Data synchronisation with USB3.0 Camera

[Patrem1]

Hi,

Not sure this is the good board but it's related to Vision and Motion and Cameras. 

We are trying to synchronise external data (EMG and Force platform) with a Sentech USB3.0 camera : STC_MBE132U3V

I got the image acquisition part working in Labview with IMAQdx functions. 

For synchronisation we are currently using an Output of the camera to send a pulse for each frame. 

The external systems record those pulses. 

I'm trying to figure which 'Output mode' would give the best synchronisation. 

I'm attaching a picture of the 'timing chart' from the camera manuel. 

It's my first time working with cameras so I'm not sure if your supposed to synchronise with the end of the exposure, the start of the exposure, just before, etc. 

For now I was using 'Exposure End' mode. 

Thank you, 

[Melanie14]

Hi Patrem1,

This White Paper goes through an option of using RTSI to synchronize vision and data acquisition.

Can you tell us more about your application and what options for Output Mode are available on your camera?

[Patrem1 · Accepted solution]

Hi,

I checked your link but the other data are not on the same system. 

The application is like that : 

Computer 1 Camera :

Usb 3.0 camera read with Labview Vision IMAQdx program we made. 

Camera has inputs and output. 

The available output mode are as follow : 

3) Trigger Output (Programmable) [10]
This “output signal” is produced from a “Trigger Input” signal applied to the camera and may be used to trigger
another downstream camera. By referencing the beginning of the “External Trigger Input” signal to the camera, the
beginning of this trigger output timing may be programmed or delayed by adjusting “Pulse delay time” under the
“Trigger tab”.
4)Trigger Output (Loop through) [11]
This function is very similar to the “Trigger Output (Programmable)” listed above. The only difference is that in this
mode the timing of the “Trigger Output” is not programmable (cannot be delayed). This mode is used to pass through
the “Trigger Input” as an output signal for various purposes including triggering other cameras. Please note there is a
fixed time delay of several hundred pixel clocks associated with this process.
5) Exposure End [12]
This “notification” output signal is sent out following the end (or completion) of an exposure. By utilizing this
“Exposure End” output signal, the system can be ensured that the exposure has been completed. For example, this
could be useful to move objects via an actuator to a next position/stage after confirming the end of exposure, etc.
6) CCD Read End Output [13]
This “notification” output signal is sent out following to the end (or completion) of each video output transmission from
the camera. By utilizing this “CCD Read End Output” signal, the system can ensure the camera has completed
transferring the previous video output signal.
7) Strobe Output (Programmable) [20]
This “Strobe Output (Programmable)” output signal may be used to drive an external strobe device. In this mode, the
beginning of the strobe output signal can be defined (programmed) referencing the beginning of the “Trigger Input”
signal with a delay timing, and the end (duration) of the “Strobe” signal can also be set.
😎 Strobe Output (Exposure) [21]
With this selection, the strobe output signal synchronizes with actual exposure timing.

You can visualize those in the attached picture of my first post. 

For now I'm using 'Exposure End'. 

EDIT : I thought about it more since my first post. I would have liked to use something like 'Strobe Output' to have the camera send it's pulse as soon as it starts taking the picture. But the problem is that if exposure time is set very low, the other systems might 'miss' it. 

For now I thought I could use the exposure time post recording to get the start of the exposure on the other systems, but this is more of a hassle. 

Computer 2 EMG :

EMG proprietary software and hardware (approx 1 kHz). 

Hardware available analog inputs and 1 TTL input. 

I'm sending the camera output to this TTL input. 

Computer 3 :

Force plate (load cells) read on a NI PCI-6221 (approx 1 kHz). 

I'm planning to send the camera output to a digital or counter input on the DAQ. 

So each time the camera takes a frame, the 2 other systems record it with their data. 

Thank you, 

[shrupa123]

Hello,

I also looked into the link and checked the specific cases. I'm not sure if we can provide support for the EMG. However, in the case of the DAQ hardware, I'm going to look into seeing whether there is a way for you to interface with it. However, there may be some intermediate hardware (like a USB3 Frame Grabber) that would need to be added.

I'll do more research to confirm this and get back to you with an update.

[Patrem1]

For now I should be alright for the interfacing part. I will simply send the TTL output of the camera to a Digital input of the NI DAQ. 

What I have left to do is an acquisition and logging program for the NI DAQmx part. 

I'm looking into maybe using SignalExpress for this. 

[AmitShachaf]

Usually with cameras you would want to go the other way around.

You can put the camera in trigger acquisition mode and sync to external trigger from your EMG system.

Usually that make the design easier. 

[Patrem1]

Hi Amit, 

For my application, the existing EMG is proprietary and does not have the possibility to output an external trigger as a 'clock', only a pulse at the beginning. 

Thank you,

[shrupa123]

Okay, that sounds good! In terms of SignalExpress, you may want to look into DAQExpress. It offers more functionality/compatibility. It is also free to download.

What is DAQExpress?

http://www.ni.com/en-us/shop/daqexpress.html

[Patrem1]

Thank you I will look into it.

Is it compatible with PCI-6221?

[shrupa123]

Yes, it should be compatible. I checked the following link for compatibility:

http://www.ni.com/documentation/en/daqexpress/latest/supported-hardware/supported-multifunction-io/