Re: [Emc-users] Tuning a servo

[Gene Heskett]

On Tuesday 08 December 2020 19:56:13 Chris Albertson wrote:

> If the output of the PID controller is force ad the measured feedback
> is the position, a P only controller will always oscillate.  Friction
> will damp it eventually.   A negative "D" will reduce the velocity and
> help with overshoot and "I" is required if the final result has an
> offset.
>
> The root cause is the force is a couple of steps removed from
> the position.
>
> If you want the system to go full speed then slam on the brakes at the
> last minute and hit the marks then you need a controller that has a
> physical model of the system and use that to predict the future and
> plan ahead.  PID is always reactive.  It can't look ahead.
>
> But PIS can come close.   After you get P tuned "close" try "D" and
> depending on how it is wired may be negative
>
I'll give that a try tomorrow. Or maybe right now since I wasn't sleeping 
well.  And with a Dgain of -2.5 got a 22mv error at 101 degrees a minute 
with little, maybe 10% ringing on the rising edge, and a less than 10% 
peak "effort" in reverse to stop it, That is a major improvement and 
doesn't trip off the psu getting stopped.  What does that 22mv mean in 
folllowing error since I have that set for about half an inch at the 
moment?

This I think might be good enough to go ahead and finish the mount 
machining and get it installed on the bs-1.  With all the excitement and 
sadness here, I've only been working on easily interruptible things.

Thanks Chris.

> On Tue, Dec 8, 2020 at 4:42 PM Gene Heskett  
wrote:
> > On Tuesday 08 December 2020 19:05:52 Chris Albertson wrote:
> > > What next?  You have set P-gain but what about I and D gains?
> >
> > That has been tried, gently, but doesn't seem to have the desired
> > effect.
> >
> > > On Tue, Dec 8, 2020 at 12:49 PM Gene Heskett
> > > 
> >
> > wrote:
> > > > Lo all;
> > > >
> > > > I'm back to playing with the servo again, following John
> > > > Thorntons instructs from the wiki article.  And I note a couple
> > > > things.
> > > >
> > > > 1. The pid_a.FF1 value has little or no effect on the amplitude
> > > > of the error. So that probably needs addressed by educating me
> > > > on how its calculated.
> > > >
> > > > 2.pid_a.FF2 isn't working as that article says it should, a
> > > > little effect on the shape but zero effect that would lead to a
> > > > zero error when cruising
> > > >
> > > > 3. pid_a.Pgain effects the amplitude of the error signal, with
> > > > about 35 being the onset of a low level oscillation, about
> > > > 10% when cruising.  But its also the lowest error at 15 to 20
> > > > millivolts.
> > > >
> > > > 4. I am getting some improvement. but nothing like the pix on
> > > > that wiki article.
> > > >
> > > > It explains that pid_a.FF1 should be 10/velocity@10V (velocity
> > > > is in machine units per second).  Since I do not yet have the
> > > > motor actually moving the BS-1 clone, nor have I managed to get
> > > > a home switch set up so I can actually measure the scale, the
> > > > scale temporarily set is likely wrong. Since I've 2 worms in
> > > > series, for playing I've a high value set for scale, 5000. With
> > > > the encoder on the back of the motor it could well be higher
> > > > than that.
> > > >
> > > > But no combination of numbers results in a cruising error of
> > > > zero, its alway plus at cruise speed.
> > > >
> > > > And if I go at more than about 30% high pwm, motor inertia
> > > > causes the servo to use reverse to stop if I ask for more than
> > > > 60 degrees a second. This use of reverse causes the supply, a
> > > > 350 watt 24 volt switcher, to do a shutdown because it thinks is
> > > > been crowbarred, and the powerdown to recover is around 3
> > > > minutes.
> > > >
> > > > I think I might have a way that will fix that as this driver can
> > > > do crowbar the motor braking if the signals are re-arranged and
> > > > fast enough. If I setup a hardware timer in the form of a a
> > > > retriggerable ooneshot drive  from the pwm signal, which is
> > > > running at 4 kilohertz, or 250u-secs pulse is a 100% signal, but
> > > > the timer timesout in 200 microseconds, it will time out and
> > > > apply the brakes for whats left of the 250 microsecond pwm cycle
> > > > if the pwn drops below 20%. This should slow the motor fast
> > > > enough it will never actually use reverse to stop.  And that
> > > > mode will never effect the psu.
> > > >
> > > > But first, what can I do about the ineffectiveness of setting
> > > > FF1 anyplace between .5 and 25. I think its effecting the motors
> > > > cruising speed but has zero effect on the amplitude or shape of
> > > > the error if enough Pgain is used to make it follow well.
> > > >
> > > > With Pgain at 25 it cruises stably, with a reasonably flat
> > > > top to the error, about 20 millivolts of error, but FF2 seems to
> > > > have little effect on the initial overshoot, or the overshoot
> > > > when stopping, and its the overshoot when 

