Monitoring EDM Monitoring Error - EDM1

What does FB MON Bit 4 mean?

An External Device Monitoring (EDM) error has been detected for the EDM1 feedback loop of the FB MON. This indicates that the feedback from safety contactors or relays, expected to open or close in response to the FB MON's output, has not been received correctly or within the allowed time. This implies a fault in the external safety output circuit or its feedback path, compromising safe monitoring.

• Auxiliary feedback contact of the monitored external safety contactor (e.g., K_SAFE_MON) is failing to open or close as expected.
• Wire break or loose connection in the EDM feedback loop from the monitored device (e.g., from K_SAFE_MON 53/54 to safety relay X13.1).
• Incorrect type of auxiliary contact used for EDM feedback (e.g., NO contact used when NC is configured, or vice-versa).
• Welded main power contacts on the external safety contactor/relay, preventing its auxiliary contact from changing state.
• Feedback loop is not closing within the expected EDM monitoring time (e.g., Parameter P_MON_EDM_TIME_1) due to mechanical delay.

Click steps to track your progress.

1. 1

   De-energize the monitored safety circuit and verify the external safety contactor K_SAFE_MON is de-energized. Measure continuity across its EDM feedback auxiliary contact (e.g., 53/54), which should be open.

2. 2

   Energize the monitored safety circuit (without active fault) and verify K_SAFE_MON pulls in. Measure continuity across its EDM feedback auxiliary contact, which should now be closed (e.g., 0 ohms).

3. 3

   Inspect the auxiliary contact block of the monitored contactor for physical damage, proper seating, and correct contact type (NO/NC).

4. 4

   Trace and measure the resistance of the EDM feedback wires from the auxiliary contacts of K_SAFE_MON back to the safety controller's EDM input (e.g., EDM_MON_IN1).

5. 5

   Verify the EDM feedback configuration parameter (e.g., P_MON_EDM_DELAY_1) in the safety controller to ensure it allows sufficient time for the contactor to operate and provide feedback.