Function Code Fc5 (Write Coil) - WAGO 750-872/020-000 Manual

156 • Fieldbus Communication
MODBUS Functions

4.2.3.5 Function Code FC5 (Write Coil)

This function writes a single output bit to the slave device.
Request
The request specifies the reference number (output address) of output bit to be
written. The reference number of the request is zero based; therefore, the first
coil starts at address 0.
Example: Turn ON the second output bit (address 1):
Byte
Byte 0, 1
Byte 2, 3
Byte 4, 5
Byte 6
Byte 7
Byte 8, 9
Byte 10
Byte 11
Response
Byte
.....
Byte 7
Byte 8, 9
Byte 10
Byte 11
Exception
Byte
.....
Byte 7
Byte 8
Field name
Transaction identifier
protocol identifier
length field
unit identifier
MODBUS function code
reference number
ON/OFF
Field name
MODBUS function code
Reference number
Value
Field name
MODBUS function code
Exception code
Example
0x0000
0x0000
0x0006
0x01 not used
0x05
0x0001
0xFF
0x00
Example
0x05
0x0001
0xFF
0x00
Example
0x85
0x01, 0x02 or 0x03
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP