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8-4. M-NET WIRING METHOD
(Points to notice)
(1) Outside the unit, transmission wires should stay away from electric wires in order to prevent electromagnetic noise from
making an influence on the signal communication. Place them at intervals of more than 5cm. Do not put them in the same
conduit tube.
(2) Terminal block (TB7) for transmission wires should never be connected to 208/230V power supply. If it is connected,
electronic parts on M-NET P.C. board may be burnt out.
(3) Use 2-core x 1.25mm
2
[AWG16] shield wire (CVVS, CPEVS) for the transmission wire. Transmission signals may not be
sent or received normally if different types of transmission wires are put together in the same multi-conductor cable. Never
do this because this may cause a malfunction.
It would be ok if M-NET wire (non-polar, 2-cores) is arranged in addition to the wiring for A-control.
(4) Ground only one of any appliances through M-NET transmission wire (shield wire). Communication error may occur due to
the influence of electromagnetic noise.
“Ed” error will appear on the LED display of outdoor unit.
“0403” error will appear on the central-control remote controller.
If there are more than 2 grounding spots on the shield wire, noise may enter into the shield wire because the ground wire
and shield wire form one circuit and the electric potential difference occurs due to the impedance difference among ground-
ing spots. In case of single spot grounding, noise does not enter into the shield wire because the ground wire and shield
wire do not form one circuit.
To avoid communication errors caused by noise, make sure to observe the single spot grounding method described in the
installation manual.
Group
remote
controller
Refrigerant
address 00
M-NET
address 01
A-control
remote
controller
A-control
remote
controller
A-control
remote
controller
Refrigerant
address 00
M-NET
address 02
Refrigerant
address 00
M-NET
address 03
Power
supply
unit for
transmission
wire
Central
remote
controller
M-NET transmission wire
✕ Bad example (Multi spot grounding of shield wire)
Good example 1 (Single spot grounding of shield wire)
Power
supply
appliance
M-NET type
outdoor unit
Central
remote
controller
Power
supply
appliance
M-NET type
outdoor unit
M-NET type
outdoor unit
M-NET type
outdoor unit
M-NET transmission wire
M-NET type
outdoor unit
M-NET type
outdoor unit
Central
remote
controller
Power
supply
appliance
M-NET type
outdoor unit
M-NET transmission wire
M-NET type
outdoor unit
M-NET type
outdoor unit
Good example 2 (Single spot grounding of shield wire)
OCH429--1.qxp 07.11.20 9:17 AM Page 23