Magnetic absolute and incremental encoder

[nForce]

I would like to know how does it work the magnetic absolute encoder and incremental one? Not the optical one.

I have these 2 signals (in attachment) from the incremental magnetic encoder. How would I calculate the speed of the motor?

Thanks.

[ataradov]

This is the same as optical encoders work.

The speed regardless of the direction (assuming that direction is constant) - just use any channel and measure the frequency (number of edge transitions in a unit of time). The RPMs are proportional to that value. Exact coefficient depends on the overall mechanical design of the system.

[nForce]

Ok, in my case it's:

(12.02 kHz * 60)/1024

From where do we get that 60 and 1024?

Thanks ataradov 

[ataradov]

1024 looks like the number of edges per revolution. Assuming you are counting only rising or falling edges, that would make your encoder to be 4096 steps/rev, which is pretty standard.

Where does 60 come from, I have no idea. Do you have any sort of gearing between the motor and the encoder?

In your case, if you count N pulses per minute, then RPM = N / 1024, since 1024 pulses constitute the full rotation.

[rstofer]

kHz is in seconds, RPM is in minutes, 60 shows up in there somewhere.

[ataradov]

Yes, that makes sense