function generator analog signal

[June Kiat]

Hi Everyone,

How do I get analog output (e.g. sine functions) from Basic Function Generator.vi using AO Write One Update.vi? Is this the right vi to write the analog output?? Do I need to build array before sending it to AO??


Help!!"

[Brent_R]

June,

The AO Write One Update.vi will only output points at the software loop rate, which is often not fast enough or determinisitic enough to generate a clean waveform. This VI is intended for immediate (software timed) updates and not waveform generation.

To get precisely timed analog output at much higher rates, you should probably be using a buffered operation. There are several good examples that show how to do buffered analog output. Take a look at Generate Continuous Sine Wave.vi and Function Generator.vi in the DAQ examples. The latter is slightly more detailed, however they both use the same concepts.

Take a look at Ch 12 in the Data Acquisition Basics manual for more info on analog output.

http://digital.ni.com/manuals.nsf/websearch/4BF
01A2B2206A4168625684F0064EFF3?OpenDocument&node=132100_US

Cheers,

Brent R.
Applications Engineer
National Instruments

[L Aguila]

June,

If you use the "AO Write One Update.VI", you will output the signal in software time. If you want this, just make the proper connections to the pins of this VI, and that's it. However, if you want to output a signal in hardware time, you must take a look at the "Getting Started with Analog Output.VI" in LV 6i, and can start to build your VI out of it. If you have LV 6.1, take a look at the "Generate Continous Sinewave.VI" and just get rid of the sinewave building section and place the wave you want to output there.

Hope this information is helpful.

L Aguila
Applications Engineer
National Instruments