Dynomotion

Group: DynoMotion Message: 1727 From: Troy Date: 8/24/2011
Subject: ENCODER RECOMENDATION

Hello,

I was hoping someone could recommend an encoder to use.  I am new to using the kflop and I would like to add encoders to the back of my nema23 stepper motors to close the loop. 

Currently all I have found is U.S.Digital E6 http://usdigital.com/products/encoders/incremental/rotary/kit/e6  I was thinking of using the 2500cpr=10000ppr encoder thinking it would match the resolution of my drive if I have it in 50microstep/full step mode.

Am I on the right track, is that resolution overkill?

The only other encoders I can find are from Avago (in the $100 ish range), but there parametric search doesn't seem to be working and I cannot find anything in kit form that matches the resolution.  Anyone have any other recommendations?


Thanks
Troy
Group: DynoMotion Message: 1728 From: Tom Kerekes Date: 8/24/2011
Subject: Re: ENCODER RECOMENDATION
Hi Troy,
 
I don't have a better recommendation.  If you find any please let us know as we get asked this a lot.
 
There shouldn't be a requirement to match the encoder resolution to the microstep resolution because the encoder can be scaled with the InputGain0 parameter.  But try to avoid a ratio that can't be represented exactly as a decimal like 0.333333333
 
Normally the higher the resolution the better unless the frequency get to be too high.  Those encoders can only output 100KHz cycles (400KHz counts)  so at 10,000 counts per rev that comes out to a max speed of 40rps = 2400RPM.
 
Consider ordering the differential output types for a few extra dollars.  Those can work as single ended as well but gives the possibility to do differential if you ever run into noise issues (Our Kanalog and SnapAmp have differential inputs).
 
Regards
TK

--- On Wed, 8/24/11, Troy <groups@...> wrote:

From: Troy <groups@...>
Subject: [DynoMotion] ENCODER RECOMENDATION
To: DynoMotion@yahoogroups.com
Date: Wednesday, August 24, 2011, 9:47 AM

 

Hello,

I was hoping someone could recommend an encoder to use.  I am new to using the kflop and I would like to add encoders to the back of my nema23 stepper motors to close the loop. 

Currently all I have found is U.S.Digital E6 http://usdigital.com/products/encoders/incremental/rotary/kit/e6  I was thinking of using the 2500cpr=10000ppr encoder thinking it would match the resolution of my drive if I have it in 50microstep/full step mode.

Am I on the right track, is that resolution overkill?

The only other encoders I can find are from Avago (in the $100 ish range), but there parametric search doesn't seem to be working and I cannot find anything in kit form that matches the resolution.  Anyone have any other recommendations?


Thanks
Troy
Group: DynoMotion Message: 1729 From: tmday7 Date: 8/24/2011
Subject: Re: ENCODER RECOMENDATION
Hello,
Keling has a few.
http://kelinginc.net/ServoMotorEncoder.html

I have been told that the CUI AMT102-V KIT Encoder is a good one.

HTH,
TroyD (differnt than one who started post.) :)

--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Troy,
>  
> I don't have a better recommendation.  If you find any please let us know as we get asked this a lot.
>  
> There shouldn't be a requirement to match the encoder resolution to the microstep resolution because the encoder can be scaled with the InputGain0 parameter.  But try to avoid a ratio that can't be represented exactly as a decimal like 0.333333333
>  
> Normally the higher the resolution the better unless the frequency get to be too high.  Those encoders can only output 100KHz cycles (400KHz counts)  so at 10,000 counts per rev that comes out to a max speed of 40rps = 2400RPM.
>  
> Consider ordering the differential output types for a few extra dollars.  Those can work as single ended as well but gives the possibility to do differential if you ever run into noise issues (Our Kanalog and SnapAmp have differential inputs).
>  
> Regards
> TK
>
> --- On Wed, 8/24/11, Troy <groups@...> wrote:
>
>
> From: Troy <groups@...>
> Subject: [DynoMotion] ENCODER RECOMENDATION
> To: DynoMotion@yahoogroups.com
> Date: Wednesday, August 24, 2011, 9:47 AM
>
>
>  
>
>
>
>
>
>
>
> Hello,
>
> I was hoping someone could recommend an encoder to use.  I am new to using the kflop and I would like to add encoders to the back of my nema23 stepper motors to close the loop. 
>
> Currently all I have found is U.S.Digital E6 http://usdigital.com/products/encoders/incremental/rotary/kit/e6%c3%82%c2%a0 I was thinking of using the 2500cpr=10000ppr encoder thinking it would match the resolution of my drive if I have it in 50microstep/full step mode.
>
> Am I on the right track, is that resolution overkill?
>
> The only other encoders I can find are from Avago (in the $100 ish range), but there parametric search doesn't seem to be working and I cannot find anything in kit form that matches the resolution.  Anyone have any other recommendations?
>
>
> Thanks
> Troy
>
Group: DynoMotion Message: 1730 From: Troy Date: 8/24/2011
Subject: Re: ENCODER RECOMENDATION


I am guessing my steppers will be spinning under 2400rpm. I suppose I need to get one of my slides hooked up and see how fast my motors can spin under load.

