If there is error such as non-exist address,then it will return function code 0x81.
For example:Send message 01 03 32 00 00 02 CA B3
Meaning:
01: Station NO.
03: Function code:read data registers
32 00 : Read address starting from 4x3200(Hex).This is the modbus address corresponding to
parameter“Status word”(60410010)
00 02:Read 2 words of data
CA B3:CRC check.
0x06:Write single data register
Request format:
Response format:If writing successful,then return the same message.
If there is error such as address over range,non-exist address and the address is read only,then it will return
function code 0x86.
For example:Send message 01 06 31 00 00 0F C7 32
Meaning:
01: Station No.
06: Function code,write single WORD
31 00: Modbus address for writing data.This is the address corresponding to parameter “control
word”(60400010)
00 0F: Write data 000F(Hex)
C7 32: CRC check.
0x10:Write multiple registers
Request format: