to visit new places, work in cool facilities, and network with other professionals. When I have had to travel for automation work, I have generally been put up at nice or at least decent hotels and had dinner out on the company dime.

Whether or not you’re travelling, you may have the ability to participate in training and continuing education so that you can continue to grow technically. Not to mention, you’re building industrial automation equipment! If you’re a person who enjoys working with automation, it’s hard to find a more interesting or challenging job.

What Should I Study If I Want to Work For an Integrator?

Of course, the answer to this question depends on what type of position you’re pursuing.

  • For a position as a skilled tradesperson (millwright, toolmaker, electrician), see if you can land an internship
    • In certain areas, certificate or Associate’s programs may be available to help you get a job as a skilled tradesperson
  • For engineering, complete a Bachelor’s degree in the field of your choice (Electrical Engineering, Mechanical Engineering, etc.)
    • Automated systems integrators may also hire persons with degrees in Industrial Automation or Mechatronics
  • If you want to work as a PLC or robotics technician, you may be able to complete a local or online training program to help get your foot in the door
    • Industrial electricians with PLC or robot experience should be qualified for this type of position

In Summary

Integrators make magic happen – they turn disparate systems into one large, cohesive “machine.”  From custom assembly of heavy, metal fixtures, to robot and controller programming, an integration shop has to be able to do it all.

Are you aspiring to work for an integrator, or would you like to relate your own work experience in integration? If so, share your story in the comments below!

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Thanks for reading! Feel free to reach out in the comments below with any questions or comments.

So, You Want to Be an Industrial Automation Engineer

Are you considering or aspiring to a career as an Industrial Automation Engineer or Controls Engineer? Awesome choice. Below, I’ll talk about what employers are looking for in an Industrial Controls Engineer. Additionally, I’ll cover what a typical workday is like and some pros and cons of automation industry jobs. Lastly, we’ll look at what a career in the automation industry might pay, and where and how to look for jobs! Keep reading for a glimpse inside the life of an Industrial Automation Engineer!

 A sample of ladder logic, a PLC programming language that uses electrical symbols on "ladder rungs." Industrial automation engineers frequently perform PLC programming using ladder logic.
“Ladder logic,” a common PLC programming language.  PLC’s are microprocessors (computers) that are used to control manufacturing equipment.  Image credit.

Are you ready to take the next step in your industrial automation career?

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Controls Engineer Position Entry Requirements

For a bit of background, I work for Ford Motor Company as an Automation Engineer. Officially, my job title is Engineering Specialist, Controls. My Bachelor’s is actually in Information Technology, with a concentration in Software Development. Luckily, I had industry experience as an Automation Technician that helped me to get in to my current job.  

Much of my job focus is on developing and debugging Programmable Logic Controller (PLC) logic and robot programs. Because PLC’s and robots are just fancy computers, I’m often able to use the programming techniques, algorithmic thinking, and knowledge of networks that I learned in my degree program. Virtually all equipment at the plant where I work is on an Ethernet/IP network. For this reason, having an understanding of TCP/IP networks is very helpful when troubleshooting communication issues.

Despite my degree choice, if you’re interested in becoming an Industrial Automation Engineer, typical Bachelor’s degrees to pursue might include Electrical Engineering, Industrial Automation, or Mechatronics. Employers often cite a Bachelor’s in a field of study related to industrial automation engineering as a minimum hiring requirement.

Of course, hiring requirements are what the employer would like in the ideal case. There’s likely some wiggle room if you have the skills to do the job. Many technicians or electricians with PLC programming experience are able to become Controls Engineers.

Experience Requirements For Industrial Automation Engineering Jobs

Many employers list experience requirements when posting a job offering for Automation, Controls, or PLC Engineers. Are you worried about or having trouble moving directly into a Controls position out of school? If so, it may be helpful to first build some industry experience as an Industrial Electrician or Automation Technician.

There are also PLC training courses which can be very valuable in terms of gaining a foundation in PLC programming. Relevant training could possibly help you to get a foot in the door if you do not have experience.  In my perception, however, employers would prefer to see one or more years of industry experience programming and debugging PLC’s.

As a side note, I’m using the terms Controls, Controls Engineer, Automation Engineer, and Industrial Automation Engineer interchangeably. Someone in this career field may even be referred to as a “PLC Engineer”.
When looking for jobs, the only thing to be careful of is that the title “Automation Engineer” is now also used in the Software Testing field. Generally, if you see the terms “PLC,” “robot,” or “CNC” mentioned in the job listing, it is an Industrial Automation position and not a Software Test Automation position.

