User manual

Appendix D Functions and data transfer
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Appendix D Functions and data transfer
The following functions are supported in the Modbus protocol:
– 03, 04 (read registers) – read one or more registers;
– 06 (write single register) – write one register;
– 16 (write multiple registers) – write block of registers;
– 17 (report server ID) – read the device name and the firmware version.
Example. Function 17 (Report Server ID)
This function is used to read the device name and the firmware version. The example with the device ad-
dress 12 is shown in Tables D1 and D2
Table D1 Format of the request (Master -> Slave)
Address
Function code
Checksum
12
17
ZZ
Table D2 Format of the response (Slave -> Master)
Address
Function code
Data length (byte)
Data
Checksum
12
17
14
SMI2 VX.YY
ZZ
Comments
The values X and YY are set by the manufacturer.