Application Note: USB3 Vision Triggering Concept

USB cameras
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This document describes triggering basics for Allied Vision USB3 Vision cameras, from best-practice rules to general examples.

7

Hello,
I would like to know the minimum time beetween two exposure in Exposure = triggerWidth?
I want to make a PIV system, and I want to make a laser light pulse at the end of the frame1 exposure, and at the beginning of the frame 2 exposure.
Could I start the 2nd exposure during the first readout active transfert in triggerWidth mode?
Thank you for your help

8

Hi,
in Exposure = triggerWidth exposure an readout may not overlap.
Please contact our support to check the camera model and further details:

Thanks
Norman

9

In addition to my previous post, tel me if I’m wrong please:
What I understand is that the exposure can occurs during previous readout only in “continuous” or “multiframe” acquisition.
If I’m right, what is the minimum time between a frame exposure’s end, and the next frame exposure’s start?
I use a Alvium 1800 U-511m
Am I understandable?

10

Hello,
Thanks a lot for your help.
So I have to choose another triggering mode.
Is there a trigger mode wich let the camera expose during the readout of the previous frame?
Thank by advance

Simon

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Hi Simon,
Alvium 1800 U-511m allows an overlap of exposure and readout in ExposureMode = Times and AcquisitionMode = Continuous.
We didn’t measure the min. time between frames yet for the Alvium 1800 U-511m, assuming it in the range of Exposure Start Delay = 61 µs at max. DeviceLinkThroughputLimit = 450 MBps.
Thanks
Norman

12

Hi, any update on what the minimum trigger delay is for the Alvium 1800? I am also interested in building a PIV system with these cameras but the answer by Norman was not sufficient for me to have the confidence of buying one. I think a lot of people are interested in this, so I am asking in a public forum in the hopes this will eventually be answered.

(i.e., what is the sensor readout time and minimum delay between end of exposure and start of next frame?)

13

Hi, trigger delay depends on the line time, which is approx.
Width / DeviceLinkTroughput for 8-bit pixel format.
PIV timing has not been evaluated yet for Alvium. Which model are you looking at?

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I was looking into the 1800 U-511m. (
2,464 x 2,064 px). How do I find DeviceLinkThroughputLimit? Is width in pixels?

Shouldn’t it be (widthheightbit depth/DeviceLinkThroughputLimit) though? That makes more sense as it is the required time to download an entire frame. If that’s the case then it would take 18ms to download a frame for the U511m at 12 bits?