ABB · AC500
A test pulse error indicates a problem with the safety module's ability to generate or detect test pulses on its input channels. This mechanism is crucial for detecting short circuits to supply voltage or ground, or open circuits, and its failure means a potential undetected wiring fault.
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1. De-energize the safety circuit and perform a resistance measurement between the input terminal (e.g., X1) and +24VDC.
2. Perform a resistance measurement between the input terminal (e.g., X1) and GND.
3. Verify the continuity of the wiring from the safety input module to the connected sensor or switch.
4. Bypass the sensor by directly connecting the input terminals according to the safety manual (if permitted) and re-test.
5. If tests confirm the input module is faulty, replace the safety I/O module.