Author Topic: external trigger  (Read 797 times)

pstest

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external trigger
« on: October 14, 2017, 05:28:52 PM »
will be measuring a rotational device.  Require to trigger camera on/off when the command to start and stop the motion is executed. Duration of mechanical motion is no greater than 400msec. Command signal to execute motion is provided remotely to a processing board/GPIO board which is connected to the remote source via windows OS computer.  camera is also operated through computer which is also controlled remotely from same source that motion command signal is issued.
What is a method to provide trigger to camera when motion command signal is executed as well as stop camera recording when motion command signal is completed.
 

tesla500

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Re: external trigger
« Reply #1 on: October 18, 2017, 12:06:21 AM »
That mode to do exactly what you want isn't yet supported. The closest thing you can do is have the camera recording, and provide it a TTL signal to end record. You can set any desired trigger delay in frames if required. You'll need to manually select the appropriate range and then save the desired 400ms range.

Let me know if you have more questions on how to set this up.

pstest

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Re: external trigger
« Reply #2 on: October 20, 2017, 05:34:27 PM »
Thanks Tesla500
Mechanical rotation events have an inherent inertial and frictional delay after the event "start" command signal is executed.  The time or frame at which the motion command input signal is executed must be known Without a known event start time, there is no basis upon which to determine acceleration/deceleration behavior or capacity to optimize the behavior.  Camera tools exist to delete frames after event is complete.

2 Potential workarounds come to mind:
    1.  Preferred work around: I purchased the switch cable w/push button S/W. 
         Hack the switch leads; connect to computer using opto-coupler FET circuit instructed with
         computer that issues the rotational event motion command signal.  My assumption is, since the
         push button is a continuity interrupt to start recording, electronic switch closure can replace
         the button. the external opto-coupled trigger circuit would have to be developed about
         required electronic parameters & specs. Aspects such as impedance, trigger signal duration, 0-
         6.6V or 5V TTL assumed to be supported?, amperage limits, etc.
         Is KronTech willing to support this effort providing the BNC port electronic parameters to assist
         in development of an opto-coupled triggering circuit?
         This support a digitally integrated test environment.

    2.  Less preferred method - place a visual signal (LED) in the FOV with the LED actuating when
         motion command signal is executed - The manual push button camera triggering would be
         followed by motion command signal execution.  this can be a manual actuation of both the
         push button and motion execution or trigger delay technique which has not been conceived on
         my part at this time.

Another question - how is data stored and retrieved from camera?

Please advise if Krontech can support info-sharing as detailed in #1 above.

Best Regards
pstest

BiduleOhm

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Re: external trigger
« Reply #3 on: October 21, 2017, 06:31:34 AM »
It's already available, see page 11 and 12 of the manual http://www.krontech.ca/uploads/9/3/8/3/93836312/chronos_1.4_user_manual_rev_3.pdf ;)

pstest

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Re: external trigger
« Reply #4 on: October 21, 2017, 07:26:16 AM »
Thank you,
Do these triggers provide method to  "Start" recording? - not overly concerned with "Stopping" recording but need to provide the camera triggering "Start" signal  on the same timeline as signal that is provided which starts the event to be video recorded. Pause in the execution of the recorded event "start" signal can be conducted to compensate for camera triggering delay. I believe the camera recording delay is 10nsec which may be negligible in the recorded event time duration of interest.


BiduleOhm

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Re: external trigger
« Reply #5 on: October 21, 2017, 08:18:01 AM »
I don't think you can trigger the start of the recording and let it stop when out of RAM because usually you just record in a loop and stop the recording after the event occurred, that's how pretty much how all hi-speed cams work.

But, as already said by David, you can use your start signal to stop the recording and set a 400 ms delay (in frames, so, for example, if you shoot at 2000 fps you need to set it to 800 frames to record 400 ms) which will basically do exactly what you want (record 400 ms after the start signal) ;)