External Sync In

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heath789
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Joined: Wed Aug 10, 2011 7:42 am

External Sync In

Post by heath789 » Fri Oct 05, 2012 10:03 am

Hello,

We are trying to trigger recording in Arena with an external analog rising-edge signal sent from a DAQ board. We are currently using a 5v signal but we can modify this as needed. We have plugged the BNC into the External Sync In port on the proper OptiHub, and have verified that the signal is getting sent through the cable, but we are not getting any events triggered in Arena. We have noticed strange occurrences that may all be related.

We set the Source to Sync In in the Synchronization dialog. If we then hit Apply, and stop then start streaming, all camera numbers turn to 1 and "HW Sync Off" is displayed in red at the top of the screen. If we revert the Source back to Internal/Wired, the system returns to normal operation.

Additionally, When we plug the analog signal into the OptiHub, instead of reading 5v as it should, it reads closer to 4.5v and shows exponential decreasing behavior.

Also, the hub that is listed in the Synchronization dialog (we have 4 hubs, 24 cameras) is different from the one we have been able to use for getting an analog out signal. We have gotten the analog out signal to work, but now we want to run things the other way.

NaturalPoint - Mike
Posts: 1896
Joined: Tue Feb 01, 2011 8:41 am
Location: Corvallis, OR

Re: External Sync In

Post by NaturalPoint - Mike » Fri Oct 05, 2012 11:41 am

Could you take a screenshot of the synchronization panel and post it?

heath789
Posts: 41
Joined: Wed Aug 10, 2011 7:42 am

Re: External Sync In

Post by heath789 » Mon Oct 08, 2012 9:54 am

Image

These are my settings.

We have tried this with veriosn 1.8.1 and 1.7.3 with no luck. Also, the sync dialog in 1.7.3 does not tell which hub serial number to use.

Are there any details about what the signal is supposed to look like? We cannot decipher things too well from the optihub manual.

We are also still getting the bleeding behavior; we send a 5v signal and it does not stay steady when plugged into the hub.

Image

NaturalPoint - Mike
Posts: 1896
Joined: Tue Feb 01, 2011 8:41 am
Location: Corvallis, OR

Re: External Sync In

Post by NaturalPoint - Mike » Mon Oct 08, 2012 12:31 pm

For both sync input and sync output, you should be using the hub that camera 1 is attached to.

Is that signal coming from external sync out or hub sync out? Can you display the graph with more usable intervals (10ms instead of 2s)?

heath789
Posts: 41
Joined: Wed Aug 10, 2011 7:42 am

Re: External Sync In

Post by heath789 » Tue Oct 09, 2012 9:36 am

The signal in the picture is what we are sending via a DAQ board to the hub. Like I said, when the BNC is disconnected from the hub it shows a steady 5v, as it should, but the signal you see is what happens when we plug the BNC into the External Sync In port on the hub. Something is causing the signal to dip and vary.

Not sure what you mean by usable intervals. It is my understanding that if I set the panel to Rising Edge, that ARENA should have started recording around 129.5 seconds and then stayed on since the signal 2s later is a falling edge. We eventually want it to react to both rising and falling edge, but we are just trying to get something to work for now. Is there some threshold we might be missing?

heath789
Posts: 41
Joined: Wed Aug 10, 2011 7:42 am

Re: External Sync In

Post by heath789 » Tue Oct 16, 2012 7:23 am

Are there any more details about this? Could you define the specs form the OptiHub manual in a little more simple terms?

NaturalPoint - Mike
Posts: 1896
Joined: Tue Feb 01, 2011 8:41 am
Location: Corvallis, OR

Re: External Sync In

Post by NaturalPoint - Mike » Tue Oct 16, 2012 4:41 pm

Which specs from the OptiHub manual? There's quite a bit of information in there,

heath789
Posts: 41
Joined: Wed Aug 10, 2011 7:42 am

Re: External Sync In

Post by heath789 » Wed Oct 17, 2012 10:10 am

VilMax = 0.8V
VihMin = 2.5V
VihMax = 13V
Max Freq = 10kHz

What I meant was, can you explain in simple terms the requirements to get the hub to respond to the signal that is sent to it? We think we have met the requirements but the hub is 1)altering our signal and 2)not causing Arena to start recording.

NaturalPoint - Mike
Posts: 1896
Joined: Tue Feb 01, 2011 8:41 am
Location: Corvallis, OR

Re: External Sync In

Post by NaturalPoint - Mike » Thu Oct 18, 2012 2:10 pm

The signal to the Optihub won't trigger (at current) a start or stop recording, it will just synchronize the exposure period of the cameras to the pulse coming through the hub. You can use this to synchronize cameras to, say, the pulse from another strobing IR source (such as a stereovision emitter) so that they don't interfere with eachother. Other uses would be to synchronize the frames to a pulse that a DAQ locks onto for data collection timing, such as with a force plate or similar. This way, you can be sure that the camera data lines up with the DAQ data when analyzing it.

Recording must still be initiated by clicking record and stop recording.

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