EMC vs. Galil Motion card (was: Will emc work for me?)

["Markus Meyer" <meyer-at-mesw.de>]

> I have a 3-axis CNC router with a PC-based control using a 
> Galil DMC-1000 card. 
> [...]

[ This is turning into a FAQ...:-( ]

We also have evaluated the Galil card so I may be able to make some
notes (I'm not an expert with these cards, just trying to remember).

Let me explain that EMC has three main layers (simplified view):

(1) The low-level components for motion control. This is called EMCMOT
and takes motion commands (f.e. "straight line to 1000,2000) and
translates it into the appropriate voltage/pulses for servos or
steppers. 

(2) A GCODE-Interpreter and program executer (EMCTASK).

(3) Several frontends that can be used interchangeably (TKEMC, XEMC,
YEMC). These will present a menu interface, allow the user to jog the
axisses graphically etc.

If you have servos, you need a card like the ServoToGo to communicate
with the servos. But this card doesn't have its own intelligence. It
only consists of some analog out and some digital in. So all the PID
controller stuff and trajectory planning is actually done from EMC, not
within the card.

So what's the matter with the Galil cards? The Galil cards (as other
motion controllers do) already have (1) built in, and partially (2)
also, although they don't take G-Code but some other, very simple,
motion control language. So the Galil card follows a very different
concept, because all critical calculation takes place on the board
rather than on the main CPU of the computer, as it does with EMC.

AISE it would be far easier to write a frontend for the Galil card that
shows some nice buttons and additionally write some script that
translates GCode into the native Galil card language than hacking EMC to
support the card, effectively throwing away (1) and (2). This only said
as a warning, your patches are of course always welcome.

HTH


Markus