Fieldbus controller 750-842
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71
Data exchange
Modular I/O System
ETHERNET TCP/IP
3.2.5.4
Data exchange between PLC functionality (CPU) and I/O modules
Through absolute addresses, the PLC functionality (CPU) of the PFC can di-
rectly address the bus module data.
The PFC addresses the input data with absolute addresses. The data can then
be processed, internally in the controller, through the IEC 61131-3 program,
whereby the flags are filed in a permanent memory area. Following this, the
linking results can be directly written in the output data via absolute address-
ing.
%IW0
%QW0
%QW255
%IW255
PII = Process Input
Image
PIO = Process Output
Image
Inputs
Outputs
I/O modules
750-4xx....6xx
PII
PIO
PLC functionality (CPU)
Inputs
Outputs
Programmable Fieldbus Controller
Fig. 3-28:
Data exchange between PLC functionality (CPU) and I/O modules
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