it doesn't fail at the same point every time. there are actually two points in the code where it fails. one is definitely after the spindle starts on a new run. the program begins with a spindle on and the spindle goes on and then it locks up.?
the other is a short time after the spindle goes off but i am less sure about that exact location.
when i restart mach3 the A axis DRO always reads 4009.something or other. i think that noise is killing the pokeys which responds by sending a shit load of a pulses which overruns the a limit and this is what kills mach3 if the limit were higher it would probably just take a few ms longer while the pokeys is going nuts. never had this problem in 7 years making many thousands of parts. other problems but never this. it only started with the usb pokeys.
i grounded my spindle motor shield, who knows.
?
?
Best regards, Spencer Chase
67550 Bell Springs Rd.
Garberville, CA 95542 Postal service only.
Laytonville, CA 95454 UPS only.
Spencer@...Spencer@...Spencer@...(425) 791-0309
(707) 223-8212
------ Original Message ------
Sent: 3/27/2020 8:22:20 PM
Subject: Re: [MachCNC] strange stopping
Spencer
?
First, your comment about the A stopping
at the same value each? time. I seem to remember from a few years back that
there was a bit of a discussion about the A having a move limit in Mach 3. ?Don’t
remember the detials
?
Second , a noise issue seldom, if? ever,
fails at exactly the same point every time. I kind of? doubt that this is your
problem.
?
On the second ?point though I had issues when
I switched PCs a few years back. ?Chased ?noise ?issues for a few weeks until I
discovered my PC LPPT port was a 3.5vdc port vs a 5 vdc one, very common on later
PC’s. (I didn’t discover that but was pointed to check that by the group) .That
voltage would allow “ANY” noise in. ?A later BOB that would handle the 3.5vdc signals
solved that issue.
?
Don
?
.?
?
?
one more thing. i never had this problem until i
switched to the Pokeys from the parallel port. so i am pretty sure that the
noise is getting into the Pokeys through the USB cable.?
so should i put a braid over the USB cable or try to
find a better shielded version and connect the ground only at the BOB ground
which is common to everything else.?
my computer does not have a three wire power supply. it
has "desktop" wall wart supply. i have no idea where the PC grounds
are connected or if the chassis is connected to anything.
Best regards, Spencer Chase
67550 Bell Springs Rd.
Garberville, CA 95542
Postal service only.
Laytonville, CA 95454 UPS only.
Spencer@...
Spencer@...
Spencer@...
(425) 791-0309
(707) 223-8212
------ Original Message ------
Sent: 3/27/2020 3:58:44 PM
Subject: Re: [MachCNC] strange stopping
Electrical noise can be a bear.? Steve
Spallings mentioned PC grounds and system or motor grounds.? I have his
PMDX-126 and unfortunately the PC I'm using internally somewhere has the DC
ground connected to the system frame which is the third earth prong on the
power cord which then connects to the motor frames through the machine metal.
The CUI encoders on the DC servos serve to further muck things up where their
DC ground is connected to the frame.? Which is of course connected to the 3
prong and so DC ground earth ground are connected in several places.? Shielding
has no rhyme or reason here but it's one place where a single ended connection
for a shield is a bit more logical.
?
My EE book on electrical noise states
that the signal grounds should never be connected to the DC power grounds or
frame.? The whole point of shielding is that it isolates the two.
?
For your system also look at magnetic
coupling.? The way a transformer works is a changing magnetic field introduces
current in windings that are also in the magnetic field.? So the spindle motor
current flowing through the wires can generate a field picked up encoder or
limit switch wires.? Short of what is called mu metal shielding the only
solution to electromagnetic interference is distance.? Route them far apart.
?
Electrostatic shielding is different.?
Twisted pairs help to null out electric field noise. Shielding can be grounded
at one end or both of the frame (third prong) earth.? The point is you only
want the noise current flowing back through the shield into the frame.? Not
through your signal wires which includes the DC 0V wires.? People tend to
forget what goes out a signal wire is still a signal as it comes back through
what is commonly called the ground or common wire.? (Some manufacturers have
called the +5V to +24V 'common' for limit switches)
?
John Dammeyer.
?
?
You are trying to fix a
wrong schematic with cosmetic changes. You sure have a ground loop somewhere.
Check your shields, they should be connected one side only with heavy short
wire to good ground. Preferably star connection.
?
i forgot to mention that, i have ferrites everywhere. that is one of
the first things i do.? i have them on the signal leads to each stepper
and even on the usb cable to the pokeys although the mfg suggested it would not
do anything. i tried a usb signal conditioner thing but it did not work,
meaning that most things plugged into it stopped working.
anyone know of a signal conditioned for usb that does work?
Best regards, Spencer Chase
67550 Bell Springs Rd.
Garberville, CA 95542
Postal service only.
Laytonville, CA 95454 UPS only.
Spencer@...
Spencer@...
Spencer@...
(425) 791-0309
(707) 223-8212
------ Original Message ------
Sent: 3/27/2020 4:03:12 AM
Subject: Re: [MachCNC] strange stopping
I would probably try
adding ferrite beads to the leads.
I have my router working really well with the following configuration.
Solid state tiny computer running win 10. Mach 3 latest version Pokeys USB CNC
thing connected to a PDMX.
I am finally getting smooth motion no lost steps etc etc. Everything
works except.
Occasionally Mach3 just stops and is totally unresponsive. Can not
reset, jog etc. The diag screen shows all ins and outs off. I have to kill Mach
3 and start again.
I am pretty sure that every time it does this, when I restart the 4th
axis DRO shows 4099.xxx? the 4th axix is angular.?
I am running a gcode with a subroutine that repeats over and over with
a tool change to allow inserting a new part for machining. i am also using the
subroutine to make it possible to count parts.?
when this failure happens is always close to the spindle motor going on
or off. it is a three phase servo run by a high quality US inverter.
Forgot the name right now but it is a good inverter not Chinese no name stuff.
I am pretty sure the spindle motor is causing noise that kills the
Pokeys. I have proper grounding and shielding.?
I changed the inverter carrier frequency from the default of 5Khz to
2khz and have not had the problem yet but it some times does not happen for a
considerable time.?
any ideas? does the 4099 signify some overflow?? does it sound
like it is inverter noise? might the lower carrier frequency be the fix?
Best regards, Spencer Chase
67550 Bell Springs Rd.
Garberville, CA 95542
Postal service only.
Laytonville, CA 95454 UPS only.
Spencer@...
Spencer@...
Spencer@...
(425) 791-0309
(707) 223-8212
