Encoders & their wiring to the UHU servo controllers

[H.O]

Do you have an working UHU servo-drive? If so, connect the encoder to the drive and turn on the loe voltage power supply but not the motor power supply. Now rotate the encoder, after a while the ERROR-LED on the UHU will turn on. If it does the encoder works.

[cnc2]

Thanks for the reply Henrik !

I didn't assemble my UHU boards yet, i was waiting for a working encoder to test the UHU with it ... there will be two unknowns the encoder & the UHU ... I'm afraid of ruining a board since i can't find the parts in here !

Do you have an other option ?

Thanks !
cnc2.

[H.O]

If you have an oscilloscope then hook it up, and look at the two channels as you spin the encoder. You should have two squarewaves with a 90° phaseshift between them, like this:

A ______-------______-------_______


B ---______-------______-------____


If you don't have an oscilloscope you'll have to try doing it with a multimeter, measure the outputs in try to find the pattern above. If the the outputs toggle between 0 and 5V it highly unlikely that you'll damage the UHU so after verifying the output voltage it may be easier to just hook it up and try it.

What resolution is this encoder?

[cnc2]

If you have an oscilloscope then hook it up, and look at the two channels as you spin the encoder. You should have two squarewaves with a 90° phaseshift between them, like this:

A ______-------______-------_______


B ---______-------______-------____


If you don't have an oscilloscope you'll have to try doing it with a multimeter, measure the outputs in try to find the pattern above. If the the outputs toggle between 0 and 5V it highly unlikely that you'll damage the UHU so after verifying the output voltage it may be easier to just hook it up and try it.

What resolution is this encoder?

Thanks for the reply Henrik !

I haven't a scope, so, i tried with the multimeter and it works !!!!

I had to figure out why it wasn't working, since i ain't using the PN100 transistors & i'm using the s9013 instead i thought the current reduced by the 1k resistors (R4 & R7) wasn't enough to energise'em(Inspired by your solution for the IR transmitter), so, i just twisted'em to short'em just to try & it works ! & thanks a lot !

This encoder is using a computers mouse sensors and has an encoder wheel with 36 counts per rev, LOL, but, if you replace the sensors with these you will be able to use the 1200 count/rev encoder wheel that comes with'em !

What do you think about software oscilloscope ?

****Edit*******

Well, i tried Zelscope (15 days trial) & took some screen shots with it, it's a software oscilloscope that uses the sound card as input, the only probe i had on hand was a double jack audio cable & i didn't know how to use two different channels at the same time so, i recorded'em separately.

On the pics you can see the amplitude is way under 5 V (it might be the scales ? not sure) in picture 1 the amplitude is a lot highier than the one in picture 2, but, with the multimeter both of them read 4.7 V when the receiver is totally hidden from IR light.

So, why this strange result ?
From what i guessed: since the teeth of the encoder wheel are triagular the channel in picture 2 gets more IR light than the other channel in picture 1, (what is a bit strange for me is when the reciever is totally hidden the multimeter reads 4.7 V & when it's almost hidden it reads 0.3 V to 0.7 V) that's why the amplitude is lower in picture 2 & that's why the Agilent IR module (from HP printes) is encased in a U shaped black housing with a really thin slot opening on the recievers side.(more precise than the one of the pic)

Correct me if i'm wrong !

I will try and see what i get with the Agilent housing + 1200 count encoder wheel.

(My English is reaching its limits, sorry !)


Thanks !

Best regards,
cnc2.

[cnc2]

Hi guys !

I saw this vid on youtube "http://www.youtube.com/watch?v=JpQFPOMUFmk"]Encoder on the scope, and what i can say is that my previous screen shots are useless and meaningless because they don't look like the signals on the vid.


Guys i need your help !


When hiding the receiver my multimeter reads 4.7 V else it is 0 V i don't understand why the software scope is giving me positive and negative "phases" , and not giving only 0 V to 4.7V squarewave ?


Is my problem from the software oscilloscope i'm using ?


I'm not an electronician so please help me with this issue.

Thanks !

cnc2.