Re: [Emc-users] 7i96 multi wire input

[Gregg Eshelman via Emc-users]

The way to wire an emergency stop circuit with 2 or more things that can 
trigger it, is to have it a normally closed circuit and every stop switch, 
mechanical or electronic, in series.
That way when anything triggers a stop it opens the circuit, the controller 
senses that and stops sending motion commands, shuts off the spindle(s), 
pump(s) etc.
What does this controller mean by "high" if "low" is grounded? If "high" is 
open circuit then you should be able to connect every fault sensor and a 
normally open E-Stop button in parallel. You'll also need to have the new 
control hardware and software able to be set to use a closed circuit instead of 
open circuit as the E-Stop condition.
   If "high" is something other than open circuit then things get more 
complicated. One may curse the engineer(s) who thought that making things more 
complex than open or closed was a neat idea. ;)
A NC E-Stop circuit is quite fail safe because if a switch fails or a wire 
breaks, the circuit goes open and the machine stops. If a wire breaks in a NO 
circuit then the E-Stop button or sensor the broken wire goes to cannot 
initiate a stop.
 On Tuesday, December 8, 2020, 04:19:16 PM MST, Sven Wesley 
 wrote:  
 Friends,

I am in the process of refreshing a CNC that has been running in "temporary
state" the last 12 years, time to give it an overhaul. I've found the magic
little piece we all call 7i96. It will do magic.

The servo drives have been running flawlessly and the plan is to keep them.
They have a neat error/reset feature via two pins and the old parallel port
BOB supports it. If one drive or an emergency stop is triggering the stop
pin, all drives will be halted by the BOB.
The manual for the drive says:

*Error line is pin number 6 in the Main connector and is a dual purpose, bi
directional line.This pin is ‘active low’, meaning that the line is
normally high indicating no problems andnormal operation. The drive will
stop if this pin is pulled low (grounded) by one of thesesources:EXTERNAL
activation; The line can be pulled low by an external source (CNCsoftware,
E-stop, etc).  INTERNAL activation; The line is pulled low by the drive
itself due to a faultcondition.*

Am I totally off the chart if I wire all the drives' pin number 6 together
and connect them to one of the inputs on the 7i96 and get it to stop the
program with a big alert? And maybe add a mechanical switch shortcutting to
ground for those panic moments?
If I am not totally stupid, what would the Mesa pin config look like?

All the best,
Sven  
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Re: [Emc-users] Tuning a servo

[Chris Albertson]

If the output of the PID controller is force ad the measured feedback is
the position, a P only controller will always oscillate.  Friction will
damp it eventually.   A negative "D" will reduce the velocity and help with
overshoot and "I" is required if the final result has an offset.

The root cause is the force is a couple of steps removed from
the position.

If you want the system to go full speed then slam on the brakes at the last
minute and hit the marks then you need a controller that has a physical
model of the system and use that to predict the future and plan ahead.  PID
is always reactive.  It can't look ahead.

But PIS can come close.   After you get P tuned "close" try "D" and
depending on how it is wired may be negative

On Tue, Dec 8, 2020 at 4:42 PM Gene Heskett  wrote:

