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'[EE] Finding stepper motor wiring'
2005\02\25@173345 by James Newton, Host

face picon face
I'm working out a way for ANYONE (read: no EE experience) to figure out what
stepper motor wire is which for a unipolar controller (read: the
linistepper) without even using a meter. I'm not sure I have it right, and
would love to hear some suggestions for better ways, etc...

So far:
---------
First, arrange the wires so that there is no way for any of them to be
contacting another.

Pick the first wire, tape it and label it "A"

Spin the motor and notice how hard it turns, then connect "A" to one of the
other wires, and spin the motor again.

- If you don't feel any difference, put that wire back and try another

- If it feels harder to turn, label that wire "A" just like the first wire,
put it back, and go on.


- When you have all the "A" wires, pick up another wire and label it "B"
then repeat the spin test until you have all the "B" wires.

- Repeat with C, D, and so on until you have all the wires in groups.

8 WIRE MOTORS:
If you only have two wires in each set and you have 4 sets (8 wires total)
you can just pick one "A" wire, one "B" wire, one "C" wire and one "D" wire
and hook them all together. This is now your common or M+ wire and the other
wires are the phases. This wiring causes the motor to behave as a unipolar
motor. It could also be wired together in a bipolar configuration if that
were desired.

6 WIRE MOTORS:
If you have two sets of 3 wires (a 6 wire motor) you need to find the center
wire of each set. Starting with the A set, label the wires A1, A2, and A3 in
any order. Connect A1 to A2. Feel how hard it is to spin. Now connect that
same A1 wire to the A3 wire and spin it again.

- If it is easier to spin, then the A2 wire is the center. Re-label A2 as
"AC"

- If it is harder to spin, then the A3 wire is the center.  Re-label A3 as
"AC"

- If it is the same, then the A1 wire is the center. Re-label A1 as "AC"


Repeat this for the B set to find the B center wire "BC"

Connect AC and BC together to form your common M+ wire. This modifies the
motor to become a unipolar stepper.

5 WIRE MOTORS:
If you have only one set of 5 wires then you have a standard unipolar motor.
Connecting ANY two of the five wires together causes the shaft to be a
little harder to turn. You might have noticed that one of the wires caused
the motor to turn even harder than the others. That was the center wire. If
all the connections seemed about the same, the first wire you picked was
probably the center.

4 WIRE MOTORS:
These can only be used as Bipolar motors.
-----

I would also love to be able to let them figure out which phase wire is A+
and which is A- and so on. That can be done by connecting coils in series,
but I'm having a hard time figuring out how to explain it in really simple
terms. Any help?

Right now, I just have them connect the common to M+, connect the phases
randomly and power the motor up. If it vibrates, swap the A+ and B+ wires.
If it turns the wrong direction, swap A+ and A-. AFTER TURNING OFF THE MOTOR
POWER!

Thanks

---
James Newton: PICList webmaster/Admin
spam_OUTjamesnewtonTakeThisOuTspampiclist.com  1-619-652-0593 phone
http://www.piclist.com/member/JMN-EFP-786
PIC/PICList FAQ: http://www.piclist.com



2005\02\28@010308 by James Newtons Massmind

face picon face
Err... Did anyone see this? Any comments? Can someone maybe just say that
they got it and why they aren't interested?

---
James.



> {Original Message removed}

2005\02\28@042407 by Midgley John

flavicon
face
James

S'funny how some stuff drops into the pool without leaving a ripple, and other stuff gets done to the point where I start losing the will to live...

Don't worry, you haven't become invisible.

John

{Original Message removed}

2005\02\28@070215 by Russell McMahon

face
flavicon
face
>> I'm working out a way for ANYONE (read: no EE experience) to
>> figure out what stepper motor wire is which for a unipolar
>> controller (read: the
>> linistepper) without even using a meter. I'm not sure I have
>> it right, and would love to hear some suggestions for better
>> ways, etc...


Without following whether every case is correct the general principal
sounds entirely reasonable. One could arguably achieve much the same
results by using an ohm-meter on a suitable range. You method is
better suited to ANYONE as it removes the need for a meter :-). The
meter does allow an easier discrimination of the versions with a
common point.

