Cause : PI Feedback below minimum value comes when drive isn't receiving a proper feedback signal from the motor, or the PID control settings are not configured correctly. This fault comes when PI Feedback below minimum value P2268

The fault code F0221 on a Siemens Micromaster 420 (MM420) indicates a proportional-integral (PI) feedback below the minimum value fault. This fault typically occurs in closed-loop control systems where the drive expects feedback from a sensor to maintain speed or position control, but the received feedback falls below the minimum acceptable threshold.

1. Change value of P2268. 
2. Adjust feedback gain.