> On Tuesday 08 December 2020 19:05:52 Chris Albertson wrote:
>
> > What next?  You have set P-gain but what about I and D gains?
> >
> That has been tried, gently, but doesn't seem to have the desired effect.
>
> > On Tue, Dec 8, 2020 at 12:49 PM Gene Heskett 
> wrote:
> > > Lo all;
> > >
> > > I'm back to playing with the servo again, following John Thorntons
> > > instructs from the wiki article.  And I note a couple things.
> > >
> > > 1. The pid_a.FF1 value has little or no effect on the amplitude of
> > > the error. So that probably needs addressed by educating me on how
> > > its calculated.
> > >
> > > 2.pid_a.FF2 isn't working as that article says it should, a little
> > > effect on the shape but zero effect that would lead to a zero error
> > > when cruising
> > >
> > > 3. pid_a.Pgain effects the amplitude of the error signal, with about
> > > 35 being the onset of a low level oscillation, about 10% when
> > > cruising.  But its also the lowest error at 15 to 20 millivolts.
> > >
> > > 4. I am getting some improvement. but nothing like the pix on that
> > > wiki article.
> > >
> > > It explains that pid_a.FF1 should be 10/velocity@10V (velocity is in
> > > machine units per second).  Since I do not yet have the motor
> > > actually moving the BS-1 clone, nor have I managed to get a home
> > > switch set up so I can actually measure the scale, the scale
> > > temporarily set is likely wrong. Since I've 2 worms in series, for
> > > playing I've a high value set for scale, 5000. With the encoder on
> > > the back of the motor it could well be higher than that.
> > >
> > > But no combination of numbers results in a cruising error of zero,
> > > its alway plus at cruise speed.
> > >
> > > And if I go at more than about 30% high pwm, motor inertia causes
> > > the servo to use reverse to stop if I ask for more than 60 degrees a
> > > second. This use of reverse causes the supply, a 350 watt 24 volt
> > > switcher, to do a shutdown because it thinks is been crowbarred, and
> > > the powerdown to recover is around 3 minutes.
> > >
> > > I think I might have a way that will fix that as this driver can do
> > > crowbar the motor braking if the signals are re-arranged and fast
> > > enough. If I setup a hardware timer in the form of a a retriggerable
> > > ooneshot drive  from the pwm signal, which is running at 4
> > > kilohertz, or 250u-secs pulse is a 100% signal, but the timer
> > > timesout in 200 microseconds, it will time out and apply the brakes
> > > for whats left of the 250 microsecond pwm cycle if the pwn drops
> > > below 20%. This should slow the motor fast enough it will never
> > > actually use reverse to stop.  And that mode will never effect the
> > > psu.
> > >
> > > But first, what can I do about the ineffectiveness of setting FF1
> > > anyplace between .5 and 25. I think its effecting the motors
> > > cruising speed but has zero effect on the amplitude or shape of the
> > > error if enough Pgain is used to make it follow well.
> > >
> > > With Pgain at 25 it cruises stably, with a reasonably flat top
> > > to the error, about 20 millivolts of error, but FF2 seems to have
> > > little effect on the initial overshoot, or the overshoot when
> > > stopping, and its the overshoot when stopping that is shutting down
> > > the supply unless I set max jog to below 60 so friction stops it.
> > > That 60 is about 1/3rd of what the motor can do in terms of output
> > > shaft rpms if fed its normal 24 volts.
> > >
> > > Anybody know what I should look at next?
> > >
> > > Thank you.
> > >
> > > Cheers, Gene Heskett
> > >
> > >
> > > --
> > > "There are four boxes to be used in defense of liberty:
> > >  soap, ballot, jury, and ammo. Please use in that order."
> > > -Ed Howdershelt (Author)
> > > If we desire respect for the law, we must first make the law
> > > respectable. - Louis D. Brandeis
> > > Genes Web page 
> > >
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
> Cheers, Gene Heskett
> --
> "There are four boxes to be used in 

Re: [Emc-users] Tuning a servo

[Gene Heskett]

On Tuesday 08 December 2020 19:05:52 Chris Albertson wrote:

> What next?  You have set P-gain but what about I and D gains?
>
That has been tried, gently, but doesn't seem to have the desired effect.

> On Tue, Dec 8, 2020 at 12:49 PM Gene Heskett  
wrote:
> > Lo all;
> >
> > I'm back to playing with the servo again, following John Thorntons
> > instructs from the wiki article.  And I note a couple things.
> >
> > 1. The pid_a.FF1 value has little or no effect on the amplitude of
> > the error. So that probably needs addressed by educating me on how
> > its calculated.
> >
> > 2.pid_a.FF2 isn't working as that article says it should, a little
> > effect on the shape but zero effect that would lead to a zero error
> > when cruising
> >
> > 3. pid_a.Pgain effects the amplitude of the error signal, with about
> > 35 being the onset of a low level oscillation, about 10% when
> > cruising.  But its also the lowest error at 15 to 20 millivolts.
> >
> > 4. I am getting some improvement. but nothing like the pix on that
> > wiki article.
> >
> > It explains that pid_a.FF1 should be 10/velocity@10V (velocity is in
> > machine units per second).  Since I do not yet have the motor
> > actually moving the BS-1 clone, nor have I managed to get a home
> > switch set up so I can actually measure the scale, the scale
> > temporarily set is likely wrong. Since I've 2 worms in series, for
> > playing I've a high value set for scale, 5000. With the encoder on
> > the back of the motor it could well be higher than that.
> >
> > But no combination of numbers results in a cruising error of zero,
> > its alway plus at cruise speed.
> >
> > And if I go at more than about 30% high pwm, motor inertia causes
> > the servo to use reverse to stop if I ask for more than 60 degrees a
> > second. This use of reverse causes the supply, a 350 watt 24 volt
> > switcher, to do a shutdown because it thinks is been crowbarred, and
> > the powerdown to recover is around 3 minutes.
> >
> > I think I might have a way that will fix that as this driver can do
> > crowbar the motor braking if the signals are re-arranged and fast
> > enough. If I setup a hardware timer in the form of a a retriggerable
> > ooneshot drive  from the pwm signal, which is running at 4
> > kilohertz, or 250u-secs pulse is a 100% signal, but the timer
> > timesout in 200 microseconds, it will time out and apply the brakes
> > for whats left of the 250 microsecond pwm cycle if the pwn drops
> > below 20%. This should slow the motor fast enough it will never
> > actually use reverse to stop.  And that mode will never effect the
> > psu.
> >
> > But first, what can I do about the ineffectiveness of setting FF1
> > anyplace between .5 and 25. I think its effecting the motors
> > cruising speed but has zero effect on the amplitude or shape of the
> > error if enough Pgain is used to make it follow well.
> >
> > With Pgain at 25 it cruises stably, with a reasonably flat top
> > to the error, about 20 millivolts of error, but FF2 seems to have
> > little effect on the initial overshoot, or the overshoot when
> > stopping, and its the overshoot when stopping that is shutting down
> > the supply unless I set max jog to below 60 so friction stops it. 
> > That 60 is about 1/3rd of what the motor can do in terms of output
> > shaft rpms if fed its normal 24 volts.
> >
> > Anybody know what I should look at next?
> >
> > Thank you.
> >
> > Cheers, Gene Heskett
> >
> >
> > --
> > "There are four boxes to be used in defense of liberty:
> >  soap, ballot, jury, and ammo. Please use in that order."
> > -Ed Howdershelt (Author)
> > If we desire respect for the law, we must first make the law
> > respectable. - Louis D. Brandeis
> > Genes Web page 
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] 7i96 multi wire input

