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Fieldbus
Abb. 3-11: Memory areas and data exchange for a field bus controller
In its memory space word 0 ... 255, the controller process image contains the
physical data of the bus modules.
#
$
The PFC variables are filled in the memory space word 256 ... 511 of the
process image.
%
&
In addition, the controller offers further memory spaces, which cannot be
accessed from the field bus side:
WAGO-I/O-SYSTEM 750
Bus System
Programmable fieldbus controller
Memory area
for input data
word 0
word 255
word 256
word 511
Memory area
for output data
word 0
word 255
word 256
word 511
The data of the input modules can be read by the CPU and from the
field bus side.
In the same manner, writing to the output modules is possible from the
CPU and from the field bus side. The value of the field bus master is
written to the output while writing on an output.
The PFC input variables are written in the input memory space from
the field bus side and read by the CPU for further processing.
The variables processed by the CPU via the IEC 61131-3 program are
filed in the output memory space and can be read out by the master.
Programmable Field Bus Controller 750-833
1
1
input
modules
3
3
IEC 61131
PFC
program
input
variables
CPU
2
output
modules
4
PFC
output
variables
• 65
Process Image
I/O modules
I
O
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