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Author Topic: Mach3 / PMDX-122 Issue  (Read 448 times)

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Re: Mach3 / PMDX-122 Issue
« Reply #20 on: March 19, 2019, 11:27:03 PM »
Craig,
When you say they require an enable signal, is that the setting in the Pins/Ports where you enable the axis?  If yes, I did enable them.
"Failure is not an option, but the option exists"
Re: Mach3 / PMDX-122 Issue
« Reply #21 on: March 19, 2019, 11:30:49 PM »
Hi,
just found this in the PMDX-122 manual.

If you use the jack or pins nominated you can use a 9VAC or 7-12VDC supply.

If you have batteries as reuelt has suggested you can use those too, just not through the jack.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach3 / PMDX-122 Issue
« Reply #22 on: March 19, 2019, 11:33:45 PM »
Thanks Craig,
I'll see what I can get rounded up tomorrow to test this and I'll post my findings. 
"Failure is not an option, but the option exists"
Re: Mach3 / PMDX-122 Issue
« Reply #23 on: March 19, 2019, 11:39:30 PM »
Hi,

Quote
I just found the power supply that I have and it's a 24VDC...


No, the manufacturer says a maximum of 12V. I commonly use 7805's, there like an asshole.....everyones got one,
and they are rated to about 30V input, so I would have thought 24V would have been fine. I would be cautious though,
you don't want to blow the IC up, it could be repaired easily enough but you don't want to tell the boss that you ignored
the manufacturers recommendation and therefore damaged it.

As far as the enable signal goes, I'm not talking about either Mach or the Bob.....but the stepper driver. The input terminals
MF+ and MF- require a constant 5V signal otherwise the drivers do nothing.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach3 / PMDX-122 Issue
« Reply #24 on: March 19, 2019, 11:44:21 PM »
Ah, I understand where your going with this now.  :) Also, I just dug through my box of cables that I've been saving since the dawn of time and found a round pin 9VDC power adapter! Lol. Now I can finally tell the wife I used one out of the box. I will post my trials tomorrow. Thanks again for the help thus far!
"Failure is not an option, but the option exists"

Offline reuelt

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Re: Mach3 / PMDX-122 Issue
« Reply #25 on: March 20, 2019, 12:23:28 AM »

No problem reuelt,
Any input is appreciated.  As far as the USB power...it was working that way when we got it so it was just left that way.  Can you elaborate as to what inputs you would be referring too?  Would the E-Stop be considered an input in said case?

Input from Limit/home switches etc. can use HIGH voltage and so through opto-isolation chips (sort of relay) for safety reason. The PC USB is grounded with with PC case so USB is NOT isolated from PC.
Usually USB power cannot also power the opto-isolation chips (sort of relays). But OUTPUT signal pins from PC will work using USB power. E-stop usually use a large AC relay to switch off a/c so it may still work with USB powering the board.
« Last Edit: March 20, 2019, 12:29:11 AM by reuelt »
"the gift of God is eternal life through Jesus Christ our Lord"
Re: Mach3 / PMDX-122 Issue
« Reply #26 on: March 20, 2019, 02:41:15 AM »
Hi,
reuelt commented:

Quote
Input from Limit/home switches etc. can use HIGH voltage and so through opto-isolation chips (sort of relay) for safety reason. The PC USB is grounded with with PC case so USB is NOT isolated from PC.

This is potentially misleading. I have attached the representative digital inputs (DB25 pins 10,11,12,13,15) and none of them are
optically isolated. If you put more than 5V on any of them you will fry the buffer IC. DO NOT USE 24V INPUTS unless you
make and provide some voltage translation. Exceed 5V input to 74LS TTL IC's frys them!

I have also attached pics of the digital outputs (DB25 pins 14,16,17) and the motor outputs (DB25 pins 2,3,4,5,6,7,8,9)
and they are not opto-isolated either.

This has implications.
First one and one only 5V supply is needed. It can be derived is different ways but still only one supply is required.
Under no circumstances apply more than 5V to any input.
Do not demand that any output exceed sink or source current appropriate to 74LS TTL. To be safe no more than 10mA
sinking or sourcing.

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

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Re: Mach3 / PMDX-122 Issue
« Reply #27 on: March 20, 2019, 04:26:56 AM »
Hi,
reuelt commented:

Quote
Input from Limit/home switches etc. can use HIGH voltage and so through opto-isolation chips (sort of relay) for safety reason. The PC USB is grounded with with PC case so USB is NOT isolated from PC.

This is potentially misleading. I have attached the representative digital inputs (DB25 pins 10,11,12,13,15) and none of them are
optically isolated.
Craig
Craig,
if your BOB inputs are not optically isolated, it must be an old model (design).
Most newer models are optically isolated (only for input pins).
See attached PIC.
For this typical BOB board for MACH3, the optical isolation chips (relays) must be powered by 12V to 24V otherwise the input pins will not work.

Gecko G540 spec also says
"Opto-isolation on all LPT signal pins"

Reuel


« Last Edit: March 20, 2019, 04:32:09 AM by reuelt »
"the gift of God is eternal life through Jesus Christ our Lord"
Re: Mach3 / PMDX-122 Issue
« Reply #28 on: March 20, 2019, 05:24:15 AM »
Hi,

Quote
if your BOB inputs are not optically isolated, it must be an old model (design).

Rubbish, while it is true that a lot of BoBs are opto isolated it is also true that a lot aren't. The pics I posted are from
the PMDX-122 manual and none of the inputs or outputs are opto isolated. I should point out the PMDX has a superb
reputation for quality products.

Quote
For this typical BOB board for MACH3

You posted a pic for a 'typical' parallel port BoB.......but it bears no resemblance to the pic posted by OP of his BoB.
Indeed look at his pic again and see if you can identify any optos, bet you can't because there aren't any.

I use MB02 BoBs from Homann Designs in Melbourne. Peter Homann is a legend in Mach circles and his MB02's don't
have optos either. I've been using them for five years.

Craig
My wife left with my best friend...
     and I miss him!
Re: Mach3 / PMDX-122 Issue
« Reply #29 on: March 20, 2019, 05:41:52 AM »
Hi,
while it might be desirable to have BoB inputs opto isolated, and of course many are,what happens with bi-directional
boards like OP's PMDX-122?.

Under normal configuration pins 2-9 are outputs, commonly step/dir for the motors. It would be unusual for outputs
to be opto isolated, especially when so many stepper drivers have opto isolated inputs. If the board is used on the second
parallel port to get more inputs then pins 2-9 will be inputs. This board accommodates this. But now you have a problem,
if you have an opto output the phototransistor is hooked to the output terminals whereas if it has an opto isolated input
the photdiode must be hooked to the terminals.

To my knowledge there is no such thing as a bi-directional opto isolator. To construct one out of opto ICs adds unnecessary
complexity, especially given the requirement for yet more isolated power supplies.

Craig
« Last Edit: March 20, 2019, 05:47:07 AM by joeaverage »
My wife left with my best friend...
     and I miss him!