Modbus Tcp Code Composition - Hisense HCPC-H2M1C Installation Instructions Manual

4 Air Conditioner Monitoring
In the head code of Modus RTU, Additional address is defaulted as 0x32, which can be changed by keys, the change
method is as shown in Table 4.2. Press the SW6+SW7 key for 3s and enter the setting mode.
NO.
1
● To reset additional address into factory default value, same operation as reset default IP address, please
Prompt
refer to Table 3.2 Set IP address No.6.
When using Modbus RTU, firstly need to configure it, please refer to Table 4.3 for the configuration parameter.
Modbus RTU Configuration Name
Additional address
Baud rate
Parity
Data bit
Stop bit

4.1.2 Modbus TCP Code Composition

On TCP/IP, one special message header is used to identify the Modbus application Data unit, which is called MBAP
message header.
While Modbus TCP ADU = 253bytes + MBAP (7 bytes) = 260bytes.
The length of MBAP message header is 7 bytes:
①Transaction identifier [2 bytes]: pairing for transaction processing. In response, Modbus adapter will copy the requested
transaction identifier.
Table 4.2 Modbus RTU additional address setting
·Press Up (SW5) or Down (SW8) until it displays "485.".
·In "485." Menu, press Select key (SW7) and confirm to enter additional address
setting mode.
·After set, press Eject/Switch (SW6) key to exit.
·Press SW7 so that additional address becomes editable, flashing in 1Hz.
·In menu, press Select key (SW7) so that the default Additional address flashes and
becomes editable.
·Press Eject/Switch key (SW6) to switch flashing, and change editable area.
·Press Up (SW5) or Down (SW8) to change the number of additional address.
Table 4.3 Modbus RTU Parameter Matching
MBAP message header
Figure 4.3 Modbus TCP/IP Frame Data
Configuration Data
0x32
9600 bps
No Parity
8bit
1bit
Modbus TCP/IP ADU
Function code
PDU
- 34 -
Remark
Default value
——
——
——
——
Data