Hisense HCPC-H2M1C Installation Instructions Manual page 35

4 Air Conditioner Monitoring
Maximum RS-485 ADU = 256 bytes, limit the length of Modbus PDU, so for serial link communication, Modbus PDU =
256-additional address (1 byte)-CRC(2 bytes) = 253 bytes. Thus RS-485 ADU = (253 bytes) + additional address (1 byte) +
CRC (2 bytes) = 256 bytes.
For example: taking the communication address control bit 0x9C8E(40078) of the first indoor unit Mapping Table as
example, refer to the Mapping Table for other indoor units as follows:
Modbus RTU code: power on the first indoor unit, write command format.
Additional address
32
Modbus device
Modbus RTU code: Modbus adapter write response code.
Additional address
32
Modbus device
Modbus RTU code: Modbus adapter write error response code.
Additional address
32
Modbus device
Modbus RTU code: the first indoor unit system Data0x9C40 (40000), read command format.
Additional address
32
Modbus device
Modbus RTU code: Modbus adapter read response code.
Additional address
32
Modbus device
Modbus RTU code: Modbus adapter read error response code.
Additional address
32
Modbus device
●When using Modbus RTU, need to place terminal resistance at both ends of the RS-485 communication line, this
Note
Modbus adapter is defaulted as supplied with terminal resistance, bit2 of DSW2 is defaulted as ON。
Function code
10 9C 8E
continuous write Communication protocol start address Write hold register
command number Byte
Function code
10 9C 8E
continuous Communication protocol start address
write command successful write hold register
Function code
90 01
Function
code+0x80
Function code
03 9C 40
continuous Communication protocol start address
read command read hold register (69)
Function code
8A
03 46 00 53 00 44 00 4E 00 59 00 32 00 51 00 20 00 08 00
EF ...
continuous Number of read bytes Successfully read Data (69
read command register Data, 138 bytes)
Function code
83 01
Function
code+0x80
Data
00 01
Write value
Data
00 01
Data
Data
00 45
Data
00 52 00 41 00 53 00 2D 00 32 00 30 00 30 00
Data
- 33 -
CRC CHECK
02 00 01
CRC CHECK
4A 71
Number of
CRC CHECK
7D CF
CRC CHECK
AE 7E
Number of
CRC CHECK
9E D3
CRC CHECK
70 FF
65 86