From: Tom Kerekes <tk@...>
Subject: Re: [DynoMotion] Still strange things happening!
To: DynoMotion@yahoogroups.com
Date: Tuesday, December 14, 2010, 3:32 AM

 

Hi Jared,

 

That sounds like noise.  I doubt that it is a problem with the +5V power.  Noise problems can be very complex.  Single ended encoders are more sensitive to noise than differential encoder signals so you need to take great care about shielding and grounding.  The idea is to reduce radiated noise from the motors and motor wiring.  And also shield any residual noise from getting into the encoder signals.  Even If the motors are idle at zero current, the motors and all the motor wiring still have the +/- 55V switching on them at 30KHz.  You might try connecting the encoder shield to KFLOP DC ground (not earth ground) at the KMotion Board end of the cable.  The Motor shields should probably go to earth ground.  Is the machine connected to earth ground directly?

 

You might also try adding a terminating resistor of 250 ~ 150 ohms as close as possible to the KMotion encoder inputs to ground.  

 

There is also an encoder digital noise filter setting you can try.  The default is to ignore glitches less than 7 clocks.  The following program changes all the filters to 100 clocks (@16MHZ).  Note that setting the filter to 100 will limit the encoder to 160,000 counts/sec max.

 

#include "KMotionDef.h"

main()
{
    FPGA(ENC_NOISE_FILTER_ADD) = 100;
}

With regard to the heater - move south where you won't need it :}

 

Regards

TK

 

Group: DynoMotion	Message: 788	From: Tom Kerekes	Date: 12/18/2010
Subject: Re: Still strange things happening!

