microDXP Technical Reference Manual
Version 3.15
October 7, 2019
28
2-5 above, and then set the
Digital Base Gain
to compensate for the difference, as
described in §3.4.3. Use command 0x8F to save the current GENSET. Please refer to the
RS-232 Command Specification for details.
2.4.4 Reading the Current GENSET
The RS-232 command to read the current GENSET table is 0x8E. Please refer to the RS-
232 Command Specification for details.
2.4.5 Saving the Current GENSET to Non-Volatile Memory
The RS-232 command to save the current GENSET table is 0x8F. Please refer to the RS-
232 Command Specification for details.
2.5 Spectrometer Settings and PARSETs
The PARSET, specified in Appendix D, is a table of peaking-time-related spectrometer
parameters, e.g. filter values, thresholds, pileup inspection settings, etc. Parameters within
the PARSET can be modified and stored such that a calibrated spectrum with optimal
settings is achieved whenever the
Peaking Time
is subsequently selected. The PARSETs
are stored in the nonvolatile flash memory. Twenty-Four (24) peaking time values, and
thus 24 PARSETs, are available.
The PARSET also contains 5 sets of gain tweaking and threshold settings, each
corresponding to the 5 GENSETs or MCA formats. Storing thresholds and gain settings
for every combination of peaking time and MCA format eliminates the need for calibrating
a given combination more than once.
The factory-set default spectrometer settings should be adequate to acquire a recognizable
spectrum. To achieve optimal performance the spectrometer settings must be adjusted, and
stored to non-volatile memory such that the optimized settings will be accessible in the
future. The slow filter
Peaking Time
should be chosen as a balance between energy
resolution and throughput requirements (see §4.9).
2.5.1 Selecting a PARSET
Each PARSET corresponds to a
Peaking Time
. In ProSpect, PARSET settings are
accessed via the Acquisition tab of the Settings panel. PARSETs 0-23 can be selected via
the
Peaking Time
drop-down list. Modifications to spectrometer settings for the selected
PARSET can be tested by pressing the
[Apply]
button, and saved to nonvolatile memory
via the
[Save]
button. Note that if you attempt to change the
Peaking Time
after changing
any PARSET settings, ProSpect will ask whether you want to abandon the changes or save
them.
The RS-232 command to select a PARSET is 0x82. Note that this command simply
retrieves one of twenty-four tables of spectrometer settings from nonvolatile memory. If
you have modified any settings associated with the current PARSET they will be lost when
command 0x82 is executed. Use command 0x8D to save the current PARSET table first.
Please refer to the RS-232 Command Specification for details.
2.5.2 Thresholds
Proper triggering on input events depends on good threshold settings, particularly for the
so-called
Trigger
(fast filter) and
Baseline
(intermediate filter) thresholds. The DSP
