Specifications

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A-3
A LAUER driver
A1.1 Description of the handling software
The enclosed -PCSKOMM PB manages the data transfer between the
transfer area (a data block by default) and a PCS 830.
The README.DOC file contains current notes concerning the use of the
various projects.
1. The PB uses the MBs 246 to 255 as temporary flags. Writing to
these MWs does not influence the PB as long as they are not
simultaneously used by interrupt programs. The contents must be
written newly on entering the PB and saved on exiting if these MWs
are required by other PBs. In no case, interrupt programs are allowed
to write to these MWs!
2. The transfer area may not be specified within the data block when
using EPROM modules. In this case, the cross-reference DB must
be adjusted in such a way that the system area and the used varia-
bles are located in the RAM area of the CPU (for instance in the data
buffer).
The implementation is limited (besides the cyclical call of the-
PCSKOMM PB) to reading of and writing to the DWs in the transfer
DB (only with default assignment!). The presence of the (selectable)
transfer DB is not examined. It must be present with the required net
length (dynamic) in the programmable controller. Otherwise the
programmable controller shows a fault (possibly only at the first call of
a present value). A general fault bit (P3) enables the communication
status to be evaluated by the ladder diagram. The data transfer has
been stopped if this fault bit is set to 1. It can be restarted by setting
the (P2) flag. Furthermore, another restart flag is required. This is
set after the first successful processing of the handling PB. The restart
flag must be reset in OB 7 and 8.
A1.2 Scan time extension
Each task requires a header with one additional word. Since the length of
task 5 depends on the number of the external variables in the display (0
to 24 words including headers if the data sources are not consecutive), a
maximum of 40 words per cycle will be transferred with the PB. The transfer
of the clock happens only every second and costs 3 additional words. All
other tasks can be neglected for the average calculation since they only
appear isolated.
On average, the processing time of the -PCSKOMM PB totals approxi-
mately 10 milliseconds (CL 300).
Refer to section 2.3.1. for the limitation of the package length. The lengths
of the individual tasks can be taken from the section 5.3.
The response is optimal if the scan time is selected sufficiently large with
the PCSKOMM PB finding a PCS 830 board ready for data interchange
in each cycle. The test and the perhaps required repetition of the packages
is organized in the PCS 830.
The design of the PCSKOMM PB contains provisions for aborting the
communi-cation on every occurring fault and signalling it to the outside.
After this, communication must be explecitely restarted using an input
(Parameters P2). Of course, this does not affect repetitions caused by
reparable faults as these are treated in the PCS 830 internally.