1 Modbus RTU Protocol
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1.4 Read input registers(Func 04–04H)
Read the Binary data of Input Registers(3X reference) in Slave device.
(1) Query (Master)
Slave
Function
(2) Response (Slave)
Slave
Function Byte count Data Data Data
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
If read the 2 values within the range from Input Register 300001(0000 H) to 300002(0001 H) on
Slave(Address 17) from Master.
Query (Master)
Slave
address
Function
11 H 04 H 00 H 00 H 00 H 02 H ## H ## H
If the values of 300001(0000 H) and 300002(0001 H) on Slave are respectively “10(A H)” and
“20(14 H)”.
Response (Slave)
Slave
Function Byte count
11 H 04 H 04 H 00 H 0A H 00 H 14 H ## H ## H