I wondered whether a meter set to volts might be useful, but
standardising the finger flick speed needed to produce the test
voltage may be too hard.

Steppers with no dc excitation would be better suited by the ohm-meter
method.



       RM


2005\02\28@080755 by olin_piclist
face picon face
James Newtons Massmind wrote:
> Err... Did anyone see this? Any comments? Can someone maybe just say
> that they got it and why they aren't interested?

I got it.  Seems like a long way to go to avoid using an ohmmeter.

I was also not sure how much you can feel a shorted winding on a stepper
motor, since most have fairly strong detent forces to begin with.  I didn't
have a stepper motor handy to try on, so I kept quiet.  Your method also has
the problem of not determining polarity easily.  If you've got 4 pairs, just
tying one from each together will only work for 2 out of the 16 possible
combinations.

Then there's the question of why is someone messing with stepper motors that
knows so little about electronics that they have a phobia for ohmmeters.  Or
at least why would you want to put yourself in the position to support them.
It seems like a no-win situation.  When something doesn't work they'll blame
you.

It did make me think a little about how to automate this with a PIC.  Plug
in up to 8 wires from a stepper motor and a few seconds later it tells you
what's what.  Then I realized this would be a low volume product and the
same people that don't want to spen $15 for an ohmmeter aren't going to
spend $200 or more for a stepper motor tester when you can buy a new stepper
motor for $20.

I've also stopped responding to general requests for help ever since I found
out you were sensoring my posts behind my back and despite your promise not
to back in October.  I now only jump into interesting intellectual
discussions or when I otherwise feel like it or have something to gain
myself.  I don't want to "support" the PIClist with free help as long as my
posts continue to be subjected to sensorship.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\02\28@081916 by kenash1

picon face
I am the fellow who had some basic questions about stepper motors. Do you
have any idea of just how to hook up a vm to a stepper? That would be more
appreciated than your lashing out at someone who's just trying to be
helpful, wouldn't it?

Ken Wilson

{Original Message removed}

2005\02\28@091932 by olin_piclist

face picon face
kenash1 wrote:
> That would
> be more appreciated than your lashing out at someone who's just trying
> to be helpful, wouldn't it?

First, I wasn't "lashing out" at James' method.  I originally kept quiet
because I didn't think I had anything to add.  I only responded when James
specifically asked why I didn't respond.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\02\28@104252 by kenash1

picon face
Does anyone have any ideas on how to identify stepper wiring beyond James?
Really want to know.

Ken Wilson

{Original Message removed}

2005\02\28@104331 by William Chops Westfield

face picon face
On Feb 28, 2005, at 5:07 AM, Olin Lathrop wrote:

> I was also not sure how much you can feel a shorted winding on a
> stepper
> motor, since most have fairly strong detent forces to begin with.

I was wondering that too, and grabbed a bipolar motor I have lying
around.  It was noticable, but not dramatic.  Fingers are capable
of generating a lot of torque, it seems.

The linstepper has a smart microcontroller inside.  Can't IT figure
things out, or at least be used to figure things out?  (I guess it's
too late?  All designed and produced?)

BillW

2005\02\28@120435 by Jay Shroff

picon face
google has the answers shown below,

for unipolar motors

http://www.doc.ic.ac.uk/~ih/doc/stepper/others/

for uni & bipolar

http://209.41.165.153/stepper/Tutorials/BiTutor.html

{Original Message removed}

2005\02\28@123142 by olin_piclist

face picon face
kenash1 wrote:
> Does anyone have any ideas on how to identify stepper wiring beyond
> James? Really want to know.

First try James' method and let us know.  It'd be interesting to see how
easy it is to feel a shorted winding.  If that doesn't work, you can
identify windings with an ohmmeter.  Getting the phase and polarity right is
more tricky.  If you've got few enough you can use trial and error.  The
most direct method is to drive the stepper by hand and look at the phase
relationship between the windings on a scope.


