FB MON Bit 2

Monitoring Discrepancy Error - Secure Input Group

Beckhoff · TwinSAFE Logic FB

What does FB MON Bit 2 mean?

A discrepancy has been detected between the 'Secure1' and 'Secure2' input channels in the FB MON function block. These inputs are used to switch off the evaluation of 'MonIn(x)' inputs. A discrepancy here means the redundant secure inputs are not in agreement, which can lead to unintended disabling of monitoring functions, potentially bypassing safety.

Complete Troubleshooting Guide

  1. 1

    Inspect the wiring for the 'Secure1' and 'Secure2' input channels, ensuring they are correctly connected, free from damage, and properly terminated.

  2. 2

    Verify the functionality of the device providing the 'Secure1'/'Secure2' signals, ensuring its redundant outputs are synchronized.

  3. 3

    Review the discrepancy time parameter for the Secure input pair in the FB MON configuration; adjust if the application legitimately has different timing requirements.

  4. 4

    Monitor the 'Secure1' and 'Secure2' signals in real-time using diagnostic tools to identify which channel is deviating.