Cause: SAFE TORQUE OFF comes when the drive has detected that the STO circuit is open or inactive, meaning it's in a safe state and will not enable torque output to the motor.

STO SAFE TORQUE OFF fault in Parker AC890 drive indicates that the Safe Torque Off (STO) function has been activated, and the drive has disabled the output to the motor, preventing it from producing torque.

Troubleshooting Steps:

Follow these steps to correct STO SAFE TORQUE OFF fault in Parker AC890 drive:

• Check External Safety Circuits: The most likely reason for this fault is that an external safety device (e.g., emergency stop button, safety gate switch, light curtain) connected to the STO input has been activated.
• Verify the Status of Safety Devices: Inspect all connected safety devices and ensure they are in their normal operating (non-tripped) state.
• Reset Safety Circuits: If a safety device was activated, it will likely need to be manually reset. Refer to the documentation for your safety devices.