What is the best way to execute code at a specific time?

[johanneshoer]

Hello,

I have a problem. I need to execute some code at a specific time: subVI A should run at e.g. 2 seconds (after start) and stop at 3.5 seconds and subVI B should execute at 3.5 seconds until 5 s. The user can choose the time points. It could also be that subVI B has to execute before subVI A or at the same time.
Time precission is not important +/- 20 ms is ok.

I have implemented it like that: In a loop (period time approx. 20ms) I query if the timeframe has come and then the subVI will be executed.

See attached picture.

I don't believe that this is an economic way. It will produce high CPU load. How can I do it better?

[johanneshoer]

and how can you insert pictures, so that you see them inside the posting and not as an attachment? 🙂

[parthabe]

Like this.   Use the "Upload or insert an image" option on the Toolbar of the Reply window.

Message Edited by parthabe on 10-13-2009 03:56 AM

[HaD]

Use "While Loop" with Case inside, and use Shift register to remember the last time that the Case was executed...

and if you need to run both vi's in parallel use two while loops.

[johanneshoer]

Aah, all right.

You've uploaded a picture with a red cross?

Message Edited by johanneshoer on 10-13-2009 04:18 AM

[johanneshoer]

@HaD

Something like this?

Johannes

LabVIEW 7.1 (!)

[johanneshoer]

I don't think that this is an optimum solution.

I see a problem. The timer value will wrap from (2^32)-1 to 0, so there might be a problem during comparison.

Even though it is very seldom, I can not accept that.

How can I improve it?   

[johanneshoer]

How is this?

Better?

Johannes 

LabVIEW 7.1

[parthabe]

Yeah, this is definitely a more correct approach.

P.S.:- PFA the missed-out attachment.

[johanneshoer]

Thanks parthabe,

but doesn't this require considerable processor power? Imagine I needed the timing accureate to a millisecond...

Is there no way similar to event structures?