Synchronization of two sub-vis!

[henkel]

I am working under LV 7.0 and I have to acquire videos through FireWire. The cameras are included into LV via an ActiveX control. So far so good. Because I have to control 2 cameras I have to start the capturing simultaneously. I have written to sub-vis where I initialize the cameras and start the capturing. Now I am wondering how to synchronize these sub-vis because sometimes the files have different lengths, up to 5 frames or about one second. Is there a way to get this thing to work?

Thanks a lot in advance,

Henning

[Ben]

Hi Henning,

Please take a look at the example included with LV that can be found at

Help >>> Find Examples...

Optimizing Applications >>> Syncronizing Tasks >>> Rendezvous with SubVIs.vi


The help for this VI follows


"
This VI is a demonstration of using a rendevouz. It creates a rendezvous of size 3 and then calls three parallel subVIs using this rendevouz.

These subVIs use the rendezvous to synchronize the beginning of their loops. Each one displays integers to a graph. Finally, they all use the rendevouz to exit at the same time.

"

Please note that this will get sub-VI sync'd up at the begining of each cycle. I have to raise the concern that the actual interaction of the sub-VI's with their respective activeX service may end up se
quential if they all execute in the user interface thread.

The technique illustrated in my cited example should get all of your files sizes to match up.

I hope this helps,

Ben