trouble with the timing between motion and acquisition

[Ernest Galbrun]

I have some difficulties with the synchronization between my acquisition device (USB-6210, analog input) and my motion device (custom motor driven by a NI 7342 controller board.

I have considered the option of using the trigger input in conjonction with the breakpoint output of the motion board, but it can not be easily obtained with the current hardware installation.

I am currently considering two options and I would like to kwow which one seems better and what timing accuracy i could obtain doing this :

a/ starting a timed acquisition with a proper clock at a given time and polling my motion board every few msec so I get the relation between time and position. The problem is I dont know how to get the precise time when acquisition starts.

b/ Starting a timed acquisition in the same way, and configuring modulus breakpoint, then polling the breakpoint status of my motion board to know the time when every position is reached.

I would like to know which solution is best, and if there is a way I could know accurately the time when my acquisition starts ? 

[MaximeR]

Hi,

It seems very difficult to synchronize your data acquisition between your USB-6210 and your PCI-7342 without wirins the cards.

Can you give more information about your system?

What is your tolerance for the timing accuracy?

Best Regards,

Message Edité par MaximeR le 09-23-2008 04:39 PM

[Ernest Galbrun]

My system is rather straightforward : I have a photocell moving on a board thanks to a 2-axis motion system. I am trying to acquire a signal on a rectangular 2D grid.

 I did not abandon the solution using a hardware trigger on the breakpoint output of my motion board. The wire is here, but I couldnt have it function and The system I have to update is 700 km from where Im doing the development, so I am a little shy on relying on hardware upgrade that I could not test until I upgrade the bench. However, I would greatly appreciate some hint about how I should do it.

Concerning the timing accuracy I am trying to get, I would be ok with 100 µsec, and 10 µsec would be great. 

[MaximeR]

Hello,

Here you will find information about how to use breakpoint on a motion controller.

http://zone.ni.com/devzone/cda/tut/p/id/4512

http://zone.ni.com/devzone/cda/tut/p/id/3916

You can make hardware-timed acquisition with your USB device. You will find some information on this page.

http://zone.ni.com/devzone/cda/tut/p/id/6829

Best regards.