Smithy CNC Mills - Manual (Page 76)

SmithyCNC Programmer’s Reference Manual: Coordinate System 8-5
g0 z0
g54 x0 y0 z0
m2
"But," you say, "why is there a G54 in there near the end." Many programmers
leave the G54 coordinate system with all zero values so that there is a modal
code for the absolute machine based axis positions. This program assumes that
we have done that and use the ending command as a command to machine
zero. It would have been possible to use g53 and arrive at the same place but
that command would not have been modal and any commands issued after it
would have returned to using the G55 offsets because that coordinate system
would still be in effect.
G54 use preset work coordinate system 1
G55 use preset work coordinate system 2
G56 use preset work coordinate system 3
G57 use preset work coordinate system 4
G58 use preset work coordinate system 5
G59 use preset work coordinate system 6
G59.1 use preset work coordinate system 7
G59.2 use preset work coordinate system 8
G59.3 use preset work coordinate system 9
8.3.1 Default coordinate system
One other variable in the VAR file becomes important when we think about off-
set systems. This variable is named 5220. In the default files its value is set to
1.00000. This means that when the EMC starts up it should use the first coordi-
nate system as its default. If you set this to 9.00000 it would use the nineth
offset system as its default for startup and reset. Any value other than an
interger (decimal really) between 1 and 9 will cause the EMC to fault on startup.