Safe torque off 1

What does FA81 mean?

Loss of one of the Safe Torque Off (STO) signals (STO1). This fault indicates an issue with one channel of the dual-channel STO safety circuit, causing the drive to enter a safe state by removing motor torque.

• Interruption or wiring fault in the STO1 signal path from the safety device to the drive.
• Fault within the external safety device connected to STO1 (e.g., safety relay output failure, E-stop contact issue).
• Internal STO circuit fault affecting only the STO1 channel.
• Parameter 31.22 STO diagnostics is set to detect single-channel loss as a fault (when running) or a fault/warning (when stopped).

Click steps to track your progress.

1. 1

   Verify the specific STO1 input signal at the drive terminal for correct voltage level (e.g., 24VDC when safe torque off is inactive).

2. 2

   Inspect the wiring for the STO1 channel from the safety device to the drive for breaks, loose connections, or damage.

3. 3

   Check the external safety device connected to the STO1 channel for proper operation and reset if necessary.

4. 4

   Ensure parameter 31.22 STO diagnostics is set appropriately; 'Fault' or 'Warning' mode will react to single-channel loss.

5. 5

   Consult the drive's hardware manual for STO wiring diagrams and signal specifications to confirm correct installation.