User manual

14 MODBUS RTU, ASCII, TCP
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3.2 MODBUS TCP
Values contained both in Request or Response messages are in hex format.
Query example in case of MODBUS TCP: 010000000009011005150001020008
Example Byte Description No. of bytes
01 - Transaction identifier 1
00 High
Protocol identifier 4
00 Low
00 High
00 Low
09 - Byte count 1
01 - Unit identifier 1
10 - Function code 1
05 High
Starting register 2
15 Low
00 High
No. of words to be written 2
01 Low
02 - Data byte counter 1
00 High
Data for programming 2
08 Low
Response example in case of MODBUS TCP: 010000000006011005150001
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
10 - Function code 1
05 High
Starting register 2
15 Low
00 High
Command successfully sent 2
01 Low