1394 slow when opening port or changing shutter speed

[DelphiDan]

After switching from using the snap mode to the grab mode, my speed increased dramatically.  This is great if you don't switch between cameras very ofter.   Now I have another problem.  I have an application that requires switching between 4 different cameras fairly fast.    This is the order I have to switch cameras.  Camera0 -> Camera1 -> Camera2 --> Camera 3.   I have to do this 6 times in that order.   This means I have to open and close each camera before going to the next camera.  Opening each camera takes about 700msec, which amounts to (700*4*6) 16.8seconds in just opening cameras.   This is way too long.   I went to firewire digital cameras because of the high resolution, but I miss the fast switching between my analog cameras using a mux box.     I know someone out there must have applications where they have to switch cameras fast.   Any solutions?

[BruceAmmons]

Set each camera to 1/4 of its max frame rate and acquire from all 4 cameras continuously and simultaneously.  Four parallel grab operations should do the trick.  Just read the most recent image whenever you need one from whichever camera you want.

Bruce

[danilo]

Hello!

Can we be more specific with time, is there any informations how faster operation can I expect?
Danilo



Hi Danilo,

GiGE cameras can certainly acquire fasters than firewire cameras in most cases. But again, For a snap, a session needs to be created every time so it represents some finite overhead per frame.

-Jaidev

 

National Instruments
Applications Engineer

[DelphiDan]

I could use more information on how to do this.     Are you saying that I can have 4 cameras open at the same time?  Meaning 4 seperate SID sessions.    

[BruceAmmons]

Yes, you can have four sessions open at the same time, as long as you don't exceed the total firewire bandwidth.

Bruce

[Jaidev]

Hi Danilo,

I dont think we have any numbers on how fast the GiGE cameras would be. It would depend on the camera.

-Jaidev