Safe torque off 1

What does FA81 mean?

Safe Torque Off (STO) signal 1 has been lost or is not correctly applied. This fault often occurs in conjunction with 5091 (if running) or A5A0 (if stopped) and signifies a problem with one leg of the dual-channel STO safety circuit. This compromise of the STO function prevents safe operation.

• Open circuit or short circuit in the wiring for STO channel 1 (e.g., between safety relay output and XSTO1).
• Failure of the external safety relay output supplying STO channel 1 (e.g., contact welding, coil failure).
• Loss of the 24VDC supply to the external safety relay or the STO circuit itself.
• Incorrect parameterization of STO supervision (e.g., parameter P50-01 STO supervision mode or delay).
• Drive's internal monitoring circuit for STO1 detects an inconsistency (e.g., voltage out of tolerance).

Click steps to track your progress.

1. 1

   Measure the voltage at drive terminal XSTO1 relative to XSTO-COM; it should be 24VDC when STO is inactive.

2. 2

   Check continuity of the wire connecting the external safety device output to drive terminal XSTO1.

3. 3

   Verify the output status of the external safety relay or safety PLC responsible for STO channel 1.

4. 4

   Confirm the 24VDC power supply to the external safety circuit is stable and within tolerance.

5. 5

   Review parameter P50-01 (STO supervision mode) to ensure it is configured correctly for the application.