[Gene Heskett]

On Tuesday 08 December 2020 18:17:11 Sven Wesley wrote:

> Friends,
>
> I am in the process of refreshing a CNC that has been running in
> "temporary state" the last 12 years, time to give it an overhaul. I've
> found the magic little piece we all call 7i96. It will do magic.
>
> The servo drives have been running flawlessly and the plan is to keep
> them. They have a neat error/reset feature via two pins and the old
> parallel port BOB supports it. If one drive or an emergency stop is
> triggering the stop pin, all drives will be halted by the BOB.
> The manual for the drive says:
>
>
>
>
>
>
>
> *Error line is pin number 6 in the Main connector and is a dual
> purpose, bi directional line.This pin is ‘active low’, meaning that
> the line is normally high indicating no problems andnormal operation.
> The drive will stop if this pin is pulled low (grounded) by one of
> thesesources:EXTERNAL activation; The line can be pulled low by an
> external source (CNCsoftware, E-stop, etc).  INTERNAL activation;
> The line is pulled low by the drive itself due to a faultcondition.*
>
> Am I totally off the chart if I wire all the drives' pin number 6
> together and connect them to one of the inputs on the 7i96 and get it
> to stop the program with a big alert? And maybe add a mechanical
> switch shortcutting to ground for those panic moments?

I would do the parallel but I'd put a 1n914 in series to a common point,
So the comon point src could be ID'd, I'd put a super bright led from a 5 
volt line to each of the alarm outputs, letting you see at a glance 
which driver is issueing the alarm.

> If I am not totally stupid, what would the Mesa pin config look like?
>
> All the best,
> Sven
>
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> Emc-users@lists.sourceforge.net
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Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] Tuning a servo

[Chris Albertson]

What next?  You have set P-gain but what about I and D gains?




On Tue, Dec 8, 2020 at 12:49 PM Gene Heskett  wrote:

> Lo all;
>
> I'm back to playing with the servo again, following John Thorntons
> instructs from the wiki article.  And I note a couple things.
>
> 1. The pid_a.FF1 value has little or no effect on the amplitude of the
> error. So that probably needs addressed by educating me on how its
> calculated.
>
> 2.pid_a.FF2 isn't working as that article says it should, a little effect
> on the shape but zero effect that would lead to a zero error when cruising
>
> 3. pid_a.Pgain effects the amplitude of the error signal, with about
> 35 being the onset of a low level oscillation, about 10% when
> cruising.  But its also the lowest error at 15 to 20 millivolts.
>
> 4. I am getting some improvement. but nothing like the pix on that wiki
> article.
>
> It explains that pid_a.FF1 should be 10/velocity@10V (velocity is in
> machine units per second).  Since I do not yet have the motor actually
> moving the BS-1 clone, nor have I managed to get a home switch set up so I
> can actually measure the scale, the scale temporarily set is likely wrong.
> Since I've 2 worms in series, for playing I've a high value set for scale,
> 5000. With the encoder on the back of the motor it could well be higher
> than that.
>
> But no combination of numbers results in a cruising error of zero, its
> alway plus at cruise speed.
>
> And if I go at more than about 30% high pwm, motor inertia causes the
> servo to use reverse to stop if I ask for more than 60 degrees a second.
> This use of reverse causes the supply, a 350 watt 24 volt switcher, to do a
> shutdown because it thinks is been crowbarred, and the powerdown to recover
> is around 3 minutes.
>
> I think I might have a way that will fix that as this driver can do
> crowbar the motor braking if the signals are re-arranged and fast enough.
> If I setup a hardware timer in the form of a a retriggerable ooneshot
> drive  from the pwm signal, which is running at 4 kilohertz, or 250u-secs
> pulse is a 100% signal, but the timer timesout in 200 microseconds, it will
> time out and apply the brakes for whats left of the 250 microsecond pwm
> cycle if the pwn drops below 20%. This should slow the motor fast enough it
> will never actually use reverse to stop.  And that mode will never effect
> the psu.
>
> But first, what can I do about the ineffectiveness of setting FF1 anyplace
> between .5 and 25. I think its effecting the motors cruising speed but has
> zero effect on the amplitude or shape of the error if enough Pgain is used
> to make it follow well.
>
> With Pgain at 25 it cruises stably, with a reasonably flat top to the
> error, about 20 millivolts of error, but FF2 seems to have little effect on
> the initial overshoot, or the overshoot when stopping, and its the
> overshoot when stopping that is shutting down the supply unless I set max
> jog to below 60 so friction stops it.  That 60 is about 1/3rd of what the
> motor can do in terms of output shaft rpms if fed its normal 24 volts.
>
> Anybody know what I should look at next?
>
> Thank you.
>
> Cheers, Gene Heskett
>
>
> --
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
> ___
> Emc-users mailing list
> Emc-users@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] 7i96 multi wire input