*****************************************************************
Embed Inc, embedded system specialists in Littleton Massachusetts
(978) 742-9014, http://www.embedinc.com

2005\02\28@125855 by kenash1

picon face
Been looking for a couple months on google and just plain missed that one.
Very helpfull. This should solve my problem.

thank you,

Ken Wilson

----- Original Message -----
From: "Jay Shroff" <.....jshroffKILLspamspam@spam@myrealbox.com>
To: <piclistspamKILLspammit.edu>
Sent: Monday, February 28, 2005 11:04 AM
Subject: Re: Re: [EE] Finding stepper motor wiring


> google has the answers shown below,
>
> for unipolar motors
>
> http://www.doc.ic.ac.uk/~ih/doc/stepper/others/
>
> for uni & bipolar
>
> http://209.41.165.153/stepper/Tutorials/BiTutor.html
>
> {Original Message removed}

2005\02\28@130333 by Tony Smith

picon face
I've seen a web page that described how to do this, long time ago, can't
remember details or where. Sorry. Possibly on the 'Jones on steppers' page.

For unipolar (5 or 6 wire), I use a battery. Almost any voltage will do. For
6 wire models, 2 wires are usually the same colours (rarely black), this is
the common. For 5 wire, apply voltage to 2 random wires and see if the rotor
turns. Remove the second wire, and randomly pick another. If the rotor moves
this time, the first wire is the common, otherwise it's the one you removed.

Then touch each wire to the battery until you find one that spins clockwise.
Call this A. Pick another wire. If it goes clockwise too, call it B, and so
on. If it doesn't, re-apply A, then pick another wire. Eventually you get
A,B,C & D, and it should spin clockwise when voltage is applied in sequence.
Reverse the sequence, and the motor should go backwards.

For bi-polar (4 wire), I use a LED. Put it across 2 wires, and spin the
rotor. If it flashes, there's your coil. Doesn't tell you polarity. (At this
point I hook it to the driver. If it doesn't work I reverse one coil). As
you spin it, it will only light on every 2nd step as the voltage reverses. I
suppose if you put a LED on each coil, and got the polarity right, they'd
flash in sequence, a bit like quadrature encoders. Could use 2 pin red/green
leds and figure out what the sequence should be if wired correctly.

Tony


> {Original Message removed}

2005\02\28@141325 by James Newton, Host

face picon face
> I got it.  Seems like a long way to go to avoid using an ohmmeter.

I actually agree. I advise people to go to RS and pick up a cheap unit.

> I was also not sure how much you can feel a shorted winding
> on a stepper motor, since most have fairly strong detent
> forces to begin with.  I didn't have a stepper motor handy to
> try on, so I kept quiet.

On the ones I've tried, its is very noticeable. The current generated by the
rotation of the magnet through the winding is coupled back into the winding
in exactly the direction necessary to oppose that motion. It's called "Lenz
law" if I remember correctly... But you probably know more about the theory
of it than I do. The important point is that ALL the energy you put into
turning the shaft comes back to prevent you from turning the shaft with the
exception of that which is normally lost in any generator / motor system. So
the net effect is pretty strong.

>  Your method also has the problem of
> not determining polarity easily.  If you've got 4 pairs, just
> tying one from each together will only work for 2 out of the
> 16 possible combinations.

Absolutely true. However, the polarity is easy to fix AFTER you get the
common wire sorted out and the phases connected in any polarity. If the
motor vibrates, you swap one A and one B phase wire. If it rotates in the
wrong direction, you swap the A wires.

> Then there's the question of why is someone messing with
> stepper motors that knows so little about electronics that
> they have a phobia for ohmmeters.  Or at least why would you
> want to put yourself in the position to support them.
> It seems like a no-win situation.  When something doesn't
> work they'll blame you.

They do blame me, but not as often as you might expect. So far, people have
been very understanding and have been willing... Ne... More interested in
learning rather than in blaming.

> It did make me think a little about how to automate this with
> a PIC.  Plug in up to 8 wires from a stepper motor and a few
> seconds later it tells you what's what.  Then I realized this
> would be a low volume product and the same people that don't
> want to spen $15 for an ohmmeter aren't going to spend $200
> or more for a stepper motor tester when you can buy a new
> stepper motor for $20.

Very true.

