NI PCIe-1430 Channels out of sync with external trigger

[mk@opc]

Hello All,

I have two NI 1430 cameralink cards.  I am utilizing the SMB connector as my trigger to start the acquisitions.  The SMB connector is hooked up to a signal which pulses every second.

I have setup my buffered acquisition to start on the trigger pulse it first sees after the initialization is complete (note that the pulses come into the card every second no matter what, but I'm only using the first "seen" pulse to start the acquisition).

The very strange thing is that ONE camera out of the four is lagging by exactly 1 second, so it seems as if that camera is not getting triggered on the first pulse, but then gets triggered on the following pulse... what I don't understand is how is that possible if the other camera on that same card DID get triggered!?!?!

Any thoughts???

Thanks!!

Mike

[fblerg]

Hi Mike,

That is odd. Perhaps it is due to some sort of signal attenuation from the triggering device. Is the same camera missing the first pulse every time? How are the PCI cards physically connected to the trigger signal? Also, what is generating the trigger signal?

[mk@opc]

So the triggering device is a GPS clock, it outputs a fairly clean 10us pulse (+5v) every second.  The same camera misses the first pulse every time, yes.  The connection goes something like GPS SOURCE -> BNC CABLE -> BNC SPLITTER (1 in 2 out) -> BNC TO SMB (2x) into each card.

I'm using external trigger ch0 for both cards, but still have an RTSI cable between the two cards... not that it should matter.

Thanks for any suggestions!

Mike

[lcady]

it is a buffer problem.  the one camera is reading one buffer late.  change the acquire to get next buffer, not  the last buffer.  increase the number of times you try to get an image.  Right now you are only looking for it once a second.  Try checking for the image many times a second.  Expect to get time outs.  clear the timeout error.  Any time you don't have a time out, then you received the image.