1 Modbus RTU Protocol
© Copyright Reserved Autonics Co., Ltd. 11
1 Modbus RTU Protocol
1.1 Read coil status (Func 01–01H)
Read output (0X reference, Coil) ON/OFF status in the slave device.
(1) Query (Master)
Slave address Function
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
(2) Response (Slave)
Slave address Function
Byte count Data Data Data
1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte 1Byte
If read the 10 output status (ON: 1, OFF: 0) within coil 000001 (0000 H) to 000010 (0009 H) on
Slave (Address 17) from Master.
Query (Master)
Slave address Function
11 H 01 H 00 H 00 H 00 H 0A H ## H ## H
If the values range from coil 000008 (0007 H) to 000001 (0000 H) on the Slave are “ON-ON-
OFF-OFF-ON-ON-OFF-ON”, and the values from 000010 (0009 H) to 000009 (0008 H) are
respectively “OFF-ON”.
Response (Slave)
Slave address Function
Byte count
(000008 to
(000010 to
Low High
11 H 01 H 02 H CD H 01 H ## H ## H