Rockwell Automation 1789-L10_L30_L60 SoftLogix 5800 System User Manual - Manual (Page 239)

Rockwell Automation Publication 1789-UM002J-EN-P - December 2012 239
Windows Considerations Appendix D
Run a SoftLogix Controller on
the Windows Operating
System The SoftLogix controller executes as a service (background program) that starts
when the Windows operating system starts and then runs at real-time priority
within the Windows operating system. Most other applications, such as word
processors and spreadsheets, run at normal priority. Because SoftLogix runs at a
real-time level, it is guaranteed to get as many CPU cycles as it needs before
allowing the CPU to execute other application programs. Only DPCs and ISRs
run before a SoftLogix controller.
Dwell Time Setting
Every SoftLogix controller has a main task that can be configured to run
continuously or periodically. If set for continuous, the main task would use all of
the Windows CPU cycles, if it were able, running as a real-time priority process.
But the dwell time configuration of the SoftLogix controller is a value in
milliseconds, which is directly added to the end of every scan of a continuous
program task. The dwell time is a period of time that counts off in real-time after
the SoftLogix controller’s continuous task. This time is like a sleep time for the
SoftLogix controller so that the Windows operating system can execute lower
priority threads.
If a SoftLogix controller’s periodic task is set to run, it runs during the dwell time,
but the time spent executing the periodic task is not added to the dwell time. The
dwell time counts in the background in real-time and the end of the dwell marks
the continuous task as ready to run. The continuous task will run as long as no
other periodic tasks are already executing or are ready to execute.
A dwell time of 0 ms does leave some dynamic amount of time of dwell that is less
than 1 ms to prevent you from using all CPU cycles, and thus locking up your
computer. When the continuous task enters the dwell time, it makes a function
call to the Windows operating system to ‘SwitchToThread,’ which is a function
that lets the next thread that needs to run go ahead and execute.
Third party peripheral devices Third-party peripheral devices, such as network cards and IDE devices should be installed directly in the computer’s
primary PCI bus. IDE devices should use PCI bus mastering. Bus mastering is the capability of writing directly to the
computer’s memory without having to use the Pentium chip to move the data. You can use Microsoft’s DMACHECK.EXE
utility to see whether a third-party card truly uses PCI bus mastering. You might also need to turn bus mastering on
within the BIOS setup of your computer. See the documentation for your computer for more information about
bus mastering.
TestTime utility The SoftLogix controller ships with a TestTime utility that you can use to determine the responsiveness of your system to
CPU interrupts. The utility measures how long it takes to respond to a software interrupt that is generated every 2 ms. It
measures the average, max, number of occurrences and standard deviation of how quickly your personal computer
responds. If you find significant delays, focus on any peripheral devices on the computer and their associated drivers. The
best way to use the utility is to run it on a new system with no software or third-party hardware installed to get a
baseline measurement. Then rerun the TestTime utility each time you install a piece of hardware or a software package to
determine if there is a anomaly.
Screen savers Disable screen savers on your computer. OpenGL screen savers have been known to generate excessive loading on a
personal computer. This can cause fluctuations in SoftLogix control because video-driver operations interrupt the
SoftLogix real-time execution priority under Windows. OpenGL is a standard for generating 2-dimensional and
3-dimensional graphics in current screen savers and animated games.
Table 11 - Windows Operating System Considerations
Consideration Description