User manual

MODBUS RTU, ASCII, TCP 13
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3. Write commands structure
The master communication device can send commands to the module to program itself or the combined counter.
More settings can be carried out, at the same time, sending a single command, only if the relevant registers
are consecutive (see chapter 5).
According to the used MODBUS protocol type, the write command is structured as follows.
3.1 MODBUS ASCII/RTU
Values contained both in Request or Response messages are in hex format.
Query example in case of MODBUS RTU: 011005150001020008F053
Example Byte Description No. of bytes
01 - Slave address 1
10 - Function code 1
05 High
Starting register 2
15 Low
00 High
No. of words to be written 2
01 Low
02 - Data byte counter 1
00 High
Data for programming 2
08 Low
F0 High
Error check (CRC) 2
53 Low
Response example in case of MODBUS RTU: 01100515000110C1
Example Byte Description No. of bytes
01 - Slave address 1
10 - Function code 1
05 High
Starting register 2
15 Low
00 High
No. of written words 2
01 Low
10 High
Error check (CRC) 2
C1 Low