User manual

MODBUS RTU, ASCII, TCP 11
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2.2 MODBUS TCP
Values contained both in Query or Response messages are in hex format.
Query example in case of MODBUS TCP: 010000000006010400020002
Example Byte Description No. of bytes
01 - Transaction identifier 1
00 High
Protocol identifier 4
00 Low
00 High
00 Low
06 - Byte count 1
01 - Unit identifier 1
04 - Function code 1
00 High
Starting register 2
02 Low
00 High
No. of words to be read 2
02 Low
Response example in case of MODBUS TCP: 01000000000701040400035571
Example Byte Description No. of bytes
01 - Transaction identifier 1
00 High
Protocol identifier 4
00 Low
00 High
00 Low
07 - Byte count 1
01 - Unit identifier 1
04 - Function code 1
04 - No. of byte of requested data 2
00 High
Requested data 4
03 Low
55 High
71 Low