Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 307)

Introduction to Programming
Chapter 10
10-33
The following is a description of some of the basic M--codes provided with
the control.
(Program Stop (M00)
When M00 is executed, program execution is stopped after the block
containing the M00 is completed. At this time, the CRT displays the
“PROG STOP” message. To restart the operation, press the
{CYCLE START} button.
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 the system installer.
End of Program (M02)
If executing a program from control memory the M02 code acts the same
as an M30, program execution is stopped and the control enters the cycle
stop state. The program is reset to the first block and a <CYCLE START>
will begin 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 M02 is executed, program execution is stopped and the control enters
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 may also result in a spindle and
coolant supply stop. For details, refer to the instruction manual prepared
by the system installer.
Tool Change (M06)
An M06 typically is used to request a tool changer to perform some tool
changing operation. Motion commands can not be programmed in an M06
block. Offset activation and tool change operation are dependent on your
system installers PAL program and AMP configuration. More details on
the tool change operation (M06) can be found on page 20-2.