Section of the data collected with PCI 1422 card connected to a CCD camera looks step-like

[uky]

I am using the PCI 1422 card with a DALSA CA-D1-0128T camera to acquire and save fluorescence data from a heart stained with a potentiometric dye. The camera is set to work at 490 frames per second. My acquisition program (made using a producer consumer loop in Labview 2009) works fine most of the times, but sometimes a small section of the collected data looks step-like (not continuous). I have attached herewith a word document containing a snap of the data. Could you please give me some suggestions as to why this happens and how can I rectify it? 

Thanks in advance 

Anuj Agarwal 

[The_Chancenator]

Hi Anuj,

First, this sounds like a very cool application.  What are you measuring? Is it in vivo?

I believe that I see what you are referring to--is it where your cursor is that you are seeing the "step" problem?  Also, could you give us a little more information aboutwhat type of data we are looking at?  Is this some sort of image analysis data?  

In terms of code structure, due to the way that LabVIEW handles image data types (it is essentially a pointer to the data instead of the data itself), I wouldn't recommend passing an image via a queue.  

So, please let me know a bit more about what type of data we are looking at, and what your code looks like, and I'll be happy to help. 

Cheers, 

[uky]

Hi Marti

Thanks for your interest in our application. We are essentially measuring the change in voltage that the surface of the heart sees as an activation travels over it. The change in voltage is proportional to the change in the fluorescence emitted by the heart (stained with a dye) and that is what the camera sees and records. The process is done in vitro. 

I put the card in a different machine yesterday and the problem got solved. I guess it was the CPU causing the problem. Although, that CPU has a 4 GB RAM and a 2.7 GHz processor. I also make sure that no other program is running while I run LABVIEW and the anti-virus software is also inactivated. Please let me know if you have any suggestions.

Thanks 

[The_Chancenator]

With Windows, it is certainly tricky to get the type of determinism you get with an RT system.  One suggestion I do  have to put some sort of wait in your acquisition (Wait or Wait until next ms multiple).  This allows the processor some time to go off and do other things, and ensures that LabVIEW doesn't eat up all of your computer resources. 

If you see the problem reappear, we can certainly take a look into code optimization. 

Good luck with your research!