Datakom DPR-400, User Manual, Page: 61 / 70

DPR-400 User Manual Rev_01 Firmware V-1.0
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Data writing can be achieved with functions 06 (write single register) or 16 (write multiple registers).
Writing single register writes on only a single register. MODBUS master device sends the query which
includes the data to be writte
n. The reply can be either “write successful” message or an error
message.
BYTE DESCRIPTION VALUE
0 Device Address 1 - 253
1 Function Code 6
2 Register Address
(Top) Writeable register addresses are listed below
3 Register Address
(Bottom) Writeable register addresses are listed below
4 Data Top Byte
5 Data Bottom Byte
6 CRC Bottom Byte CRC calculation is explained below
7 CRC Top Byte CRC calculation is explained below
An example message is given below which writes the value 0010h to the address 40h (64 decimal).
01 06 00 40 00 10 89 D2 (each byte is expressed by 2 hexadecimal characters)
Expected return message same as query:
BYTE DESCRIPTION VALUE
0 Device Address 1 - 253
1 Function Code 6
2 Register Address
(Top) Writeable register addresses are listed below
3 Register Address
(Bottom) Writeable register addresses are listed below
4 Data Top Byte
5 Data Bottom Byte
6 CRC Bottom Byte CRC calculation explained below
7 CRC Top Byte CRC calculation explained below
Error return message:
BYTE
AÇIKLAMA DEĞER
0 Device Address Same as query
1 Function Code 134 (Function code+128)
2 Error Code 2: Invalid Address
10: Write Protected
3 CRC Bottom
Byte CRC calculation explained below
4 CRC Top Byte CRC calculation explained below
14.5. WRITING DATA