Deif SGC 120 - Page 66

Byte Field Comments
4 Number of registers to write - high byte
Number of registers to write must be between 1 to
255
5 Number of registers to write - low byte
6 Number of data bytes to follow (n)
7 Value at first register
... ...
6+n Value at last register
7+n/8+n Error check CRC
Standard response from SGC controller server for function 16
Byte
Field Comments
0 Server address As configured in the controller.
1 Function code 
2 First register address - high byte
16-bit register address, register address map is
described in the Register map.
3 First register address - low byte
4 Number of registers written - high byte
Number of registers that have been written.
5 Number of registers written - low byte
6/7 Error check CRC
Command from Modbus client for function 3
Byte
Field Comments
0 Server address As configured in the controller.
1 Function code 
2 First register address - high byte
16-bit register address, register address map is
described in the Register map.
3 First register address - low byte
4 Number of registers to read - high byte
Number of registers to read must be between 1 to
255
5 Number of registers to read - low byte
6/7 Error check CRC
Standard response from SGC controller server for function 3
Byte
Field Comments
0 Server address As configured in the controller.
1 Function code 
2 Byte count (n)
Equals to number of registers to be read times two.
8-bit even number between 2 to 250.
3 First register - high byte Number of registers that have been written.
4 First register - low byte
... ...
1+n Last register - high byte
2+n Last register - low byte
 Error check CRC
User manual 4189341340A EN Page 66 of 76