Counter problem

[MikeDahl]

Hello

I'm new to LabVIEW.

I want to make a program to measure RPM by using a switch between AI15 and +5V on the USB-6215. I have setup a program in labview "Sample on demand" and a filter, because when i connect a wire only to the AI15 i get a very noisy signal. But when the USB-6215 is on "sample on demand" the filter doesn't work???? Only in Continuous mode..

Can somebody please look my vi to help me modify the program to measure rpm? 

[DavidMaidman]

You haven't included your VI

[MikeDahl]

Sorry, here it is 🙂

[DavidMaidman]

The filter you are using expects a number of points (for example in the form of a waveform or an array of points), whereas you are passing it a single point.

You could try the following: -

Acquire a number of points and build waveform/array point by point then filter when there are a number of points (you could store the points on a FIFO basis, or filter after all data has been acquired.)

Or, use a filter that works on a point by point basis

[DavidMaidman]

Also,

it looks like you are measuring a digital signal - if so why have you conected it to an analogue input?

[MikeDahl]

Hello

It's because i dont know how to do it :s if you may could help, it would be great. The DAQmx is setup to measure analog voltage.. 

[DavidMaidman]

You can find lots of examples in LabVIEW.

Try Help>>Find Examples then select Hardware Input and Output>>DAQmx

Similarly you can find some filtering examples; Help>>Find Examples then select Aanalysing and Processing Signals>>Filtering and Conditioning

Rather than filtering have you considered adding some hysteresis to your switch level?

[smercurio_fc]

moved here