Comprehensive Guide to Inhibiting Devices in Siemens PLC 1214: Practical Steps and Solutions

ControlNexus has been a trusted name in the industry since 2013, specializing in Siemens PLCs, HMIs, and Inverters. Our goal is to provide clear, actionable advice to help you optimize your automation systems. This guide will walk you through the process of inhibiting devices in the Siemens PLC 1214.

Key Takeaways

What is Device Inhibition?The process of stopping or preventing a specific action from taking place in the PLC system.
Tools NeededTIA Portal software, Siemens PLC 1214, latest firmware updates.
Steps to Inhibit DevicesConfiguration in TIA Portal, implementing inhibition with SFC12 D_ACT_DP, testing and validation.
Common IssuesFirmware mismatches, configuration errors, and diagnostic obstacles.
Expert TipsEnsure firmware is up-to-date, use diagnostic OBs, and follow detailed step-by-step guides.

1. Introduction

Inhibiting devices in your Siemens PLC 1214 is crucial for maintaining control and ensuring safety in your automation systems. This guide provides a detailed walkthrough to help you master this process.

2. Understanding Inhibition and Interlock


  • Inhibition: Stopping or preventing a specific action directly, ensuring the action cannot take place.
  • Interlock: Preventing an action due to the absence of a necessary condition, thus indirectly stopping the process.


Inhibition and interlock may seem similar but differ significantly in their applications:

  • Inhibition acts as a direct barrier.
  • Interlock depends on the presence or absence of other conditions.

Practical Examples

  • Chemical Processing: An inhibitor might prevent a chemical reaction, while an interlock ensures a process only occurs under specific conditions.
  • Industrial Automation: Inhibition might stop a machine entirely, while an interlock could allow partial operation based on safety conditions.

3. Step-by-Step Guide to Inhibiting Devices in Siemens PLC 1214


Before you begin, ensure you have:

  • TIA Portal Software: Make sure it’s installed and updated.
  • Siemens PLC 1214: Verify the model and firmware version.
  • Firmware Updates: Confirm that the PLC firmware is up-to-date to avoid compatibility issues.

Step 1: Configuration

  1. Open TIA Portal: Start the TIA Portal software.
  2. Create a New Project: Set up a new project for your Siemens PLC 1214.
  3. Configure Hardware: Add the PLC and configure the necessary I/O modules.
  4. Set Parameters: Define the parameters for the devices you want to inhibit.

Step 2: Implementing Inhibition

  1. Use SFC12 D_ACT_DP: This system function block is essential for enabling and disabling devices.
  2. Write the Code: Implement the code using SFC12 to inhibit the desired devices. “`plaintext CALL SFC 12, “InhibitDevice” LADDR := W#16#100 REQ := TRUE RET_VAL := MW10 BUSY := M10.0
  3. Compile the Project: Ensure there are no errors before proceeding. devices.

Step 3: Testing and Validation

  1. Download to PLC: Transfer the compiled project to your Siemens PLC 1214.
  2. Run Diagnostics: Use diagnostic tools to check for errors.
  3. Validate Inhibition: Verify that the devices are correctly inhibited as per your configuration.

4. Firmware Updates and Compatibility

Importance of Firmware Updates

  • Ensures Compatibility: Keeping your firmware up-to-date ensures smooth operation and compatibility with the latest software features.
  • Fixes Bugs: Updates often include fixes for known issues.

Update Instructions

  1. Download Firmware: Obtain the latest firmware from the Siemens support website.
  2. Update Process: Follow the instructions to update your PLC’s firmware.
  3. Reconfigure if Needed: Sometimes, firmware updates may require reconfiguration of your PLC settings.

Troubleshooting Firmware Issues

  • Common Issues: Mismatched firmware versions can cause inhibition problems.
  • Solutions: Refer to Siemens support forums for specific troubleshooting steps and advice from experts.

5. Practical Troubleshooting Tips

Common Issues

When inhibiting devices in Siemens PLC 1214, some common issues you might encounter include firmware mismatches, configuration errors, and diagnostic challenges. Here’s how to address them effectively:

Firmware Mismatch

  • Problem: The PLC firmware does not match the project configuration, leading to errors.
  • Solution: Ensure that your PLC firmware is up-to-date and compatible with your project configuration. Regularly check for firmware updates on the Siemens support website.

