User manual

Chapter 3 Software Overview
NI-DAQ User Manual for PC Compatibles 3-42 ni.com
3.
WFM_Rate
to convert a data output rate to a timebase and an update
interval that generates the rate you want.
WFM_Rate
only supports
some devices. Because it does not have a device number parameter,
it cannot return an error if you use it with a non-supported device.
See the NI-DAQ Function Reference Online Help file for supported
devices.
4.
WFM_ClockRate
or
WFM_Set_Clock
to set the update rate (see the
NI-DAQ Function Reference Online Help file to find out which
function supports your device).
5.
WFM_Group_Control
(with operation=
START
) to start the waveform
generation in the background and return to your application after the
waveform generation has begun.
The next step in Figure 3-15 shows how the call to
WFM_Check
.
WFM_Check
retrieves the current status of the waveform generation. Your
application uses this information to determine if the generation is complete
or should be stopped.
The final step is to call
WFM_Group_Control
(operation=
CLEAR
).
The
CLEAR
operation performs all of the necessary cleanup work after a
waveform generation. Additionally,
CLEAR
halts any ongoing waveform
generation.