AVT Guppy firewire camera low frame rate in externa; trigger mode

[Viswanath]

Hello all,

I recently installed AVT GUPPY F-036B firewire camera. I am using LabVIEW 8.2 and IMAQdx 2.0.5. The camera is working properly with internal trigger acquisition mode. I can vary frame rate by adjusting shutter speed.

When i want to trigger externally using Format 7_mode 0, i get lower number of frames per sec than applied external pulse. Suppose, i have taken a particular case in which applied pulse frequency is 25Hz pulse with pulse width 50 microsec.his pulse is applied to hirose cable attached to the camera and used Triggered grab.vi from example finder in IMAQdx palette. When i run the vi frame rate measure is only 6.8fps at max.

What could be causing the decrease in frame rate?? I have attached all the camera attributes parameter values and triggered acquisition vi image etc.

Any help is greatly appreciated.

Thanks

[Vladimir Drzik]

I think the main problem is in the value of Packet Size. The FireWire bus always transmits 8000 packets per second. With packet size 388, you are transmitting just about 3MB of data per second. While the size of 640x480 image is about 300kB, you cannot reach 25 FPS. I'd recommend always setting the packet size value to the highest number the driver allows you. This rule might not be true only if you are using more cameras on one bus.

The second issue is the length of your triggering signals. I am not quite sure, but 50 us seems a bit too short to be reliable. We are using the Guppies in an industrial enviroment and transmitting the triggering signal over a 10m cable. Under such conditions, 1 ms triggering pulse time is not reliable, while 10 ms is. Perhaps your setup is not so sensitive, but anyway, I wouldn't trust the 50 us pulse.