Encoder to meause RPM with Labview

[Alex995]

Hello,

I have recently acquired an NI USB 6002 and I'm looking to use it in order to measure the revolutions per second of a rotating shaft, and then log this data in Labview. I havent purchased an encoder yet as I'm pretty clueless with instrumentation(I'm trying to chage this). The shaft rotates at around 20 revs per sec, and will be slowed to hault. The RPS needs to be logged over this decceleration. 

Could somebody please suggest a LabView compatable encoder which is relatively easy to set up and a basic plan as to how the rps could be logged? I'm open to the idea of both mechanical and optical encoders, however like I said, I dont know which would be more appropiate. 

Thanks for your time.

Alex

[GerdW]

Hi Alex,

the USB6002 only supports a simple "up" counter as is noted in the specs. The counter expects TTL signals, so your encoder should output TTL-compatible signals or you need to add a small simple PCB with voltage level conversion.

In LabVIEW you would read the counter at (more or less) constant time intervals, take the difference and divide by the time interval to get the rotation speed. Quite basic stuff…

[preston_johnson]

An alternative to the counter function, is to use an analog input from a magnetic, eddy current, or laser speed sensor

Consider Monarch Instruments for industrial speed sensors

Banner also has some lower cost ones that I have seen used on rotor kits. 

You then get a pulsing time waveform, and can calculate frequency from the time waveform

Preston

[Alex995]

 Hi Gerd,

Thanks for taking the time to offer your help. Ill be sure to take that into account.

Apologies for the trivial nature of this problem, I'm a mech eng student trying expand my knowledge of this sort of stuff. Unfortunately our syllabus doesn't cover it in depth. 

Thanks again,

Alex