[Peter C. Wallace]

On Wed, 9 Dec 2020, Sven Wesley wrote:


Date: Wed, 9 Dec 2020 00:53:25 +0100
From: Sven Wesley 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: Re: [Emc-users] 7i96 multi wire input

Den ons 9 dec. 2020 kl 00:37 skrev Peter C. Wallace :


On Wed, 9 Dec 2020, Sven Wesley wrote:


Date: Wed, 9 Dec 2020 00:17:11 +0100
Friends,



I am in the process of refreshing a CNC that has been running in

"temporary

state" the last 12 years, time to give it an overhaul. I've found the

magic

little piece we all call 7i96. It will do magic.
...
The manual for the drive says:
Error line is pin number 6 in the Main connector and is a dual purpose,

bi

directional line.This pin is active low, meaning that the line is
normally high indicating no problems and normal operation.
...


Am I totally off the chart if I wire all the drives' pin number 6 together

and connect them to one of the inputs on the 7i96 and get it to stop the
program with a big alert?


I think this is possible if you wire the 7I96 input commom
to +5V so the can sense a logic low. You could also
use a 7I96 output to short the fault pin to ground
if you wanted a software reset capability

Peter Wallace
Mesa Electronics



Hi Peter, thanks for your quick reply!
I'm not sure I am following you, the wire should already be high if it is
in normal state?
There is another pin on the drives for resetting a previous error, it works
the same way and an output should work. Today I use a simple push button
inside the cabinet. :)
/Sven



Yes, the fault pin is normally high and pulled down when a fault occurs
(this allows the fault pins from all axis to be paralleled)

A 7I96 output could be used to reset all drives if desired

A side effect of using a common +5 for the 7I96 inputs is that
you must use a common ground for all limit/home switches etc


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Peter Wallace
Mesa Electronics

(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.



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Re: [Emc-users] 7i96 multi wire input

[John Dammeyer]

That sounds a lot like the UHU_ESTOP circuit.  I've attached a PDF of it.  
Maybe that will help.
John


> -Original Message-
> From: Sven Wesley [mailto:svenne.d...@gmail.com]
> Sent: December-08-20 3:17 PM
> To: Enhanced Machine Controller (EMC)
> Subject: [Emc-users] 7i96 multi wire input
> 
> Friends,
> 
> I am in the process of refreshing a CNC that has been running in "temporary
> state" the last 12 years, time to give it an overhaul. I've found the magic
> little piece we all call 7i96. It will do magic.
> 
> The servo drives have been running flawlessly and the plan is to keep them.
> They have a neat error/reset feature via two pins and the old parallel port
> BOB supports it. If one drive or an emergency stop is triggering the stop
> pin, all drives will be halted by the BOB.
> The manual for the drive says:
> 
> 
> 
> 
> 
> 
> 
> *Error line is pin number 6 in the Main connector and is a dual purpose, bi
> directional line.This pin is �active low�, meaning that the line is
> normally high indicating no problems andnormal operation. The drive will
> stop if this pin is pulled low (grounded) by one of thesesources:EXTERNAL
> activation; The line can be pulled low by an external source (CNCsoftware,
> E-stop, etc).  INTERNAL activation; The line is pulled low by the drive
> itself due to a faultcondition.*
> 
> Am I totally off the chart if I wire all the drives' pin number 6 together
> and connect them to one of the inputs on the 7i96 and get it to stop the
> program with a big alert? And maybe add a mechanical switch shortcutting to
> ground for those panic moments?
> If I am not totally stupid, what would the Mesa pin config look like?
> 
> All the best,
> Sven
> 
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UHU_ESTOP.pdf
Description: Adobe PDF document
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Re: [Emc-users] 7i96 multi wire input

[Sven Wesley]

Den ons 9 dec. 2020 kl 00:37 skrev Peter C. Wallace :