> I've also stopped responding to general requests for help
> ever since I found out you were sensoring my posts behind my
> back and despite your promise not to back in October.  I now
> only jump into interesting intellectual discussions or when I
> otherwise feel like it or have something to gain myself.  I
> don't want to "support" the PIClist with free help as long as
> my posts continue to be subjected to sensorship.


You are very welcome to your opinion and feelings on that subject. I have no
expectation for your to continue to participate. Do so or not as you wish.
My request was sent to the entire list, and even after my second request, I
did not have a specific expectation that you, Olin, would respond.

I do appreciate your response here, thank you.

---
James Newton: PICList webmaster/Admin
.....jamesnewtonKILLspamspam.....piclist.com  1-619-652-0593 phone
http://www.piclist.com/member/JMN-EFP-786
PIC/PICList FAQ: http://www.piclist.com



2005\02\28@144629 by steve

flavicon
face
> First try James' method and let us know.  It'd be interesting to see
> how easy it is to feel a shorted winding.  If that doesn't work, you
> can identify windings with an ohmmeter.  Getting the phase and
> polarity right is more tricky.  If you've got few enough you can use
> trial and error.  The most direct method is to drive the stepper by
> hand and look at the phase relationship between the windings on a
> scope.

I have quite a collection of steppers and in most cases the difference in
detent torque with a coil shorted or not, is quite noticeable. However, in
one case, it wasn't. That was with an old 5" floppy drive motor. Probably
the one most likely to be found surplus.
Needless to say, the ones with a gearhead are a problem.

Once the centre taps have been determined, the phasing is quite easy
to determine for all but an 8 wire motor, as they are relative to each
other. Call the coil end wires A, B, C & D. Try to run the motor at a very
low step rate (eg.1 step/sec). If the motor steps back and forth, swap B
& C. If it runs backwards, swap A & B.

Steve.


==========================================
Steve Baldwin                          Electronic Product Design
TLA Microsystems Ltd             Microcontroller Specialists
PO Box 15-680, New Lynn                http://www.tla.co.nz
Auckland, New Zealand                     ph  +64 9 820-2221
email: EraseMEstevespam_OUTspamTakeThisOuTtla.co.nz                      fax +64 9 820-1929
=========================================



2005\02\28@154249 by James Newtons Massmind

face picon face
Hey Ken,

Thanks <GRIN> but please let ME know, OFFLIST, if you have concerns about
another members behavior? Thank you.

Now, I did find some documentation on ohming out stepper motors that is a
little more detailed that what I've been providing with the linistepper, but
not much.

http://www.stepperworld.com under Tutorials / Unipolar. He says "You can use
an ohm-meter to find the center tap - the resistance between the center and
a leg is 1/2 that from leg to leg.  Measuring from one coil to the other
will show an open circuit, since the 2 coils are not connected. "

What is missing is a step by step method of using the above to figure out
the coils. Rather than try to document it, I'm going to try to find the time
to write a little JavaScript program that will collect the information you
find from measuring the coils and use that to show you the circuit.

That is an interesting challenge huh? <GRIN>

---
James.



> {Original Message removed}


'[EE] Finding stepper motor wiring'
2005\03\01@034324 by Peter L. Peres
picon face


On Sun, 27 Feb 2005, James Newtons Massmind wrote:

> Err... Did anyone see this? Any comments? Can someone maybe just say that
> they got it and why they aren't interested?

Does it have to be 'without any meters' ? How about a computer program
where you enter the number of wires and measured resistances (web based
would be nice, no ?).

Peter

2005\03\01@143841 by James Newtons Massmind

face picon face
> On Sun, 27 Feb 2005, James Newtons Massmind wrote:
>
> > Err... Did anyone see this? Any comments? Can someone maybe
> just say
> > that they got it and why they aren't interested?
>
> Does it have to be 'without any meters' ? How about a
> computer program where you enter the number of wires and
> measured resistances (web based would be nice, no ?).
>
> Peter


Exactly my thought. Do you have such a thing?

---
James.



