Changing Ring Light Intensity

[Kgsalo]

Hello Guys

I need help with Ring Light Intensity. I am working on a project that has 3 ring lights and I need to be changing their intensities for respective programs/Functions. I am currently using NI 9476 36 V, 32-Channel (Sourcing Output), 500 µs C Series Digital Module to send a high/low signal to trigger the lights ON/OFF.  Is there any way I can use the NI 9476 to change the Intensity since it's just a DIGITAL Module? I was thinking that i may need Analogue Output Module to be able to achieve this. Is there any LabVIEW DIGITAL-OUTPUT Module or VI or converter that I can use to send the signal to Trigger Lights ON/OFF and change intensities as well?

Any suggestions will be appreciated.

Thanks 

[OregonGumby]

You should be able to change the digital signal to PWM which stands for pulse width modulation.  You need to send pulses fast enough that you don't get flicker - 60Hz or more.  Then you just vary the width of the positive pulse to get the light intensity you want.  If the positive pulse is equal to the off time, it's a 50% PWM which will give you half the power.  You will need to experiment how that translates to perceived brightness.  Half power doesn't necessarily mean half brightness.

[MichaelS78]

The problem here is the module is too slow to get good resolution pwm at a high enough frequency for what is likely to be a high shutter speed machine vision application.  I have a machine vision system which has to use ambient lighting which is 50hz led lighting and I have to use very slow shutter speed or else I get black frames.  The problem here of course is image blur if there is any vibration. It might be necessary to choose a much higher speed crio digital module.  I am not sure that pwm is recommended for vision lighting which is why lighting controllers are often very expensive analogue controllers. 

[Kgsalo]

Is there any way you can elaborate or share an example of your VIs?

I am only using 1 DAC module.

[Kgsalo]

do you have any example to share?

Thanks 

[OregonGumby]

Here is how to use LabVIEW to generate PWM:

https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000x1P0CAI&l=en-US