what is the purpose of the use of waveforms in analog generations?

[newbieeng]

Hi all. I am really confused on analog generation with daqmx on my NI 9188 chassis with NI 9263 module. I looked all examples shipped with labview 2009 but I could not understand anything. I want to control a motor and an universal controller (relay) by sending constant analog voltage. I want to do it with hardware timed instead of software timed. I tried to work just one channel of the module NI 9263 and encountered errors of buffer size. How to posible generate analog voltage from one channel without error? In examples, almost all of them, waveform is used. What is the logic of it? Do I have to use waveform? I just want to generate constant analog voltage for each channel and control them during run of the program. but waveforms vary between - and + ranges of numbers. I do not need - side. What could I do?

[Dennis_Knutson]

A waveform data type is nothing more than an array of Y values, a start time (t0), and time between samples (dt). I don't know why you think is has to contain negative values. The Y values can be anything, a single point, multiple points of the same value, etc. You have the option to write a waveform or a single scalar with the DAQmx Write. I don't understand the need for hardware timing unless you want to output an array of values with specific timing between points.

[newbieeng]

I am preparing a vi that is capable of acquiring, analyzing, and controlling of a test system. I need to control a compressor in accordance with acquired temperature values. For accurate synchronization, I want to use hardware time of the chassis 9188. For utilize hardware timing, analog generation needs to use waveforms. And waveforms are not constant functions. They fluctuates between negative and positive values by generating sinus, square, saw, etc. signals. However, I need to utilize constant signal by use of constant functions (for ex. f(x)=10). This is why I want to utilize hardware time on my system. But I realized that it is too complicated, so I decided to go through with software timing. I wish I would not encounter a problem in synchronization of proceess tasks. Thank you for your advice.

[Dennis_Knutson]

You didn't pay attention to what I said. A waveform does NOT have have to contain both positive and negative values.