Rockwell Automation 8520-GUM 9/Series CNC Grinder Operation and Programming Manual Documentation Set - Manual (Page 309)

Introduction to Programming
Chapter 10
10-31
The following describes the basic M codes provided with the control.
(1) Program Stop (M00)
When the control executes M00, program execution is stopped after the
block containing the M00 is executed. At this time, the CRT displays the
“PROG STOP” message. To restart the operation, press the
<CYCLE START> button.
(2) Optional Program Stop (M01)
The optional program stop function has the same effect as the program stop
function, except that it is controlled by an external switch. That is, when
the OPTIONAL PROGRAM STOP switch is placed in the OFF position,
the M01 code in the program is ignored. This switch and the appropriate
PAL programming are the responsibility of your system installer.
ATTENTION: Once axis reciprocation begins, it continues
through program block execution until stopped by a G80, an
end of program (M02, M30, M99), a change to manual mode or
an emergency stop. This means executing an M00 or an M01 in
a part program does not necessarily stop the reciprocating axis.
(3) End of Program (M02)
If you execute a program from control memory, the M02 code acts the
same as an M30. The control stops program execution and enters into the
cycle stop state. The program is reset to the first block and a <CYCLE
START> begins part program execution over again (see M99 for auto
cycle start).
If executing a program from an external device (such as a tape reader),
when the control executes M02, it stops program execution and enters into
the cycle stop state. The M02 does not cause a tape rewind. The tape
reader must be rewound using some other method before program
execution can resume.
With some machines, the M02 code can also result in a spindle and coolant
supply stop. For details, see the instruction manual prepared by your
system installer.