What Does An Automation Engineer Do Every Day?

Of course, the answer to this question depends on the company for which you work and your place in the hierarchy. I can only relate my own experience and that of the other Industrial Automation Engineers that I work with. I’d love to hear any comments from other Automation Controls Engineers. How do your responsibilities differ from my own? I would be happy to add your commentary to this post.

Control and automation engineering is a job of many hats. Most days, you will take on a variety of roles, from project management, to personnel administration, to emergency troubleshooting. In my position, my two primary job functions are breakdown response and Continuous Improvement.

Responding To Breakdowns

A plume of white smoke. If you've "let the smoke" out of your electronics, that's probably not good.
With electronics, you’re supposed to try to keep the smoke inside the equipment. If you see smoke coming out of a circuit board, that’s usually a bad sign.

The name of the game in industrial automation is production – a lot of production. Companies make money by building as many parts as possible during their production employees’ regularly-scheduled work day. For this reason, overtime hurts profits. Downtime hurts profits.

Manufacturing companies make money when the line is running and when it’s running fast. Jobs Per Hour, or “JPH”, is a key indicator of the health of a factory. There is, of course, some upper limit to how quickly any given process can occur. As a general rule: the more units you can build in a given time (hence, “Jobs Per Hour”), the better.

In such a fast-paced environment, and with equipment moving back and forth dozens, hundreds, or thousands of times per hour, things break! Cables fail, bearings wear out, sensors wiggle out of alignment; Murphy’s Law is active, big time. When things break, factories have a Maintenance Department that is responsible for figuring out what’s wrong and fixing it – as quickly as possible.

Automation And Control Engineer Roles On Breakdowns

Where I work, the Controls Engineer’s role on breakdowns is somewhere between supervision and high-tier tech support.  As a salaried employee, the Controls Engineer is responsible to the company for ensuring that the equipment gets back up and running as quickly as possible.  Sometimes, this means fixing the problem at hand. Sometimes, however, it means finding a creative way to work around the problem.  For this responsibility, you may need to lead and direct maintenance personnel. You will succeed as a Controls Engineer if you:

  • Keep a cool head under pressure
  • Become knowledgeable about your facility’s equipment
  • Direct others so that they are able to think and perform their best

I wouldn’t describe myself as an introvert, but I’m not the most extroverted person in the world, either. To succeed in breakdown response, I strive to become knowledgeable about as many systems as I can. If I know what to do to fix a problem, I can help to guide the team to success.

An animation of Johnny Five, a fictional robot, reading a book extremely quickly.
INPUT. MORE INPUT.  Image credit.

Follow-Up After Breakdowns

It’s also the Control and Automation Engineer’s job to follow up after breakdowns. I think of this role as “harvesting information”. It will be your job to figure out the nitty-gritty details of what went wrong. Once you understand the problem, you can communicate it to others. This helps your organization to become faster and more knowledgeable. Many breakdowns consist of the same problems, occurring over and over again.

Once your organization knows the cause of a problem, and how to correct it, you can improve your “MTTR”. MTTR, or “Mean Time To Repair”, is a term that describes how long it takes to recover from an issue on average. Reducing MTTR raises your “availability”. Availability is what percentage of your factory’s productive time is spent actually building units. When you raise availability, you often raise JPH – and that means success for your organization.

Filling Your Organization’s Knowledge Gaps

At times, you may be working with equipment that isn’t commonly used or that does not commonly break. A production line might be down, and there may not be anyone around who is deeply knowledgeable.  In these cases, the Automation Engineer is often asked to follow up on the problem. You may have to contact the equipment’s manufacturer, if necessary. Once you understand the issue, you may be asked to provide technical write-ups and how-to’s for the factory’s maintenance personnel.  Some skill in technical writing can come in handy here.

Another possibility is that you will have to perform a temporary repair to get the line going. In cases like this, you’ll need to come back during scheduled maintenance time to finish the job and restore the equipment to its original state. You will need solid organizational skills to ensure that you are resolving important issues when follow-up is needed.

While breakdowns have the potential to be stressful, they are also sometimes the best teachers. Nothing makes being knowledgeable about a piece of equipment more relevant than when it brings the factory to a halt and no one seems to know how to fix it.

