IMAQdx "One Shot" image acq.

[CraigGraham]

I'm playing with a firewire camera in IMAQdx, LV7.1. Yeah, not got round to updating to 8.

I've done an ugly as hell test VI (that I'm not going to post in its present form) that's based around the code in "IMAQdx Snap.vi". The only functional changes are to put the Start Aquisition...Get Image...Stop Acquisition group of sub VIs inside a while loop to snap an image every time I hit a button, and to monitor and display the output of various digital lines as it's happening. What I've discovered is that the camera is actually taking 2 shots each time. Further investigation reveals that, even if I load the original "IMAQdx Snap.vi" and put a breakpoint after the "Get Image", the camera keeps triggering. The "one shot" doesn't seem to actually mean single shot.

Anyone else come across this?

[Neville D]

QUOTE(CraigGraham @ Mar 20 2007, 10:41 AM)

I'm playing with a firewire camera in IMAQdx, LV7.1. Yeah, not got round to updating to 8.

I've done an ugly as hell test VI (that I'm not going to post in its present form) that's based around the code in "IMAQdx Snap.vi". The only functional changes are to put the Start Aquisition...Get Image...Stop Acquisition group of sub VIs inside a while loop to snap an image every time I hit a button, and to monitor and display the output of various digital lines as it's happening. What I've discovered is that the camera is actually taking 2 shots each time. Further investigation reveals that, even if I load the original "IMAQdx Snap.vi" and put a breakpoint after the "Get Image", the camera keeps triggering. The "one shot" doesn't seem to actually mean single shot.

Anyone else come across this?

What are the camera trigger settings when you examine in NI-MAX?

I would check there. Maybe its set to "free-run" mode instead of software trigger mode.

Try the old-style IMAQ example to see if there is any issue there.

I don't have any camera hardware to check at present, but last I played with it, IMAQdx worked fine under LV 7.1, Windoze as well as LV 7.1 RT for Snap and Grab.

I have about 8 installs running LV8.2 RT, IMAQdx RT on PXI, with no problems (hardware triggered grab image).

Neville.

[CraigGraham]

QUOTE(Neville D @ Mar 20 2007, 06:13 PM)

What are the camera trigger settings when you examine in NI-MAX?

I would check there. Maybe its set to "free-run" mode instead of software trigger mode.

No, could find nothing like that in MAX. I didn't have the old IMAQ on the machine so couldn't try the old examples.

What it turned out to be was a register "ISO_ENABLE" inside the camera. This register gets set when calling IMAQdx Start Acquisition and overrides the single/multishot settings defined by the "configure acquisition" VI to force the camera into free running. Writing a zero to it immediately after calling start acq. gets everything working fine.

This behaviour is there even when setting the camera to a non-ISO capture mode in MAX so I don't know whether it's a bug/camera dependent issue or some obscure setting I can't find, but it's a fairly painless fix.