Supplementary Conditions Regards Software And Hardware - Siemens SINUMERIK 840Di System Overview

02.2001
4.5 Supplementary conditions regards software and hard-
ware
As it is generally known, Windows NT is not an operating system designed for hard
real time requirements whereby the term 'hard real time requirements' is to be un-
derstood in this context as a defined response time of the operating system due to
an external event in the range of a few µ seconds.
One of the advantages provided by the method developed by Siemens is that the
real time capability of the operating system can be achieved with Windows NT
standard facilities so that the compatibility with Windows NT is fully maintained. To
this aim, the NC system software is integrated in Windows NT using via a specific
Kernel Mode driver, thus integrating its own real time system providing for the ap-
propriate real time requirements parallel to Windows NT.
Real time violations
A PC is generally an open system whose hardware and software can be extended
and modified by components of different manufacturers. Real time violations can
therefore occur if inappropriate PC components or configurations influence the
system behavior such that the NC system software cannot be activated at the de-
fined time.
The term 'inappropriate PC components' denotes in this conjunction drivers or
hardware extensions that have a negative influence on the real time behavior due
to interrupt blocking times too long or PCI bus locks in conjunction with PCI bus
mastering or DMA mode. In case of real-time violations from 200µs up, the opera-
tional reliability of the NC system software is no longer guaranteed. Depending on
the size of the real time violation, the system response can be as follows:
•
Display of an error message
•
Alarm with the axes stopped by the NC
•
Alarm and drive-independent stopping of the axes
The real time behavior of a SINUMERIK 840Di can be watched using the NC/PLC
system diagnosis included in the 840Di-Startup user interface.
Certification of extensions
To be able to offer high quality and reliability performance of the whole system, a
SINUMERIK 840Di is supplied completely configured and ready to operate.
To this aim, the system components used are subject to a certification procedure at
SIEMENS as the system manufacturer. Within the framework of this certification
procedure, the observance of the real time capability of the entire configuration is
proven and documented in all relevant operating modes.
In the case of modifications to or extensions of PC components (hardware and/or
software) by any third persons, no mandatory statements can be made by Siemens
© Siemens AG 2001 All Rights Reserved
SINUMERIK 840Di System Overview (SYI) - 02.2001 Edition
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