Hi Jared,   >>  I connected the machine to earth ground   good   >> Then I connected the motor shielding to the machine frame next to each motor mount   good   >> The encoders no longer float at idle   good   >> Exactly how do I connect the encoder shields to dc ground?   At the end of the encoder cable near KMotion JP3, connect the shield to GND (ie JP3 pin 40).  Both the encoder GND wire (inside the cable) and the shield will be connected to KMotion JP3 GNDs   The shield at the other end of the encoder cable (near the encoder) can be left dis-connected.   >>  Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack?   Yes, a simple 1/4 watt 200 ohm resistor.  You will need two resistors per axis.  As close as possible to KMotion connect one end of the resistor to the encoder A signal (ie JP3 pin 15), and the other end of the resistor to ground (JP3 pin 40).  Similarly connect the other resistor, one end to the encoder B signal (ie JP3 pin 16), and the other to ground (JP3 pin 40).   I assume by "float" you mean that the position drifts and doesn't repeat?   No problem asking questions.  Noise problems are very difficult to solve.  I wish I had a simple solution for you.   Regards TK   Group: DynoMotion Message: 808 From: cell.vlad Date: 12/22/2010 Subject: Re: Still strange things happening! Grounding and voltage conversion - it is a serious issues. Grounding : - Always chose the single point to ground. - Do not allow current flow through grounding shield. - Make a different Signal and Current Grounding. Voltage conversion.  In KFlop is used progressive LVTTL I/O which is allow to reduce the total pover consumption, but is sensitive to "Ground Noise".  Most converters from 5, 10, 15, 30 v to LVTTL need to be very carefully engineered and properly grounded. Incorrect voltage level handling would cause "Ground Noise", which will lead to sudden signal trip  or  fluctuations. Also, during conversion, consider to use some frequency filtration. Look on maximum allowed frequency response on specific channel and build an passive or active filtration. It is a specially important to deal with a fast data processing system, like KFlop. I do not see any advises or drawings from Dyno on this, but if some one have them, please post here. Happy Milling, Vlad   Group: DynoMotion Message: 817 From: Jared Tesmer Date: 12/27/2010 Subject: Re: Still strange things happening! Back again Tom  Ok I connected the sheilds to there respective grds. That caused no problems. When I connected the a and b signals to ground through a 1/4 watt 220 ohm resister ( closest to 200 ohm they had) the encoders would not work at all. I have been told by someone else to connect the encoder sheilding to earth ground star point? He also said to connect the a and b signals to +5v through the resisters?  Do you see a problem with this theory? As of now is there nowhere else to go? Is there something that can be connected in line to the signal that can clean them up and keep them straight? Not your fault but this is driving me mad!!! Last is there some way to connect the encoders A, A-, B, and B- to k-motion and would that fix the problem? Thanks again. Jared  --- On Sat, 12/18/10, Tom Kerekes <tk@...> wrote: From: Tom Kerekes <tk@...> Subject: Re: [DynoMotion] Still strange things happening! To: DynoMotion@yahoogroups.com Date: Saturday, December 18, 2010, 9:20 PM   Hi Jared,   >>  I connected the machine to earth ground   good   >> Then I connected the motor shielding to the machine frame next to each motor mount   good   >> The encoders no longer float at idle   good   >> Exactly how do I connect the encoder shields to dc ground?   At the end of the encoder cable near KMotion JP3, connect the shield to GND (ie JP3 pin 40).  Both the encoder GND wire (inside the cable) and the shield will be connected to KMotion JP3 GNDs   The shield at the other end of the encoder cable (near the encoder) can be left dis-connected.   >>  Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack?   Yes, a simple 1/4 watt 200 ohm resistor.  You will need two resistors per axis.  As close as possible to KMotion connect one end of the resistor to the encoder A signal (ie JP3 pin 15), and the other end of the resistor to ground (JP3 pin 40).  Similarly connect the other resistor, one end to the encoder B signal (ie JP3 pin 16), and the other to ground (JP3 pin 40).   I assume by "float" you mean that the position drifts and doesn't repeat?   No problem asking questions.  Noise problems are very difficult to solve.  I wish I had a simple solution for you.   Regards TK   Group: DynoMotion Message: 818 From: carlcnc Date: 12/28/2010 Subject: Re: Still strange things happening! Jared I was reading all your posts, Might I suggest you get on cnczone , post your encoder problems there. There are a lot of savvy and helpful guys there. Given that turning on your shop heater causes more issues I would double check that you have a good ground back to mains. Carl --- In DynoMotion@yahoogroups.com, Jared Tesmer <judrandom@...> wrote: > > > > > > > Back again Tom >  Ok I connected the sheilds to there respective grds. That caused no problems. When I connected the a and b signals to ground through a 1/4 watt 220 ohm resister ( closest to 200 ohm they had) the encoders would not work at all. I have been told by someone else to connect the encoder sheilding to earth ground star point? He also said to connect the a and b signals to +5v through the resisters?  Do you see a problem with this theory? As of now is there nowhere else to go? Is there something that can be connected in line to the signal that can clean them up and keep them straight? Not your fault but this is driving me mad!!! Last is there some way to connect the encoders A, A-, B, and B- to k-motion and would that fix the problem? Thanks again. > Jared  > > --- On Sat, 12/18/10, Tom Kerekes <tk@...