synchronization of DAQ and IMAQ devices for high speed acquisition (1000fps, for example)

[olivier_vi]

Hello,
I have a question about the use of a PCI1422 and a PCI-MIO-16E-4 and their capacities of synchronization. I use a digital camera which produces 1000 frames per seconde and I would like to have a synchronized acquisition of data at the same frequency or a multpile of this frequency.

I installed the two cards on the same computer and I linked them with a RTSI cable. In the Labview environment, with the 'Route signal.VI' for example, I splitted the clock signal between the two devices (the IMAQ device is the master device) and I tested them: I set them so as to have 1000 images and 1000 points and I used a LED and a arbitrary Waveform generator which produced a sequence of short pulses.

The result is that the two acquisitions began together but when I took a reading of the different pulses on the images and on the data, I noticed that the events (pulse light produced by the LED) didn't have the same index (perhaps, the starts of the two acquisitons are not exactly the same) and the difference of index varied (for an acquisition, 0 to 20-30 points can separate the image (which shows the starting) and the data (which shows a increase of the voltage).

I know that with my camera, I have a uncertainty by the fact that the reading of the CMOS matrice takes a certain time and when the trigger signal occurs, it exists a certain delay until the camera have the capacity to produce data to the I/O port. But, what I don't understand is why the index varies, I don't understand and that is the point on which I would like to have some explanations so as to understand and so as to find a solution.

I thank you by advance for your help

[SanaaT]

Hello Olivier_vi,

To respond to your question, I need more information about your system :
1 - Version NI-DAQ?
2 - You work with DAQmx or Traditional DAQ?
3 - Version NI-IMAQ?
4 - The language you use? Version?

If possible and if the program is not large, can you please send it?

Waiting for your response.

Sanaa T
National Instruments France

[olivier_vi]

Hello,

Answers to your questions are:
- NI-DAQ 7.2.0f1
- I work with DAQmx (7.2.0f0)
- NI-IMAQ 3.1.0
- I use Labview 7.1

I send you the VI I told you the last time and I tried to improve the results by adding the VI "DAQmx Start trigger (digital edge)" (I used a second RTSI line so as to route the frame start signal), but I didn't see any différence.

I would like to have your point of view about something else(which concerns always my problem but this time on a technical point).
I measured the frequencies of the FEN and frametrigger signals: the frametrigger frequency is always half of the FEN frequency, is it normal?
Is it possible to configure a PCI-1422 card so as to have this two signals at the same frequency, and so as to use all the capacities of the camera?

I thank you so much for your help.

Olivier

[olivier_vi]

Hello,
I contact you to prevent you that I found the reason why my acquisition system didn't work well. The problem came from a bad configuration of the PCI 1422 card in the Measurment and Automation Explorer software.

However, I have now a question which concerns the programmation. I use a PCI-MIO-16E-4 card to measure a signal and a trigger to detect an specific event in this signal. Each time a event occurs, I trigger an image acquisition and moreover, I would like to skip a certain number of images for each trigger event. I read the notice of the VI "IMAQ configure trigger2" and it is written that only linescan camera are able to do that.

Despite that, does it exist an other solution?

Thank you.

[SanaaT]

Hello Olivier_vi,

If you can not use Scan Line solution, you can try to add delay in the RTSI pulse and then begin image acquisition.
In your case, the camera provides 1000 Frames/s, so if you need to skip 5 frames, add 5 ms delay.
Then, don't forget that you can also use DAQ device's counter to add delay in pulse. Please see example below :
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=B45EACE3DFDF56A4E034080020E74861&p_node=DZ52328&p_source=External

Hope this help.

Sanaa T
National Instruments France

[olivier_vi]

Hello,
I read in the example you sent me that the VI work NI TIO card and I have a MIO card. Could this difference can involve a different behaviour?
Thank you

[olivier_vi]

Hello,
I found the solution so as to produce a clock signal delayed of certain value and I think that is a very accurate solution. I didn't followed the principle of the VI you sent me yesterday. I found in the Labview "toolbar" a function which is called "Delayed pulse genrator config" and which permits to produce a clock signal delayed with regard to an other clock signal and it is possible to configure the delay.
In my soft, I use the "Delayed pulse genrator config.VI" to configure the counter, the "counter start.vi" to begin the work of the counter, a while loop so as to have a VI which works continuously and after the "counter stop.vi".
I thank you for your help.