No one begins a career in Controls knowing everything. When you work in automation controls engineering, every day should be an opportunity to learn more about the equipment, network, protocols, and infrastructure with which you’re working. You will greatly sharpen your skills and knowledge as a Controls Engineer by following up on the breakdowns.

Continuous Improvement

Breakdowns are emergent events (they just happen all of a sudden). When the factory stops making parts, it’s “all hands on deck” to get things moving again.  While breakdowns are the “event-driven” part of the job, my “default state” is working on Continuous Improvement projects.

Continuous Improvement is exactly what it sounds like; it is a practice and mindset of continually boosting production capabilities. This is done by working to improve safety, quality, cost, JPH, MTBF, MTTR*, or sometimes just making things easier for the people who supply and repair the automation lines.

*JPH, MTBF, and MTTR are metrics that summarize the productivity of equipment in an automated factory.  JPH, or “Jobs Per Hour,” is simply how many units you are building per hour.  As a general rule, the more, the better!  Mean Time Between Failure is how often, on average, you are able to use a piece of equipment before it breaks down. Mean Time To Repair, explained above, is how long, on average, it takes you to get the equipment back up and running when it does break.

Factories come in all shapes and sizes, but for me at Ford’s Super Duty Body shop, the factory is enormous. There are dozens of lines of automation just on my side of the shop, with each unit travelling more than a mile in its journey to become a truck! Continuous Improvement is all of the little changes and improvements made throughout the entire shop. These changes contribute to a gradual betterment of production, repair, and ease of use.

As an industrial automation engineer, Continuous Improvement is a focal point of my job. Luckily for me, this is a part of my job that I very much enjoy. As I’ll describe below, Continuous Improvement is a chance to develop solutions to my organization’s problems – and then make those solutions come to life.

A picture of a Ford Super Duty body; just the metal cab, unpainted with no trim installed. As an industrial automation engineer, you may have the opportunity to be part of some really cool processes.
This is what I build; the world’s first aluminum heavy-duty pickup.

How Do You Perform Continuous Improvement?

Continuous Improvement is what I find most rewarding, as the task is essentially this:

  • Identify a problem that, if fixed, would improve production or repair in some way
  • Come up with a way that you think you can fix it
  • Research and purchase the equipment, components, sensors, etc. that you would need to make it happen
  • Wait for the parts to come in and then work with other people in the factory to implement your solution
  • Stand back and marvel at the results!

It’s pretty cool to know that you’ve personally organized improvements that subtly alter the manufacturing process for every unit your organization builds. Projects come in all shapes and sizes.. I’ve worked on projects that took only a few hours, such as adding lights to show operators when to load parts, and I’ve worked improvements that took coordinated efforts during scheduled downtime over weeks, including a modernization project (upgrading the capabilities of older equipment by adding modern processors and interfaces).  

If you want to become an Industrial Automation Engineer, it will sure be helpful if you enjoy this kind of work. Your organization will have issues that it needs to solve through automation engineering – and you’ll be the one doing the engineering. As I mention above, Continuous Improvement is a part of my job that I love. I get to design and implement solutions, and then see those solutions come to life in front of me.

Continuous Improvement In Industrial Automation Engineering

At the time of this writing, I have a project active to automate the shutdown of my side of the shop at the end of each shift – a task that is currently handled manually on each automation line by Production Supervisors.  If everything goes my way, I’ll be taking a process that currently involves about two dozen people throughout the shop placing holds on their lines at certain times, and consolidating the same functionality into a single interface on which the Production Manager can stop the lines however they like for the next shift.

For this project, I will develop new PLC logic, create new PanelView screens, and work with smart, engaged people. Together, we’ll implement and debug the solution until it’s working flawlessly. Personally, I love to solve puzzles and figure out how things work. If you are that type of person as well, you were made for this part of the job.

An example Human-Machine Interface, of the type that might be found in an industrial factory. This particular screen shows the status of two pumps overlaid on top of a schematic of the overall system. Industrial automation engineers often design HMI screens and program corresponding PLC logic to drive the screens.
“PanelView” is a brand name for an “HMI,” or Human-Machine Interface. HMI’s, in this context, are rugged, programmable touch-screen displays found throughout a factory. You don’t want people to have to go to the controller logic every time there’s an issue. HMI’s provide a GUI with which operators and maintenance personnel can control the equipment.

Succeeding At Continuous Improvement

Success in executing Continuous Improvement will require many of the same skills that you will need when responding to breakdowns. You’ll need to track your projects and purchases. Further, you’ll need to share your vision with others and organize their efforts in completing the work.