> wrote: > > > From: Tom Kerekes <tk@...> > Subject: Re: [DynoMotion] Still strange things happening! > To: DynoMotion@yahoogroups.com > Date: Saturday, December 18, 2010, 9:20 PM > > >   > > > > > > Hi Jared, >   > >>  I connected the machine to earth ground >   > good >   > >> Then I connected the motor shielding to the machine frame next to each motor mount >   > good >   > >> The encoders no longer float at idle >   > good >   > >> Exactly how do I connect the encoder shields to dc ground? >   > At the end of the encoder cable near KMotion JP3, connect the shield to GND (ie JP3 pin 40).  Both the encoder GND wire (inside the cable) and the shield will be connected to KMotion JP3 GNDs >   > The shield at the other end of the encoder cable (near the encoder) can be left dis-connected. >   > >>  Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack? >   > Yes, a simple 1/4 watt 200 ohm resistor.  You will need two resistors per axis.  As close as possible to KMotion connect one end of the resistor to the encoder A signal (ie JP3 pin 15), and the other end of the resistor to ground (JP3 pin 40).  Similarly connect the other resistor, one end to the encoder B signal (ie JP3 pin 16), and the other to ground (JP3 pin 40). >   > I assume by "float" you mean that the position drifts and doesn't repeat? >   > No problem asking questions.  Noise problems are very difficult to solve.  I wish I had a simple solution for you. >   > Regards > TK >   > > > > > From: Jared Tesmer <judrandom@...> > To: DynoMotion@yahoogroups.com > Sent: Sat, December 18, 2010 5:41:32 PM > Subject: Re: [DynoMotion] Still strange things happening! > >   > > > > > > > Ok Tom I'm a little confused. I connected the machine to earth ground. Then I connected the motor sheilding to the machine frame next to each motor mount. I hope thats right. The encoders no longer float at idle. They still float while running programs. It gets worse the more axis that run at the same time. Exactly how do I connect the encoder sheilds to dc ground on the k-motion board? The encoders are connected to the 2 grounds on the jp3 and one of the two on the jp4. Would I connect the sheild to the encoder ground and both to the board together? Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack? Also would I connect one end to the encoder ground and the other to the ground used at the board? Kind of a buffer between the two? Probably driving you crazy by now. Thanks >   >   > Jared > > --- On Tue, 12/14/10, Tom Kerekes <tk@...> wrote: > > > From: Tom Kerekes <tk@...> > Subject: Re: [DynoMotion] Still strange things happening! > To: DynoMotion@yahoogroups.com > Date: Tuesday, December 14, 2010, 3:32 AM > > >   > > > > Hi Jared, >   > That sounds like noise.  I doubt that it is a problem with the +5V power.  Noise problems can be very complex.  Single ended encoders are more sensitive to noise than differential encoder signals so you need to take great care about shielding and grounding.  The idea is to reduce radiated noise from the motors and motor wiring.  And also shield any residual noise from getting into the encoder signals.  Even If the motors are idle at zero current, the motors and all the motor wiring still have the +/- 55V switching on them at 30KHz.  You might try connecting the encoder shield to KFLOP DC ground (not earth ground) at the KMotion Board end of the cable.  The Motor shields should probably go to earth ground.  Is the machine connected to earth ground directly? >   > You might also try adding a terminating resistor of 250 ~ 150 ohms as close as possible to the KMotion encoder inputs to ground.   >   > There is also an encoder digital noise filter setting you can try.  The default is to ignore glitches less than 7 clocks.  The following program changes all the filters to 100 clocks (@16MHZ).  Note that setting the filter to 100 will limit the encoder to 160,000 counts/sec max. >   > #include "KMotionDef.h" > main() > { >     FPGA(ENC_NOISE_FILTER_ADD) = 100; > } > > With regard to the heater - move south where you won't need it :} >   > Regards > TK > >   > > > > > From: judrandom <judrandom@...> > To: DynoMotion@yahoogroups.com > Sent: Mon, December 13, 2010 9:01:34 PM > Subject: [DynoMotion] Still strange things happening! > >   > > Hi again Tom > I seem to be having a similar problem as another user. The encoders hold count on the axis screen when nothing else is running. Here is what I observed. When motor power is plugged to the board the count on all three encoders slowly change moving upwards of a hundreds of counts and more over time. This is with no motor power enabled just plugged in. > When I plug in the heater in the shop the count change is faster and more pronounced. The cables I used for the encoders are sheilded four conducter stranded wire. If I tie the metal shielding to the machine the encoders hold position with no motor power enabled. When I enable motor power with the sheilding connected to the machine the encoders start to count upwards dramaticaly. So when nothing else is running is the only time my encoders are reliable. This makes me wonder if the encoder power is the problem. Maybe it is dropping low as more power is being used? The encoders are powered by the 5V logic and grounds from the 40 and 16 pin connectors. The one connected to the 16 pin power and ground fluctuate the most. Am I missing something? Would a dedicated 5V > supply for each encoder help solve this? If so do I still use the ground from the headers or ground them in some other way? I hope this makes sense. Thanks > > Jared > Group: DynoMotion Message: 819 From: Jared Tesmer Date: 12/28/2010 Subject: Re: Still strange things happening! Thanks Carl   I have been a member of cnczone for many years and its a great site. The questions I had about connecting the a and b resisters to +5v instead of ground came from info I got fom al the man on cnczone. I just wanted to make sure it would not hurt the k-motion board in any way. Thanks Jared --- On Wed, 12/29/10, carlcnc <cebcnc@...