Safe torque off warning

What does A5A0 mean?

The Safe Torque Off (STO) function has been activated, but the drive is stopped, leading to a warning instead of a fault depending on parameter 31.22. This warning indicates that the STO safety chain has been interrupted or activated while the drive was not running.

• STO input signal (typically two channels) interrupted or missing while the drive is in a stopped state.
• External safety device (e.g., emergency stop, safety gate) activated, causing the STO inputs to drop, with the drive already stopped.
• Parameter 31.22 STO diagnostics is configured to generate a 'Warning' (options 1 or 3) when STO is active and the drive is stopped.
• Wiring fault (e.g., loose connection) in the STO safety chain that causes an STO activation.

Click steps to track your progress.

1. 1

   Verify that all external safety devices (e.g., emergency stop buttons, safety gates) in the STO circuit are in their safe operating state and not activated.

2. 2

   Check the STO input signals (typically digital inputs for STO1 and STO2) at the drive terminals for proper voltage levels (e.g., 24VDC when safe torque off is inactive).

3. 3

   Inspect the wiring of the STO safety chain for any breaks, loose connections, or short circuits.

4. 4

   Review parameter 31.22 STO diagnostics to understand how the drive reacts to STO activation when stopped, ensuring the setting is appropriate for the application.

5. 5

   If the warning persists, test the functionality of external safety devices connected to the STO inputs.