Additionally, you may need to justify your purchases to your manager! You’ll need good judgment for what will help the shop and can be done affordably. You will need to know when to defend your ideas, and when to accept rejection gracefully, if appropriate.

You need to be able to approach things somewhat scientifically. It’s important to strive to understand the behavior of the systems that you’re working with to the greatest extent possible, given your available time, so that you can develop a solution that will function as you expect.

As a final note, Continuous Improvement is another excellent opportunity to acquire new and hone existing skills, as you won’t typically be under the pressure of the breakdown environment. When you’re doing development (writing new logic or developing new screens), it will often be in an offline, scheduled downtime type situation. This means you’ll have some room to breathe and figure out how to make things work the way you need them to work. You can play around with new equipment or software and gain experience and skills. You can then bring your new knowledge to future projects – and can call upon it at future breakdowns.

Pros And Cons Of Being An Automation Engineer

While I love my job, every position has some good and some bad. I want to give you an honest sense of what I see as the pros and cons of a career in Industrial Automation.

Industrial Automation Engineering Pros:

  • Technically Challenging I love learning and striving for mastery of new systems. If you’re like me, it’s awesome to be surrounded every day by a fortress of high-tech equipment. It’s your job to become the expert!
  • Pride My grandfather turned 100 the year that I was hired into my current job. I was incredibly proud to tell him that I would be working for Ford Motor Company as an Automation Engineer
  • Pay Many Controls positions should easily reach six figures. This is particularly true if a lot of travel and overtime are involved
  • Benefits If you’re hiring into a position as an Automation Engineer, chances are that it’s with an established company. You can likely expect a decent insurance and vacation package
  • Being a Part of Something – My work in automation has taken me to three countries (my short time in Germany was awesome). I’ve been to awesome major facilities including Ford and Tesla plants. Become a skilled Controls Engineer, and you could work for some of the biggest, most high-tech manufacturers on Earth

Cons Of Being An Industrial Automation Engineer:

  • Long Hours – I have worked 8’s, 10’s, and 12’s for Ford. I work 12-hour shifts on my current schedule, and have worked 12’s throughout most of my other experience in the industry
  • Rotating Shifts – Depending on the company and its seniority policies, you could be stuck periodically working a shift that you don’t like (night shift, weekends, etc.). In some organizations, you might be stuck on a shift you don’t like until someone leaves their position or the company
  • Travel – Depending on the position, extensive travel may be required. This can be very stressful for families. The flip side to this is that you will often be paid more while travelling. So, travel might be a pro, depending on your personal situation
  • Labor Relations – Speaking as a salaried employee in a union shop, your success may hinge on your ability to elicit the best out of others. If your shop operates under a union contract, you might also need to tread carefully in regards to what work you can and cannot perform on operational equipment
  • Stress – When the line is down, the company is losing money. People will be looking to you to get everything back up and running

Weird Schedules Could Be Good Or Bad

Let me offer another point of view in regards to my schedule: while the 12’s are long days, consider that the average person working a nine-to-five job works 10 days out of every 14. Nine-to-five employees work M-F, then off two days, then M-F, then off two, and so on.

Because I work 12’s, I only work 7 days out of every 14. I’d try to explain my schedule, but it’s much easier to just show you. I work the green days on this calendar:

A calendar showing the days that I work.
I told you it’s a weird schedule

Now, this looks a bit strange and horrible at first, but now consider:

  • I have 4 days off in a row every other week
  • Every other week, I only have a 2-day work week
  • If I take 2 days of vacation on my 2-day work week, I am off of work for 9 days

I’ve only ever seen this schedule implemented at Ford, but my point in mentioning this is that in manufacturing, there may be multiple options for you as far as what shift you work. You may be able to find something that really works well for your family and lifestyle.

Automation Engineer Salary – Let’s Talk Turkey

So, what can you expect in terms of salary as an Industrial Automation Engineer? Controls Engineering (again, I’m using the terms “controls” and “industrial automation” interchangeably) is a demanding field requiring solid technical, organizational, and people skills. Automation Engineers can expect to earn a decent income.

