User manual

Chapter 3 Software Overview
© National Instruments Corporation 3-41 NI-DAQ User Manual for PC Compatibles
WFM_Scale
Translates an array of floating-point values
that represent voltages into an array of
binary values that produce those voltages.
The function uses the current analog output
configuration settings to perform the
conversions.
WFM_Set_Clock
Sets an update rate for a group of channels.
Waveform Generation Application Tips
This section outlines a basic explanation of constructing an application
with the Waveform Generation functions. The flowcharts are a quick
reference for constructing potential applications from the NI-DAQ function
calls.
Basic Waveform Generation Applications
A basic waveform application outputs a series of voltages to an analog
output channel. Figure 3-15 illustrates the ordinary series of calls for a
basic waveform application.
The first step of Figure 3-15 calls
WFM_Scale
.The
WFM_Scale
function
converts floating-point voltages to integer values, thus producing the
voltages (DAC values) you want.
You have two options available for starting a waveform generation.
The first option is to call the high-level function
WFM_Op
.The
WFM_Op
function immediately begins the waveform generation after you call it.
If the number of iterations is nonzero,
WFM_Op
does not return until the
waveform generation is done and all cleanup work is complete. Setting
the iterations equal to 0 signals NI-DAQ to place the waveform generation
in continuous double-buffered mode. In continuous double-buffered mode,
waveform generation occurs in the background, and the
WFM_Op
function
returns immediately to your application. See the Double-Buffered
Waveform Generation Applications section later in this chapter for more
information.
The second option to start a waveform generation is to call the following
sequence of functions:
1.
WFM_Group_Setup
(required only for the AT-AO-6/10) to assign one
or more analog output channels to a group.
2.
WFM_Load
to assign a waveform buffer to one or more analog output
channels.