2005\03\01@144028 by Peter L. Peres

picon face

On Mon, 28 Feb 2005, James Newtons Massmind wrote:

> That is an interesting challenge huh? <GRIN>

Yes ? <re-grin>

Peter

2005\03\01@144045 by Peter L. Peres

picon face


On Mon, 28 Feb 2005, James Newtons Massmind wrote:

> That is an interesting challenge huh? <GRIN>

The normal way to do it is by arbitrariluy picking a wire as 'first'
one, then measure all others vs. it, then pick the second etc. This is
easier shown by a table: Assume you have 6 wires, assign a number to
each, then measure ohms so:

R( 1, 2         ) = V?
R( 1,   3       ) = V?
R( 1,     4     ) = V?
R( 1,       5   ) = V?
R( 1,         6 ) = V?
R(   2, 3       ) = V?
R(   2,   4     ) = V?
R(   2,     5   ) = V?
R(   2,       6 ) = V?
R(     3, 4     ) = V?
R(     3,   5   ) = V?
R(     3,     6 ) = V?
R(       4, 5   ) = V?
R(       4,   6 ) = V?
R(         5, 6 ) = V?

Each row yields one reading. You have to tell the users to mark open
readings, f.ex. using -1 as reading for an open reading. Tell the users
to ignore (remove from the count and measurement) any wires that do not
appear to be connected to the others (case ground, shaft encoder etc)

The algorythm to find the coils is as follows: for each wire set a
variable (in an array). Then add the resistances measured from that wire
to all the others. Do not add anything for open reading or zero reading.
The common wires will then be the bins with the lowest counts. The wires
connecting to them, will be all the wires that do not read open
connected to each of them.

e.g.:

max = 0
min = MAXINT // or something like that
for i=0, i<6, ++i
       bin(i) = 0
       for j=0, j<i, ++j
               R (i+1lj+1) != +inf ? bin(i) += R(i+1,j+1)
               bin(i) > max ? max = bin(i)
               bin(i) < min ? min = bin(i)
       rof
rof
// now we know min and max for each bin so we can slice the values by it
slice = (max + min) / 2 // or something like slice = (min * 11) / 9
for i=0, i<6, ++i
       tag[i] = 0 // mark seen wires so we catch mistakes
       if bin(i) < slice // found a common wire
               if tag[i]
                       print "you made a mistake, probably around wire $i, try again"
                       exit bad
               else
                       tag[i] = 1 // got it
               fi
               print "common: $i, phases:"
               for j=0, j<6, ++j
                       if (i != j) && (R(i+1,j+1) != +inf)
                               if tag[j]
                                       print "you made a mistake, \
probably around wire $j, try again"
                                       exit 1
                               else
                                       tag[j] = 1
                               fi
                               print " $j"
                               tag[j]
                       fi
               rof
               print "\n"
       fi
rof
// finally find orphaned wires and report them
for i=0, i<6, ++i
       if tag[i] == 0
               print "orphaned wire: $i"
       fi
rof
// done

You can postpone writing results until after all the errors are caught
by setting values in strings and then printing the strings if no errors
were found (the strings would store the good values).

This kind of problem can be solved much nicer in Prolog ;-)

Peter

2005\03\01@215229 by James Newtons Massmind

face picon face
Too cool of you to post this! Thanks!

In the language you are using here, is 0 or 1 considered true? Also, what
does the "tag[j]" on the line after the print " $j" do?


If we are not to "add anything for open reading or zero reading" and we are
"using -1 as reading for an open reading" then "R (i+1lj+1) != +inf" needs
to be something like "(R (i+1,j+1) != +inf) && (R (i+1,j+1) > 0)" correct?

In javascript, I did
                       r = R(i+1,j+1);
                       x = ( isNaN(r) ? 0 : parseFloat(r) );
                       bin[i] += (0<x ? x : 0 );
Where isNaN returns true if r is not a number so x becomes 0 if r is empty
and the numeric value of r otherwise.
bin[i] is incremented only if x is greater than 0.

"slice = (min * 11) / 9" seems to work better than "slice = (max + min) / 2"
but why not just "if (bin[i] <= slice) " rather than "if (bin[i] < slice) "
since this also managed the case where min == 0. Then slice can just be set
to min. Or am I missing something there?

I also added some checks for coil resistance readings that vary from one
phase to the next and for phase to phase resistances that aren't double the
coil resistance.