> On Wed, 9 Dec 2020, Sven Wesley wrote:
>
> > Date: Wed, 9 Dec 2020 00:17:11 +0100
> > Friends,
>
> > I am in the process of refreshing a CNC that has been running in
> "temporary
> > state" the last 12 years, time to give it an overhaul. I've found the
> magic
> > little piece we all call 7i96. It will do magic.
> > ...
> > The manual for the drive says:
> > Error line is pin number 6 in the Main connector and is a dual purpose,
> bi
> > directional line.This pin is active low, meaning that the line is
> > normally high indicating no problems and normal operation.
> > ...
>
> Am I totally off the chart if I wire all the drives' pin number 6 together
> > and connect them to one of the inputs on the 7i96 and get it to stop the
> > program with a big alert?
>
> I think this is possible if you wire the 7I96 input commom
> to +5V so the can sense a logic low. You could also
> use a 7I96 output to short the fault pin to ground
> if you wanted a software reset capability
>
> Peter Wallace
> Mesa Electronics
>

Hi Peter, thanks for your quick reply!
I'm not sure I am following you, the wire should already be high if it is
in normal state?
There is another pin on the drives for resetting a previous error, it works
the same way and an output should work. Today I use a simple push button
inside the cabinet. :)
/Sven

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Re: [Emc-users] 7i96 multi wire input

[Peter C. Wallace]

On Wed, 9 Dec 2020, Sven Wesley wrote:


Date: Wed, 9 Dec 2020 00:17:11 +0100
From: Sven Wesley 
Reply-To: "Enhanced Machine Controller (EMC)"

To: "Enhanced Machine Controller (EMC)" 
Subject: [Emc-users] 7i96 multi wire input

Friends,


I am in the process of refreshing a CNC that has been running in "temporary
state" the last 12 years, time to give it an overhaul. I've found the magic
little piece we all call 7i96. It will do magic.

The servo drives have been running flawlessly and the plan is to keep them.
They have a neat error/reset feature via two pins and the old parallel port
BOB supports it. If one drive or an emergency stop is triggering the stop
pin, all drives will be halted by the BOB.
The manual for the drive says:







*Error line is pin number 6 in the Main connector and is a dual purpose, bi
directional line.This pin is ??active low??, meaning that the line is
normally high indicating no problems andnormal operation. The drive will
stop if this pin is pulled low (grounded) by one of thesesources:EXTERNAL
activation; The line can be pulled low by an external source (CNCsoftware,
E-stop, etc).  INTERNAL activation; The line is pulled low by the drive
itself due to a faultcondition.*

Am I totally off the chart if I wire all the drives' pin number 6 together
and connect them to one of the inputs on the 7i96 and get it to stop the
program with a big alert? And maybe add a mechanical switch shortcutting to
ground for those panic moments?
If I am not totally stupid, what would the Mesa pin config look like?

All the best,
Sven


I think this is possible if you wire the 7I96 input commom
to +5V so the can sense a logic low. You could also
use a 7I96 output to short the fault pin to ground
if you wanted a software reset capability


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Peter Wallace
Mesa Electronics

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[Emc-users] 7i96 multi wire input

[Sven Wesley]

Friends,

I am in the process of refreshing a CNC that has been running in "temporary
state" the last 12 years, time to give it an overhaul. I've found the magic
little piece we all call 7i96. It will do magic.

The servo drives have been running flawlessly and the plan is to keep them.
They have a neat error/reset feature via two pins and the old parallel port
BOB supports it. If one drive or an emergency stop is triggering the stop
pin, all drives will be halted by the BOB.
The manual for the drive says:







*Error line is pin number 6 in the Main connector and is a dual purpose, bi
directional line.This pin is ‘active low’, meaning that the line is
normally high indicating no problems andnormal operation. The drive will
stop if this pin is pulled low (grounded) by one of thesesources:EXTERNAL
activation; The line can be pulled low by an external source (CNCsoftware,
E-stop, etc).  INTERNAL activation; The line is pulled low by the drive
itself due to a faultcondition.*

Am I totally off the chart if I wire all the drives' pin number 6 together
and connect them to one of the inputs on the 7i96 and get it to stop the
program with a big alert? And maybe add a mechanical switch shortcutting to
ground for those panic moments?
If I am not totally stupid, what would the Mesa pin config look like?

All the best,
Sven

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Re: [Emc-users] Gecko G213V failed yet again.

[John Dammeyer]

Hi Gene,

> From: Gene Heskett [mailto:ghesk...@shentel.net]
> On Tuesday 08 December 2020 02:04:49 John Dammeyer wrote:
> 
> > > I think I'd be measuring the ohmage and inductance of each winding
> > > in that motor. A partially shorted winding would be on my suspects
> > > list.
> > >
> > > They should match within a few %. A 10% diff would condemn it in my
> > > CET mind.
> > >
> > > Cheers, Gene Heskett
> > > --
> >
> > Thanks for the suggestion.
> > I'll check that too although I'm leaning to epoxy PC board material
> > converted to conductive carbon.

