as from the samples with my program.The problem is that I am trying to add a timers to control the amount of analong output begin time and end time.I know how to get the timer, but I don't know what parameters need to set in the shell of the program.ThanksI'm not really sure what you mean by controlling your analog output begin time and end time. Are you talking about putting one voltage level out at a time between timer intervals or starting a series of different ouput voltages at each timer interval?
The first thing you should do is become familiar with the timer control by looking at the timer.prj example in the C:\MeasurementStudio\cvi\samples\userint directory. Once you are familiar with how a timer's callback function and event model works look at the following.
If you are trying to control a single output voltage that will change each timer interval you can use the AO_Update function inside of the timer's callback function to do this. You should look at the "AOOnePoint" examples in the C:\Program Files\National Instruments\NI-DAQ\Examples\VisualC\Ao NI-DAQ C/C++ examples installation directory to get more familiar with how to put a single voltage on an output channel at a time. (The examples in the NI-DAQ Visual C folder use the DAQ C API and the source files can be used in both CVI or Visual C++, regarded that you have properly linked in the proper import libraries and pointed to the directory for the header files in the respective environments.)
If you want to actually start the generation of a series of output voltages every time a timer's callback function is called you will need to generate a "waveform" as described int the "WFMSingleBufSync" example in the same directory as the "AOOnePoint" examples. One thing to note though is that this "waveform" being outputted in this scenario will end on its own when all of the datapoints in the series have been generated. If you are actually wanting to stop a waveform's generation based on some software timebase, you might want to look at creating a regenerated waveform as illustrated in the "WFMDoubleBuf" or "WFMSingleBufRegenerated" examples, and when you want to stop the generation, call a function like DAQ_Clear inside of your timer's callback function to stop the analog output from updating.
Jason F.
Applications Engineer
National Instruments
www.ni.com/ask
