ORTEC DSPEC Pro, Hardware User Manual

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APPENDIX B. LIST MODE IN THE DSPEC PRO
The DSPEC Pro is equipped with List Mode, which streams spectroscopy data directly to the
computer, event-by-event, without the data “dead periods” associated with the acquire-store-
clear-restart cycle of standard spectrum acquisition.
MAESTRO v7 supports our List Mode MCBs with menu and toolbar commands, as well as
commands in our automated JOB streams. See the MAESTRO user manual for detailed
information.
This appendix provides details about the List Mode that will enable experienced programmers,
using the ORTEC C
ONNECTIONS
Programmer’s Toolkit with Microsoft
®
ActiveX
®
Controls to
write custom software applications for acquiring and saving List Mode data. For additional
information, see:
http://www.ortec-online.com/Solutions/applications-software.aspx?tab=2
B.1. List Mode Data
In List Mode, each detectable event that would normally be histogrammed as a spectrum is sent
to the computer in the form of a pulse-height value along with a time stamp that indicates the
time the pulse arrived. The data can be analyzed by the computer in real time to determine if
some significant event has occurred, or can be streamed to disk for analysis at a later time.
B.1.1. Spectrometer Data Format
List Mode data is retrieved from the DSPEC Pro spectrometer by calls to the C
ONNECTIONS
MIOGetData() DLL function or the C
ONNECTIONS
control GetRawData() method. A minimum
of 4 and a maximum of 16384 32-bit words of data can be requested at a time. Each request for
data returns a block of 32-bit list mode words that begin with a 32-bit integer number of valid
bytes followed by a 3-word C
ONNECTIONS
time stamp, thus the minimum of 4 words in a
request. The first word is the number of bytes returned, not including the first 4 bytes. The
minimum value returned here is 12, indicating 3 C
ONNECTIONS
time stamp words only, and the
maximum is 65532, indicating 3 C
ONNECTIONS
time stamp words plus 16383 data words.
The C
ONNECTIONS
time stamp represents the 64-bit Windows file time that corresponds to the
exact time that the request for data is sent to the spectrometer. At the exact time the C
ONNEC
-
TIONS
requests data from the spectrometer, the spectrometer creates a hardware time word in the
list mode data stream that indicates the corresponding time within the spectrometer. The 16-bit
real time number on the hardware time word is from the same time source as the 16-bit real time
stamps on each of the ADC words. Using the C
ONNECTIONS
time stamp and the hardware time
word you can determine the 64-bit Windows time associated with each ADC word in the buffer.