Clock signal trigger to IMAQ through RTSI

[aarthisiva]

Hi,

I need to synchronize IMAQ and DAQ through RTSI. For this purpose I need to provide digital clock signal (30000 Hz) as trigger signal to IMAQ through RTSI. The counter output VI privided clock signals to only physical channels and not to RTSI (NI terminal). Kindly let me know how I can provide clock input to RTSI.

Thanks & Regards,
Aarthi

[ThSa]

Hi,
have you seen the following KB and discussion forum entries:
http://digital.ni.com/public.nsf/websearch/66F794370E52A61486256E94004CE4BC?OpenDocument
http://forums.ni.com/ni/board/message?board.id=200&message.id=1397&requireLogin=False
http://forums.ni.com/ni/board/message?board.id=200&message.id=3241&requireLogin=False

Best regards,
ThSa

[aarthisiva]

Hi,

Yes. I looked at those posts before and I have already tried using the HSYNC signal from IMAQ to synchronise my DAQ signal generation. The HSYNC signal serves as the clock source for DAQ signal generation. I have also synchronied the start of DAQ generation with start of Acquisition with the "Acquisition in Progress" signal. Though the synchronization begins correctly, it goes out of sync after some time. This happens specifically if we configure the IMAQ to acquire more points per line (eg Problem occurs for 2048 pixels instead of 1024 pixels). I guess this could be because the IMAQ can take more time to grab large number of points. However, I dont quite understand why this should affect the synchronization. So I thought of providing a trigger for line scan acquisition with a clock signal of period slightly greater than the integration time of the line scan camera. Hence I posted my first question asking how to generate and provide clock to RTSI because I couldnt find help for it anywhere. Kinidly let me know the answer for this. I also found a example Vi named LL Trigger Each Line from encoder. This uses some scaled encoded signal to trigger line scan acquisitions. I dont understand how scaled encoded signals are produced. Please clarify the same and also let me know if you can think of why there is a problem with synchronization after some time.

Thanks & Regards,
Aarthi

[Savageaggie]

Aarthi,

Thanks for your post.  The following document explains RTSI more fully and how to trigger IMAQ boards as a slave off another board:

http://sine.ni.com/apps/utf8/niepd_web_display.display_epd4?p_guid=B45EACE3DC5556A4E034080020E74861

I found a pretty good description of scaled encoder signals in our NI-IMAQ Function Reference Help.  When you install NI-IMAQ, this help file should be placed in the C:\Program Files\National Instruments\NI-IMAQ\Docs folder (I attached below for you as well just in case).  Search for "scaled encoder" and it should be the first link that pops up.  Hope this helps out!

Thanks,

Scott Savage

National Instruments

Applications Engineering

www.ni.com/support