WAGO-I/O-SYSTEM 750 XTR
Fieldbus Communication 157
750-352/040-000 FC ETHERNET G3 XTR
Manual
Version 1.3.0
lowest value.
The assignment is thus made from 7 to 0 as follows:
Table 73: Assignment of Inputs
OFF OFF OFF ON OFF OFF ON OFF
Bit
0
0
0
1 0
0
1
0
Coil
7
6
5
4 3
2
1
0
Exception
Table 74: Exception of Function Code FC1
Byte
Field name
Example
...
Byte 7
MODBUS function code
0x81
Byte 8
Exception code
0x01 or 0x02
11.2.3.2 Function Code FC2 (Read Discrete Inputs)
This function reads the input bits from a slave device.
Request
The request specifies the reference number (starting address) and the bit count
to be read.
Example: Read input bits 0 to 7
Table 75: Request of Function Code FC2
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
0x02
Byte 8, 9
Reference number
0x0000
Byte 10, 11
Bit count
0x0008
