Cause : Safe Disable Signal Input comes when one Safe Disable channel is open while the other channel is closed. The signals to the Safe Disable inputs are wrong or the wiring is incorrect.

"hbbf" fault in yaskawa drive indicates a problem with the Safe Torque Off (STO) functionality. The HbbF fault occurs when one or both of the  Safe Disable input terminals (H1 and H2) on the drive are open (not receiving a signal).

1. Check Connections: Verify that the cable connecting the safety device to the drive's Safe Disable terminals (H1 and H2) is securely plugged in at both ends. Inspect the cable for any signs of damage.
2. Safety Device: Ensure the external safety device is functioning correctly according to its specific instructions.
3. Consult Manuals: Refer to the Yaskawa user manuals for your specific drive model for detailed troubleshooting steps related to the HbbF fault code.