Smithy CNC Mills - Manual (Page 43)

SmithyCNC Programmer’s Reference Manual:O Codes
SmithyCNC Programmer’s Reference Manual: O-Codes 4-2
O-CODE OVERVIEW
O-codes provide for flow control in NC programs. Each block has an associated
number, which is the number used after O. Care must be taken to properly
match the O-numbers.
The behavior is undefined if
* Other words are used on a line with an O- word
4.1 Subroutines: "sub", "endsub", "return", "call"
Subroutines extend from a O- sub to an O- endsub. The lines inside the subrou-
tine (the "body") are not executed in order; instead, they are executed each
time the subroutine is called with O- call.
O100 sub (subroutine to move to machine home)
G0 X0 Y0 Z0
O100 endsub
(many intervening lines)
O100 call
Inside a subroutine, O- return can be executed. This immediately returns to the
calling code, just as though O- endsub was encountered.
O- call takes up to 30 optional arguments, which are passed to the subroutine
as #1, #2, ..., #N. Parameters from #N+1 to #30 have the same value as in
the calling context. On return from the subroutine the previous values parame-
ters #1 through #30 (regardless of the number of arguments) will be restored
to the values they had before the call.
Because "1 2 3" is parsed as the number 123, the parameters must be enclosed
in square brackets. The following calls a subroutine with 3 arguments:
O200 call [1] [2] [3]
Subroutine bodies may not be nested. They may only be called after they are
defined. They may be called from other functions, and may call themselves
recursively if it makes sense to do so. The maximum subroutine nesting
level is 10.
Subroutines do not have "return values", but they may change the value of
parameters above #30 and those changes will be visible to the calling code.