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Chapter 2 Function Reference — WFM_Group_Control
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National Instruments Corporation 2-421 NI-DAQ FRM for PC Compatibles
Note If you invoke this function to clear continuous waveform generation that was
stopped previously because of an underflow error,
WFM_Group_Control does not
report the occurrence of the underflow error. If you want to check for this type of
error, invoke function
WFM_Check prior to invoking WFM_Group_Control to
clear waveform generation.
Note For the MIO-16/16D, counter 2 must be available in order to use waveform
generation. If an interval scan is in progress (see
SCAN_Start) or a CTR function
is using counter 2, waveform generation cannot proceed.
For Lab and 1200 Series analog output devices, if the rate is smaller than
15.26 pts/s and counter B0 is busy in a data acquisition operation, waveform
generation cannot proceed.
For the AT-MIO-16F-5, AT-MIO-64F-5, and AT-MIO-16X, one of the counters
1, 2, or 5 must be available. NI-DAQ uses the first available counter among
counters 5, 2, and 1, in that order. If counter 5 is in use, and NI-DAQ if forced to
use counters 2 or 1, a RTSI line must also be available.
On Am9513-based MIO devices, to trigger a waveform generation operation
externally, you can do so by first changing the gating mode of the counter
NI-DAQ uses.
On Am9513-based MIO devices,
WFM_OP uses either the default gating mode
(none) or the gating mode you specify through the
CTR_Config function. You
need to connect your trigger signal to the gate pin on the I/O connector.
operation = 2 (PAUSE): Temporarily halts waveform generation for the group of
channels. NI-DAQ maintains the last voltage written to the
DAC indefinitely.
Note This value of operation = 2 is not supported for the AT bus E Series devices
(except the AT-MIO-16XE-10), the 4451 devices, the 4551 devices, or the
DAQArb 5411 devices.
operation = 4 (RESUME): Restarts waveform generation for the group of channels that
previously halted by operation = PAUSE.
Note This value of operation = 4 is not supported for the AT bus E Series devices
(except the AT-MIO-16XE-10), the 4451 devices, the 4551 devices, or the
DAQArb 5411 devices.
When you have halted a waveform generation by executing PAUSE, RESUME restarts the
waveform exactly at the point in your buffer where it left off. If n iterations of the buffer
remained to be completed when you executed operation = PAUSE, those n iterations are