The javascript/web page translation is at
http://www.piclist.com/techref/io/stepper/wires.htm and seems to work up to
6 wire motors.

This still doesn't find the ORDER of the phases, but I can't see a way to do
that with out applying power or using a dual trace 'scope.

---
James.



> {Original Message removed}

2005\03\02@112220 by Howard Winter

face
flavicon
picon face
James,

On your original post (I didn't get round to replying earlier) I'm not sure your 8-wire technique will work,
because there are too many combinations of sequence and polarity, even when the 4 pairs are identified.  If
you have the C-pair backwards, it may still rotate, but with a jitter as C is activated.  I'm not sure how you
detect the problem, but attaching a clothes-peg ("pin" in the USA) and connecting one coil at a time in the
suspected sequence may make this possible - needs thinking about and I don't have time at the moment.

On Tue, 1 Mar 2005 18:52:24 -0800, James Newtons Massmind wrote:

>...<
>
> The javascript/web page translation is at
> http://www.piclist.com/techref/io/stepper/wires.htm and seems to work up to
> 6 wire motors.

I just tried this and it seems to have a fixation for 1 and 2 to be common, against any evidence!  :-)

I set up:
Pins Res
1-3  3
1-4  6
3-4  3
2-5  3
2-6  7
5-6  4

Now I think this should produce:
common: 3  phases: 1, 4,   common: 5  phases: 2, 6,
but it says:  
common: 1, phases: 3, 4,   common: 2, phases: 5, 6,

Hope this helps!

Cheers,

 


Howard Winter
St.Albans, England


2005\03\02@120140 by Jack Krause

flavicon
face
Hello all,

I've been noticing the stepper motor wiring thread.  Haven't been reading
the content, but would like to offer my two-bits worth.

I use a sure-fire technique for identifying two-phase stepper motor wiring
(5,6,8 wire) that requires only a d-cell battery, or a battery plus an
ohmmeter.

Here are examples for 6 and 8 wire motors (I'll use the battery+ohmmeter
method, because any old ohmmeter will work and almost everybody has one)

6 Wire:

With the ohmmeter, separate the wires into two groups of three (there'll be
continuity among the three in a group, but no continuity between the groups)

As you are testing, make sure that none of the motor wires are shorted
together, other than the ones specified in the test.

Arbitrarily label the wires in one set a, b, and c. Twist together a and c
and hold them to one side of the battery while holding b to the other side.
Does the motor turn easily? If yes, then b is the center and a and c are the
ends.  If no, then try again: twist together leads b and c and connect them
to one side of the battery and lead a to the other .  Motor turn easily? If
yes, then a is the center.  If not, then try again: twist together leads a
and b and connect them to one side of the battery land c to the other.
Motor turn easily? If yes, then c is the center.  If no, then there’s an
unknown problem because those are the only combinations. Repeat the
labelling and test sequence for the other set of wires.

8 Wire:

Take your ohmmeter and find the pairs of leads that have continuity between
them and those four pairs are the two windings (each split in half). Just to
make sure you don’t get snookered, measure between one wire of one winding
and one wire of all the other windings and make sure you don’t have
continuity there. Label the four pairs of leads: a, b;  c,d;  e,f;  g,h.

Make sure none of the motor wires are shorted together.

Turn the motor shaft and note how difficult (or easy) it is to turn.  Hold
wires a and b to the ends of the battery.  Note how hard the shaft turns (it
should turn a lot harder than before).   Twist lead a to c and lead b to d.
Hold leads to battery.  Does the shaft turn as easily as when no power was
applied? If yes, then you have found the two halves of one of the windings
and you have them connected parallel-opposing.  You can now label the leads:
a=1, b=2,d=3,c=4.  If no, then twist a to d and b to c.  Connect battery.
Rotate easily? If yes, then a=1,b=2,c=3,d=4.  If no, then twist a to e and b
to f. Connect battery.  Rotate easily? If yes, then a=1, b=2,f=3,e=4.  If
no, then twist a to f and b to e.  Connect battery.  Rotate easily?  If yes,
then a=1,b=2,e=3,f=4.  If no, then twist a to g and b to h.  Connect
battery.  Rotate easily?  If yes, then a=1,b=2,h=3,g=4. If no, then twist a
to h and b to g.  Connect battery.  Rotate easily?  If yes, then a=1,
b=2,g=3,h=4.  If no, then there has been an error, because those are all the
combinations.
At this point let’s say you have successfully identified leads 1,2,3,4.  Now
to identify leads 5,6,7,8.  Put leads 1,2,3,4 out of the way, but make sure
they are not shorted together.   Relabel the remaining leads as a,b,c,d.
Repeat the part of the testing above that involves a,b,c,d, but use lead
numbers 5,6,7,8 for your results instead of 1,2,3,4.

