Specifications

6-8 Command Syntax
SRS Residual Gas Analyzer
ID? RGA Identification Query.
MI1 Set initial scan mass to 1 amu.
MF100 Set final scan mass to 100 amu.
FL1.0 Turn on the filament to a 1.0 mA emission current.
NF* Use default noise floor setting. (sets scan rate and averaging.)
AP? Query the number of scan points to be received by the computer.
SC1 Trigger a single analog scan.
Programming tips
x Whenever possible, immediately follow a command that sets a parameter value with
one that queries the parameter setting in the RGA memory. For example, the second
command in the list above should be followed by a MI?, and a number 1 should be
echoed by the RGA.
x Whenever practical, check for errors at the end of command execution to make sure
“everything went well”.
x Even though the RGA head can store multiple commands in its receive buffer, it is
highly recommended that the host computer wait for the response of a query before a
new command (especially a new query) is transmitted to the RGA. This simplifies the
communications and also eliminates buffer overwrites.
x Commands that involve hardware control (such as turning the filament or the CDEM
on) trigger diagnostic checks on the hardware as they are executed. Since the
command execution time can be rather long, the RGA prompts the end of execution
by sending back the value of the STATUS byte to the computer. Always check the
value of the STATUS Byte returned for possible errors. In cases where a hardware
error is reported retry the command one more time before declaring a hardware
problem.
x With the exception of the ion current values, the output of the RGA are ASCII
character strings terminated by a <LF><CR> terminator. Ion signals are represented
as integers in units of 10
-16
Amps, and transmitted directly in hex format (four byte
integers, 2’s complement format, Least Significant Byte first) for maximum data
throughput.