Mitsubishi Electric PUZ-M200YKA Service Manual page 22

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.
Centralized
controller
supply unit
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.
O Bad example (Multi spot earthing of shield wire)
Centralized
controller
M-NET transmission wire
Centralized
controller
M-NET transmission wire
Centralized
controller
M-NET transmission wire
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.
OCH737
Refrigerant
address 00
M-NET
address 01
Power
A-control
remote
controller
Power
M-NET type
supply unit
outdoor unit
Good example 1 (Single spot earthing of shield wire)
Power
M-NET type
supply unit
outdoor unit
Good example 2 (Single spot earthing of shield wire)
Power
M-NET type
supply unit
outdoor unit
Refrigerant
address 00
M-NET
address 02
A-control
A-control
remote
remote
controller
controller
M-NET type M-NET type
outdoor unit outdoor unit
M-NET type M-NET type
outdoor unit outdoor unit
M-NET type M-NET type
outdoor unit outdoor unit
22
Refrigerant
address 00
M-NET
address 03