Reset Error 1

What does C001 mean?

A static TRUE signal is detected at the Reset input of a safety function block (e.g., SF_EmergencyStop, SF_ESPE, SF_AOPD) while it is waiting for a primary safety input or during activation in a specific state (e.g., 8001). This condition prevents the safety function from resetting properly or clearing error states. Consequently, it keeps associated safety outputs in a safe (FALSE) state, inhibiting normal operation.

• Persistent short circuit on the physical Reset input wiring (e.g., terminal X1.5) to a 24VDC supply.
• Incorrectly configured safety PLC logic (e.g., in a Siemens F-CPU) holding the software Reset input TRUE prematurely.
• Mechanical failure of the physical Reset push-button (e.g., illuminated E-stop reset), causing it to remain stuck closed.
• Auxiliary sensor or feedback device (e.g., door interlock feedback) incorrectly maintaining an active state, forcing the Reset input TRUE.
• Welded contacts within a safety relay or contactor used in the Reset circuit, keeping the reset path energized.

Click steps to track your progress.

1. 1

   Measure the voltage at the physical Reset input terminal (e.g., X1.5 or the corresponding input module terminal) with a multimeter to confirm 0VDC when the reset is not intended.

2. 2

   Disconnect the physical wiring to the Reset input at the safety module (e.g., PLC safety input card) and check if the fault clears; if so, the issue is external to the module.

3. 3

   Inspect the physical Reset push-button for mechanical binding or debris; actuate it several times and verify its contact status with an ohmmeter (NC contacts should open when pressed).

4. 4

   Review the safety PLC program logic (e.g., S7-Safety Advanced, Studio 5000 Logix Designer) to ensure the Reset input is only commanded TRUE after all primary safety inputs are satisfied.

5. 5

   If an external safety relay or contactor drives the Reset input, verify its contact status (e.g., 3-pole NO contacts) using an ohmmeter when de-energized and energized.

6. 6

   Check diagnostic LEDs on the safety input module (e.g., Siemens 6ES7326-2BF10, Allen-Bradley 1734-IB8S) for specific input channel status.