Digital input time measurement with LabView RT and cFP-2010 + cFP-DI-301

[Tom C]

I want to measure the time between a 0-to-1 transition and a 1-to-0 transition on my Compact Fieldpoint digital input module cFP-DI-301. I use LabView RT 7.1 and a cFP-2010 controller.

It is possible to do this by polling the digital input line (FP Read.vi) with a regular time interval and using the timestamp as the time reference. But is there any way to get an event/interrupt when the digital input value changes? In that way, I would not have to poll the digital input, and I would be able to save processor time of the cFP controller.

[Vesa_K]

Hi Tom C,

FieldPoint 2010 module supports only polling in Real-time mode. Your cFP-2010 can be used as event driven controller only if the application is not executed in RT (the controller is used in 'FP-1600 mode'). I guess that this is not what you want to do. So run the application in RT mode and keep polling digital inputs in tight loop. You also have a possiblility to use priorities to provide CPU time for other tasks.

There's a list about Poll Driven and Event Driven FieldPoint controllers in web:

http://digital.ni.com/public.nsf/websearch/31C23F7F5B5973A486256E910059EB67?OpenDocument

Vesa K

National Instruments