F550 Parameter or Memory Card read fault in ABB DCS800 drive indicates a "Parameter or Memory Card Read Fault." This means that the drive is unable to read the necessary parameters or data from the internal memory or an external memory card.

1. Review the parameter settings to ensure they are correct and consistent.
2. Check for any errors or inconsistencies that may be causing the fault.
3. Restarting the drive can sometimes resolve temporary software glitches.