Muting Discrepancy Error - OSSD Input Group

What does FB MUTING Bit 1 mean?

A discrepancy has been detected in the OSSD (Output Signal Switching Device) input group (e.g., OssdIn1/OssdIn2) within the FB MUTING function block. These inputs typically come from a safety light curtain or area scanner. A discrepancy means the redundant OSSD signals are not synchronized, indicating a fault in the safety device or its wiring, compromising the primary safeguarding function and stopping the machine.

• Faulty or misaligned safety light curtain causing inconsistent OSSD output signals (OssdIn1, OssdIn2).
• Wiring short-circuit or open-circuit on one or both OSSD input lines to the safety PLC (e.g., terminals X2.1, X2.2).
• Electromagnetic interference (EMI) affecting the OSSD signal integrity during transmission to the safety controller.
• Contamination or damage to the light curtain's emitter or receiver optics.
• Parameter 'OSSDDiscTime' (e.g., P_OssdDiscTime) set too short for the actual OSSD signal delay.

Click steps to track your progress.

1. 1

   1. Check the diagnostic indicators on the safety light curtain emitter and receiver for proper operation and alignment (e.g., green status LEDs).

2. 2

   2. Power down the system, then perform a continuity test on the OSSD wiring from the light curtain outputs to the safety input terminals (e.g., X2.1, X2.2).

3. 3

   3. With power restored, use an oscilloscope to measure the OSSD signals (OssdIn1, OssdIn2) at the safety PLC input terminals for synchronized switching behavior.

4. 4

   4. Clean the protective windows of the safety light curtain emitter and receiver with a non-abrasive cleaner.

5. 5

   5. Review and potentially increase the 'OSSDDiscTime' parameter (e.g., from 50ms to 100ms) in the safety controller configuration.