These tests are sure-fire and work every time.  Hope this helps.

Bill Krause

{Original Message removed}

2005\03\02@132338 by Peter L. Peres

picon face


On Tue, 1 Mar 2005, James Newtons Massmind wrote:

> Too cool of you to post this! Thanks!
>
> In the language you are using here, is 0 or 1 considered true? Also, what
> does the "tag[j]" on the line after the print " $j" do?

It is a pseudo language and my rendering of it is full of
inconsistencies (like using bin(i) and tag[i], both being array
references).

> If we are not to "add anything for open reading or zero reading" and we are
> "using -1 as reading for an open reading" then "R (i+1lj+1) != +inf" needs
> to be something like "(R (i+1,j+1) != +inf) && (R (i+1,j+1) > 0)" correct?

assuming +inf is represented as -1 as I proposed, make that R(i+1,j+1) != -1

> In javascript, I did
>                        r = R(i+1,j+1);
>                        x = ( isNaN(r) ? 0 : parseFloat(r) );
>                        bin[i] += (0<x ? x : 0 );
> Where isNaN returns true if r is not a number so x becomes 0 if r is empty
> and the numeric value of r otherwise.
> bin[i] is incremented only if x is greater than 0.

Yes, that is the idea.

> "slice = (min * 11) / 9" seems to work better than "slice = (max + min) / 2"
> but why not just "if (bin[i] <= slice) " rather than "if (bin[i] < slice) "
> since this also managed the case where min == 0. Then slice can just be set
> to min. Or am I missing something there?

min is not supposed to be 0, unless there is a short. Getting users to
take meaningful readings for < 1 ohm windings with a $5 DVM will be
interesting anyway. The idea of slice is that the measured values will
be all around R and 2*R, where R is the approximate winding resistance.
Then after min/max slice will be approximately R+2*R/2 = 3/2*R and the
farthest from either group's strays (iow poor measurments) (I hope).

{Quote hidden}

That is correct, you cannot find the order easily, but I have something
in mind that involves a $1 magnetic compass and some thin wire coils
wound around it ... let it sit for a while it isn't just there yet.

Peter

2005\03\02@152919 by James Newtons Massmind

face picon face
Thanks for taking the time to try it!

Vie fixed it to manage your sample correctly and added it as "6 wire sample
2"

Anyone else care to try?

---
James.



> {Original Message removed}

2005\03\02@161334 by James Newtons Massmind

face picon face
Thanks Jack (Bill? Mr. Krause?)

I appreciate it very much. It would seem that you could do the same thing
just by shorting leads together. E.g. without the battery, but perhaps the
voltage makes the difference more obvious?

I have added your method to
http://www.piclist.com/techref/io/stepper

---
James.



> -----Original Message-----
> From: piclist-bouncesspamspam_OUTmit.edu
> [@spam@piclist-bouncesKILLspamspammit.edu] On Behalf Of Jack Krause
> Sent: 2005 Mar 02, Wed 09:04


2005\03\02@215318 by Jack Krause

flavicon
face
James

External excitation is necessary in order to establish steady-state (D.C.)
phase relationships between the windings.
You can determine empirically that self-exctitation won't work by thinking
about shorting the three leads of one of the windings of a 6 wire motor.
Short them in any possible combination and rotor restriction will occur.
Try an analogous scenario with an 8 wire motor and the results will be
similar, but more complex because of the unknown phase relationships of the
windings before they're sorted out.
You gotta have external excitation.

