Max FPS Problem

[simply_me]

Hello,

The vi has a producer/consumer architecture, and according to the camera specs (the attached file) it should be easily above 100FPS.

The acquired image is setup to be ~60 by 300 and my trigger time is 25usec. Also, the FPS of the producer and consumer are almost always equal (which seems odd to me). I think it the problem is in Measurements and Automation. Any suggestion on how to begin to trouble shoot it?

Thank you,

[BruceAmmons]

I would test it in MAX before trying to use it in a program.

You should be able to set it up in free run mode (no trigger) and get it to run at the same speed you want, if the camera can go that fast.  I am pretty sure MAX could handle the triggered mode too, as long as the trigger is being generated.  Watch the FPS indicator in the lower right corner of the video window.

Once you are sure the camera can capture images at the rate you want, check it out from your program.  If your program runs considerable slower than what you got in MAX, you have an issue in your program.

Bruce

[simply_me]

Hi Bruce,

Thanks for the reply.

When the trigger is off I get to almost 400FPS, and when it is on I get ~20FPS (please see the attached files).

My trigger is controlled by the hardware, when it is on, but it still should be as high as when the trigger is off because the hardware trigger time is ~20usec, and my shutter is ~25usec. What could be the problem?

[BruceAmmons]

How often does your trigger pulse?  I assume a 20 usec pulse time is plenty, or it wouldn't be triggering at all, unless it is right at the threshold for the camera.

My advice is to read the camera manual very carefully.  Download a detailed manual if you don't have one.  It should explain how long the trigger needs to be on, how long it needs to be off, how often you can trigger, the different trigger modes (there are usually several).  If you make sure you are doing everything right that the camera requires, you should be able to get the rate you want.

Bruce

[simply_me]

I'll be looking for the user manual. I trigger every ~25usec. Any triggering faster than 400FPS (what I got when the trigger was off) should work though, correct? Aren't the trigger modes given by NI?

Thank you again.

[BruceAmmons]

The triggering should be slower than 400 fps.  Anything faster than 400 fps, you will skip triggers while the camera is busy.  400 fps is about 2.5 msec per frame, and your trigger is way faster than that.

The camera manufacturer decides the triggering options available.  There are several standard methods, and most cameras support them.  NI just acquires the images after they are triggered.

I assume you do have the trigger signal connected directly to the camera somehow, and you are not trying to use the NI interface to relay the triggers to the camera.

Bruce

[simply_me]

Hi Bruce,

The setup is such that a pulsed laser is triggered and 10usec later the camera is triggered. The duty cycle of the laser is longer than the camera's so they always overlap. Both are triggered using a function generator without any software assistance. 2.5msec will cause the saturation, I'll try to play around with the power/gain at work tomorrow, but are missed frames cause a decrease in FPS?

I think I'll call the manufacturer tech support tomorrow.

Thank you,

[BruceAmmons · Accepted solution]

It sounds like you are confusing pulse/trigger duration and the time between pulses.  It sounds like you want your trigger pulse to last 20 usec, which is fine.  It should be enough to trigger the camera.  Likewise, the shutter time of 25 usec is fine.  Your problem is that you need to wait 2.5 msec between the pulses.  You can't use a square wave generator with equal on/off times.

Bruce

[simply_me]

Hi Bruce,

Just to give you an update, I managed to increase FPS up to 0.5KHz, it was a camera trigger mode setting that made all the difference.

Thanks again for your help.

[BruceAmmons]

I figured it was a trigger mode or something like that.  It is always a good idea to read the manual carefully when you get into details like that.

Bruce