Using two NI USB 6501 as counters?

[matses_51]

Hello

Im working with a project at my school. Im going too build a dyno that measures the torque on RC cars. All i need is two sensor who counts the rolls rpms. I was hoping i could use two NI USB 6501 modules using the P2.7 ports to log the spesific RPM. With the help og the rolls massinertia i can calculate the torque the car is developing.

I was thinkin of using two inductive sensors.

Is there possible to use two NI USB 6501 to perform this task?

Can the NI USB 6501 be simulated in labview? I cant find it in the list.

Message Edited by matses_51 on 02-10-2009 04:29 AM

[Wayne.C]

matses_51,

Any frequency measured using the event counter in a 6501 would not be very accurate.  If you are stuck with using the 6501, then I would consider building up a frequency to voltage converter circuit and feeding resulting voltage to an analog input.  There a several semiconductor companies that produce single chip solutions for this.

[JCAndle]

You could use an external circuit like a 555 timer to create a gate pulse.  I am not sure if the 6501 supports the feature but the drivers have calls for it -- using another digital input as the gate.

Use the 555 timer to make a "somewhat" stable 1 second pulse (or whatever you need) then use a digital output to trigger the 555, starting a measurement..  Hook a callback on the falling edge of the gate signal to know when to read.

If the 555 (or similar) is not stable enough, use a quartz oscillator and a divider to get a precision timebase but this gets more involved...