Midea ATOM B Series Service Manual page 52

2.4.5 Procedure
Communication wires P Q E have short
circuited or disconnected
Communication wires P Q E are not
connected in a daisy chain
IDU power supply is abnormal
Wires between outdoor main PCB and
electric control box communication
terminals block are loose
Interference from high voltage (220V or
Communication wires are close to a source
of electromagnetic radiation such as
transformer or strong fluorescent lamp
The length of communication wire is over
Clear all indoor unit address by setting
switch S1 and then automatically
addressing indoor unit by setting S1 too
repower on to confirm whether fault clear
Replacing outdoor main PCB resolves the
Replace electric control box
communication terminals block
Notes:
1. Measure the resistance among P, Q and E. The normal resistance between P and Q is 120Ω, between P and E is infinite, between Q and E is infinite.
2. S1 switch setting as below table; for every times setting, you need to repower on to make the switch dial function works.
E2
1
No
No
No
No
higher) wires
No
No
1200m
No
No
error
No
Yes
Reconnect the communication wires
Connect the communication wires in a
Yes
Yes
Ensure normal power supply
Yes
Ensure the wires are connected properly
Ensure the communication wires and
Yes
high voltage wires are separated
Remove the source of interference, or
Yes
add additional shielding to the
Reduce the wire length to less than
Yes
1200m or strengthen the signal
Some indoor unit address repeat,
Yes
2
,
Atom B Series VRF 50/60Hz
daisy chain
communication wires
maintain to use
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