A power-up diagnostic error was detected in one of the optional interfaces (PH9/PH10, probe changer, soft probe, or host computer RS-232 interface).
The actual interface is identified in the previous error:
Error MP-522 - D/A board conversion failure (MP-30 only)
Error: MP-523 - RS-232 host interface failure
Error: MP-524 - RS-232 PH9/PH10 interface failure
Error MP-525 - RS-232 Probe changer interface failure
You should follow the steps for the related error listed above.