Unfortunately, the Bureau of Labor Statistics does not have a listing for “Industrial Automation Engineer,” “Controls Engineer,” or “Automation Engineer.” Here are the average salaries listed on various career and industry sites for “Controls Engineer” or “Electrical Controls Engineer” (this information last updated 30 Dec 2019):

SiteAverage Salary
Glassdoor$73,526
Indeed$81,834
Payscale.com$76,178
ZipRecruiter$82,078
ControlEng.com$100,339
Salary.com (Engineer I)$70,702
Salary.com (Engineer II)$88,665
Salary.com (Engineer III)$106,564

PLC Engineer Jobs – Where And How To Get One

If you have the right education and/or experience to pursue a position as a Controls Engineer (or Industrial Automation Engineer, or PLC Engineer, or however you want to say it 🙂 ), where should you start looking? Well, like many jobs, there are a lot of avenues by which you can apply for a position as an Automation Engineer. Overall, here are the angles of attack when trying to get hired on as a Controls Engineer:

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Getting A Job As An Automation Engineer By Applying To Companies Directly

In my opinion, there are two steps you need to take before proceeding on any portion of your job search:

  1. First, get your resume in order!
  2. Then, get a set of professional, business-casual attire in order!

Got those taken care of? If so, let’s apply for jobs.

To make a long story short, there are a lot of ways to apply for a position as an Automation Engineer online. I don’t discount the notion of walking into a company wearing a tie (or other appropriate business clothing) and handing out your resume.

With that said, more and more companies are posting their openings online, which means they’re receiving more and more applications. It’s my personal opinion that you have to respond in kind. By this, I mean that if you are actively pursuing a career as a PLC engineer, you will need to apply for many, many openings in the hopes of receiving a few calls.

Applying for so many Controls Engineer positions online can be painful and time-consuming. With that said, the good news is that you’ll likely be exposed to a variety of positions. In your search, you might stumble upon a PLC Engineer job or two that really piques your interest. Here are some places you can look online for Automation Engineer careers:

Big Job Boards

Of course, there are the common, big-name job boards. Companies in many different industries are posting positions on these boards. There are a ton of these boards out there. Below, you’ll find just a few of the PLC engineer searches from the big boards:

Technical Recruiting Sites

There are also job postings through technical recruiters. Here are a few of the PLC engineer job searches on boards of this type:

Industry-Specific Job Boards

Have a passion for work in a particular industry? You can try job boards that are industry-specific, such as:

Additional Resources

Some other options might include applying for positions with contract companies, or applying to a company or for a position that you admire directly. There are a lot of places on the Internet to apply for a job. So, get your resume together, and get to it!

Reach Out To Your Network To Get Hired As A PLC Engineer

We all know the old adage, “it’s not what you know, it’s who you know”. While I don’t think this is always the case, it is certainly nice to have someone on the inside who can put in a good word for you. At the very least, it’s a lot easier to get an interview if someone mentions your name to the hiring manager.

  • Are you a student?
    • Your instructors likely know people and companies in the industry
    • See if they know of any job openings or if the school has any intern or co-op opportunities
  • Are you an intern?
    • Talk to people within the company or organization for which you work
    • Ask about what you need to do to align yourself for consideration for a full-time position
  • Go to job fairs and other industry gatherings!
    • Search in your area for job fairs, trade shows, etc. related to your industry
    • Dress professionally, bring some resumes in document protectors, and meet people!

Professional Networking In The Information Age

Not everyone is in a position where they know someone who can help them get an interview. While we aren’t all that lucky, we are all lucky enough to have access to an awesome networking platform – LinkedIn.

If you are searching for jobs, or searching for people to fill jobs, it’s absolutely my opinion that you should have an up-to-date, professional profile on LinkedIn. It’s free, it’s easy, and there are lots of people who are trying to fill the positions you’re applying for. Those people are on LinkedIn looking for people like you.

Talk To A Technical Recruiter About Controls Engineer Openings

As you can imagine, searching for a position as an Automation Engineer is hard work. Why take on all of that responsibility yourself, when you can engage someone else (or even several other people) to help you out?

You’re in luck. Technical recruiters will take on some of this workload for you. What’s more, you don’t pay a technical recruiter. The hiring company pays them. In fact, you’re doing them a bit of a favor by reaching out to them. You’ve saved them the time of finding you, the qualified candidate. So, for free, you basically get an agent who will try to link you and your resume with job openings in your area. That’s not a bad deal, if you ask me.

How To Connect With A Technical Recruiter

Linking up with a technical recruiter is easy:

  1. First, open your web browser
  2. Next, type “technical recruiting” in Google
  3. Then, click the Maps option
  4. Lastly, call a recruiter

If you do this, I bet you an ice cream cone that there will be several technical recruiting firms in the city closest to you. With those easy steps, you’ll be on the phone with a technical recruiter.