[H.O]

Hi CNC2,

I think the srange looking waveform in your screenshots is due to the fact that you're using the soundcard as the input. The input on the soundcard is built to "measure sound" ie AC and usually has a small capacitor in series to stop DC from entering the circuitry and the waveform you see is a result of that capacitor - I think.

Try spinning the encoder a lot faster and see if you can get a waveform that looks better. However, I really think you should connect the encoder to a drive and try it. Turn it a bit and after a certain amount of pulses the drive will error - that will prove if the it works or not.

Edit: I looked at the Zelscope website, in the FAQ section I found this:

Q: Can Zelscope display DC voltage?
A: No. All known sound cards contain a capacitor which provides AC coupling and prevents DC from reaching the card's analog to digital converter. Low-frequency oscillations (below 15-20Hz) usually get through, but may be distorted.

[cnc2]

Hi CNC2,

I think the srange looking waveform in your screenshots is due to the fact that you're using the soundcard as the input. The input on the soundcard is built to "measure sound" ie AC and usually has a small capacitor in series to stop DC from entering the circuitry and the waveform you see is a result of that capacitor - I think.

Try spinning the encoder a lot faster and see if you can get a waveform that looks better. However, I really think you should connect the encoder to a drive and try it. Turn it a bit and after a certain amount of pulses the drive will error - that will prove if the it works or not.

Edit: I looked at the Zelscope website, in the FAQ section I found this:

Outch ! (i feel stupid) i should have read the FAQ

Thank you so much Henrik ! you're bringing me back to business, thanks !

What do you mean when you say "a waveform that looks better" ?

When i spin the encoder a lot faster i get a waveform with the same amplitude (with the problem of positive and negative phases) but i get more "ticks" on Zelscopes screen, and the "ticks" get closer as the encoder spins faster. (like on the left of the screen shot)

The problem of the small amplitude of the channel 2, came from some mis alignement or a false contact on the old mouses pcb, i succeeded in getting the same amplitude as channel 1 when moving the receiver. the screen shot shows the waveform when spinnig the encoder faster while moving the sensor.

I'm really afraid of frying a driver, but if there's no other option i'll be obliged to try it !

Best regards,
cnc2.

[H.O]

Hi,
Never mind the idea of spinning it faster - it didn't seem to do what I was hoping for......

As long as you verify (with a voltage meter) that both outputs toggles between 0V and 5V (0-0.7V when "low" is OK and 4-5V when "high" should be fine), you can't really fry the drive. It still may not WORK but it won't damage the drive and without a proper scope it's probably the easiest way.

[cnc2]

Hi,
Never mind the idea of spinning it faster - it didn't seem to do what I was hoping for......

As long as you verify (with a voltage meter) that both outputs toggles between 0V and 5V (0-0.7V when "low" is OK and 4-5V when "high" should be fine), you can't really fry the drive. It still may not WORK but it won't damage the drive and without a proper scope it's probably the easiest way.

Ok,
i'll start assembling my first UHU driver hoping it to work.

Thanks for your help Henrik !

Regards,
cnc2.

[tenmetalman]

Hello,
for those of us with a limited electronics back ground can you tell or show us how and where you connect to the UHU HP drive card to see the above signals. I & others I assume, have been slow to try & check for the signal for fear of smoking the drive
Thanks
Paul

[H.O]

Hi Paul,
If you have a scope and a differential encoder then you can look at the signals by hooking the scope to the two pads labeled J1 & J2 (two square solder pads to the left of U5). That will show you the A- and B-channel of the encoder on 'the inside' of the differential receiver.

If you don't have a differential encoder then you connect the encoder to these same solder pads and remove U5. You can still connect the scope to these same pins/pads to look at the signals.

Connect the GND clips on the scope to one of the GND-pins in the DB15 encoder connector for example.

But really, the easiest way to check if the encoder works is to just connect it and spin it with your fingers, if the RED fault LED on the HP-UHU lights up after a while it works if it doesn't you need to investigate it further. Don't turn on your HV motor power supply if you do this test, just the 15V power supply!

HTH
/Henrik.

[tenmetalman]

Henrik,
Thanks for your reply, I have a Velleman personal scope that I've never used.So I was thinking it would be nice to see the wave form................ I've had the darn thing for probably s year & never used it.
Thanks again
Paul