37
11. Modbus TCP server
11. 7. “Write Multiple Registers” (16 = 16#10) function
This Modbus request is used to write a number (No. of Registers) of adjacent words starting at a given address (Starting Address).
Thevalues to be written are supplied one after another (First Register Data V Last Register Data).
Request format:
Response format:
Exception response format:
Byte Meaning
0 Function Code = 16#10
1 Starting Address Hi
2 Starting Address Lo
3 No. of Registers Hi (0)
4 No. of Registers Lo (1 - 100)
5 Byte Count (B = 2 × No. of Registers)
6 First Register Data (Hi)
7 First Register Data (Lo)
… ……………
B+4 Last Register Data (Hi)
B+5 Last Register Data (Lo)
Byte Meaning
0 Function Code = 16#10
1 Starting Address Hi
2 Starting Address Lo
3 No. of Registers Hi (0)
4 No. of Registers Lo (1 - 100)
Byte Meaning With the VW3A3310d Ethernet card
0 Function Code = 16#90
1 Exception Code
01 (Illegal Function)
02 (Illegal Data Address)
03 (Illegal Data Value)
04 (Illegal Response Length)