> wrote: From: carlcnc <cebcnc@...> Subject: [DynoMotion] Re: Still strange things happening! To: DynoMotion@yahoogroups.com Date: Wednesday, December 29, 2010, 12:08 AM   Jared I was reading all your posts, Might I suggest you get on cnczone , post your encoder problems there. There are a lot of savvy and helpful guys there. Given that turning on your shop heater causes more issues I would double check that you have a good ground back to mains. Carl --- In DynoMotion@yahoogroups.com, Jared Tesmer <judrandom@...> wrote: > > > > > > > Back again Tom >  Ok I connected the sheilds to there respective grds. That caused no problems. When I connected the a and b signals to ground through a 1/4 watt 220 ohm resister ( closest to 200 ohm they had) the encoders would not work at all. I have been told by someone else to connect the encoder sheilding to earth ground star point? He also said to connect the a and b signals to +5v through the resisters?  Do you see a problem with this theory? As of now is there nowhere else to go? Is there something that can be connected in line to the signal that can clean them up and keep them straight? Not your fault but this is driving me mad!!! Last is there some way to connect the encoders A, A-, B, and B- to k-motion and would that fix the problem? Thanks again. > Jared  > > --- On Sat, 12/18/10, Tom Kerekes <tk@...> wrote: > > > From: Tom Kerekes <tk@...> > Subject: Re: [DynoMotion] Still strange things happening! > To: DynoMotion@yahoogroups.com > Date: Saturday, December 18, 2010, 9:20 PM > > >   > > > > > > Hi Jared, >   > >>  I connected the machine to earth ground >   > good >   > >> Then I connected the motor shielding to the machine frame next to each motor mount >   > good >   > >> The encoders no longer float at idle >   > good >   > >> Exactly how do I connect the encoder shields to dc ground? >   > At the end of the encoder cable near KMotion JP3, connect the shield to GND (ie JP3 pin 40).  Both the encoder GND wire (inside the cable) and the shield will be connected to KMotion JP3 GNDs >   > The shield at the other end of the encoder cable (near the encoder) can be left dis-connected. >   > >>  Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack? >   > Yes, a simple 1/4 watt 200 ohm resistor.  You will need two resistors per axis.  As close as possible to KMotion connect one end of the resistor to the encoder A signal (ie JP3 pin 15), and the other end of the resistor to ground (JP3 pin 40).  Similarly connect the other resistor, one end to the encoder B signal (ie JP3 pin 16), and the other to ground (JP3 pin 40). >   > I assume by "float" you mean that the position drifts and doesn't repeat? >   > No problem asking questions.  Noise problems are very difficult to solve.  I wish I had a simple solution for you. >   > Regards > TK >   > > > > > From: Jared Tesmer <judrandom@...> > To: DynoMotion@yahoogroups.com > Sent: Sat, December 18, 2010 5:41:32 PM > Subject: Re: [DynoMotion] Still strange things happening! > >   > > > > > > > Ok Tom I'm a little confused. I connected the machine to earth ground. Then I connected the motor sheilding to the machine frame next to each motor mount. I hope thats right. The encoders no longer float at idle. They still float while running programs. It gets worse the more axis that run at the same time. Exactly how do I connect the encoder sheilds to dc ground on the k-motion board? The encoders are connected to the 2 grounds on the jp3 and one of the two on the jp4. Would I connect the sheild to the encoder ground and both to the board together? Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack? Also would I connect one end to the encoder ground and the other to the ground used at the board? Kind of a buffer between the two? Probably driving you crazy by now. Thanks >   >   > Jared > > --- On Tue, 12/14/10, Tom Kerekes <tk@...> wrote: > > > From: Tom Kerekes <tk@...> > Subject: Re: [DynoMotion] Still strange things happening! > To: DynoMotion@yahoogroups.com > Date: Tuesday, December 14, 2010, 3:32 AM > > >   > > > > Hi Jared, >   > That sounds like noise.  I doubt that it is a problem with the +5V power.  Noise problems can be very complex.  Single ended encoders are more sensitive to noise than differential encoder signals so you need to take great care about shielding and grounding.  The idea is to reduce radiated noise from the motors and motor wiring.  And also shield any residual noise from getting into the encoder signals.  Even If the motors are idle at zero current, the motors and all the motor wiring still have the +/- 55V switching on them at 30KHz.  You might try connecting the encoder shield to KFLOP DC ground (not earth ground) at the KMotion Board end of the cable.  The Motor shields should probably go to earth ground.  Is the machine connected to earth ground directly? >   > You might also try adding a terminating resistor of 250 ~ 150 ohms as close as possible to the KMotion encoder inputs to ground.   >   > There is also an encoder digital noise filter setting you can try.  The default is to ignore glitches less than 7 clocks.  