I was planning on getting the differential encoders. I was working on a breakout board design for myself with the Ti encoder decode chip and some level shifters for the non 5v tollerant I/Os.

Instead of making my own board could I do the same thing with kanalog, and my steppers, I would rather work on other parts of my project then designing a circuit board, I just assumed kanalog was for servos only?

Group: DynoMotion Message: 1731 From: Tom Kerekes Date: 8/24/2011
Subject: Re: ENCODER RECOMENDATION
Hi Troy,
 
It is possible to use Kanalog with Step/Dir outputs but there are limitations as it consumes KFLOP's JP7 and JP5 connectors where the Step/Dir Outputs normally come out.
 
By unplugging JP5 from KFLOP to Kanalog you can still have access to 4 KFLOP Step/Dir outputs.  But this reduces the number of differential receivers on Kanalog from 16 to 8.  Everything else on Kanalog will function the same.
 
There is also another option to Mux the 4 Step/Dir Outputs from JP5 to JP4 and JP6 (2 each).  But only one on each of JP4 and JP6 can then be used in open collector mode.  It this manner you retain all 16 of Kanalog's differential inputs.
 
If you are interested I can provide more details.
 
Regards
TK

--- On Wed, 8/24/11, Troy <groups@...> wrote:

From: Troy <groups@...>
Subject: Re: [DynoMotion] ENCODER RECOMENDATION
To: DynoMotion@yahoogroups.com
Date: Wednesday, August 24, 2011, 11:44 AM

 


I am guessing my steppers will be spinning under 2400rpm. I suppose I need to get one of my slides hooked up and see how fast my motors can spin under load.

I was planning on getting the differential encoders. I was working on a breakout board design for myself with the Ti encoder decode chip and some level shifters for the non 5v tollerant I/Os.

Instead of making my own board could I do the same thing with kanalog, and my steppers, I would rather work on other parts of my project then designing a circuit board, I just assumed kanalog was for servos only?

Group: DynoMotion Message: 1732 From: Troy Date: 8/24/2011
Subject: Re: ENCODER RECOMENDATION
I looked at those but they seem to have a lot less resolution then my 2500cpr=10000ppr resolution encoders. 

If I understand the datasheet properly I think those encoders are not optical encoders they are capacitive and they say they are limited to 2048ppr.

I am still not sure whether I need the 10000ppr resolution, but it seems as long as long as I don't over do the rpms there is no harm in using the higher resolution encoders.

Group: DynoMotion Message: 1734 From: Troy Date: 8/25/2011
Subject: Re: ENCODER RECOMENDATION

Hi TK

Well, I am pretty far along with my board, and I am shooting for 6 axis of closed loop steppers, so it might be easier for me to just keep trucking along with my board design.   

Maybee you can answer this for me, are you familiar with the amc26v32 differential line receiver (is this what you used on the kanalog, it seems pretty common)?  If so do you know what I should do with G and Ginv.  On the chart in the datasheet it looks like I should pull one high and one low.


Thanks
Troy
Group: DynoMotion Message: 1735 From: Tom Kerekes Date: 8/25/2011
Subject: Re: ENCODER RECOMENDATION
Hi Troy,
 
I can't find a reference for that part number, but it is probably a variation of the one we use which is AM26LS32ACD.  The G and /G are the enables.  Set G high and /G low.
 
Regards
TK

--- On Thu, 8/25/11, Troy <groups@...> wrote:

From: Troy <groups@...>
Subject: Re: [DynoMotion] ENCODER RECOMENDATION
To: DynoMotion@yahoogroups.com
Date: Thursday, August 25, 2011, 3:23 PM

 

Hi TK

Well, I am pretty far along with my board, and I am shooting for 6 axis of closed loop steppers, so it might be easier for me to just keep trucking along with my board design.   

Maybee you can answer this for me, are you familiar with the amc26v32 differential line receiver (is this what you used on the kanalog, it seems pretty common)?  If so do you know what I should do with G and Ginv.  On the chart in the datasheet it looks like I should pull one high and one low.


Thanks
Troy