Machsupport Forum
Third party software and hardware support forums. => PoKeys => Topic started by: oddname on October 10, 2018, 01:25:39 AM
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To make a long story short(er). It started when I wash hooking up the basic things needed to get my oxcnc moving.
Started with this; https://www.youtube.com/watch?v=9u8CvoVQZXc very odd movement, same with pendant or no pendant, it doesnt move cleanly.
Checked other axis, they wont allmost budge, but they are easy to move by hand.
Then I checked further, removed all things keeping a load on the steppers, this is what happens now
https://www.youtube.com/watch?v=Cdbz5dgRhq0 https://www.youtube.com/watch?v=z5oYCf9BRnY
Checked drivers, tried 1/2-1/4 Microstepping.
Thought maybe I did a booboo on the cables, but A+ A- B+ B- seems to connect to where they should
So I checked the motion controller > driver cabling, A Ok there aswell, connected as shown on diagram + alarm, (https://imgur.com/pmZQ36a.png)
not sure if wiring this wrong might give me the erors I am having, as a final trial I will be making new basic cables just like this diagram. (https://i.imgur.com/LQCw9C4.png)
Any other final ideas would be awesome :)
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Hi,
from the sound of the stepper on your video I would have guessed that the signaling current to the stepper drive is
marginal/not enough. Can you put an ammeter in the DIR line and establish what the signaling current is?. From the specs
it should be at least 10mA.
Craig
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Does a multimeter work for this?
Just measure pin to gnd when trying to move?
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Hi,
no, that measures voltage, you want to know the current.....current s responsible for the photodiodes light output
in the drives optocoupler. With insufficient current the light output decreases markedly then the phototransistor
won't switch or saturate like it should.
If your multimeter has a DC current measurement range, that would work. Remember when your multimeter is in current measuring
mode your probes are almost shorted together....if you forget and try to measure the supply voltage to earth say then you'll pop something.
Craig
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I have never measured current before, but the MM can do it.
So just insert the MM in between the connection, should I just leave the driver connected and put the MM in the circuit between them then?
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Hi,
no, you have to remove the normal connection and replace it with the multimeter circuit.
In current mode you might think of the multimeter as 'a bit of wire with a probe at each end'. It just so happens that the 'box of tricks'
the current passes through measures and displays the current.
Craig
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Yeah I was a bit unclear, I should think of the MM as the wire between pokeys and driver in the circuit for the Dir pin.
Any other ideas on what could be wrong? I havent connected anything wrong considering i checked pins, nothing that should damage anything atleast.
Polabs recommend Dir+ Step+ of my driver to the signal pins on the pokeys and the negative ones to gnd (My driver has both Dir+ Dir - etc, currently my + pins are fed 5v and negative = connected to signal of the pokeys. Maybe this will help out, not sure though yet :) Cablestuff on the mail, but I can make a quick rework of an old cable to test.
Thinking about it, 5v to the signalpin ins on the driver and then signal aswell from the pokeys to negative pins, cause of issue?
This could also explain the sound when enabling the drivers, sounds like a screeching noise and then holds torque as should, this could be a lead!
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Hi,
if you measure the current in the DIR circuit you will establish whether the logic you have used to wire the pins is
correct. Have you measured the current?
Craig
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I havent measured but I did connect now as polabs suggested, in contact with support there aswell, but still the same problem, less crunching if I unplug the encoder, but I think it is just deciding if the "twitch" when enabling is movement that shouldnt be there so it compensates.
But all in all still no motion.
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Hi,
MEASURE THE CURRENT!!!! If you don't know what current is exciting the photodiodes you don't know whether they
are working.
Craig
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Just to be sure I just put the MM in between the circuit connecting the dir pins on both pokeys and driver right? so that this acts as wire so to speak?
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Did, not sure if correct, MM set to measure mA, MM pins acting as a connection between Pulse/step of controller and driver, no readouts what so ever.
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Hi,
the attached pic is from the PoKeys manual,
depending on the type of output (with or without the resistor) the output may not
have the grunt to reliably signal your driver.
Just to be sure I just put the MM in between the circuit connecting the dir pins on both pokeys and driver right? so that this acts as wire so to speak?
Yes.
Did, not sure if correct, MM set to measure mA, MM pins acting as a connection between Pulse/step of controller and driver, no readouts what so ever.
Do you have another low current circuit that you know works just to be sure that your meter is good and
you know how to use it. Most multimeter current circuits have a fuse internal to the meter and its very common for that fuse to
have popped. The only way you can tell is to run some current thruogh it with a known good circuit.
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The combination should work, pretty much the same here;
http://www.machsupport.com/forum/index.php/topic,32462.0.html Just a big brother of mine.
What can cause my signals to not possibly be strong enough? Faulty board?
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Hi,
What can cause my signals to not possibly be strong enough? Faulty board?
No, I don't think its a faulty board, and I think its close enough to work as intended, we would know for sure one way
or another if you would only measure the current!
These are from the PoKeys 57CNC manual, I assume you have it?
On page 16 is the listing of the pin types in the motor output header, note all three outputs are of type DO_5.
On page 18 is a representative circuit of the DO_5 type output. The signal originates in the MCU and is buffered, that is the triangular symbol,
the current passes through the 100 Ohm resistor. PoKeys have put the resistor in the circuit to protect the buffer IC. If you accidentally shorted the
output to ground the current would be limited to about 50mA, probably just low enough that the IC doesn't fry up!
