Two fire wire cameras attached with a PCI card, give error when feeds of both are viewed at the same time

[Asad_Tirmizi]

Hello All, 

My set up includes two firewire cameras. I have detected them both and i can get the feed of both the cameras. Switching between the two as and when required. But as my project requires camera fusion, i need to get the feed of both at the same time. When i try to get the feed of both the cameras at the same time, the "transfer engine" gives error. All attempts to remove the error seem to go in vain. Any bright ideas. Please find attached the VI as well for further elaboration. 

[Intaris]

Firewire cameras reserve bandwidth on the bus.  Having two cameras on one bus means they need to share the bendwidth, but if you have video modes set where they need more than 50% of the available bandwidth, you will get exactly this error.

Reduce the refresh rate or resolution of the cameras and it should work fine.  Or connect both cameras to seperate firewire controllers.

Please note that not all firewire PORTS are connected to different controllers.... Most 4-port FW cards multipley the ports on ONE controller.

Shane

[Asad_Tirmizi]

Hello intaris, 

I completely understand what you have said, However for the purpose of clarification i would want to ask. That if there are two firewire ports avaiable on the card, does'nt that mean that it has the capacity to control two fire wire devices. If that wasnt the case why would there be two ports.

Secondly. I completely agree with the controller parts, perhaps that is the only reason why the transfer engine is exhibiting problems but how can i know whether the card i am using has two controller or a single controller. Well that can be checked from the manufacturer though. 

Anyways, I would try to tone down the parameters which i understand from your post are lesser frames per second ? and then post back to you on the results.

Thanx for the help buddy, i highly appreciate that.

have a nice day. 

[Intaris]

Like I said before, a lot of these firewire cards have multiple ports and ony one controller because it makes them appear better value (more > less, right?).  A two-port / one controller card WILL control two devices, but they will share the available bandwidth.

If you look in the hardware devices list of your PC, you'll see if you have one or more controllers available.  I reckon it's only one because cards with more than one controller are expensive and it's unlikely that one is bought by mistake.

Shane.

[Asad_Tirmizi]

Ive checked the card with the manufacturer, its single controller as u said. Now i am trying to make both of the cameras run at around 15 fps instead of the originally planned 60 fps. do u think that will help. I ask that because at the present i am still stuck with programming to tone down the frames. Have you seen my VI which is basically taken from examples. Any suggestion on toning down the frame rate. 

[Intaris]

You can set the video mode to 15 fps and then it should work fine.

Each camera has its own set of commands for the settings, so maybe you could (for a quick experiment) set the fps in MAX and then carry on from there.

Regards

Shane.