Omega OMP-MODL, Руководство пользователя

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7... H
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ROGRAMMING
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SING THE
OMP-MODL 7-14
Program Net Execution Speed
NOTE: The information presented in this section is
provided for Users that are attempting to collect data at
faster rates (such as Samples per Second).
Users utilizing the OMP-MODL for data collection at
slower rates (eg Samples per Minute) may opt to skip
this section and refer to it later when faster rates are
required.
Due to the nearly unlimited flexibility and potential variations of Program Net
designs, it is difficult to specify the actual speed performance of Program
Nets. In an attempt to relate to the OMP-MODL User a feel for the Program
Net processing speeds to be expected, the following guidelines are
presented.
Additionally, a number of example Program Nets are provided in Appendix B
with their approximate execution speeds. From this information, a feel for
the speed of execution of most Program Nets can be developed.
Program Net Performance Guidelines
The time required for a Program Net to execute within the OMP-
MODL is a function of a number of variables including:
♦
Total number of icons in the Program Net - with a
greater number of icons to process each time the
Program Net loops, more time is required.
♦
Type of icons - different types of icons require various
amounts of time to process. For example, a
Thermocouple input icon requires a considerable
amount of processing time to perform the analog to
digital conversions, CJC measurements, and the
associated math. On the other end of the speed
spectrum, a Data Memory icon merely stores data into a
memory location... an operation which can be performed
very quickly.
♦
Program Net design - Program Nets can be developed
that have varying execution times that are a function of
inputs or values within the Net. A simple example of
this is a Program Net that scans a single digital input (eg
switch state) and only enables the logging of 10
thermocouple input channels when the switch is closed.
In this example, the digital input could be scanned very
fast when open, but when it closes, extra processing
time is required for the 10 thermocouple channels.
An Empirical Answer...
After optimization of a Program Net with consideration of the above
guidelines, the best way to determine the speed performance of a
Net is to upload it to a OMP-MODL and run it. If maximum speed is
the goal, the driving Sample Rate Clock rate can be set to a
minimum (eg 1mS) and the program can be tested. Review of the
data and actual sample times will result in a very accurate execution
rate value.