Stanford Research Systems RGA100, Руководство по эксплуатации и программированию

Страница: 290 / 362

Appendix D
SRS Residual Gas Analyzer
5
program flow much more quickly than by simply looking at the code. Bear in mind that performance of
the program slows drastically as it creates this ““movie”” of what goes on during execution.
Layers in the SRS RGA Development Kit
Communications Layer VIs
What are the communications layer VIs?
The VIs in the communications layer encapsulate the low-level serial communication commands as well
as doing some communications housekeeping. They allow the maximum in flexibility when creating
custom LabVIEW programs.
When should I use this layer?
The communications layer is only required when your application requires something not addressed by
the operations layer. These VIs are what many people get when they download ““LabVIEW drivers”” from
an instrument manufacturer’’s web site. The SRS RGA LabVIEW Development Kit goes far beyond this
primitive layer. Most users should work at the operations layer first, only using the communications layer
when strictly necessary.
An oversimplified example
CommExamplec.vi will run a single scan over a user-specified mass range. Note that a waveform chart is
used, and the abscissa units are not mass but rather simply the number of data points. Furthermore, the
ordinate is not in units of pressure, but is in the raw ampere reading returned from the RGA. This
example is simply meant to introduce you to some concepts used in the operations layer and to verify the
communications are functioning correctly under the LabVIEW environment. It is not meant as an
example to emulate or as a starting point for development.
Try the example:
Open LabVIEW
Select the RGA LabVIEW Library
Open the Communications example, CommExampleC
From the front panel, set the mass range for the scan
Make sure the virtual LED labeled ““Scan Enabled”” is lit
Set the COM port to be the same as the COM port the RGA is using
Run the VI