OSSD Input Discrepancy Not Reset
Beckhoff · TwinSAFE Logic FB
What does FB MUTING Bit 9 mean?
A discrepancy error in 'OssdIn1'/'OssdIn2' was detected and has not yet been acknowledged or reset. This indicates a persistent underlying issue with the OSSD input group that needs active resolution and acknowledgment before normal operation can resume. The system will remain in a safe, stopped state.
Common Causes
- The initial discrepancy condition in 'OssdIn1'/'OssdIn2' (from ref=37) has not been rectified.
- Faulty wiring or signal integrity issue on the external reset input line for the muting function (e.g., input X1.6).
- Persistent malfunction of the safety light curtain's OSSD outputs, continuously sending inconsistent signals.
- Improperly configured reset logic within the safety PLC for the muting function block.
- Residual electrical charge or ground fault impacting the OSSD input lines, preventing proper signal stabilization.
Repair Steps & Checklist
Click steps to track your progress.
- 1
1. Thoroughly investigate and correct the root causes of 'Muting Discrepancy Error - OSSD Input Group' (ref=37), focusing on light curtain status and OSSD wiring.
- 2
2. Verify the functionality of the designated reset button or HMI command and confirm its corresponding input signal (e.g., X1.6) reaches the safety controller.
- 3
3. Use an oscilloscope to verify that both OSSD input signals (OssdIn1, OssdIn2) are stable and synchronized at the safety PLC terminals.
- 4
4. Check the configuration of the FB MUTING function block in the safety program, specifically verifying the reset conditions and parameters.
- 5
5. Temporarily disconnect and then reconnect the OSSD inputs to the safety PLC terminals (X2.1, X2.2) to ensure no residual electrical issues are present, then perform a reset.