Unfortunately I can't see which transistor pins go to which terminal pins.  But 
it appears there isn't a lot of conduction between the winding pins since 
without the motor connected nothing gets warm.

The winding resistances are the same and actually motion is quite smooth. 

But with the 58.5VDC toroidal power supply meant originally to run a 4 axis 
stepper conversion there's lots of power there to create the specified current. 
 Now assume for example it's 7 amps and the motor measures at 1.2 ohms on each 
winding.  That's 8.4V steady state across the winding or 58W in the motor.

Now we know of course the chopper design will apply the 58V for as long as 
needed to maintain say the 7A at the top of the micro-stepping curve.  So 
assume we have 2 ohms DC resistance in a now burnt traces in between layers.  
With 7A through that 2 ohms there's a 14V drop.  Not a big deal with the 58V 
supply.  But 14V and 7A is 98W.  Easily enough to slowly raise the temperature. 
 And for all I know the resistance is even higher.

I hit ESTOP which removes DC power.  Plugged the motor back in.  ESTOP off and 
the reflective temperature probe shows the bottom pin of the connector quickly 
reach 40C from 22C.  During all this time the motor itself is barely warm.

A far east stepper driver rated for up to 110VDC and 8A is on the way.  Be here 
next Wednesday so then I can verify that it's the driver.

And no answer back from Gecko.
John




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[Emc-users] Tuning a servo

[Gene Heskett]

Lo all;

I'm back to playing with the servo again, following John Thorntons instructs 
from the wiki article.  And I note a couple things.

1. The pid_a.FF1 value has little or no effect on the amplitude of the error. 
So that probably needs addressed by educating me on how its calculated.

2.pid_a.FF2 isn't working as that article says it should, a little effect on 
the shape but zero effect that would lead to a zero error when cruising

3. pid_a.Pgain effects the amplitude of the error signal, with about 35 
being the onset of a low level oscillation, about 10% when cruising.  But its 
also the lowest error at 15 to 20 millivolts.

4. I am getting some improvement. but nothing like the pix on that wiki article.

It explains that pid_a.FF1 should be 10/velocity@10V (velocity is in machine 
units per second).  Since I do not yet have the motor actually moving the BS-1 
clone, nor have I managed to get a home switch set up so I can actually measure 
the scale, the scale temporarily set is likely wrong.  Since I've 2 worms in 
series, for playing I've a high value set for scale, 5000. With the encoder on 
the back of the motor it could well be higher than that.

But no combination of numbers results in a cruising error of zero, its alway 
plus at cruise speed.

And if I go at more than about 30% high pwm, motor inertia causes the servo to 
use reverse to stop if I ask for more than 60 degrees a second.  This use of 
reverse causes the supply, a 350 watt 24 volt switcher, to do a shutdown 
because it thinks is been crowbarred, and the powerdown to recover is around 3 
minutes.

I think I might have a way that will fix that as this driver can do crowbar the 
motor braking if the signals are re-arranged and fast enough. If I setup a 
hardware timer in the form of a a retriggerable ooneshot drive  from the pwm 
signal, which is running at 4 kilohertz, or 250u-secs pulse is a 100% signal, 
but the timer timesout in 200 microseconds, it will time out and apply the 
brakes for whats left of the 250 microsecond pwm cycle if the pwn drops below 
20%. This should slow the motor fast enough it will never actually use reverse 
to stop.  And that mode will never effect the psu.

But first, what can I do about the ineffectiveness of setting FF1 anyplace 
between .5 and 25. I think its effecting the motors cruising speed but has zero 
effect on the amplitude or shape of the error if enough Pgain is used to make 
it follow well.

With Pgain at 25 it cruises stably, with a reasonably flat top to the 
error, about 20 millivolts of error, but FF2 seems to have little effect on the 
initial overshoot, or the overshoot when stopping, and its the overshoot when 
stopping that is shutting down the supply unless I set max jog to below 60 so 
friction stops it.  That 60 is about 1/3rd of what the motor can do in terms of 
output shaft rpms if fed its normal 24 volts.

Anybody know what I should look at next?

Thank you.

Cheers, Gene Heskett


-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 

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Re: [Emc-users] Sample code

[ken.strauss]

Those look useful so thanks! 

I'm doing the software that receives the serial data so I should able to
read and process everything fast enough to not require flow control. Even if
I miss a message the next update message will be good enough. I'll probably
include a start of message and definitely include a checksum. Alternatively
use no start of message and calculate a running checksum for the last N
bytes (number determined by the coordinate accuracy desired) received and
discard everything until a valid checksum is received.