Bill

{Original Message removed}

2005\03\03@102013 by Howard Winter

face
flavicon
picon face
James,

On Wed, 2 Mar 2005 12:29:13 -0800, James Newtons
Massmind wrote:

> Thanks for taking the time to try it!

No problem - I like to help when I can (that's just not
very often! :-)

> Vie fixed it to manage your sample correctly and added
it as "6 wire sample
> 2"

Errr - now it gets mine right, but the first 6-Wire
sample is now wrong!  It says the commons are 2 & 5, and
it should be 1 & 4.

Cheers,


Howard Winter
St.Albans, England


2005\03\03@131341 by James Newtons Massmind

face picon face
But... I'm confused... You aren't finding the phase relationships in your
method are you? You are finding the common and the which are the phases, but
not the order of the phases. You can do the same thing by shorting the
wires...

Am I missing something? Sorry if I'm being dense.

---
James.



> {Original Message removed}

2005\03\03@132712 by James Newton, Host

face picon face
Ah, yes, it does, doesn't it <SAD>

Ok, I don't have time to mess with it further at this point. It will have to
sit on the list of "I tried" until someone else can tell me what I'm doing
wrong.
http://www.piclist.com/techref/io/stepper/wires.htm

---
James.



> {Original Message removed}

2005\03\03@134255 by Dave VanHorn

flavicon
face
At 01:27 PM 3/3/2005, James Newton, Host wrote:
>Ah, yes, it does, doesn't it <SAD>
>
>Ok, I don't have time to mess with it further at this point. It will have to
>sit on the list of "I tried" until someone else can tell me what I'm doing
>wrong.
>http://www.piclist.com/techref/io/stepper/wires.htm

It seems you're a little twisted.
I pulled up the 6 wire demo, and it shows:

1>2 N
1>3 N
2>3 2N

When I entered mine, I did it as
1>2 N
1>3 2N
2>3 N

and same for the next phase with wires 4,5,6
It told me I had an orphaned wire?

I'd pre-fill the form boxes to "open" so that it's obvious that an unfilled
box means no connection observed.


2005\03\03@181336 by Jack Krause

flavicon
face
You ARE finding the phase relationships.

If you short across any winding or portion of a winding on a hybrid stepper,
you will cause the rotor to turn (cog) much harder.  You can use this method
to determine which wires are common to a winding, but not a whole lot else
is evident.

BUT if you excite a portion of one winding (from center-tap to one end
("phase") of a phase winding  on a 5 or 6 wire motor, or one of the
half-windings on an 8-wire motor) AND excite equally AND IN THE OPPOSITE
POLARITY the other portion of that same winding (from center tap to the
other end ("phase") of the same winding in a 5 or 6 wire motor, or the other
half-winding associated with the same phase on an 8-wire motor) the motor
will turn freely because the net excitation to the stator is zero.  This
situation will only occur when you are exciting two half-windings of the
SAME PHASE in this manner.  Therefore using this method you can sort out
center-taps, associated half-windings, winding polarities, and phase
association in the motor.

(In case you're wondering; when you short the two outside ends of a winding
in a 5 or 6 wire motor and then apply excitation (the battery) across the
center-tap and the shorted ends, you are applying excitation to the
half-windings in parallel, OPPOSED POLARITY.  If you draw a schematic of the
hookup this becomes evident.)

I suggest you give the method a try.  The proof is in the pudding.

Bill

{Original Message removed}

2005\03\03@190504 by James Newtons Massmind

face picon face
Ahhhh... That did it, now I understand.

Thanks, and I will try that...

---
James.



{Quote hidden}

2005\03\04@162619 by Peter L. Peres

picon face


On Wed, 2 Mar 2005, James Newtons Massmind wrote:

> Thanks Jack (Bill? Mr. Krause?)
>
> I appreciate it very much. It would seem that you could do the same thing
> just by shorting leads together. E.g. without the battery, but perhaps the
> voltage makes the difference more obvious?
>
> I have added your method to
> http://www.piclist.com/techref/io/stepper

The battery will cause the motor to have a definite detent (even motors
which normally haven't got much of a detent when moved by hand). This
may be helpful. The compass idea needs some more stewing ;-)

Peter

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