Midea V8 VRF Series Service Manual page 66

6.1.18 C51 - Abnormal communication between the IDU and wired controller
Note: The error code C51 can be triggered either at the IDU side or at the wired controller side.
Error display

Error impact 
ODU of the same system: operate normally.

Error trigger

Error recovery
Automatic recovery

Possible cause



Troubleshooting
Digital display
Triggered at the IDU side: The faulty IDU and other IDUs of the same system: operate normally.
Triggered at the wired controller side: The wired controller is unavailable.
Triggered at the IDU side: If the main control board of an IDU has lost communication with wired
controller for 2 min
Triggered at the wired controller side: If the wired controller has not received any reply from the main
control board of an IDU for 1 min
The wired controller is damaged
The IDU main control board is damaged.
Communication cables are loose or the communication port is faulty.
Communication cables have short-circuited or been cut off.
Are communication cables
loose or communication ports
Is the communication
cable disconnected or short
No
Is the fault cleared after
replacing the wired controller?
No
Replace the main control
board of the IDU
Triggered at the IDU side
The error code "C51" can be
queried by entering the spot
check interface of the panel or
display box, but the error code is
not displayed on the wired
controller.
C51
Yes
wrong?
No
Yes
circuited?
Yes
V8 VRF Indoor Units
Display position
Triggered at the wired
controller side
The error code "C51" is
displayed only on the wired
controller rather than on the
panel or display box.
Properly connect the cables
and ensure they are connected
to the right ports
Replace the communication
cable and properly connect the
cable
The wired controller is
damaged, so change the wired
controller
65