WAGO-I/O-SYSTEM 750
Fieldbus Communication 221
750-880, 750-880/025-000 ETHERNET Programmable Fieldbus Controller
Manual
Version 1.0.1
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To execute a desired function, specify the respective function code and the
address of the selected input or output data.
Note
Note the number system when addressing!
The examples listed use the hexadecimal system (i.e.: 0x000) as their numerical
format. Addressing begins with 0. The format and beginning of the addressing
may vary according to the software and the control system. All addresses then
need to be converted accordingly.
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Table 89: List of the MODBUS functions in the fieldbus controller
Function code
Function
Access method and description
Access to resources
FC1
0x01
Read Coils
Reading of several single input bits
R:
Process image,
PFC variables
FC2
0x02 Read
Input
Discretes
Reading of several input bits
R:
Process image,
PFC variables
FC3
0x03 Read
Multiple
Registers
Reading of several input registers
R:
Process image,
PFC variables,
internal variables,
NOVRAM
FC4
0x04 Read
Input
Registers
Reading of several input registers
R:
Process image,
PFC variables,
internal variables,
NOVRAM
FC5
0x05
Write Coil
Writing of an individual output bit
W:
Process image,
PFC variables
FC6
0x06 Write
Single
Register
Writing of an individual output
register
W:
Process image,
PFC variables,
internal variables,
NOVRAM
FC11
0x0B Get
Comm
Event Counters
Communication event counter
R:
None
FC15
0x0F Force
Multiple
Coils
Writing of several output bits
W:
Process image,
PFC variables
FC16
0x10 Write
Multiple
Registers
Writing of several output registers
W:
Process image,
PFC variables,
internal variables,
NOVRAM
FC22
0x16 Mask
Write
Register
W:
Process image,
PFC variables,
NOVRAM
FC23
0x17 Read/Write
Registers
Reading and writing of several
output registers
R/W:
Process image,
PFC variables,
NOVRAM