Dynomotion

Group: DynoMotion Message: 5163 From: michaelthomasn Date: 6/8/2012
Subject: Heidenhain encoder not countiong properly
Tom,

I have Heidenhain ROD 426 5000 line differential encoders on this Studer grinder that I'm trying to get going.

They seem to read about 10800 counts per revolution. They ought to read 20,000.....correct?

They recommend a 120ohm resistor across each pair.....but I noticed that Kanalog has 480ohms internal......so I did not add any additional. Is that a potential issue for me?

I also see now that they recommend a 4.7k resistor from each wire in the pair to their respective ground or 5v.....It says this will prevent switching of the receiver during line break. I assume this means the a+ will go to 5v, and the a- to ground.

Does that make any sense to you?

I do not have any resistors connected at this point.....neither across pairs or from each individual.

Would this explain my lack of proper counting?

I am powering the encoders from the Kanalog.

Mike
Group: DynoMotion Message: 5164 From: Tom Kerekes Date: 6/8/2012
Subject: Re: Heidenhain encoder not countiong properly
Hi Mike,
 
You might search for a manual and include a link.  But I can't see why it wouldn't work without any resistors.  You might try adding a ~160 ohm external resistor (at Kanalog) to bring the termination down to 120 ohms.  But I wouldn't expect it to miss half the counts just because of non-ideal termination.  A common problem is to not have the + or - input properly connected and as a result the Kanalog input is left floating.  In this case it is common to get a result like you are seeing.  The first thing to check is all 4 signals at the Kanalog terminals to make sure they are all being driven high and low.  Ideally with a scope but a voltmeter can also be used.  I think the 4.7K pull up/down are to avoid a broken wire situation partially working like you are describing.  Rather it will make it not count at all.  You might also check if the count repeats when you return back to the same place.  There is also an InputGain0 parameter that can scale the input counts.  Verify that that has a magnitude of 1.
 
Regards
TK

From: michaelthomasn <michaelniksch@...>
To: DynoMotion@yahoogroups.com
Sent: Friday, June 8, 2012 2:18 PM
Subject: [DynoMotion] Heidenhain encoder not countiong properly

 
Tom,

I have Heidenhain ROD 426 5000 line differential encoders on this Studer grinder that I'm trying to get going.

They seem to read about 10800 counts per revolution. They ought to read 20,000.....correct?

They recommend a 120ohm resistor across each pair.....but I noticed that Kanalog has 480ohms internal......so I did not add any additional. Is that a potential issue for me?

I also see now that they recommend a 4.7k resistor from each wire in the pair to their respective ground or 5v.....It says this will prevent switching of the receiver during line break. I assume this means the a+ will go to 5v, and the a- to ground.

Does that make any sense to you?

I do not have any resistors connected at this point.....neither across pairs or from each individual.

Would this explain my lack of proper counting?

I am powering the encoders from the Kanalog.

Mike
Group: DynoMotion Message: 5165 From: oxforduniv Date: 6/8/2012
Subject: Re: Heidenhain encoder not countiong properly
Is it possible it is 2500p/rev? Also some versions of the ROD426 only went to 3600p/rev, the 160khz version.
Al.
--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Mike,
>  
> You might search for a manual and include a link.  But I can't see why it wouldn't work without any resistors.  You might try adding a ~160 ohm external resistor (at Kanalog) to bring the termination down to 120 ohms.  But I wouldn't expect it to miss half the counts just because of non-ideal termination.  A common problem is to not have the + or - input properly connected and as a result the Kanalog input is left floating.  In this case it is common to get a result like you are seeing.  The first thing to check is all 4 signals at the Kanalog terminals to make sure they are all being driven high and low.  Ideally with a scope but a voltmeter can also be used.  I think the 4.7K pull up/down are to avoid a broken wire situation partially working like you are describing.  Rather it will make it not count at all.  You might also check if the count repeats when you return back to the same place.  There is also an InputGain0 parameter that can
> scale the input counts.  Verify that that has a magnitude of 1.
>  
> Regards
> TK
>
>
> ________________________________
> From: michaelthomasn <michaelniksch@...>
> To: DynoMotion@yahoogroups.com
> Sent: Friday, June 8, 2012 2:18 PM
> Subject: [DynoMotion] Heidenhain encoder not countiong properly
>
>
>  
>
> Tom,
>
> I have Heidenhain ROD 426 5000 line differential encoders on this Studer grinder that I'm trying to get going.
>
> They seem to read about 10800 counts per revolution. They ought to read 20,000.....correct?
>
> They recommend a 120ohm resistor across each pair.....but I noticed that Kanalog has 480ohms internal......so I did not add any additional. Is that a potential issue for me?
>
> I also see now that they recommend a 4.7k resistor from each wire in the pair to their respective ground or 5v.....It says this will prevent switching of the receiver during line break. I assume this means the a+ will go to 5v, and the a- to ground.
>
> Does that make any sense to you?
>
> I do not have any resistors connected at this point.....neither across pairs or from each individual.
>
> Would this explain my lack of proper counting?
>
> I am powering the encoders from the Kanalog.
>
> Mike
>
Group: DynoMotion Message: 5166 From: michaelthomasn Date: 6/8/2012
Subject: Re: Heidenhain encoder not countiong properly
Well....everything checks out fine.

The problem turned out to be with a certain moron who failed to realize that the encoder was not, in fact, attached to the motor....but directly to the ballscrew.

It counts 20,000 times per ballscrew turn, and about 10,800 per motor revolution.

Lol.....sorry for the bother.

Everything is working well so far.

Thanks once more.

Mike


--- In DynoMotion@yahoogroups.com, Tom Kerekes <tk@...> wrote:
>
> Hi Mike,
>  
> You might search for a manual and include a link.  But I can't see why it wouldn't work without any resistors.  You might try adding a ~160 ohm external resistor (at Kanalog) to bring the termination down to 120 ohms.  But I wouldn't expect it to miss half the counts just because of non-ideal termination.  A common problem is to not have the + or - input properly connected and as a result the Kanalog input is left floating.  In this case it is common to get a result like you are seeing.  The first thing to check is all 4 signals at the Kanalog terminals to make sure they are all being driven high and low.  Ideally with a scope but a voltmeter can also be used.  I think the 4.7K pull up/down are to avoid a broken wire situation partially working like you are describing.  Rather it will make it not count at all.  You might also check if the count repeats when you return back to the same place.  There is also an InputGain0 parameter that can
> scale the input counts.  Verify that that has a magnitude of 1.
>  
> Regards
> TK
>
>
> ________________________________
> From: michaelthomasn <michaelniksch@...>
> To: DynoMotion@yahoogroups.com
> Sent: Friday, June 8, 2012 2:18 PM
> Subject: [DynoMotion] Heidenhain encoder not countiong properly
>
>
>  
>
> Tom,
>
> I have Heidenhain ROD 426 5000 line differential encoders on this Studer grinder that I'm trying to get going.
>
> They seem to read about 10800 counts per revolution. They ought to read 20,000.....correct?
>
> They recommend a 120ohm resistor across each pair.....but I noticed that Kanalog has 480ohms internal......so I did not add any additional. Is that a potential issue for me?
>
> I also see now that they recommend a 4.7k resistor from each wire in the pair to their respective ground or 5v.....It says this will prevent switching of the receiver during line break. I assume this means the a+ will go to 5v, and the a- to ground.
>
> Does that make any sense to you?
>
> I do not have any resistors connected at this point.....neither across pairs or from each individual.
>
> Would this explain my lack of proper counting?
>
> I am powering the encoders from the Kanalog.
>
> Mike
>