What causes fault code SAFE-GUARDMON1 (Guard Monitoring Relay — Channel Fault)?

One guard switch contact failed — one channel reads differently from the other. Wiring fault on one channel — broken wire, loose terminal, or short to ground. Guard switch actuator misaligned — one channel actuates but the other doesn't. Relay input module failed on one channel — only receiving signal from one input. Discrepancy timer expired — too much time between channel transitions

How do I fix fault code SAFE-GUARDMON1?

Check guard monitoring relay LED indicators — identify which channel is faulted. Test the guard switch — open and close the guard slowly, watch both channel LEDs on the relay. If one channel doesn't respond, check wiring from that channel back to the relay terminals. Test guard switch contacts with multimeter — both NC and NO contacts must operate correctly. Replace guard switch if one contact is dead — do not bypass the failed channel. After repair, reset the monitoring relay per manufacturer procedure

Guard Monitoring Relay — Channel Fault

SAFE-GUARDMON1

Guard monitoring safety relay detected a channel fault. Dual-channel monitoring of guard switches has a discrepancy or one channel is not reading correctly.

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safety guard monitoring relay channel discrepancy switch

Probable Causes (ranked)

One guard switch contact failed — one channel reads differently from the other
Wiring fault on one channel — broken wire, loose terminal, or short to ground
Guard switch actuator misaligned — one channel actuates but the other doesn't
Relay input module failed on one channel — only receiving signal from one input
Discrepancy timer expired — too much time between channel transitions

Fix Steps

1 Check guard monitoring relay LED indicators — identify which channel is faulted
2 Test the guard switch — open and close the guard slowly, watch both channel LEDs on the relay
3 If one channel doesn't respond, check wiring from that channel back to the relay terminals
4 Test guard switch contacts with multimeter — both NC and NO contacts must operate correctly
5 Replace guard switch if one contact is dead — do not bypass the failed channel
6 After repair, reset the monitoring relay per manufacturer procedure

Field Trick

When a guard monitoring relay trips on channel discrepancy, it means one contact is slower than the other. It doesn't mean the switch is dead — it means it's DYING. Replace it now. A switch that trips discrepancy today will fail completely next week, and a complete failure is harder to diagnose because you lose the error code.

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