回應： chatter monitor

[abashore]

Hi All, being a LV newbie, I have a question on building a chatter monitoring system. Basically, I have a USB 6210, monitoring various DC voltages. What I need to do is detect a dropout that is greater than say, 20 mSec. I'm able to set the voltage threshold, and output a boolean true to a case structure to make things happen. However, I don't know how to set a time threshold. 

For example, if I'm monitoring a voltage, and I set a low threshold of 1.5V and .02 sec and I get a 1.1V signal over a time of .5 sec I would need to light an indicator and log the droput info to a file. 

Currently I have the simulate signal VI, but I would replace it with DAQ Asistant or DAQMX task

I have LV 2012 SP1

Thanks,

[Lennard.C]

Hi abashore,

You could use Elapsed Time Express Vi to give you a true boolean value via its Time has Elapsed? output terminal. You can also auto reset it when it reaches the threshold time or you can manually reset it.

Elapsed time Express VI: http://digital.ni.com/public.nsf/allkb/05A9C3B0A4D5A7638625712B006FB30F

Warmest regards,

Lennard.C 

[William1225]

Hi, abashore,

You can also use the time tick to colloect the duration lower than the DC threshold.