design time-bounded visionapplication on reatlime

[BeKo]

Hello,
I want to do a position control  with a vision system. Therefore, I would like the vision algorithms to evaluate on LabView Real Time. But I do not know how I design a vision application on RT.  How do I have  to program time Bounded Execution? At the beginning I would like to calibrate the whole system. The position acquisition (actual value) is done with IMAQ Find Circular edges. Are there any information to build vision applications for real-time  or examples? Thank you.

[Elmar_NI]

Hello Beko,

i dont know which real time platform do you have. A PXI System with LV Realtime and a framegrabber card or a Compact Vision System (CVS). First you should add your realtime target to your Labview Project. But i think its very helpful if you look at the webcast.

http://zone.ni.com/wv/app/doc/p/id/wv-162

Kind regards,

Elmar

[BeKo]

Hello,
I habve the Labview ETS System on a desktop pc with a firewire camera. I viewed the webcast and I built an example application. But I have some questions:

1. You should pre-allocate resources during initialization before entering the time-bounded code (with IMAQ Initiialize Timed Exceution) -> But I need the IMAQdx Grab.vi in the timed environment, to get continuous images.

2. I must also define also settings (like contrast, scan direction) in the time-bounded while loop -> is there another possibility or alternative ?

3. I must also redefine the ROI in the while-loop, because my object for edge detection ( in Sub-Vi) is moving in the image and I want to confine the search area -> Is this okay in the time critical loop?

Kind regards,
Beko

[Elmar_NI]

Hello Beko,

to your questions:
1. in your application code in the attachement you preallocate the buffer with the Grab setup vi. LV create a ring buffer and the grab function in the while loop overwrite the old images.
Open context help for more information about the function itself.

2. You can get and set parameters with the property node. If you want change the settings during the runtime you must place the property node in the while loop.
To find out the correct property please look at Start/Programme/National Instruments/Vision/Documentation/NI Imaqdx and open the "NI-IMAQdx_Function_Reference.chm"
And display Attributes by name.

3. It depends on the frame rate. For example if your frame rate is 25fps the interation of the loop is 40ms. If you place extra code in the time critical loop that need more time to execute as 40ms it dosent work.

Kind regards,
Beko