Real Time Vision Problem

[SebastiaanNL]

Hi,

For the project that I'm currently working on, I encountered the following problem.

I'm working on a Real Time target (PXI) to create a Real Time image processing program. To realize real time determenism, I want to use the Timed Execution VI's of the Vision RT VI's. The problem is that a lot of image processing VI's won't work when the Timed Execution VI's are used. I know from Labview documentation that I should use Vision VI's from the PreAllocated library, these are VI's created for use with time-bounded operation. Only a lot of image processing VI's aren't in the PreAllocated library. Some usual vision VI's do work when using Timed Execution, but a lot won't work. This would be no problem if all those VI's would have a preallocated counterpart, but the number of preallocated VI's is a bit scarce. For instance, IMAQ Threshold does work when using them in combination with Timed Execution, but IMAQ Remove Particle won't work with Timed Execution and doesn't have a preallocated version.

When using VI's that are not compatible with Timned Execution I receive the following error message:
Error -1074396138 occurred at an unidentified location

Possible reason(s):

IMAQ Vision:  (Hex 0xBFF60416) The function is not supported when a time limit is active.

Could anyone answer one of the following questions:
- Is there a list with vision VI's that will work and won't work in combination with Timed Execution?
- Are there more PreAllocated VI's than in the preallocated.llb file in the directory: Labview 8.2\vi.lib\vision
- Is there a solution to this problem?

A big thanks in advance for anyone who can help me.

Message Edited by SebastiaanNL on 05-10-2007 09:58 AM

[SebastiaanNL]

Anyone?

[RikPrins]

Hello Sebastiaan,

In answer on your questions:

- Is there a list with vision VI's that will work and won't work in combination with Timed Execution?

Go to the NI Vision for LabVIEW VI Reference Help which can most easely entered by using the Context help Window in LabVIEW by clicking on the detailed help link on any of the Vision VI's. Go to the Index tab and start typing PreAllocated as the keyword to search for. You will find a topic in the list and when doubleclicking it you will get the information you want in the right part if the screen.It will give you a list of all supported VI's.

- Are there more PreAllocated VI's than in the preallocated.llb file in the directory: Labview 8.2\vi.lib\vision

The VI's which are in the list in the help file are supported.

-  Is there a solution to this problem?

The only solution I could think of is using a timed loop. You can give a timed loop timming parameters. When an iteration of the timed loop does not meet its setup looprate you could abort the loop and handle the rest of the program in the way you would like. For more infomation on how to use timed loops refer to the LabVIEW Help.

Regards,

RikP - National Instruments Applications Engineering

[SebastiaanNL]

Thank you RikP for your help, I really apreciate it. But if anyone has an other solution or something to add, don't hasitate to post it.