-Original Message-
From: Chris Albertson  
Sent: December 8, 2020 12:10 PM
To: Enhanced Machine Controller (EMC) 
Subject: Re: [Emc-users] Sample code

I wanted to do about the same thing and found this:
http://linuxcnc.org/docs/html/hal/halmodule.html

Also in addition to the above you will need to write to a serial port.
Here is a walkthrough:
https://pyserial.readthedocs.io/en/latest/shortintro.html

Are you designing the USB device?  If so you might want to add some protocol
around the data.  At least a flag value at the start and a simple crc at the
end.

On Tue, Dec 8, 2020 at 7:53 AM  wrote:

> I am attempting to produce a Python component which periodically 
> outputs X/Y/Z/A coordinates via a serial port that is actually a USB
connection.
> This is similar to what is required for pendants that display the 
> current coordinates. Can anyone suggest a tutorial or source code that 
> could be adapted to my needs?
>
> I have looked at 
> http://linuxcnc.org/docs/html/man/man1/xhc-hb04.1.html
> but
> I'm hoping for something simpler and a little easier to adapt to Python.
>
>
>
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-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] Sample code

[Chris Albertson]

I wanted to do about the same thing and found this:
http://linuxcnc.org/docs/html/hal/halmodule.html

Also in addition to the above you will need to write to a serial port.
Here is a walkthrough:
https://pyserial.readthedocs.io/en/latest/shortintro.html

Are you designing the USB device?  If so you might want to add some
protocol around the data.  At least a flag value at the start and a simple
crc at the end.

On Tue, Dec 8, 2020 at 7:53 AM  wrote:

> I am attempting to produce a Python component which periodically outputs
> X/Y/Z/A coordinates via a serial port that is actually a USB connection.
> This is similar to what is required for pendants that display the current
> coordinates. Can anyone suggest a tutorial or source code that could be
> adapted to my needs?
>
> I have looked at http://linuxcnc.org/docs/html/man/man1/xhc-hb04.1.html
> but
> I'm hoping for something simpler and a little easier to adapt to Python.
>
>
>
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-- 

Chris Albertson
Redondo Beach, California

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[Emc-users] Sample code

[ken.strauss]

I am attempting to produce a Python component which periodically outputs
X/Y/Z/A coordinates via a serial port that is actually a USB connection.
This is similar to what is required for pendants that display the current
coordinates. Can anyone suggest a tutorial or source code that could be
adapted to my needs?

I have looked at http://linuxcnc.org/docs/html/man/man1/xhc-hb04.1.html but
I'm hoping for something simpler and a little easier to adapt to Python.



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Re: [Emc-users] [was Spindle indexing] now rigid tapping help

[Przemek Klosowski]

And a/o about 13:30 local, I am alone again. My Dee has passed.
>

 Gene, my sincere condolences.
Please let me express my respect for how you took care of your loved one,
giving companionship and comfort.
You are an inspiration to us young'uns.

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Re: [Emc-users] Gecko G213V failed yet again.

[John Dammeyer]

> From: Roland Jollivet [mailto:roland.jolli...@gmail.com]


> Solder a bridging wire under the pcb directly to the output Fet or whatever.
> And/or maybe solder wires from the posts to an off-board connector so there
> are no connectors on the board itself.
> 
I'm not sure which FET to solder to unfortunately.  It's a 4 layer board (maybe 
even 6) and the problem is likely the converted epoxy to carbon between the two 
pins going to one terminal.  So there's current flow through the PC board 
itself.  
Now if GECKO's provided schematics then perhaps...

I could spend hours trying to fix it or instead replace it with one that costs 
$79 Cdn and PRIME shipping. 

So by the 16th I'll have a new driver.  Meanwhile I'm working on an AC Servo 
solution just because...

John
 



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[Emc-users] Gecko G213V failed yet again.

[Roland Jollivet]

Solder a bridging wire under the pcb directly to the output Fet or whatever.
And/or maybe solder wires from the posts to an off-board connector so there
are no connectors on the board itself.



On Tue, 8 Dec 2020 at 06:39, John Dammeyer  wrote:

> The attached photo is of the last time but this time it's not much
> different.  I've resoldered the posts, cleaned everything up including
> polishing the posts and installed a new connector.  With only a few minutes
> running the connector is already quite hot.
>
> So I'm guessing the problem is in one of the middle layers of the PC board
> and either the fibreglass is already so carboned up that it's conducting or
> the trace for the one winding is pretty well toast and has a high
> resistance therefore acting like a toaster.  8-(
>
> So it's a 1200 oz-in stepper motor with a 60V power supply moving the knee
> up and down using a 3:1 reduction to the 0.25" pitch screw.
>
> Any suggestions for an alternative drive?  Really don't want to get
> another Gecko at $201.65 Cdn.
>
> Since I still have two extra HP_UHU drives and 2 STMBLs going to a DC
> Servo motor wouldn't be any more expensive other than the work of mounting
> it and maybe increasing the reduction ratio.  So maybe I should just look
> for an AC or DC Servo motor.
>
> John
>
>
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