Troubleshooting 7 Troubleshooting 7.1 “Failure“ LED flashing? а Short circuit Ш Indication: “failure“ LED: flashing red light Ш Cause: Short circuit or overload at an output. Ш Reaction: All outputs are disabled. Ш Corrective action: - Find short circuit (e.g. by disconnecting all outputs and reconnecting them one by one). – Remove short circuit – Restart PLC 7.2 LEDs „run/stop“ and „failure“ light up red а Undervoltage Ш Indication: „run/stop“ LED: permanent red light „failure“ LED: permanent red light Ш Cause The system supply voltage falls below a threshold so- mewhere between 16 and19 V. Ш Reaction: The user program stops, all non-remanent operands and outputs =0. Ш Corrective action:
- Switch supply voltage off and back on again. 153