Stanford Research Systems RGA100, Operating Manual And Programming Reference

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6-48 Scan and Measurement Commands
SRS Residual Gas Analyzer
Echo: Query Response.
Set the Initial Mass value (in amu) for Analog and Histogram scans.
The first ion current transmitted during an analog or histogram scan corresponds
the mass-to-charge ratio specified by the MI parameter.
Note that the initial mass setting is shared by both Histogram and Analog scans,
and must be an integer number.
Parameters:
MIparam, param: 1-M_MAX: The parameter represents the initial scan mass
in amu units.
The upper mass limit depends on the SRS RGA model number: M_MAX=100
for RGA100, 200 for RGA200 and 300 for the RGA300.
MI* : The initial mass value is set to its default value.
Default value: 1.
MI? : Returns the value of initial mass to be measured during scans.
Error checking:
Number parameters must be within the specified range, and be integers.
The mass value set by MI must always be less than or equal to the final mass
setting MF or else a parameter-conflict communications error is generated.
The absence of a param (i.e. MI) generates a bad parameter error .
MRparam, param:0 - M_MAX
Description : Single Mass Measurement
Echo: Ion Current
Excecute a single ion current measurement at a specified mass setting. The
parameter is the
integer mass number (mass-to-charge ratio in amu units) at
which the measurement is performed.
The type of detector and noise-floor settings to be used by the measurement must
be selected in advance with the NF and HV commands.
The precision and duration of the measurement are totally determined by the NF
parameter value. The scan rates and signal-to-noise ratios for the different NF
settings of the electrometer are listed in a table in the Electrometer section of the
““RGA Electronic Control Unit”” chapter. The command execution time includes
some initial time spent waiting for the Quadrupole Mass Filter and the
electrometer response to settle. As usual, a compromise must be made between
signal-to-noise and measurement time.