Author Topic: Pokeys, mach4 no go?!  (Read 1370 times)

0 Members and 1 Guest are viewing this topic.

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #10 on: October 10, 2018, 02:11:02 PM »
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?

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #11 on: October 10, 2018, 02:52:17 PM »
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.

Offline joeaverage

  • Active Member
  • Posts: 4,508
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #12 on: October 10, 2018, 04:33:24 PM »
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.

Quote
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.

Quote
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.

My wife left with my best friend...
     and I miss him!

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #13 on: October 10, 2018, 11:46:45 PM »
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?

Offline joeaverage

  • Active Member
  • Posts: 4,508
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #14 on: October 11, 2018, 02:13:33 AM »
Hi,

Quote
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
 
« Last Edit: October 11, 2018, 02:16:09 AM by joeaverage »
My wife left with my best friend...
     and I miss him!

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #15 on: October 11, 2018, 03:07:05 AM »
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 :)

Offline joeaverage

  • Active Member
  • Posts: 4,508
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #16 on: October 11, 2018, 03:27:55 AM »
Hi,

Quote
MM is brand new so it shouldnt be shorted, but not really a top of the line fluke Smiley 

Doesn't need to be.

Quote
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
My wife left with my best friend...
     and I miss him!

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #17 on: October 11, 2018, 04:07:47 AM »
Might be me reading it wrong, but it does seem to have uA not sure about the range though.




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 )
« Last Edit: October 11, 2018, 04:09:45 AM by oddname »

Offline joeaverage

  • Active Member
  • Posts: 4,508
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #18 on: October 11, 2018, 04:27:57 AM »
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.

Quote
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.



My wife left with my best friend...
     and I miss him!

Offline oddname

  • Active Member
  • Posts: 20
    • View Profile
Re: Pokeys, mach4 no go?!
« Reply #19 on: October 11, 2018, 04:43:49 AM »
I will measure again, just getting hold of a ammeter I know that works for sure :)