Function Code Fc2 (Read Discrete Inputs); Table 73: Assignment Of Inputs; Table 74: Exception Of Function Code Fc1; Table 75: Request Of Function Code Fc2 - WAGO -I/O-SYSTEM 750 XTR Manual

WAGO-I/O-SYSTEM 750 XTR
750-352/040-000 FC ETHERNET G3 XTR
lowest value.
The assignment is thus made from 7 to 0 as follows:

Table 73: Assignment of Inputs

OFF OFF OFF ON
Bit
Coil
Exception

Table 74: Exception of Function Code FC1

Byte
...
Byte 7
Byte 8
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
Byte 0, 1
Byte 2, 3
Byte 4, 5
Byte 6
Byte 7
Byte 8, 9
Byte 10, 11
0 0 0 1
7 6 5 4
Field name
MODBUS function code
Exception code
Field name
Transaction identifier
Protocol identifier
Length field
Unit identifier
MODBUS function code
Reference number
Bit count
Fieldbus Communication 157
OFF OFF ON OFF
0 0 1 0
3 2 1 0
Example
0x81
0x01 or 0x02
Example
0x0000
0x0000
0x0006
0x01 not used
0x02
0x0000
0x0008
Manual
Version 1.3.0