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

Introduction to Programming
Chapter 10
10-29
The miscellaneous function is designated with an address M followed by a
two or three-digit numeric value. Because many of these are set by
industry standards, they are usually referred to as M codes.
When a miscellaneous function is designated in a block containing axis
motion commands, the control’s PAL program determines if the M codes
are executed:
at the same time as the axis motion
before the axis motion
after the axis motion is completed
You can also alter this order of execution by using the paramacro feature,
system parameter #3003 (see page 20-19).
Your system installer determines in AMP if M and G codes get reset every
time the control executes an M02 or M30 end of program command. If the
control does reset M and G codes, modal M and G codes revert back to
their power-up condition and non-modal M and G codes are reset to their
default values. If the control does not reset M and G codes, all modal and
non-modal M and G codes remain at their present value.
Table 10.F shows the basic M codes for the control. A part program block
can contain as many basic M codes as you want. If more than one M code
from any group is programmed in the same block, the right-most M code
in that block for that group is the active M code for the block.
Your system installer may have defined additional M codes in PAL. As
many as 4 M-codes can be activated in any one block. If you program
more than 4 in any one block, the right-most 4 in that block are activated.
The control ignores other M-codes in the block. See documentation
provided by your system installer for details on non-basic M codes and
their operation.
10.5.6
M Words
(Miscellaneous Functions)