National Instruments AT-MIO-64F-5, Руководство пользователя

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Register Map and Descriptions Chapter 4
AT-MIO-64F-5 User Manual 4-6 © National Instruments Corporation
Bit Name Description (continued)
10 INTGATE Internal Gate Ð This bit controls internal and external A/D
conversions. When INTGATE is set, no A/D conversions take
place. When INTGATE is cleared, A/D conversions take place
normally. INTGATE can be used as a software gating tool, or to
inhibit random conversions during setup operations.
9 RETRIG_DIS Retrigger Disable Ð This bit controls retriggering of the
AT-MIO-64F-5 data acquisition circuitry. When RETRIG_DIS is
set, retriggering of the data acquisition circuitry is inhibited until
the end of the previous operation is acknowledged by clearing the
DAQPROG bit in Status Register 0. When RETRIG_DIS is
cleared, the data acquisition circuitry may be retriggered any time
following the end of the previous acquisition sequence.
8 DAQEN Data Acquisition Enable Ð This bit enables and disables a data
acquisition operation that is controlled by the onboard sample-
interval and sample counters. If DAQEN is set, a software DAQ
Start or hardware (EXTTRIG*) trigger starts the programmed
counters, thereby initiating a data acquisition operation. If
DAQEN is cleared, software and hardware triggers have no effect.
7 SCANEN Scan Enable Ð This bit controls multiple-channel scanning during
data acquisition. If SCANEN is set and DAQEN is also set,
alternate analog input channels are sampled during data acquisition
under control of the channel configuration memory. If SCANEN
is cleared and DAQEN is set, a single analog input channel is
sampled during the entire data acquisition operation. When
SCANEN is set, the SCANCLK signal at the I/O connector is
enabled. Otherwise, it is disabled.
6 SCN2 Scan Mode 2 Ð This bit selects the data acquisition scanning mode
used when scanning multiple A/D channels. If SCN2 is set and
SCANEN and DAQEN are set, interval-channel scanning is used.
In this mode, scan sequences occur during a programmed time
interval, called a
scan interval . One cycle of the scan sequence
occurs during each scan interval. If SCN2 is cleared and SCANEN
and DAQEN are set, continuous channel scanning is used. In this
mode, scan sequences are repeated with no delays between cycles.
5 CNT32/16* 32 or 16 Bit Sample Count Ð This bit selects the count resolution
for the number of A/D conversions to be performed in a data
acquisition operation. If CNT32/16* is cleared, a 16-bit count
mode is selected and Counter 4 of the Am9513A Counter/Timer
controls conversion counting. If CNT32/16* is set, a 32-bit count
mode is selected and Counter 4 is concatenated with Counter 5 to
control conversion counting. A 16-bit count mode can be used if
the number of A/D sample conversions to be performed is less than
65,537. A 32-bit count mode should be used if the number of A/D
sample conversions to be performed is greater than or equal to
65,537.