Memory Areas - WAGO -I/O-SYSTEM 750 User's Installation And Configuration

66 • Fieldbus controller 750-842
Data exchange
3.2.5.1

Memory areas

Fig. 3-26: Memory areas and data exchange for a fieldbus controller
In the memory space word 0 ... 255, the controller process image contains the
physical data of the bus modules.
(1) The data of the input modules can be read by the CPU and from the field-
(2) In the same manner, writing on the output modules is possible from the
The PFC variables are filed in the memory space Word 256 ... 511 of the proc-
ess image.
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.
In addition, with the ETHERNET TCP/IP controller all output data are mirror
imaged on a memory space with the address offset 0x0200 which allows to
read back output values by adding 0x0200 to the MODBUS address.
fieldbus
master
bus side.
CPU and from the fieldbus side. The value of the master is put out on the
output while writing on an output.
Programmable Fieldbus Controller
memory area
for input data
1 1
word 0
input
modules
word 255
3 3
word 256
PFC
input
variables
word 511
memory area
for output data
2
word 0
output
modules
2
word 255
word 256
4
PFC
4
output
variables
word 511
I/O modules
IEC 61131-
program
CPU
I
Modular I/O System
ETHERNET TCP/IP
O
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