BECKHOFF C1220 - Manual (Page 3)

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3 Beckhoff Lightbus System Description
Beckhoff Lightbus - PC interface card C1220
Beckhoff Lightbus System Description
The Beckhoff Lightbus consists of an intelligent central module and a field
bus based on fibre-optic conductor.
Beckhoff Lightbus
&RQ
WURO
'D
WD
$G
UHVVHV
+RVW V\VWHP
&HQWUDO PRGXOH
%HFNKRII /LJKWEXV
ILEHU RSWLF ULQJ
,2 PRGXOH
,2 PRGXOH
,2 PRGXOH 7HUPLQDO URZ
7HUPLQDO URZ
7HUPLQDO URZ
The Beckhoff Lightbus is coupled to the host System via a DPRAM, thus
guaranteeing fast and convenient communication.
Bus couplers for Beckhoff Bus terminals and diverse I/O modules are
available for processing the process image. Modules and bus couplers are
linked to one another in a ring structure. Thanks to the use of fibre-optic
conductor, interference sensitivity is low and the data transfer rate of 2.5
Mbaud is high. Errors occurring in the fibre-optic ring are detected by the
central module and are reported to the host system. Implemented ring
diagnostics functions enable swift error detection and remedying.
A communication protocol optimized for speed and simplicity has been
defined for data transfer between the central module and I/O modules.
Below, this communication protocol is also referred to as a telegram.
Communication on the fibre-optic ring is controlled by the central module. It
sends telegrams which pass through the individual modules and terminal
rows in the fibre-optic ring, and which are ultimately received again and
checked.
A telegram consists of the telegram frame and contents.