Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 726)

Program Interrupts and
Dressing Interrupts
Chapter 22
22-6
Figure 22.2
Type 2 Program Interrupts
Programmed Path
Path of Interrupt
Interrupt
occurs
Return path
Motions due to
Delayed interrupt
(3 retrace blocks)
Return path
Motions due to
Immediate Action
interrupt
(3 retrace blocks)
Part program
path before
interrupt
M99 M99
Number of retrace blocks for type 2 interrupts
You can alter the number of blocks that the control retraces when returning
to the start-position of type 2 interrupts. The default number of retraced
blocks is 4; however, you can alter that number by programming one of
these M codes:
Programming an: Retraces:
M900 zero blocks
M901 one block
M902 two blocks
M903 three blocks
M904 four blocks
You can program these M codes in any block in the main program before
the control executes the interrupt program. You can also program them
within an interrupt, though the M code does not go into effect until
execution is returned to the main program. If not programmed, the default
is four blocks. The default is automatically reset at the end-of-program
commands (M02 or M30), E-STOP reset, or control reset.
The number of retrace blocks as set with this M code is the same for all
active or inactive interrupts. If an interrupt is enabled after this M code is
programmed, it takes on the number of retrace blocks as programmed with
this M code.