So, make sure your resume’s up-to-date and call a couple of these folks up. Let them know what education and experience you can bring to the table as a future Controls Engineer. In my experience, there will be several people who are sitting by their phone right now, hoping that someone like you will call. Well, assuming it’s during working hours on a business day, anyway.

Let Us Link You With Opportunities

Wouldn’t you know it, but our organization is literally built to help you advance your career in industrial automation?

Click the link above and spend just a few moments telling us about yourself and your goals. We’ll work to get your name out there with the kinds of organizations you’re hoping to become a part of. We want to help you move forward in your automation career.

Is A Controls Job Right For You?

To me, the biggest question you have to ask yourself is whether you like solving problems and learning about new equipment.  

  • Do your interests include electronics and programming?
  • Are you the type of person who has to read and tinker until you understand what you’re doing?

If so, then you might do well as an Automation Engineer. If you’re in it for the money, you could probably fake it till you make it even if your interests aren’t well-aligned. With that said, the engineers I know who are very successful are people who gobble up as much knowledge as they can at every turn, and are regarded as world-class experts in their specialties.

Are you currently applying for a position as an Automation Engineer? Are you still in college, considering possible career paths for your future? Wherever you are in your journey, tell us about it in the comments below. We love to hear from other technicians and engineers.


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NO and NC (Normally Open and Normally Closed) Proximity Sensor Basics

When I was learning PLC programming, I remember scratching my head about some of the concepts surrounding proximity sensors. Digital or analog, Normally Open (NO or N.O.), or Normally Closed (NC or N.C.)?  What exactly does it mean for a sensor to be NO or NC? What effect will it have when I’m checking the state of the sensor at the PLC or other controller?

Proximity sensors set up on an automation line.
Common “barrel proxes” (pronounced “prawksez”) set up to detect parts or features of parts as they move down a conveyor. When objects made of certain materials (depending on the sensor type) pass in front of a proximity sensor (sometimes referred to as a proximity switch), it is “made,” changing the state of its output signal.

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NO and NC, and Other Proximity Sensor Basics

NO or NC refers to the way that a sensor is wired and in what state its output signal will be when the sensor is “made.” A sensor is “made” when an object is present that the sensor has been set up to detect. The characteristics of the sensor determine whether or not an object will detected. These characteristics can include its detection type (inductive, capacitive, ultrasonic, photoelectric, etc.), sensing range (how far away the part can be from the sensor), and other factors.  The point of a proximity sensor, or “prox,” is to know that an object is there or not there. When a sensor detects an object, its output state changes.

Digital sensors

Someone might refer to the types of proximity sensors described above as “digital proxes.”  In this context, digital has a somewhat different denotation than the typical use of the word outside of industrial automation. If a sensor is “digital,” it only has two possible output states: on or off.

There are a multitude of different sensors on the market. There are small sensors, large sensors, laser sensors, sensors like the barrel proxes above which have no configuration whatsoever, sensors that require quite a bit of set up, and everything in between. If a sensor’s sole purpose is to detect whether or not an object is present somewhere, its output is typically digital (either on or off). For this reason, people sometimes refer to sensors of this type as “switches”. Like a light switch in your home, they either turn an output on or off.

In this regard, you can think of the behavior of a prox switch or other digital output as being just like that of the paperclip switch that turned on a small lightbulb in your 2nd grade science class. The prox sensor is the paperclip, and the target passing in front of the prox is your hand pushing down on the paperclip to change the switch’s output state.

Analog sensors

Aside from digital outputs, there are devices with “analog” outputs. Analog sensors output a specific value within a range (anywhere from 2V to 10V, for instance). As one example, sensors with analog outputs can be used to tell a machine how far away something is.

Click the following link if you’d like to learn more about the differences between digital and analog sensors. For now, let’s take a look at how Normally Open and Normally Closed sensors differ in their behavior:

Normally Open Devices

A graph depicting an example of sensor output behavior for a Normally Open sensor. By default, the sensor's output is off, or "low." When the sensor detects an object in its sensing range, the output is switched on. When the object then leaves the sensor's range, the output returns to its default state of low.
This graph shows the behavior of a simple, Normally Open proximity sensor as an object passes in front of the sensor and then passes out of its sensing range. When an NO proximity sensor detects its target, its output signal is turned on (energized with voltage). When the object is no longer detected by the sensor, the output state changes back to the original state (no voltage on the signal wire). Click the image to view full size.