The following program changes all the filters to 100 clocks (@16MHZ).  Note that setting the filter to 100 will limit the encoder to 160,000 counts/sec max. >   > #include "KMotionDef.h" > main() > { >     FPGA(ENC_NOISE_FILTER_ADD) = 100; > } > > With regard to the heater - move south where you won't need it :} >   > Regards > TK > >   > > > > > From: judrandom <judrandom@...> > To: DynoMotion@yahoogroups.com > Sent: Mon, December 13, 2010 9:01:34 PM > Subject: [DynoMotion] Still strange things happening! > >   > > Hi again Tom > I seem to be having a similar problem as another user. The encoders hold count on the axis screen when nothing else is running. Here is what I observed. When motor power is plugged to the board the count on all three encoders slowly change moving upwards of a hundreds of counts and more over time. This is with no motor power enabled just plugged in. > When I plug in the heater in the shop the count change is faster and more pronounced. The cables I used for the encoders are sheilded four conducter stranded wire. If I tie the metal shielding to the machine the encoders hold position with no motor power enabled. When I enable motor power with the sheilding connected to the machine the encoders start to count upwards dramaticaly. So when nothing else is running is the only time my encoders are reliable. This makes me wonder if the encoder power is the problem. Maybe it is dropping low as more power is being used? The encoders are powered by the 5V logic and grounds from the 40 and 16 pin connectors. The one connected to the 16 pin power and ground fluctuate the most. Am I missing something? Would a dedicated 5V > supply for each encoder help solve this? If so do I still use the ground from the headers or ground them in some other way? I hope this makes sense. Thanks > > Jared > Group: DynoMotion Message: 822 From: karmannelectric Date: 12/29/2010 Subject: Re: Still strange things happening! Re: Still strange things happening! <snip> I don't remember from the beginning of this thread; can I ask you to re-post the make and model number of these encoders? Is it the same encoder for all motors? Would you consider replacing the encoder? I have a suspicion that the encoder might not have enough "drive" for the cable length; either as designed, or the output driver might have gotten damaged. After I see the data sheet, I might have some suggestions on how to test. Thanks, - Steven Ciciora Group: DynoMotion Message: 827 From: Jared Tesmer Date: 12/30/2010 Subject: Re: Still strange things happening! Hi Tom   I think I got the float problem fixed! It was definately ground related. Now I noticed a few other accuracy issues. When I perform a move either in the step responce screen or the g-code screen it seems to be the same issue. 1" for my setup should be 122880 encoder counts. since its a multiple of 4096 the motor when moving 1" should be at the same shaft angle when a move is complete as when it started I believe. Instead the return to position is always different. When measuring axis movement with a micrometer the position change for x and y both show the same problem(need to check Z). The return to position is 3 thousands of an inch further back then its supposed to be and accumulating each time. An example would be first move returns to .125, second move returns to .122, third .119, fourth .116 etc...etc. Do you know if this would be fixed with backlash comp? Is it still having counting issues just the same error each time? Could it be the step count is wrong? Thank you again. Jared --- On Sat, 12/18/10, Tom Kerekes <tk@...> wrote: From: Tom Kerekes <tk@...> Subject: Re: [DynoMotion] Still strange things happening! To: DynoMotion@yahoogroups.com Date: Saturday, December 18, 2010, 9:20 PM   Hi Jared,   >>  I connected the machine to earth ground   good   >> Then I connected the motor shielding to the machine frame next to each motor mount   good   >> The encoders no longer float at idle   good   >> Exactly how do I connect the encoder shields to dc ground?   At the end of the encoder cable near KMotion JP3, connect the shield to GND (ie JP3 pin 40).  Both the encoder GND wire (inside the cable) and the shield will be connected to KMotion JP3 GNDs   The shield at the other end of the encoder cable (near the encoder) can be left dis-connected.   >>  Also not sure what a terminating resistor is. Is it just a normal resistor from radio shack?   Yes, a simple 1/4 watt 200 ohm resistor.  You will need two resistors per axis.  As close as possible to KMotion connect one end of the resistor to the encoder A signal (ie JP3 pin 15), and the other end of the resistor to ground (JP3 pin 40).  Similarly connect the other resistor, one end to the encoder B signal (ie JP3 pin 16), and the other to ground (JP3 pin 40).   I assume by "float" you mean that the position drifts and doesn't repeat?   No problem asking questions.  Noise problems are very difficult to solve.  I wish I had a simple solution for you.   Regards TK   Group: DynoMotion Message: 828 From: Tom Kerekes Date: 12/31/2010 Subject: Re: Still strange things happening! Hi Jared,   It sounds like you are making progress.  But no, backlash can't accumulate in that manner so you still must be losing/gaining counts. I think you should try the resistor termination.  I might have suggested a too low resistance as Russ mentioned.  If you don't have any specs on the encoders check with a voltmeter to see what voltages you get as they switch high and low.  Use as low a resistance as possible where the high signal still goes above 2.8V.   You might try increasing the digital filter that I described earlier also.   Regards TK