Gree Ultra Heat GMV Multi VRF Series Owner's Manual page 44

Ultra Heat GMV Multi VRF_Heat Recovery Serial
(1) For modular outdoor units, if there are multiple outdoor modules, then the master unit must be the first
outdoor module on the communication wire and should not connect with IDU (master unit is set by S7 of the
outdoor main board).
(2) For modular outdoor units, if there are multiple outdoor modules, then the indoor units must be connected
with the last slave module of ODU (slave unit is set by S7 of the outdoor main board).
(3) Communication wire and power cord must be separated.
(4) Communication wire must be of proper length. Extension is not allowed.
(5) IDUs must be connected in series. The last mode exchanger D1/D2 connecting with ODU must be
connected with the communication matched resistance (supplied in the list of ODU spare parts). The ODU
D1/D2 must be connected with the communication matched resistance (installed before factory).
(6) For modular outdoor units, if there are multiple outdoor modules, the communication matched resistance
(installed before factory) of slave modules connecting with D1/D2 must be removed.
(7) For modular outdoor units, if there are multiple outdoor modules, S7 dip switch of master unit is "00", and
S7 dip switch of slave unit is "10", otherwise, the system main board will display CJ which means address DIP
switch code of system is shocking.
(8) For multi-refrigeration systems, when it is necessary to connect with a centralized controller, the
communication lines connecting with all the ODUs G1/G2 must be connected in series, and the last
refrigeration system master unit G1/G2 must be connected with the communication matched resistance
(supplied in the list of ODU spare parts).
(9) For multi-refrigeration systems, the address dip switch S3 of the master unit must be set by different
numbers according to Ultra Heat technical service manual, and slave unit S3 can't be set.
4.8.2 Communication connection between IDU and wired controller
There are 4 kinds of connection between IDU and wired controller, as shown below:
Fig.46 One wired controller controls one IDU Fig.47 Two wired controller controls one
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