gvstemp

Thanks a ton for the advice. It seems like using LL Ring for my application is the best bet and to trust that at the camera end there is not jitter in the frame rate (once set). I use a MC1362 Mikrotron camera, does any one has any experience/benchmarks on how reliable the frame-rate is ? Anyway, I will try to set up the ring and see if I can record at 3-4kHz for long enough times. Thanks a ton for your time and advises

I have a relted question. Actually the more I read on this, the more questions I have So seems like there are a few ways of doing this ( this = high speed imaging (3000Hz-5000Hz), then writing to disk and later post-processing) 1. Use Grab VI and attach a time stamp to it (like for the filename) and write this combo. to a queue, later dequeue to post process. 2. using "LL Sequence.VI" 3. using " LL ring.VI" or "buffered ring" In Grab VI... the timestamps is the way to check FOR SURE that the frame rate is what I set it to be. ( Framerate = #frames/Total Time; and (N- (N-1)) frametimestamp = exposure time (should be constant) however, in the "Sequence" or "Ring" option, is there a way to get accurate time stamps of the acquired frame ? Seems like I can only set total number of frames (N) and maybe measure total time for acquisition and get the average framerate. Not very good for me, since I cant be sure that every frame was acquired with deltaT = (1/framerate). So whats the final word on "best way" to do highspeed image acquisition and writing to disk problem ?

thanks for the reply ! Am a newbie at IMAQ functions. I looked again at the NI-IMAQ functions to find a VI that can do high speed (3k-4k frames per second) streaming to disk. Couldnt find. Can you please elaborate which VIs would help ? An example would also be greatly appreciated. I was also thinking using the "LL Sequence.VI" to acquire N images. however I dont know and couldnot figure out a way to get time stamps for these frames. In post processing steps I use time information in the object tracking. So that might not be a solution for me. Any other advice will be appreciated. thanks

Hi Antoine Châlons I have been looking for a solution for "high speed grab with saving to disk". This particular thread seemed VERY interesting, however, you mentioned that you posted an example VI in some other thread and I cant seem to find that linked thread. Particularly you linked to http://forums.lavag....ate-t11317.html and this link just takes me back to the lavag forum main page. I am very curious at looking at your celebrated solution for highspeed grabbing. Also you mentioned in one of your replies above == I have another application running with a Basler A504 camera and PCIe 1429, we acquire 4000frame per second (1000*128*8bit) during 1 second, so at that speed we don't even try to stream to disk, it's about 650Mbytes/s.. a CD ! So be configure a ring buffer, start the acquisition, stop it when all the fames have been acquired then we have all the time we want to save to hard drive. Complete different application, but the code is just slightly different === As for my attempts, I can tell the following: I am trying to acquire images at 3000-4000Hz (400x400x8bit), for as long as I possible can. I am using a CMOS Mikrotron MC1362 camera with PCIe1433 card. In my first attempt I am trying to acquire a set number of frames N (say N= 4000). So used Queues (of size N+1000) and Grab Acquire VI. As soon as I grab the image, I assign a time stamp to it and this cluster of (Image + time stamp), I write to a queue. Once the entire N frames are acquired, I Dequeue and post process. I first tried to write the purple IMAQ image reference wire (rookie mistake, thinking that that was the actual image) to the queue and realised that I was writing the last frame N times to the queue. (Hence I reached to this Forum). At present my solution is: After the Grab Acquire.Vi, I convert Image to Array and write this array (IMAQ to Array.VI) to the queue (with time stamps). At the Dequeue end, I convert the array back to image for post processing. This works.... but I am limited to 1500-1900 Hz only. The camera (at this image size) is capable of 3000Hz. The whole convert-to-array step slows down the system. I would really like to look at your code that you used for 4000Hz acquisition, as well as the code for 'long measurement'. Since I cannot seem to find the examples that you had uploaded in the linked thread, can you please upload the example again ? will appreciate much. Thanks. GVS