camera not found imaqdx

[Jason_P]

Hi Eric,

I'm using an old analog video camera connected to an Axis 241 video server.  If you aren't seeing the same behavior, I think you are right that it must be specific to my setup.  On my end, the behavior is VERY reproducible.  I did try your DNS-SD program... I can ping the Axis video server, but when I actually ran "dns-sd -B XXX.XXX.XXX.XXX" (with the actual address of the Axis server, of course), I got:

Browsing for XXX.XXX.XXX.XXX

DNSService call failed -65540

I get this response whether the server is plugged in or unplugged.  

Any other thoughts?  I've tried everything I can think of at this point...  At the end of the day, I can live with the issue if I have to.  I can make it so if the app can't find the camera at startup, it posts a dialog asking the user to check the hardware and then shuts down. But I really would prefer a solution that actually allows the app to recover gracefully. 

Thanks,

Jason

[BlueCheese]

Hi Jason,

Your arguments passed to the dns-sd app are not quite valid.You passed it the -B (browse) argument but with an IP address rather than a DNS-SD service name. If you run it as I described: dns-sd.exe -B "_axis-video._tcp" it should sit there running (until you hit control-c) showing all cameras as they are added and removed from the network. Try that in the same case as your application and see what it does.

It might be possible that your old Axis server has an older version of an mDNS daemon that might be buggy or not fully-compliant. Normally when you plug the camera in it should announce itself. If it weren't, then that would explain the situation you are seeing where if the camera is not around when an initial browse request is sent (when IMAQdx is first started) it might not see the camera added for some amount of time.

As another debugging step, if both MAX and your application are freshly started when the camera is unplugged, then you plug the camera in, does MAX start seeing the camera or does it show the same behavior as your app? I'd be very surprised if they showed different behavior.

Eric

[Jason_P]

Hi Eric,

Ooops!  I misunderstood your instructions...When I ran it with the correct parameters, I could see my Axis server appear on the list about a minute after it was powered up  (along with a few others on our network).  However, if I powered it back down again, it stayed on the list.  MAX shows the same behavior.

I think this is key... If the my app is started when the camera is on MAX's list while actually being offline, my app will never connect.  It will always report camera not found. But if my app is started with the camera either online and visible in MAX, or not initially visible in MAX, it will connect.  I just discovered that second condition this morning.  I did a reboot of my system with the server unplugged.  I started both my app and MAX.  With the server offline, the camera was not visible in MAX.  About a minute after plugging the server back in, the camera appeared in MAX and was recognized by my app.

It really looks to me like something behind the scenes is hanging on to information that is out of date.  When the server goes offline, I would think the camera should disappear in MAX.  I think the fact that it doesn't suggests that whatever is keeping track of the IMAQdx devices is not updating properly, and may be feeding old info to my both MAX and my app.  MAX seems to handle this ok, but I haven't been able to duplicate how MAX is "rediscovering" the camera.

JasonP - CLD