Gree GMV5 Series Service Manual page 364

7. Troubleshooting
7.1 Hardware Faults
Symptom
A software
communication fault
alarm is reported,
and some or all units'
running state is not
displayed or cannot
be controlled.
GMV5 DC INVERTER VRF UNITS SERVICE MANUAL
Possible Cause
Communication lines of units are
not twisted pairs (except for lines
connecting BACnet gateways
and PCs, other communication
lines must be twisted pairs).
Communication lines are loose;
or polarities of communication
lines connecting BACnet
gateways and ODUs whose
control DIP switches are 0 are
reverse (G1, G2 reverse).
Communication lines connecting
ODUs and IDUs interrupt.
Communication lines interrupt.
Communication lines are short
circuited.
Twisted pairs are too close to the
power lines (less than 15 cm
clearance), resulting in
disturbance that affects
communication.
Communication interface
connection error
Troubleshooting
Replace the communication
lines with twisted pairs.
Connect the gateways and
ODUs in a correct way;
make sure their polarities
are correspondent, that is,
G1 to G1 and G2 to G2.
Weld the interrupted lines.
Weld the interrupted lines.
Repair the short circuited
part.
Separate the two types of
lines. If their clearance is
less than 15 cm, cover them
with sheath separately.
Refer to the BACnet
Technical Manual to
361