Transcript:
[0m:00s] Hey, I’m Mitchell. Welcome to another video in the RSP Education Series. Out in the field, your machines are talking, but are you listening? From sensors that say, “Hey, I’m here,” to transmitters quietly feeding your PLC pressure and level data, every control panel is a hub for critical real-world signals. But which devices matter most, and how do you make sense of their signals? Whether you’re building panels, troubleshooting, or just getting started in automation, this is the foundational knowledge you need to know. Let’s break down the most common field devices and how they wire into your system. If you like this kind of content and want more educational videos, please like and subscribe. This video is for educational purposes only. Consult a professional for your application. RSP Supply is not liable for any misuse of this information. With that said, let’s dive right in.
[0m:55s] Out in the field, you’re going to be wiring devices into control panels located on machines, tanks, or along conveyors. These devices feed data into your system. Let’s talk about the most common types. First are discrete, or digital, devices. These are simple on-or-off type devices. Examples include limit switches that detect when something hits a stop or reaches the end of its travel, photo eyes that use light to detect the presence of an object, and proximity sensors that detect metal (inductive) or non-metal (capacitive) materials without contact. These typically send an on or off signal using two or three wires connected to a digital input module in your panel.
[1m:49s] Next are analog devices, which measure real-world values like temperature, pressure, or level. Pressure transmitters send a continuous signal such as 4 to 20 milliamps based on pressure readings. RTDs and thermocouples measure temperature changes, while ultrasonic and radar sensors measure tank levels. Encoders track position or speed, often outputting pulses or numeric data. Analog signals often need extra electronics to get their data into your PLC, and that’s where signal conditioners come in.
[2m:21s] Signal conditioners convert signals to match your PLC’s input requirements. For example, if a pressure transmitter outputs 0 to 10 volts but your PLC only reads 4 to 20 milliamps, a signal conditioner bridges that gap. It can also isolate signals to prevent noise or ground loops, scale inputs so they read accurately, and filter interference in noisy environments.
[2m:46s] Speaking of scaling, this step converts raw data into real-world numbers. If your PLC reads 32768 and you want that to represent 100 PSI, you have to scale it. Some users handle scaling within the PLC, while others use signal conditioners. Either way, it’s crucial to translate sensor data into usable information for your control system.
[3m:02s] The bottom line is this: discrete devices like limit switches and photo eyes give you simple yes or no feedback, while analog devices like pressure sensors and RTDs provide detailed measurements of the real world. Signal conditioners convert, isolate, and scale those signals so your PLC can read them accurately. Understanding the flow from field devices to controllers is what makes a control panel intelligent, not just a metal box. Stick around for more videos in this series as we explore how to make your automation systems smarter, cleaner, and more reliable. For hundreds of thousands of other industrial automation products, visit rspsupply.com, the internet’s top source for industrial hardware.