Re: [CAD_CAM_EDM_DRO] G-code interpreter/stepper controller

On most CNC machines there are 2 switches on each side of the axis. One is a
limitswitch , the other one is a security switch.
The limitswitch can be handled within software. Once a switch is hit, the
motor decelerates and stops in a normal way (the same as you hit the stop
button).
The security switch disables all drivers and must be " hard wired ".

very good specs. Is the system based on some microcontroller ? Is the
interpreter running on the host computer ?
Is software based on EMC ?

Luc

----- Original Message -----
From: "bschwand" <bschwand@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Tuesday, November 05, 2002 8:30 PM
Subject: [CAD_CAM_EDM_DRO] G-code interpreter/stepper controller


> Hi everybody,
>
> I am in the finishing/debugging stages of a 3 axis stepper controller/
> G-Code interpreter.
>
> The missing part is how to handle endswitches.
>
> My assumption is that hitting an endswitch is a catastrophic failure,
> and it should never happen; therefore I was going to have the
> controller freeze all movements, signal the error (a big red LED) and
> let the operator shutdown the system, manually back off the tools,
> etc. and restart.
>
> I think that trying to have the tool be "smart" and back off the tool
> itself, etc. could possibly lead to damaging the machine and or part
> being machined.
>
> Does this make sense ? What is usually done, or expected in such a
> case ?
>
> Please let me know what you think is the best way to handle
> endswitches, and if you have experience with other systems or
> software, let me know how it is done.
>
> BTW, this system has the following features:
>
> - communicates with the host computer through a serial RS232 port
> (the host could be a palm pilot :-) ), use of hardware (RTS/CTS)
> flow control to ensure dataflow integrity.
> - embedded basic G-Code interpreter that supports linear and
> circular interpolation in all axis
> - extensible to up to 8 axis (through an extension board, to be
> designed)
> - automatically goes to low-current (holding) setting for a given axis
> if that axis has not been active for 100 milliseconds
> - active current control through integrated chipset, thus very little
> wasted power. Running and holding current are configurable through
> separate potentiometer, up to 3 amp per axis (although I have not
> tested this much power lacking the needed power supply...)
> - each axis can be configured as to what the positive or negative
> direction is (to accomodate for different machine configuration)
> - configurable "rapid transverse speed" (G00 code)
> - configuration settings are saved in permanent memory (eeprom) so
> they remain between shutdown/reset.
> - up to 10'000 steps per seconds (is this overkill ? my steppers stall
> after 900 steps/sec...)
>
> Currently supports unipolar steppers, in full-stepping mode. A bipolar
> stepper power board will come next.
>
> All feedback much appreciated, thank you.
>
> bruno
>
>
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