Programming instructions

Chapter 17 NI 5411 Devices
© National Instruments Corporation 17-3 DAQ Hardware Overview Guide
NI 5411 Device Waveform Generation
The NI 5411 for ISA and PCI can generate arbitrary waveforms at the
output at the sustained update rate of 40 MHz. The waveforms are first
loaded as segments into the waveform memory on the device. Waveforms
then can be generated as a sequence of any combination of segments.
Because you can loop over the segments and link to any other looped
segments, the effective waveform memory becomes even larger.
Figure 17-1 shows the concept of waveform sampling, waveform
segmentation, and waveform sequencing.
Figure 17-1.
Examples of Waveform Generation
Because deep memory is available on the NI 5411 for ISA and PCI, you do
not need to tie up the bus by transferring the waveforms as they are being
generated. Various operational modes, such as continuous, stepped, and
burst, are available on these devices to further enhance the capabilities of
your arbitrary waveform generation.
DDS Mode
The NI 5411 devices have a 32-bit accumulator, which is used with a
16,384-sample lookup memory to create a Direct Digital Synthesizer
(DDS). The lookup memory is dedicated to the DDS mode only and cannot
be used in ARB mode. You can store one cycle of a repetitive waveform;
for example, a sine wave, a triangular wave, a square wave, or an arbitrary
Wavelet1 Wavelet2
Segment Loop Count = 3
Wavelet3
Segment Loop
Count = 1
Wavelet4 Wavelet5
Segment Loop
Count = 2
Wavelet6
Segment Loop Count = 4
Waveform Points Form
A Waveform Segment(1)
Loops of Waveform Segment(1)
Form A Wavelet
Waveform Segment(2) Waveform Segment(3)