User's Manual

Chapter 2 Function Reference — Select_Signal
NI-DAQ FRM for PC Compatibles 2-380
© National Instruments Corporation
Use this signal for gating the waveform generation. For example, if you call this function with
signal =
ND_OUT_EXTERNAL_GATE, source = ND_PFI_9, and
sourceSpec =
ND_PAUSE_ON_HIGH, the waveform generation will be paused whenever the
PFI 9 is at the high level.
If you do not call this function with signal =
ND_OUT_EXTERNAL_GATE, NI-DAQ uses the
default values, source =
ND_NONE and sourceSpec = ND_DONT_CARE; therefore, by default,
the waveform generation is not gated.
signal =
ND_OUT_UPDATE_CLOCK_TIMEBASE
Use this signal as an input into the DAQ-STC update timer. The update timer generates timing
by counting the signal at its input and producing an
ND_OUT_UPDATE signal after the
specified number of occurrences of the
ND_OUT_UPDATE_CLOCK_TIMEBASE signal
transitions.
If you do not call this function with signal =
ND_OUT_UPDATE_CLOCK_TIMEBASE, NI-DAQ
uses the default values, source =
ND_INTERNAL_20_MHZ and
sourceSpec =
ND_LOW_TO_HIGH.
signal =
ND_PFI_0 through ND_PFI_9
The following table summarizes all the signals and source for the I/O connector pins PFI0
through PFI9.
source sourceSpec
ND_PFI_0 through ND_PFI_9 ND_LOW_TO_HIGH and ND_HIGH_TO_LOW
ND_RTSI_0 through ND_RTSI_6 ND_LOW_TO_HIGH and ND_HIGH_TO_LOW
ND_INTERNAL_20_MHZ ND_LOW_TO_HIGH
ND_INTERNAL_100_KHZ ND_LOW_TO_HIGH
signal source sourceSpec
ND_PFI_0
through
ND_PFI_9
ND_NONE ND_DONT_CARE
ND_PFI_0 ND_IN_START_TRIGGER ND_LOW_TO_HIGH
ND_PFI_1 ND_IN_STOP_TRIGGER ND_LOW_TO_HIGH
ND_PFI_2 ND_IN_CONVERT
(Refer to the
Special Considerations when
source =
ND_CONVERT
section
for more information.
ND_HIGH_TO_LOW
ND_PFI_3 ND_GPCTR1_SOURCE ND_LOW_TO_HIGH