Midea MV8M-120WV2RN1 Engineering Data page 95

8.3.2 Outdoor unit and indoor units' P Q E communication
Communication wiring design and installation should adhere to the following requirements:
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 0.75mm three-core shielded cable should be used for communication wiring. Using other types of cable can lead to
interference and malfunction.
 Do not bind the communication line, refrigerant piping and power cable together.
 When the power cable and communication line are laid in parallel, the distance between the two lines must be 5cm or
more to prevent signal source interference.
 The P Q E communication wires should be connected one unit after another in a daisy chain from the outdoor unit to
the final indoor unit as shown in Figure 3-8.5. At the final indoor unit, a 120Ω resistor should be connected between
the P and Q terminals. After the final indoor unit, the communication wiring should NOT be continued back to the
outdoor unit – that is, do not attempt to form a closed loop.
 The P and Q communication wires should NOT be connecting to E.
 The shielding nets of the communication wires should be connected together and grounded. Grounding can be
achieved by connecting to the metal casing adjacent to the P Q E terminals of the outdoor unit electrical control box.
 All IDUs in a system must be powered through a uniform power supply so that they can be powered on or off at the
same time.
 The communication wiring (P, Q, E) must through the magnetic ring from the main board to the IDUs.
 Applicable standards: EN 55014-1 and EN 55014-2. The communication line must be shielded wire.
Figure 3-8.5: P Q E communication wiring configuration – IDUs uniform power supplied
RS-485(P Q E) communication
L1+La+Ln≤1200m,Communication wiring 3*0.75mm
ODU
P Q E
L1
Main control board
Q E
P
Shield layer must
be grounded
Connect to the ODU PQE
2
N L
Circuit breaker
Distribution box
1# IDU
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P Q E
L L L L N N N
La
(n-1)# IDU
...
P Q E
V8 Mini R410A VRF 50Hz
Communication wire
Power wire
Distribution box
n# IDU
P Q E
Ln
Resister
L L L L
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