BECKHOFF C1220 User Manual
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Beckhoff Lightbus System Description
Beckhoff Lightbus - PC interface card C1220
The Beckhoff Lightbus consists of a physical ring which can be split into 8
logical rings for processing the process image. A logical ring only operates
on selected modules and terminal rows that are defined by means of so
called Communication Description Lists (CDLs). Transfer of the CDLs from
the host system to the central module will be discussed in further detail
later.
The process image is made available to the host system via the DPRAM.
The DPRAM is split into three areas:-
- Data:
Input, output and flags
- Communication: Initialization, test, analysis and configuration of the
Beckhoff Lightbus
- Process control: Updating of process images
To this end, the central module requires a 4 k byte area in the address
space of the host system.