How to Read Temperature using an RTD Sensor

How to Read Temperature using an RTD Sensor

This tutorial will demonstrate how to read temperature with an RTD Sensor using a Maple Modular PLC and an RTD Module in MapleLogic.

Software Required

Hardware Required

Wiring Diagrams

Ladder Diagram

After starting a new scanned program in MapleLogic, here is a simple method in communicating with a PLC and an RTD Module using Ladder Diagram.

  • Use the “Always ON” system bit (F10) to turn ON the application instruction for the RTD Module.
  • FROM: Refers to Analog Input communication.
  • H0001: Refers to Slot 1 on your Chassis.
  • 1: Refers to Channel 1 on the RTD Module according to the buffer memory.
  • D01: Stored in this memory register.
  • 1: It’s one word.

RTD Module Buffer Memory – Find this in the MapleLogic Help Files.

Online Communication

  • Go to the Online tab
  • Click “Link + Download + Monitor” to go online with your PLC.

When online, you can see the live values from the RTD Module.

+101 in the application instruction reads as 10.1°C.

  • Over to the left side of your project, double click the RTD Module to open the configuration window.
  • The RTD Module Setup window is now open.
  • Double click Channel 1.
  • Use the drop down menu to choose the RTD type.
  • Click OK.

After setting the configurations, you MUST click “Write” to save the settings to the PLC.

After writing to the PLC, click “Status” to view the live values from the RTD Module.

View the live values from the RTD Module in the RTD Module Status.

The Values should reflect in the ladder diagram as well.

RTD Error Status

There are several reasons why your RTD Module can trigger an error code. A few could be a wire disconnection, exceeding the maximum and minimum temperature ranges or a power outage, to name a few.

Below you will see a live camera feed of the PLC and the RTD Module connected to a PT-100 RTD Sensor.

One of the wires is disconnected resulting in a blinking error light on the RTD Module and an error code in the RTD Module Status window.

Re-connect the wire back in the RTD Module.

The blinking error light won’t clear until the “Reset Error” button is pressed in the RTD Module Status window.

Click it and it will clear the error code back to “0” and the red light on the RTD Module will stop blinking.

Sample Project

The project shown above was designed for the specific hardware mentioned at the beginning of the tutorial and is intended to provide you guidance when programming your unit. If you are using models other than the ones specified in this sample project, similar steps can be duplicated within your own project.

Download MapleLogic Sample Project

Resources & Documentation

Maple PLC/MapleLogic Resources

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