hardware-triggered timer

[mha2010]

Hi,

 although similar posts exist that I have to play with a little bit I have a specific question:

I would like to be able to have an output timer (let's say 1KHz) that is hardware based, by which I mean the software only starts it or finishes it, and the rest is not in software (so it can be deterministic and runs without labview)... now I would like to start the timer (trigger) or stop it using another port in hardware...

My ideal case would be something like this: labview app starts the timer task (without stoping the timer task) suppose the pc restarts (so the app is not running anymore)... the timer is supposed to continue running until a hardware port gives a pulse and then the timer is triggered to stop... the same thing for starting, a hardware signal gives a pulse and the timer is triggered to start.

[DFGray]

The timers on most DAQ boards will do what you want if you set up the start and stop triggers correctly.  The functionality will differ based on what DAQ board you have (E series, M series, X series, etc.), but you should be able to do it.  If you want the ultimate solution, use one of the R-series FPGA boards or a CompactRIO system and program exactly what you want into the FPGA.

[mha2010]

I guess it is not possible in cDAQ as I am concerned...

Althu,

I managed to use an analog output with a 100kHz external clock on cDAQ which I can just use. The problem with that is that somehow, it stops working after several minutes. The setup is a continuous time waveform written, and the several minute thing is not dependent on the buffer size or the rate of the clock or number of samples.

[DFGray]

Let us know what hardware you have and we may be able to give you a solution.

[mha2010]

I have cdaq9172,

with modules

9263

9264

9203

9205

9421

9476

9472

9725

I was also creating a counter by 9472. Is that working all onboard when using implicit timer?

[DFGray]

I know you can do what you want with a cRIO backplane and your modules, but am unfamiliar enough with cDAQ to need help.  I have forwarded your question to someone who should be able to help.  Ping again if you have not received a response in a reasonable amount of time.

[Ben_Craig]

Restarting a machine with an E, M, X, or S series board in it will cause all counter tasks to get stopped / aborted.

Is your host PC going to sleep and/or hibernating?  That would also cause the counter task to abort.

You can have a counter task that consumes almost no CPU while it is running.  Once you have started the counter task, you can just have your application (not your computer!) sleep in a loop.  You may want to query "Is Task Done?" periodically to make sure there have been no hardware errors, but that is all the work that the software should have to do once the task has started.