Calculate RPM using NI 9402

[Spieler]

I am attempting my first simple Labview DAQ project, though I am more comfortable with Signal Express.

My torque sensor has a +/- 5Vdc, 60 pulse/revolution speed output. The speed will be up to 200 RPM, so I was aimed towards a NI 9402 High Speed Digital I/O module for my CompactDAQ chassis. When I used DAQ Assistent to configure the counter, it indicated that there were no supported devices found. Is there some easy code to calculate shaft RPM with the 9402 configured as a digital input?

Thanks

[MarkGrot · Accepted solution]

Are you using a cDAQ-9172 chassis?  If so, your NI 9402 needs to be in slot 5 or 6 to use any counter functionality.  This restriction does not exist for newer chassis.  Try moving the module to one of those slots.  You should now be able to select counter channels using the DAQ Assistant.

[Spieler]

Thanks, after switching the module to slot 5 it recognized it immediately. I'm still having trouble setting it up to convert the pulses to a rotational speed. I hoped to have a simple frequency output that I could apply the math to, but I have not had any luck.

[DTriip]

I have the same module and am also trying to calculate RPM from a transducer that outputs 60 pulses/revolution however I am using the cRIO platfrom and I believe the Express scripts do not work with cRIO, correct? What would be the best way to go about programming this calculation then?

Best,

Dan

[DTriip]

Solved my own problem by using the "Configuring a Counter to Measure Period" help article in Labviews menus.