SCHNEIDER PLC - PLC Tutorial-1 PLC analog input scaling for pressure input

Introduction

This tutorial will guide you through the process of scaling analog inputs for the Schneider Zelio PLC controller, specifically for measuring pressure or temperature. Understanding how to properly scale these inputs is essential for accurate readings in automation applications.

Step 1: Understanding Analog Input Scaling

Before diving into the scaling process, it’s important to grasp what analog input scaling is. Analog inputs can represent a range of values, such as pressure or temperature, and scaling converts these raw values into meaningful units.

• Definition: Scaling involves mapping raw input values (e.g., voltage) to a specific range (e.g., 0 to 100 PSI).
• Importance: Proper scaling ensures that the PLC interprets the analog signal correctly, enabling precise control and monitoring.

Step 2: Configure the Hardware

Ensure that your Schneider Zelio PLC is properly set up to receive analog inputs.

• Wiring: Connect the sensor (for pressure or temperature) to the appropriate analog input terminals on the PLC.
• Check Compatibility: Verify that the sensor output is compatible with the PLC’s analog input specifications.

Step 3: Access the PLC Programming Software

To perform the scaling, you will need to access the software used for programming your Schneider PLC.

• Open Software: Launch the Schneider programming software on your computer.
• Project Setup: Create a new project or open an existing one that includes your PLC configuration.

Step 4: Define the Input Parameters

Set up the parameters for the analog input in the PLC software.

• Input Type: Select the type of analog input based on your sensor’s output (e.g., 0-10V or 4-20mA).
• Scaling Values: Input the minimum and maximum values for the scaling. For example:
  • Minimum: 0 PSI
  • Maximum: 100 PSI

Step 5: Implement the Scaling Function

Use the scaling function provided in the software to calculate the scaled value from the raw input.

• Scaling Formula: The typical formula used is:

  Scaled Value = ((Raw Input - Min Raw) * (Max Scale - Min Scale) / (Max Raw - Min Raw)) + Min Scale
  

• Example: If you have a raw input of 5V, and you are scaling it to 0-100 PSI:
  • Min Raw = 0V, Max Raw = 10V
  • Min Scale = 0 PSI, Max Scale = 100 PSI
  • Scaled Value = ((5 - 0) * (100 - 0) / (10 - 0)) + 0 = 50 PSI

Step 6: Test the Configuration

Once you have set up the scaling, it is crucial to test the configuration to ensure it works as intended.

• Simulation Mode: If available, use the simulation mode in the software to check the input and output values.
• Real-World Testing: Connect the sensor and observe the readings on the PLC to verify accuracy.

Conclusion

In this tutorial, you learned how to scale analog inputs for the Schneider Zelio PLC when measuring pressure or temperature. By following these steps, you can ensure that your PLC accurately interprets sensor data, leading to improved automation processes. For further learning, consider exploring advanced topics such as PID control and integration with other automation systems.