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Author Topic: Mach3 motion control over two LPT ports?  (Read 7074 times)

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Mach3 motion control over two LPT ports?
« on: February 20, 2011, 03:37:25 AM »
Hello,

I've just built my 4th axis and use a G540 as my controller.  Problem is I slave the A axis to the X axis to contol two ballscrews.   So when I use my 4th axis I need to disengage the the X axis to use the A axis for rotary control.   I have a spare Xylotex controller that I was thinking I could use to control the 4th axis and keep the other three axis working properly.   But will Mach3 allow two LTPS to work concurrently for motion control?



Brad.

Offline djc

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Re: Mach3 motion control over two LPT ports?
« Reply #1 on: February 20, 2011, 04:08:05 AM »
...will Mach3 allow two LTPS to work concurrently for motion control?

I don't see why it won't. Effectively you have four axes on five sets of pins.

Were it me, I would try to arrange all axes to be through the same parallel port simply to avoid any potential probems at the hardware/port level.

Do you have independent home switches on the slaved axes (allows correction of any skew/racking)?

Offline Tweakie.CNC

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Re: Mach3 motion control over two LPT ports?
« Reply #2 on: February 20, 2011, 07:16:27 AM »
Hi Brad,

I use a seperate 'stand alone' psu and controller for my 4th axis which connects to a second PCI card configured as LPT2. Mach has no problem with sharing the tasks between ports #1 and #2.

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.
Re: Mach3 motion control over two LPT ports?
« Reply #3 on: February 20, 2011, 07:47:19 AM »
Exellent.  Thanks for the feedback.  I'll get another LPT port and give it a go.  Now I just need to disengage 2 of the other axis off the xylotex.  I heard they tend to blow if motors arent connected.


Do you have independent home switches on the slaved axes (allows correction of any skew/racking)?

Umm... nope.  I'm kind of learning this stuff on the go.  If I have skew or racking I dont know about it!!   ???

Brad.

Offline djc

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Re: Mach3 motion control over two LPT ports?
« Reply #4 on: February 20, 2011, 10:08:10 AM »
>> Do you have independent home switches on the slaved axes (allows correction of any skew/racking)?

Umm... nope.  I'm kind of learning this stuff on the go.  If I have skew or racking I dont know about it!!

The reason I asked is because if you don't, as you have confirmed, you could get away without a slaved axs: just put two step wires and two direction wires from your BoB to each X-stepper controller. Effectively you are splitting the output from Mach.

The beauty of the slaving and independent home switches is if one side gets out of synch. with the other (so the gantry will skew or rack), you can home the machine and when one side touches its switch, it will stop and wait for the other side to touch (thus deskewing). Once both home switches are triggered, then the axis numbers are changed.
Re: Mach3 motion control over two LPT ports?
« Reply #5 on: February 21, 2011, 08:19:35 AM »
$25 PCI card did the trick.  Just had to alter the hex code in Mach3 for LPT2 to match the hex code for the new parallel port.  As Im using the Xylotex 4 axis controller to control the rotary A-axis and I now have 3 spare controllers also.  :)  What else can I motorise  :D



Brad.

Offline Tweakie.CNC

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Re: Mach3 motion control over two LPT ports?
« Reply #6 on: February 21, 2011, 08:27:39 AM »
Quote
What else can I motorise  Cheesy

I suppose that depends on your age Brad  :D

Tweakie.
Success consists of going from failure to failure without loss of enthusiasm.  Winston Churchill.