126
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Fieldbus Communication
MODBUS
Functions
WAGO-I/O-SYSTEM
750
ETHERNET TCP/IP
4.2.3.6 Function Code
FC6 (Write single register)
This function writes the value of one single output register to a slave device in
word format.
Request
The request specifies the reference number (register address) of the first
output word to be written. The value to be written is specified in the “Register
Value” field. The reference number of the request is zero based; therefore, the
first register starts at address 0.
Example: Write a value of 0x1234 to the second output register.
Byte
Field name
Example
Byte 0, 1
Transaction identifier
0x0000
Byte 2, 3
protocol identifier
0x0000
Byte 4, 5
length field
0x0006
Byte 6
Unit identifier
0x01 not used
Byte 7
MODBUS function code
0x06
Byte 8, 9
reference number
0x0001
Byte 10, 11
Register Value
0x1234
Response
The reply is an echo of the inquiry.
Byte
Field name
Example
.....
Byte 7
MODBUS function code
0x06
Byte 8, 9
Reference number
0x0001
Byte 10, 11
Register Value
0x1234
Exception
Byte
Field name
Example
.....
Byte 7
MODBUS function code
0x85
Byte 8
Exception code
0x01 or 0x02
Содержание 750-341
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