The downside is that if the output has to either source or sink any current the output voltage will suffer. With zero or near zero current from the output
the voltage of the pin will be 4.5V to 5V when high and 0.5V to 0V when low ie full TTL voltage swing. If the output is required to source/sink 10mA then the high voltage
will be reduced to 3.5V - 4.0V and the low voltage will increase to 1.5V - 1.0V. That is to say that the overcurrent protection resistor is now affecting the voltage swing of the output
so much that its borderline for TTL output.
Note that PoKeys determined that the output voltage swing is still acceptable if the input has to source/sink 8 mA.
Your stepper driver inputs require 10mA to switch so your PoKeys is borderline to drive the signals into the stepper driver. This is why I want you
to measure the current. Its going to be touch and go whether it will work without some modification. I think it will work but we absolutely NEED TO MEASURE
THE INPUT CURRENT TO THE DRIVER INPUTS.
If you cant do it yourself find someone who can.
If it turns out that the current is not enough don't panic we can fix that with a amplifier or MOSFET...easy. Still I think that the combination should work as is
if only you would knuckle down and make the required measurement.
Craig
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Will try again, connected my multimeter between the pins, used MDI to "move X" far away to get the signal to stay yet nothing.
MM is brand new so it shouldnt be shorted, but not really a top of the line fluke :)
Read in the manual for it now, if measuring up 40mA the resolution is 10mA so it seems it wouldnt be able to read out 8mA then? Am I reading that correct then so below 10mA would = 0? Never done current-readouts so this is all new to me :)
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Hi,
MM is brand new so it shouldnt be shorted, but not really a top of the line fluke Smiley
Doesn't need to be.
Read in the manual for it now, if measuring up 40mA the resolution is 10mA so it seems it wouldnt be able to read out 8mA then
That doesn't sound right. If a meter can read 40mA then it should have uA resolution. Post the manual. If that meter is not right or good
enough beg steal or borrow one that is. You also need some way to confirm its working. Either way we need that measurement otherwise we
are just guessing.
Craig
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Might be me reading it wrong, but it does seem to have uA not sure about the range though.
(https://i.imgur.com/ecbYbrJ.png)
But considering the enable-pin also is the same type of pin, and enable does seem to work. On-off = holding torque - no holding torque.
Shouldnt step dir also be ok then? (I know, measure to know :D )
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Hi,
so long as you don't use the 10A range any of the other ranges have the resolution to read 10mA or so accurately.
Shouldnt step dir also be ok then?
Yes, I agree, so it is important to measure it and find out why its not working.
My guess is that you don't have the PoKeys and/or Mach setup correctly and there are no signals coming out of the PoKeys,
we would know foe sure once you measure it.
I've posted eight times and on each occasion I've asked you to measure the current into the DIR pin, fist when going in one direction and
then again when going in the other. I'm sick of asking.
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I will measure again, just getting hold of a ammeter I know that works for sure :)
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Confirmed working MM in the way over now, so Will do some measurements today /tomorrow
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I am more confident now that I will do a successful measurement next, realized just now when looking at a picture, "hey I measured step not dir..." :/
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Sorry for the delay , but measured Dir. Finally with something I trust
10mA one dir, 0 for the other
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Hi,
that's good news....it means the PoKeys can signal the drivers with the arrangement you have.
The question is why are the motors not moving?
There seems to be a couple of possibilities.
1) The PoKeys is not producing Step pulses
2) The drivers are not set up correctly and not responding to the pulses they are being sent.
We need to devise some tests or strategies to determine which.
I think the simplest is to measure either the current or voltage of the Step output. If the output is producing pulses it will be
on for half the time and off for the other half. I would expect the voltage (or current) would be about half what the active Dir
output would be.
Try issuing an MDI like:
G0 X100 and then put your multimeter (in normal voltage mode) between the PoKeys output and 0V. What result do you get?
Craig
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I will try that when back at the machine, I did another test today though, I get sliiight movement, same exact movement no matter which motor, driver and port I use, so the issue is atleast consistent :)
I can get the movement below, but in the exact same range. So say I move from 4mm to -1 at -1 it switched dir and move x-amount of mm, then no more no matter which value, then I change direction and when it get backs to -1 it move the other way x-amount of mm.
Se video
https://www.youtube.com/watch?v=zsnJS0QHTQs
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Well I got thing moving sort of.
All axis working, sort of, with some issues now.
Slave for my 2x motors axis (Y) is only accepting one of the motors, holding torque works, yet no movement.
Is there Another slave-axis bug in the plugin? Read a thread where that was the case of an older version of the plugin.
And motion isnt smooth, how to fix that, not even during a long jog it seems.
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see motion here;
https://www.youtube.com/watch?v=zQd1yhOI0kk
Not really smooth, just jogging here :)
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And all works!!! It was a little bit of this, a little bit of that.
Biggest issue was using usb over ethernet, works flawlessly now!
Thank you ALL for the great support :)
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:)
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Another add-on to my thread.
I am setting up home and + limits for the XY axis, but how to I set that home also = limit - ?
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Hi,
the PoKeys has so many inputs why are you trying to combine home and limit functions into one?
In Machs early days when everyone had a parallel port there was only five inputs and you had to combine things. Now with
so many inputs you don't have to do it anymore.
It reduces confusion....one switch, one input pin, one function.
Craig
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Simple, home and limit - is the same position I want to use :) better to just combine then.