Need Help!- direct inputs in mach 3 mill

[steelfixer]

Hi all.
I need some help with a problem I am having with Mach 3 milling.
I am acutally running my astronamy telescope using nema 23 stepper motors and Mach 3 milling program.
When I am tracking a star / planet I use the X axis to control the rotation of the telescope mount.
I use the Y axis to control the up and down movement.
I use the Z axis to control the focus.
Now the problem I need to solve is this.
When the G code is running the X axis I need to be able to 'direct input ' commands to the Y and Z axis without stopping the program running.
Is this possible and if so how.
Thanks

[Al_The_Man]

It might be difficult with G code without stopping the program? do you want to overide existing commands or add new ones manually?
Al.

[steelfixer]

Hi there
I need to be able to use the Z axis manually to focus the telescope without stopping the progam.
The only way I can do it at the moment is to stop the program. The trouble is if I do that the star I am tracking will go out of view and then I have to find it again which ruins the photograph I am taking.
Is there another language I can use that will let me do what I need to do.
thanks

[Al_The_Man]

Do you need the Z under G code control at all?
If not would purely manual operation of the Z be better and do it outside of the program?
Al.

[steelfixer]

that is exactly what I need but how do I do it.

[Al_The_Man]

AFAIK there is no way in Mach, but I was thinking along the lines of a simple manual step/dir indexer hooked directly to the Z stepper drive input, bypassing Mach altogether.
This could be no more than a low res quadrature encoder the output to the step/dir inputs of the drive?
The typical manual handwheel is 100p/rev, but any low res encoder should work?
Al.

[steelfixer]

That sounds good to me if I had any idea what you were talking about.lol
I take it I have to run a different controller for the z axis driver.
I therefore assume I need to remove the green and green /white wires from my breakout board and wire themup to another source.
Is there any way I can send the commands through the printer port cable direct from the computer?.
sorry i am not to clever with this sort of thing.

[Al_The_Man]

If you want to pursue it I could go into more detail it may take a very small amount of minor electronics if you are up to it.
What I had in mind operates outside of Mach and the PC altogether and is purely manual.
Just a small stand alone unit hooked directly up to the drive input.
I do not really use Mach so I am only going by my minimal experience with it, but AFAIK Mach, like most CNC controllers cannot co-process two separate simultaneous move sets.
If it had a double control capability such is is used in a two turret lathe that runs two separate programs, maybe.
Al.

[doorknob]

If it's OK to do the focusing through a separate box of electronics, there are a lot of threads here showing how to build things such as a "rotary table indexer" that might be usable for your application. You would connect the output to a stepper motor driver board. One such example is http://www.cnczone.com/forums/open_s...e_indexer.html

Or there are threads describing various PIC microcontroller or Arduino-based stepper motor controllers that you could use along with a "MPG" (manual pulse generator) or "pendant" that would be a box with a knob that you turn, and the stepper would turn when you turned the knob.

Both of those approaches would require at least some electronics and microcontroller knowledge.

You could probably find similar "off the shelf" solutions, but the cost might not be acceptable.

[Al_The_Man]

I would not think a PIC was necessary, if the right encoder resolution is selected, then it could drive direct.
If I interpret correctly, a number entry is not required?
The nice think about off the shelf MPG's is it has an indent built in.
Al.

[steelfixer]

thank you for help folks I think electronics are out of my scope at the moment I have had another idea that I want to try.
I can download a single axis controller program and run that from my laptop whilst still running the Mach 3 from my desktop.
we will see what happens.

[Al_The_Man]

I had though initially of another PC, but didn't think you may have wanted the extra overhead.
Whatever works.
Al.