Hi

It all depends on the type of encoder you use.

https://en.wikipedia.org/wiki/Rotary_encoder

http://qringtech.com/2010/09/15/diy-encoder-rpm-torsion-vibration/

For encoders with ABZ signals, you get pulses at certain times and you can work out the angle from these by counting these pulses.

The Z channel provides one pulse per rotation. You know that your encoder has N pulses per revolution, so a pulse on channel A at t1, t2, .. tk whan be counted and you will have 360 degrees angle after N pulses are counted and rotation is monotous. The B channel usually is 90 degrees offset from the A channel which allows you to work out if your rotation is back/forth. 

The above will give you angle values (say variable A) at different times (say variable T) where the time spacing depends on your measurement.

Once you have angle and time vectors, you are free to plot the signals as plot(A,T).

If you want to output and, e.g. listen to your signal, you can use your computer's sound card to do so using the matlab function wavwrite. You then resample the signal, e.g. using the function interp1 from arbitrary time steps to time steps decided by the sound card's supported sampling frequency, fs. The new time signal would be T2 = [0:1/fs:(length(T)-1)/fs]. The command would then be A2 = interp1(T,A,T2).

The wav file is generated as wavwrite(A2,fs,Nbits,'filename.wav'), where Nbits usually is 16 (as is used on CD records). Please note that the 16-bit wave file is scaled such that the maxium amplitude is unity or near unity to provide the best Signal to Noise ratio for listening.

Sincerely

Claes

Claes Richard Fredö: Thanks. I use  a rotary encoder( ES304-1000-2-24) for my experiment. I recorded an output (attached file). I want to convert the digital signal of encoder output to analog. How can I do it?!!!

Hi

Using Google, I cannot find any product model ES304-1000-2-24.

A guess is 1000 pulses per revolution, 2 channels and 24 Volt feed to drive it.

If output is TTL, each pulse should give you 5 Volt.

If it is not A/B/Z type but absolute position encoded, I cannot help you.

Suggestion - rotate the encoder 360 degrees by hand, log the signal output as analog signal and count the pulses. If it is A/B you get 1000 pulses on both channels and you can see if they are 90 degrees separated. If if is A/Z, you get 1000 pulses on Channel A and 1 pulse on Channel Z.

If you only have digital input, the digital unit will trig on the pulse and give you the time at which it trigged.

It is up to you to reconstruct the angle from the pulse-timing-data.

Here are some more Matlab links that may or may not help

http://se.mathworks.com/help/daq/examples/measure-angular-position-with-an-incremental-rotary-encoder.html

http://se.mathworks.com/help/physmod/elec/ref/incrementalshaftencoder.html

and another information link

http://www.electronics-tutorials.ws/io/io_2.html

/Claes

Hi

I read suggestions from Mr Claes Richard and feel that he is right from working professional expert. As the use of rotatory encoder is to measure angular speed & position. Mr Richard explained it very well. I think Mr Jamaleddin is required to use out put of encoder to activate another actuator or device. The actuator required input in analog or continuous form. If the output of encoder is digital format then convert value to equivalent to analog and use interpolation methods to smooth the signal. I think this is useful for you. 

Hi

Perhaps this document & homepage section can help?

http://content.heidenhain.de/presentation/basics/en/index.html

http://www.heidenhain.com/en_US/fundamentals/interfaces/

http://www.heidenhain.com/de_EN/php/documentation-information/brochures/popup/media/media/file/view/file-0668/file.pdf#page=

There exists electronics that convert TTL pulses to sine wave output, where the peak-to-peak time distance is the angle output, though Matlab is then not part of the picture.

/Claes

I am curious, what is the need of converting digital signal back to analog? Maybe that will help someone answer it to your preferred solution..

If u want only analog display it can be seen through workspace variable in the MATLAB, by plotting that variable through right click.

If u want only analog display it can be seen through workspace variable in the MATLAB, by plotting that variable through right click.