Angular position of incremental rotary encoder without knowing RPM

[ngio]

Hi All,

I have seen a few topics where people have coupled an encoder to a motor and are determining the angular position of the drive shaft.  Although if this motor is a gas powered motor how can I monitor the pulses? the issue arrises because the measure angular position.vi uses an input for rpm even though the rpm is not constant just like the velocity is not constant.  

What I'm trying to get at, is a way for labview to measure the amount of rising edges (i.e. ticks on the optical incremental encoder wheel) and display it in a waveform graph without knowing the precise rpm of the engine.  I presume once converted to angular quantities, i will get a distorted sine curve, although this is what I'm looking for.  

If you have any suggestions or require more information I will gladly provide it.

Thanks,
Nick 

[aeastet]

Some DAQ cards have high speed encoder counters that can give angle without rpm. It is very simple to do. You only have to set up the system input how many poles you have on your encoder and hook up the A and B pole of the encoder and the DAQ card does the rest.

[ngio]

Thanks for the quick response.  I was planning on using a NI 9201 to measure a simple voltage input through an Analog channel.  I also have a NI9263, NI9213 and NI9401 at my disposal if I need them.  Are either of these one of the DAQ cards that you were referring to when you mentioned the high speed encoder counters?

Thanks,

Nick 

[ngio · Accepted solution]

I found this article on the website...  very helpful, I will try it on monday but for now I will accept it as a solution since it does not require an RPM input.

http://www.ni.com/gettingstarted/setuphardware/dataacquisition/quadratureencoders.htm

Thanks,
Nick