1 Modbus RTU Protocol
© Copyright Reserved Autonics Co., Ltd. 13
1.3 Read holding registers(Func 03–03H)
Read the Binary data of Holding Registers(4X reference) in Slave device.
(1) Query (Master)
Slave
Function
(2) Response (Slave)
Slave
address
Function Byte count
Data Data Data
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
If read the 2 values from Holding Register 400001(0000 H) to 400002(0001 H), in Slave(Address
17) from the Master.
Query (Master)
Slave
address
Function
11 H 03 H 00 H 00 H 00 H 02 H ## H ## H
If the value of 400001(0000 H) on Slave is “555(22B H)” and the value of 400002(0001 H) is
“100(64 H)”.
Response (Slave)
Slave
address
Function Byte count
11 H 03 H 04 H 02 H 2B H 00 H 64 H ## H ## H