Configuration Errors

  • Problem: Incorrect settings or parameters in the hardware configuration can cause device inhibition issues.
  • Solution: Double-check all configuration settings in TIA Portal. Make sure that the parameters for the devices you want to inhibit are correctly set.

Diagnostic Obstacles

  • Problem: Difficulty in identifying the exact cause of issues during the inhibition process.
  • Solution: Use diagnostic OBs (Organization Blocks) such as OB82, OB86, and OB121 to capture and address hardware and programming errors. These tools are crucial for effective troubleshooting.

Diagnostic Tools

Using diagnostic tools can help you pinpoint and resolve issues quickly. Here are some key diagnostic OBs:

  • OB82 (Diagnostic Error Interrupt): Handles hardware diagnostic errors, providing detailed information about the nature of the fault.
  • OB86 (Rack Failure): Manages errors related to rack or station failures, helping you identify issues in the hardware setup.
  • OB121 (Programming Error): Captures programming errors, allowing you to troubleshoot and correct code-related issues.

Real-World Troubleshooting Examples

Let’s look at some practical examples of troubleshooting device inhibition in Siemens PLC 1214:

Case Study 1: Firmware Mismatch

A user encountered a mismatch error due to outdated firmware. The issue was resolved by:

  1. Updating the Firmware: Downloading the latest firmware from the Siemens support website.
  2. Reconfiguring the Hardware: Ensuring that all settings in TIA Portal matched the updated firmware specifications.

Case Study 2: Incorrect SFC12 Implementation

Another user faced issues with device inhibition due to incorrect implementation of SFC12 D_ACT_DP. The solution involved:

  1. Revising the Code: Correcting the code to properly implement SFC12.
  2. Following Siemens Guidelines: Consulting Siemens documentation and support forums for accurate coding practices.

6. Expert Advice and Best Practices

Advice from Industry Experts

Here are some expert tips to help you effectively inhibit devices in Siemens PLC 1214:

  • Keep Firmware Updated: Regular firmware updates ensure compatibility and fix known issues.
  • Use Diagnostic OBs: Implement OB82, OB86, and OB121 for effective troubleshooting and error handling.
  • Follow Detailed Steps: Adhere to step-by-step guides and Siemens documentation for accurate configuration and implementation.

Avoiding Common Pitfalls

To avoid common mistakes, make sure to:

  • Verify Compatibility: Ensure that all hardware and software components are compatible and up-to-date.
  • Double-Check Configurations: Carefully review all configuration settings in TIA Portal.
  • Consult Experts: Utilize Siemens support forums and technical documentation for expert advice and solutions.

Enhancing System Reliability

Ensuring the long-term reliability of your PLC system involves:

  • Regular Maintenance: Perform regular maintenance checks and updates.
  • Thorough Testing: Test all configurations and code implementations thoroughly before deploying them in a live environment.
  • Documentation: Keep detailed records of all configurations, updates, and troubleshooting steps.

7. Additional Resources

For further assistance and advanced learning, explore these additional resources:

8. Conclusion

Summary of Key Points

Inhibiting devices in Siemens PLC 1214 requires careful configuration, up-to-date firmware, and effective troubleshooting. By following the detailed steps and expert advice provided in this guide, you can ensure the reliable and efficient operation of your PLC systems.

Call to Action

Implement these steps and share your experiences with us. For more detailed guides and expert advice on Siemens PLCs, visit ControlNexus.

9. FAQs

Frequently Asked Questions

  • What is the difference between inhibition and interlock?
    • Inhibition directly prevents an action, while interlock depends on the absence of a necessary condition.
  • How do I update the firmware on my Siemens PLC 1214?
  • What diagnostic tools should I use for troubleshooting?
    • Use OB82, OB86, and OB121 for diagnosing and addressing hardware and programming errors.

Leave a Reply

Your email address will not be published. Required fields are marked *

8 + twenty =


Subscribe now for exciting deals and updates.

Don't Miss Out on Exclusive Offers!