As mentioned above, the purpose of a proximity sensor is to tell a machine when something is present in front of the sensor.  So, what actually happens when the sensor detects an object?  Well, the sensor’s output changes state. This means that the sensor either energizes an output signal wire with a small amount of electricity, or not.

Like a light switch at your house that is off, an NO sensor will not, by default, put out a voltage to its output wire. Returning to the paperclip circuit analogy, an NO sensor’s default state is similar to the paperclip lifted off the thumbtack. The switch breaks the output circuit by default; hence, the output circuit is “normally open”. Referring to the graph above, when an NO sensor is in its default state (does not detect a target), the sensor’s output is off.

What happens when the sensor is made?

When an appropriate object passes within the sensor’s sensing range, the sensor outputs a voltage through its signal wire. This signal can indicate to a controller that the target has “made” the sensor. So long as the target remains within sensing range, the prox will continue to provide voltage on its output signal.

What’s the point of this? This is how the sensor “tells” the controller: “hey, I’m energizing my output as a signal to you that there is something in front of me right now.”

As you can see in the graph above, once the object passes out of the range of the sensor, the sensor will turn off its output. A controller would now see that the sensor is in its normal, “off” state.

As a brief aside, there are quite a few ways to refer to something as being “on” or “off”.  Below are some other ways you might hear someone refer to a signal as being on or off.  In my opinion, all of these are more or less equivalent:

OnOff
HighLow
EnergizedExtinguished
LitOut
MadeNot Made

Normally Closed Devices

NC sensors and other devices behave exactly opposite to NO devices in regards to their outputs. NC devices are, as indicated by their name, normally closed, meaning that their output is on by default.  Only when an object makes the sensor does the signal actually turn off.  Here’s a simplified graph of the signal behavior for an NC sensor:

A graph depicting an example of sensor output behavior for a Normally Closed sensor. By default, the sensor's output is high. When the sensor detects an object in its sensing range, the output is switched off. When the object then leaves the sensor's range, the output returns to its default state of being energized.
Here you can see that the behavior of a Normally Closed sensor is directly opposite that of an NO sensor; they are the negation of each other.
When an NC prox is made, the signal is actually “brought low.” Click the image to view full size.

If you understood the behavior of Normally Open sensors, then you also understand the behavior of Normally Closed sensors; one is simply the inverse of the other.  If an NO and NC sensor were set up to detect the same object, the NO sensor’s output would be on when the NC sensor was off, and vice-versa.

Default Output StateOutput State When Sensor Is Made
NO SensorsOffOn
NC SensorsOnOff

Why choose an NO or an NC sensor?

Due to these differences in output behavior, Normally Open and Normally Closed sensors are better or worse for certain applications.

All cables and electrical components will eventually fail.  To get an idea of why you might choose one sensor or another, let’s first talk about how we want our systems to behave when a cable or sensor is damaged, and we no longer get the signals we’re relying on to control machine motion.

The two most common types of electrical failures are “opens” and “shorts,” with opens being the most common.  An open is an unwanted break in a circuit. Cuts, crushing, or other damage to the cable can cause an open.

An example of a Normally Closed application: Emergency Stop

Modern factories are populated throughout with “E-Stop buttons”. Emergency Stop buttons can be used by anyone in the facility if an unsafe condition is observed. Slap an E-Stop, and all machine motion will come to a halt as quickly as possible.

A red emergency stop button that would be present throughout a factory for use in an emergency to stop the factory.
A typical E-Stop button.

Remember that you can think of a prox sensor as just another type of switch. What we traditionally think of as a switch is usually switched by mechanical action. Proxes are typically solid-state devices with internal electronics that turn outputs on and off. An E-Stop is an example of a true mechanical switch. When someone presses an E-Stop, metal contacts inside of the device open or close its output circuits.

NC or NO?

Let’s consider whether the E-Stop should be a Normally Open or Normally Closed device. With a Normally Open E-Stop, the button’s outputs will be off (open) when the button is in its default (not pressed) state.

In an emergency, someone hits the E-Stop.  The mechanical action of pressing the button causes the normally open contacts to close, energizing the button’s outputs. Now the controller can detect those outputs, and we can use this status in our logic to halt machine motion. Cool.

Except… let’s return to the concept of an unwanted break in our circuit. What happens if the cable that connects the E-Stop button to the controller has been damaged?

