Sensors for logic modules

A logic module is a programmable controller (also known as a PLC) that allows machinery to perform processes without human intervention. They have an integral role to play in commercial and industrial settings, where they can automate certain aspects of machine functioning such as start-stop processes and operating temperatures.

To reduce the amount of wiring you need, a logic module links digital signals from sensors through an input module. Sensors typically co-exist alongside other input types like switches and buttons to inform the way the logic module operates.

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What are logic module sensors?

A logic module sensor is one of the input devices that provides signals to a PLC. While the logic module is already somewhat prepared for its purposes by the setting it has been pre-programmed with, it must also be able to respond to its surroundings in real time. This is where the sensors come into play.

What types of sensors are there for logic modules?

Proximity sensors

There is a myriad of digital and analog sensors you can link up to your logic module. Proximity sensors are a particularly common type. These are digital sensors that detect nearby metal objects using magnetic fields. Proximity sensors in cars can assist with parking or alerting the driver to obstacles in the road. They are also integral to the agricultural industry and manufacturing operations. Other examples include:

• Optical sensor: This is a type of digital sensor with a longer range than most proximity sensors. It can sense objects within a certain range but may need regular cleaning so that dirt and dust don't block visibility.
• Capacitive sensor: This type of sensor is also similar to a proximity sensor, but it only detects non-conductive materials.
• Ultrasonic proximity sensor: This detects a solid object by way of high-frequency sound.
• Photoelectric sensor: This sensor projects a light beam to detect the presence or absence of physical objects. Some can detect colors or measure distance accurately through triangulation.
• Inductive sensor: Uses a high-frequency magnetic alternating field to detect any object that is electrically conductive and close to the sensor.

Pressure sensors

These are useful when working with liquid or gas and you need to determine whether the pressure is correct and safe. Some examples include:

• Absolute pressure sensor: This type of pressure sensor specializes in barometric measurements. It is useful for monitoring the weather or navigating with accurate altitude detection.
• Differential pressure sensor: This sensor gives a positive or negative reading. It measures the change of pressure between two points in a system. It can help check release valves or flow rate, for example.
• Gauge pressure sensor: Measures the relative difference between two types of pressure. There is often a membrane attached to a resistor that provides an output value of deflection forces.

What are the uses for a logic module sensor?

To answer this question, we need to appreciate the differing purposes of digital and analog sensors. Digital logic module sensors can provide a simple "yes" or "no" response, which can then stop or start the PLC. They can send signals that tell it whether there is an item on a conveyor belt or if a tank is full, for example.

An analog logic module sensor answers more complex questions about these processes. They often help provide the digital sensors with any extra information they might need. They can answer questions about how far an item is from a destination or how full it is, for example. This is made possible by an analog sensor's ability to convert a variable physical quantity into a voltage or current that the logic module can understand.

Smart sensors are an alternative that is becoming increasingly common, especially as the Industrial Internet of Things becomes more prevalent. When connected to the internet, these sensors can diagnose issues and provide details about why a piece of equipment might not be functioning correctly.

What should you consider when choosing logic module sensors?

When choosing the right sensors to connect to your logic module, there are several factors you must consider:

• Accuracy: Some sensors offer more precise measurements than others. In some scenarios, you may not need a high level of accuracy.
• Dynamic range: Some sensors offer a larger range of operation, so consider the extremes of what you need yours to cover.
• Reliability: Your sensor must give readings that are reliable and accurate within its working conditions. Check a product's datasheet to find the conditions in which it can function reliably.
• Response time: Check the sensor can respond to stimuli within the time you need it to.

Why choose RS to supply your logic module sensor?

As one of North America's leading distributors of sensors for logic modules and sensor accessories, you can trust our expertise. In our catalog, you can find sensors for logic modules from leading brands like Siemens, Balluff, and Banner Engineering.

Outstanding customer service is at the heart of our offering. For this reason, we provide same-day dispatch on many of our items, as well as a straightforward returns policy.

If you'd like to know more about our logic module sensors before you buy, please don't hesitate to contact us today. Our expert hub is also a useful and informative tool, full of the latest product guides and industry updates.