Autonics krn100 series, User Manual

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1 Modbus RTU protocol
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1.4 Read Input Registers(Func04–04H)
Reads the binary data of Input Registers(3X reference) in the Slave device.
(1)
Query(Master)
Slave Address
Function
(Command) Starting Address No. of Points(Number of data) Error Check(CRC16)
High Low High Low Low High
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
(2) Response(Slave)
Slave Address
Function
(Command)
Byte Count
(Number of
data byte)
Data Data Data
Error Check(CRC16)
Low High
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
The below is to read 2EA value within Input Register 30001(0000 H) to 30002(0001 H) on the
Slave(Address 17) from the Master.

Query(Master)
Slave Address
Function
(Command) Starting Address No. of Points(Number of data) Error Check(CRC16)
High Low High Low Low High
11 H 04 H 00 H 00 H 00 H 02 H ## H ## H
The below example is when 30001(0000 H) value on the Slave is “10(A H)” and 30002(0001 H)
value is “20(14 H)”.

Response(Slave)
Slave Address
Function
(Command)
Byte Count
(Number of
data byte) Data Data Error Check
(
CRC16)
High Low High Low Low High
11 H 04 H 04 H 00 H 0A H 00 H 14 H ## H ## H
CRC16
CRC16