FB CONNECTION SHUTDOWN Bit 0

Connection Shutdown Discrepancy Error - Input Group 1

Beckhoff · TwinSAFE Logic FB

What does FB CONNECTION SHUTDOWN Bit 0 mean?

A discrepancy has been detected in input group 1 for the FB CONNECTION SHUTDOWN. This means the redundant input signals ('DeactivateX TRUE') are not in agreement, which prevents the Connection Shutdown function from reliably commanding a SHUTDOWN state or detecting it from the assigned Connection. This poses a risk to controlled deactivation and will stop the machine.

Common Causes

  • Connection shutdown discrepancy in Input Group 1.
  • Safety interlock loop 1 has a wiring fault.
  • One or more safety inputs in group 1 are not in the expected state.
  • Door or guard switch in group 1 is not closed properly.
  • Emergency stop button in group 1 is active.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Inspect the wiring for input group 1, ensuring both channels providing the 'DeactivateX TRUE' signals are correctly connected, free from damage, and properly terminated.

  2. 2

    Verify the functionality of the input devices providing the 'DeactivateX TRUE' signals; ensure their redundant outputs are synchronized.

  3. 3

    Review the discrepancy time parameter for input group 1 in the FB CONNECTION SHUTDOWN configuration; adjust if application-specific timing requires it.

  4. 4

    Monitor the individual input channels for group 1 in real-time using diagnostics to identify which channel is deviating or delayed.

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Verified technical data. Last updated: March 2026

Related Faults

Source: Beckhoff TwinSAFE Logic FB