4-2
ENGLISH
Read registers
MODBUS protocol manual
MODBUS TCP
Values contained both in Query or Response messages are in hexa format.
Query example in case of MODBUS TCP: 01000000000D010300000004
Example Byte Description No. of bytes
01 - Transaction identifier 1
00 High
Protocol identifier 4
00 Low
00 High
00 Low
0D - Byte count 1
01 - Unit identifier 1
03 - Function code 1
00 High
Starting register 2
00 Low
00 High
No. of words to be read 2
04 Low
Response example in case of MODBUS TCP: 0100000000070103080000000000000FCF
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
03 - Function code 1
08 - No. of byte of requested data 2
00 High
Requested data 8
00 Low
00 High
00 Low
00 High
00 Low
0F High
CF Low