Programming instructions

Chapter 17 NI 5411 Devices
DAQ Hardware Overview Guide 17-4 www.ni.com
wave in the lookup memory. Then, you can change the frequency of that
waveform by just sending one instruction. The frequency switching is
phase continuous. This mode is extremely useful for very fine resolution
function generation. You can generate sine tones up to 16 MHz with a
resolution of 10 MHz. Because this mode uses an accumulator, waveform
generation loops back to the beginning of the lookup memory after passing
through the end of the lookup memory.
The SYNC output is a transistor-transistor-logic (TTL) version of the sine
waveform being generated at the output. You can think of the SYNC output
as a very high-resolution, software-programmable clock source for many
applications. You also can vary the duty cycle of SYNC output on the fly
by using software control. The SYNC output might not carry any meaning
for any other types of waveforms being generated.
No linking or looping capabilities are available in this mode; however, very
simple triggering is available. DDS mode should be used for standard
function generation rather than for arbitrary waveform generation.
NI 5411 Device Waveform Pattern Generation
The NI 5411 devices can generate 16-bit digital TTL patterns that
correspond to the analog waveform being generated. The NI 5411 provides
a clock signal with this 16-bit digital output so that you can test your digital
device by latching these digital patterns. The digital pattern generation also
can use the full linking and looping features, triggering and timing features
of the NI 5411 for ISA and PCI. The pattern generation feature is useful for
testing digital devices like parallel DACs and serial DACs. It is useful in
testing semiconductor devices.
NI 5411 Device Pattern Generation Timing
The NI 5411 devices can generate waveforms based on an internal 40 MHz
update clock. Further division of the clock up to 65,535 segment loops is
possible by using an internal interval counter that is 16-bit wide. Set the
interval settings before starting the waveform generation.
You also can phase-lock the internal timebase to an external reference
frequency of 1 or 10 MHz. This feature is very useful for multiple-device
synchronization. You can do the phase-locking by using an external
I/O connector or by way of a RTSI clock line on a RTSIbus.