Specifications

Features and Operation 5-11
SRS Residual Gas Analyzer
alarm parameters, and graph trace colors.
In Annunciator mode each channel value (partial pressure) is acquired directly from the
RGA head by individually querying the partial pressure for the appropriate mass. This
is done for all the selected masses using the present scan schedule as a trigger.
Library (Mode Menu )
Library mode displays the selected library gas fragment patterns in a histogram graph.
When split with a histogram or analog graph, the mass range of the library will
automatically match that graph's range for easy comparison of gases. All library
information is read from the "srsgas.lib" ASCII file located in the same directory as
"rga.exe". This file may be edited (with a text editor) to add, delete, or modify gases in
the library. The exact library file format must be preserved for proper operation of this
mode.
The Library Traces (bars) colors may be changed by either double clicking on the bars
directly or by using the Traces command (Graph menu).
The library scan parameters (displayed mass range) may be changed using either the
Scan Parameters… command in the Scan menu or the shortcut button of the Parameter
button .
Data Acquisition
The terms Data Acquisition and Scanning are used interchangeably in the SRS RGA
documentation. A scan implies that the SRS RGA Head is performing ion current
readings and sending the data over the RS232 cable to the PC running the RGA program
at a fixed rate of 28.8 kbaud. This data is graphed using the currently active display
mode chosen by the user. The speed of graphing depends on the hardware used and can
vary with types of CPUs, video cards, Serial ports etc.
The main procedure for establishing a live scan is outlined below:
1. Turn on the SRS RGA Head.
2. Establish a connection between the RGA program and Head (Head menu or
Connection button).
3. Select the desired display mode (Mode Menu or mode button).
4. Turn On the Filament (Head menu or Filament button).
5. Select the desired scan parameters (Scan menu or Parameter button).
6. Select the desired trigger rate (Scan menu or Schedule button).
7. Select the Start scan command (Scan menu or Start button).
Scan Data Logging
Scan Data logging (or scan logging ) is used for saving raw scan data to disk without the
overhead that comes with saving an RGA Head file.