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Function Description
WAGO-I/O-SYSTEM 750
750-806 Fieldbus Controller DeviceNet
TM
Manual
Version 2.0.0
7.3.1
Communication Interfaces
For the data exchange, the fieldbus controller has essentially three interfaces:
•
interface to the fieldbus (fieldbus master)
•
PLC function of the fieldbus controller (CPU)
•
interface to the I/O modules.
There is a data exchange between: fieldbus master and the I/O modules, PLC
function of the fieldbus controller (CPU) and the I/O modules and between the
fieldbus master and PLC function of the PFC (CPU).
The PLC functionality of the PFC (CPU) accesses the data via IEC 61131-3
variables.
Access from the fieldbus side is fieldbus specific.
7.3.2
Memory Space
A memory range of 256 words (word 0 ... 255) is available in the fieldbus
controller for the process image of the physical input and output data.
The fieldbus controller has an additional memory area for the figure of PFC
variables defined according to IEC 61131-3. In this extended memory area (each
word 256 ... 511), the PFC variables are mapped behind the physical process data.
Access by the PLC to process data is made independently from the fieldbus
system in all WAGO fieldbus controllers; access is always conducted through an
application-related IEC-61131-3 program.
How the data is accessed from the fieldbus side depends on the fieldbus however.
