Machsupport Forum

Mach Discussion => General Mach Discussion => Topic started by: emtffkev on March 06, 2008, 12:05:12 AM

Title: Testing LPT Port
Post by: emtffkev on March 06, 2008, 12:05:12 AM

Is there a way to test whether or not your lpt port is working properly? I cannot get my steppers to jog or turn with Mach3. I'm at a loss and have debugged everything except the lpt port. Not sure how to do this as I've been spoiled with USB most of my computer life and LPT is a fairly alien subject to me.

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 12:13:30 AM

Hello,
Here is one of several topics found with the Forum Search.  http://www.machsupport.com/forum/index.php/topic,4574.0.html
It may help you.
RC

The Forum SEARCH is a powerful tool.

Title: Re: Testing LPT Port
Post by: emtffkev on March 06, 2008, 12:26:00 AM

I'm not sure if I'm doing this correctly, but I seem to be getting a constant 0.03 v when i put my meter on pins 25 for ground and 2 for x-dir. Those are the settings for my controller. That is what I have set within mach3.

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 12:34:33 AM

Are you jogging x left and right ? One direction should read 0v, and the other direction should read 5v.

Title: Re: Testing LPT Port
Post by: emtffkev on March 06, 2008, 12:36:32 AM

I'm getting 0.03v constant, jogging or not. I am jogging the x left and right and nothing changes. I do have a constant voltage of near 5v on pin 4 and some of the other higher pins...not on pin 2 like I should.

Title: Re: Testing LPT Port
Post by: Chip on March 06, 2008, 12:43:51 AM

Hi, Emtffkev

Not all printer port's use/support all the Gnd. pin's 18-25, So try the others Gnd pin's also.

Your axis dir pins need 0 for one dir and 5 Volts for the other dir.

Some printer port's only putout 3 - 3.5 volts and don't work very well if at all.

Hope this Helps, Chip

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 12:52:07 AM

Thanks Chip, I realized that as I posted. That's what I get for trusting my memory.
And.....it's late.
Thanks for the correction,
RC

Title: Re: Testing LPT Port
Post by: emtffkev on March 06, 2008, 12:58:17 AM

Ok, checked with all grounds and getting same readings...

I am getting 3.5v on 2 of the pins...4.5 on others...and .03 on the rest beside grounds...

None are changing with or without jogging...they are all a constant voltage.

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 02:05:20 AM

The only other item  I've seen mentioned is to try the other driver in the Mach3 folder.
Might try it if you haven't already.
RC

Title: Re: Testing LPT Port
Post by: emtffkev on March 06, 2008, 01:23:54 PM

Just want to update...All works fine now, I needed the alternate driver and everything works ok. Got the motors spinning like mad...

Thanks!

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 01:59:20 PM

EXCELLENT  8)
I got that from Chip in an earlier topic.
Thanks to Chip, ;)
RC

Title: Re: Testing LPT Port
Post by: jimpinder on March 06, 2008, 02:39:23 PM

As a matter of course, it is no good trying to test your LPT1 socket using the motor driver outputs. Since the outputs are pulsed, depending on speed, the voltage you see on the output pins will vary.

It is better to configure Mach 3 to put out M3, M4, M7 or M8 signals  to pins. These are constant signals, either on or off, and are much easier and more reliable to test.

Title: Re: Testing LPT Port
Post by: Overloaded on March 06, 2008, 02:42:29 PM

I think that's why the dir. pin was specified. One dir. is high and the other is low..no pulse.
If I followed correctly.....if.
RC

Title: Re: Testing LPT Port
Post by: Chip on March 06, 2008, 03:41:29 PM

Hi, RC

That's correct, When testing motor output's, " Dir " pin's are used as thy will be high 5 volt's in one dir. and 0 volt's the other direction.

Jim, Step pulse's you need a Scope to see them, I'll agree.

Thanks, Chip

Title: Re: Testing LPT Port
Post by: Hood on March 06, 2008, 04:52:37 PM

Actually you can use a voltmeter as a crude way of seeing the step pulse, set to a mV range and go at different feed rates. The faster you go the higher the voltage, as I said its crude but can be handy for guys without scopes as a rough guide.
Hood