voltage ramp

[bassinbc]

The attached voltage ramp works. The supVI that actually does the ramp is timed correctly and will complete on time. However, the calling VI seems to take some time to pass and receive variables and the total time gets off. The ramp is for cDAQ-9172 using module NI 9263. I setup an array of 9 elements that can be scaled upward if needed. You would simply duplicate the last case, add a repeat control to the global vi and change the references to the new repeat control (note the repeat controls are hidden in the global VI). To make the program end you simply put the same sequence number in the last sequence. If you had three sequences then on the third sequence you would select sequence 3. When sequence 3 completes the program ends. Use the repeat to step back over a previous sequence numerous times before moving to the next sequence. This all works ok just runs a bit long as stated above. Glad to share this VI and hope someone could guide me on how to correct the timing issue. If someone has a completely new way of doing this I'm open to suggestions.

[griffindore]

Hi bassinbc,

The time probably gets off because you are creating your DAQ task and clearing the task each time the subVI is called. There is overhead to doing this. I also notice that everything is being timed with software timing. There's no guarantee that your timing will be accurate when performing software timing. You may want to consider calling the create and clear task functions in a seperate part of the program rather than the subVI that is repeatedly called. I hope this helps!

[bassinbc]

Thanks for your replay. I tried that and it didn't help. The time to voltage setting can be adjusted to get the correct time (add or substract time as needed). That will be the easiest way.