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76 •
Fieldbus coupler/controller
Review
Fig. 3-7: Data exchange between PLC functionality (CPU) of the PFC and I/O modules
Note
A process image restructuring may result if a node is changed or extended. In
this case the process data addresses also change in comparison with earlier
ones. In the event of adding a module, take the process data of all previous
modules into account.
3.2.6.2.2 Addressing the PFC variables
The PFC variables are to be found in the memory ranging from word 256 to
512. When programming an internal PLC application, the CPU accesses PFC
variables via absolute addresses. However, depending on the data type used, the
same physical address space is addressed differently.
Tab. 3-3: Utiliztation of the address range for PFC variables
Bit Address
Byte Address
Inputs
I/O modules
%IW0
PII
%IW255
Inputs
PLC functionality (CPU)
Programmable Fieldbus Controller
Byte addresses
1024
512
511
0
Outputs
750-4xx....6xx
%QW0
PIO
%QW255
Outputs
Word addresses
512
256
255
0
Word address .0 to .15
1st byte:
2 x Word address
2nd byte:
2 x Word address + 1
PII = Process Input
Image
PIO = Process Output
Image
g012943d
Double word addresses
256
128
127
0
L
W
ON
ORKS
®
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