Safe torque off

What does A5A0 mean?

This warning is generated when the drive is stopped and either one or both Safe Torque Off (STO) signals are lost. It indicates that the STO function is active or improperly engaged, preventing the drive from starting, but not necessarily tripping if already stopped. This is a crucial indication of a safety circuit status.

• External safety circuit is intentionally open (e.g., E-stop pressed) or was previously opened and not reset.
• STO input signals (XSTO1, XSTO2) are not both present at 24VDC, indicating a single-channel discrepancy.
• A momentary glitch or flicker in the 24VDC supply to the STO circuit, causing a transient signal loss.
• External safety relay or safety PLC failed to release the STO signals back to an active state.
• Wiring fault in the STO circuit (e.g., loose connection, poor crimp) causing intermittent signal loss.

Click steps to track your progress.

1. 1

   Confirm all external safety devices (e.g., E-stop, safety gates) are in their non-tripped state and reset if necessary.

2. 2

   Verify 24VDC is consistently present at both XSTO1 and XSTO2 terminals relative to XSTO-COM.

3. 3

   Check the status of the external safety relay or safety PLC to ensure its outputs for STO are active and latched correctly.

4. 4

   Inspect STO wiring (XSTO1, XSTO2) for loose connections, damage, or intermittent contact that could cause signal drops.

5. 5

   Cycle power to the external safety circuit and then the drive to ensure proper initialization of STO signals.