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05(0x05) Force a Single Coil (Write DO)
This function code is used to set the status of a single coil or a single digital output value.
[Request]
Byte
Description
Size
Value
00
Net ID (Station Number)
1 Byte
1 to 247
01
Function Code
1 Byte
0x05
02-03
DO Address
2 Bytes
Refer to the Modbus address depends on your slave
device for more details.
Byte 02 = high byte
Byte 03 = low byte
04-05
Output Value
2 Bytes
0xFF 00 sets the output to ON.
0x00 00 sets the output to OFF.
All other values are invalid and will not affect the
coil.
Byte 04 = high byte
Byte 05 = low byte
[Response]
Byte
Description
Size
Value
00
Net ID (Station Number)
1 Byte
1 to 247
01
Function Code
1 Byte
0x05
02-03
DO Address
2 Bytes
The value is the same as Bytes 02-03 of the
Request
04-05
Output Value
2 Bytes
The value is the same as Bytes 04-05 of the
Request
[Error Response]
Byte
Description
Size
Value
00
Net ID (Station Number)
1 Byte
1 to 247
01
Function Code
1 Byte
0x85
02
Exception Code
1 Byte
Refer to the Modbus Standard Specifications for
more details.
