Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 734)

Program Interrupts and
Dressing Interrupts
Chapter 22
22-14
Your system installer can determine if an interrupt program is to be
called as a paramacro or a subprogram when executed. If you call it as
a paramacro, remember that this assigns a new set of local parameters
for the interrupt. If you call it as a subprogram, the same set of local
parameters that apply to the interrupted program applies to the
subprogram.
If you choose an interrupt as a macro program, it cannot be a macro that
requires the assignment of local variables in the calling block. It cannot
require an argument.
Always call macro type interrupts as the G65 non-modal type. G66 and
G66.1 modal types cannot be called. See page 20-50 for details on G65
type macros.
The interrupt program must contain an M99 block. Any axis motion
commands that are to the left of the M99 code in the block results in an
error. The control executes other programming commands to the left of
the M99 code in the block. The control ignores any characters to the
right of the M99 code or any blocks following the M99 code.
An M02 or M30 end of program command can also be used at the end
of the interrupt program. If an end of program command is executed in
an interrupt program, the control will assume it has completed program
execution of both the interrupt and the main program. Any remaining
blocks in the interrupt or main calling program are not executed. If
executing a program from memory the main program is reset to the first
block.
The interrupt program cannot contain any grinding cycles (G8n.n).
However, turning cycles (G20 and G24) and threading operations (G33
and G34) are permitted in an interrupt program.
Coordinate system offsets are illegal in an interrupt program. This
includes G52, G92, G92.1, and G92.2.
Any inherent modality from the main program, such as an active modal
paramacro, turning routine, or grinding cycle, is temporarily canceled
during the execution of an interrupt.
Only one interrupt can be executed at a time. All can be active at once,
but only one can be executed. This means that an interrupt cannot be
executed during the execution of another interrupt, nor can a dressing
interrupt be executed during a program interrupt.