A simplified schematic depiction of an E-Stop circuit. A power supply on the left feeds power to an E-Stop switch which feeds an input to a controller on the right. There is a break in the connection between the E-Stop and controller.
A simplified depiction of an E-Stop circuit. The E-Stop is shown as an NO switch for the purpose of illustrating the concept; in reality, E-Stops are typically NC. If the E-Stop were NO, a break in the wire would prevent the stop signal from reaching the controller in an emergency. Click image to view full size.

Safety first

If the E-Stop is a Normally Open device, and its cable becomes damaged, then when we go to activate the E-Stop, we will never get a signal back to our controller telling it to halt production. To the controller, a damaged electrical system and the default output of a Normally Open switch look exactly the same. In either case, there would be no incoming voltage to the controller’s input.

If the E-Stop in this example were Normally Open, you would only check for its output signal when you needed it to stop the line. As a result, you have no way of knowing whether the button or cable is damaged until it’s too late. A Normally Open switch wouldn’t just be a bad choice for this application, it would be dangerous. In an emergency, an ineffective E-Stop could contribute to someone being severely injured or killed.

Making the right choice for the right application

For this reason, E-Stops and most safety devices are Normally Closed. When a Normally Closed E-Stop is in its default position, the contacts close the circuit and return a signal to the controller indicating that the system is safe. Because the E-Stop returns a signal constantly, any condition that causes the E-Stop signal to go low will be detected. Aside from someone actually pressing the button, some other possible causes for losing the E-Stop safe signal might include loss of power to the system, failure of the E-Stop’s cable, or failure of the E-Stop button itself.

Now, since our Normally Closed E-Stop is always sending a signal back to the controller when it’s in the safe position, we set our logic up so that we must constantly see the signal from the E-Stop to allow the factory to run.  You could think of this type of Normally Closed signal as a constant “thumbs-up” to the controller that the system is safe.  In the controller logic, machine motion would only be permitted when the expected signals from all safety devices are present.

A view of a pilot in the cockpit of an American military jet. The pilot is giving the thumbs up sign with his left hand.
Who’s got one thumb and flies a jet?

Along this same line of thought, other sensors that detect unsafe conditions, such as tank overfill, are typically Normally Closed. Because NC sensors return a signal by default, any loss of that signal will immediately indicate that the system is not safe.

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An example of a Normally Open application: Part Present

For less safety-critical applications, Normally Open sensors work just fine and in fact are found more commonly in industrial automation than NC sensors.  In certain cases, use of an NO sensor would actually be preferable, and many people find it easier to interpret the behavior of NO sensors when it comes time to debug an electrical or programming issue.

“Part Present” applications, for instance, often use NO sensors.  Let’s say that you want a robot to pick up a part and move it to another location. When the robot moves to the “pick position,” you want to be able to verify that the part is positioned in the robot’s “end effector” before allowing the robot to attempt to move the part. An end effector is a fixture bolted to the robot arm that is custom-built for picking up a particular part.

Normally Open sensors are ideal for this type of Part Present detection, as they only send the signal that the part has been picked up if they actively sense material. If a cord or sensor is damaged in this type of application, the sensor will simply never output its signal. Because the robot won’t see the necessary signal, robot motion will halt until the problem can be corrected.

Two yellow Fanuc robots are moving pieces of metal in an automation cell.
Two Fanuc robots performing material handling operations in an automation cell.  Their end effectors are the orange fixtures attached to the ends of the robotic arms.  The end effectors likely use Normally Open “part present” sensors to verify that the part is properly loaded before moving away from the pickup positions.

NC and NO Sensors

There’s a common thread in both the Normally Closed and the Normally Open applications described above. With either NO or NC, you want positive indication before you allow the system to move. By positive indication, I mean that you want the PLC to see the signal from the sensor go high.

In the E-Stop application, you want to be able to move the system by default. You only want to disable motion if a certain condition is met (someone slaps the E-Stop). Hence, you want the signal to be on by default (Normally Closed). You only want the signal to go low if your system isn’t safe.

In the Part Present application, you want the robot to stop at the pickup position by default. You only want to enable motion under certain conditions (the part positioned properly in the end effector). Hence, you want the signal to be off by default (Normally Open). You only want the signal to go high if your part is properly loaded.


Hopefully, this has shed a bit of light on some of the basics of proximity sensors, including the concepts of Normally Open and Normally Closed. There is a lot to be said about the many sensors on the market and their functionality. Click the following link for an in-depth look at the various types of sensors and how they work.

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