Re: [CAD_CAM_EDM_DRO] Re: parallel port finally obsolete?

Mach3 is a Windows based programme which outputs and inputs
control lines for stepper motors on a bi-directional
parallel port.
Because we wish to control at least two axes to mill or turn
complex curves the g-code interpreter has to time the control
pulses to the stepper motors relative to each other. Mach3
does this timing in the host computer and then pulses the
relevant pins in the parallel interface.
The RepRap solution using an Arduino board is to programme
the micro-controller to interpret g-code instructions and
produce
the control pulses for the stepper motors.
The SmoothStepper also does the timing on its board and
takes serial instructions from Mach3 using a dedicated
plugin. I assume
that it has an interpreter on the board.
Therefore the answer to the question "Is the parallel port
obsolete" is "yes". The parallel port enables the use of
Mach3, but
Windows is a multitasking system with interrupts. Mach 3
has to alter the operating system to stop it multitasking so
that its
timing continues to be accurate. If you have legacy
equipment with Windows XP and parallel ports then Mach3
continues to be usable.
If however you are building new equipment the USB ports
should be used and the interpretation and timing done by a
separate
microcontroller.
It would be a giant step forward if ArtSoft could be
persuaded to programme and sell a microcontroller chip
which could be instructed
by Mach5 through a USB port. Because the programme code on a
microcontroller can be locked so that it cannot be replicated
ArtSoft would have a viable means of selling their software
and avoiding piracy.
Maybe ArtSoft would consider this if there were sufficient
requests.
Stuart Harrison