GMV5 DC INVERTER VRF UNITS SERVICE MANUAL
281
(3) Function DIP Switch-CAN Bus Matched Resistance Setting
The master ODU of air conditioning system or the gateway located at either end of the CAN2 bus (see
the topological drawing) should include a matched resistance; otherwise the normal communication
would fail.
The eighth position of this function DIP switch is used to set the matched resistance of the CAN2 bus.
When the Modbus gateway is located at either end of the CAN2 bus, it shall be coupled with a matched
resistance and the eighth position should be set to ―0‖.
When the Modbus gateway is located at neither end of the CAN2 bus, no matched resistance is required
the eighth position should be set to ―1‖.
ODU system 2
Master outdoor unit 1
ODU system 16
Master outdoor unit 1
ODU system 1
Master outdoor unit 1
……
With the matched
resistance
With the matched
resistance
Without the
matched resistance
Without the
matched resistance
CAN2 bus
Master ODU of Master ODU of Master ODU of
ODU system 1 ODU system 2 ODU system n
ODU system 2
Master outdoor unit 1
ODU system 16
Master outdoor unit 1
ODU system 1
Master outdoor unit 1
……
With the matched
resistance
With the matched
resistance
Without the
matched resistance
Without the
matched resistance
CAN2 bus
The following figure shows how to set matched resistance:
8
With
matched
resistance
configured
Without
matched
resistance
configured
8
indicates the position
of toggle switch
Function
1 65432 7 8
0
1
0
1
Note: The master ODU at either end of the CAN2 bus must be configured with matched resistance as
well. The following figure shows how to set matched resistance for GMV5 DC converter multi-online air
conditioning units and specific position:
Master outdoor unit
Matched
resistance
Master ODU
Matched resistance
(4) Function DIP Switch-RS485 Bus Matched Resistance Setting
The seventh position of this function DIP switch is used to set the matched resistance for the RS485 bus
(herein, it is the Modbus bus)
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