22
OCH737
8-4. M-NET WIRING METHOD
Points to note:
(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 5 cm. Do not put them in the same
conduit tube.
(2) Terminal block (TB7) for transmission wires should never be connected to 220–240 V power supply. If it is connected,
electronic parts on M-NET P.C. board may burn out.
(3) Use 2-core × 1.25 mm² 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 is acceptable if M-NET wire (non-polar, 2-cores) is arranged in addition to the wiring for A-control.
(4) Earth 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 centralized remote controller.
If there are more than 2 earthing spots on the shield wire, noise may enter into the shield wire because the earth wire and
shield wire form 1 circuit and the electric potential difference occurs due to the impedance difference among earthing spots.
In the case of single spot earthing, noise does not enter into the shield wire because the earth wire and shield wire do not
form 1 circuit.
To avoid communication errors caused by noise, make sure to observe the single spot earthing method described in the
installation manual.
Centralized
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
Centralized
controller
M-NET transmission wire
O
Bad example (Multi spot earthing of shield wire)
Good example 1 (Single spot earthing of shield wire)
Power
supply unit
M-NET type
outdoor unit
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
M-NET type
outdoor unit
M-NET transmission wire
M-NET type
outdoor unit
M-NET type
outdoor unit
Good example 2 (Single spot earthing of shield wire)
Centralized
controller
Centralized
controller
Power
supply unit
Power
supply unit
