FB MON Bit 1

Monitoring Discrepancy Error - Input Group 2

Beckhoff · TwinSAFE Logic FB

What does FB MON Bit 1 mean?

A discrepancy has been detected between the channels of input group 2 in the FB MON function block. This means the redundant inputs are not switching in sync or are reporting different states, indicating a potential sensor fault, wiring issue, or incorrect timing that could compromise the monitoring function, leading to a safety stop.

Complete Troubleshooting Guide

  1. 1

    Inspect the wiring for input group 2, ensuring both channels are correctly connected, free from damage, and properly terminated.

  2. 2

    Verify the functionality of the input device(s) connected to group 2, checking both redundant outputs if applicable, for consistent operation.

  3. 3

    Review the discrepancy time parameter for input group 2 in the FB MON configuration; adjust if the application legitimately has different timing requirements.

  4. 4

    Monitor the individual input channels for group 2 in real-time using diagnostic tools to observe their switching behavior and identify which channel is deviating.