Rockwell Automation 8520-MUM 9/Series CNC Mill Operation and Programming Manual Documentation Set - Manual (Page 775)

Chapter 30
Using a 9/Series Dual--processing System
30-7
On some machines or systems, it is often necessary to synchronize the
operations of 9/Series dual processes. For example, if one process is
drilling holes while the second process is tapping the holes, it is extremely
important that the drilling process completes before the second process
attempts tapping of the hole.
Figure 30.1
Example of When Process Synchronization is Necessary
+X
+Y
First process must complete drilling before second process
can begin tapping.
Process 1
Drilling
Process 2
Tapping
Part program synchronization is accomplished between processes through
the use of special M-codes. These M-codes are in group 13, and they are
non-modal. The M-codes reserved for synchronization are M100 - M199.
When you execute a synchronization M-code in one process, that process
halts until a block containing the same synchronization M-code is executed
in the second process. In the case of the tapping example in Figure 30.1,
placing one of these M-codes before the tapping block and after the
drilling block causes the tapping block to pause (not execute) until the
drilling block has completed.
These synchronization M-codes cannot be programmed in a block with
other commands. The only other types of information you can program in
a synchronization block are:
N-codes (block number)
O-words (program name)
Program comments (text enclosed by parentheses () )
Synchronization M-codes are not allowed in the last block of the part
program. This can cause the part program to pause indefinitely, waiting
for the next part program block (which does not exist) to become ready.
30.3
Synchronizing Multiple Part
Programs