Stanford Research Systems RGA100, Operating Manual And Programming Reference

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10 Appendix D
SRS Residual Gas Analyzer
As shown in the figure, the Simple Table example uses just six VIs. All the VIs in gray are taken from
the operations layer, while the only one that is not is the general SRSRGA Error handler VI. Just as in the
communications layer example, you can see that an error cluster is propagated through the six VIs.
However, rather than propagating the SRSRGA VISA session explicitly, the session is propagated by
referring to its reference number (or refnum). By double-clicking on the sub-VIs that appear to the right
of the Open VI, you will see that each VI takes the refnum as input, then passes it to SRSRGAo Get
Session. This VI accesses the serial communications session referred to by the SRSRGA refnum, and
sends commands or receives data from that session. By using the operations level, you don’’t have to
worry about dealing with the VISA session directly; the VIs in this layer will handle that for you.
After taking your input from the specifications cluster and opening an SRS RGA session, the Start Table
VI sets the electron emission and calibrates any noise floor / electron multiplier parameters if necessary.
Within the while loop, the Measure Table VI sends repeated MR queries to the RGA, and formats the
binary data into an array of pressure readings. This array is plotted in the P vs. t graph that is visible on
the front panel. The rate at which the data appears is governed by the multiple millisecond delay in the
while loop. The user sets the delay from the front panel. The condition for the while loop is simply that
the user has not stopped the scan and that no errors are present. If the while loop ends, the mass filtering
is turned off, as is the electron multiplier and the filament. Any errors are reported at this time.
Simple Analog
Try the example:
Open LabVIEW
Select the RGA LabVIEW Library
Open the Simple Analog example, SRSRGAa Simple Analog
From the front panel of the VI, set the COM port that the RGA is using
Set the noise floor, mass, and electron multiplier state
Run the VI