ORTEC DSPEC Pro, Руководство пользователя по оборудованию

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DSPEC Pro
®
Digital Gamma-Ray Spectrometer User’s Manual 794380D / 0914
94
Refer to the Win-32 function GetSystemTimeAsFileTime() for more information about the
64-bit time format contained in these words.
In the case where the data acquisition program does not get all of the data from the spectrometer,
the data block will not contain a hardware time word. In this case the data acquisition program
must immediately request another block of data from the spectrometer in order to find the corre-
sponding hardware time stamp. Note that the second block will begin with another C
ONNEC
-
TIONS
time stamp, which will correspond to another hardware time word. The data acquisition
program must associate the first C
ONNECTIONS
time stamp to the first hardware time word and
the second C
ONNECTIONS
time stamp to the second hardware time word even though the first
hardware time word appears after the second C
ONNECTIONS
time stamp. For example, if you
request 16384 words and the first returned word is 65532 indicating that 16380 data words plus
4 overhead words were returned, you should immediately request another block of data.
The DSPEC Pro has buffer storage for up to 96k 32-bit words. Therefore, six requests may be
needed to drain the buffer and find all of the hardware time words. In practice, a program buffer
of 96k words would always hold enough data to drain an instrument buffer assuming that all six
requests were made in less than 1 second.
The following tables describe the format for the list-mode data as returned by C
ONNECTIONS
from the DSPEC Pro spectrometer:
31 30 29 16 15 0
ADC Word 1 1 14-bit ADC value 16-bit real time in 200nS ticks
RT Word 1 0 30-bit real time in 10 ms ticks
LT Word 0 1 30-bit live time in 10 ms ticks
Table 3. Spectrometer List Mode Data Format.
31 24 23 16 15 8 7 0
Hdw Time
00000000 00000000 16-bit real time in 200nS ticks
C
ONNECTIONS
Time
00000001 Byte 2 Byte 1 Byte 0
C
ONNECTIONS
Time
00000010 Byte 5 Byte 4 Byte 3
C
ONNECTIONS
Time 00000011 00000000 Byte 7 Byte 6
ADC CRM 00000100 00000000 Counts per 10 ms period
Ext Counter 1 00000101 00000000 Counts per 10 ms period
Ext Counter 2 00000110 00000000 Counts per 10 ms period
Table 4. Spectrometer List Mode Data Format.