In previous Haas pallet-changing machines, the G188 code was used to call a part program from the Pallet Schedule Table (PST), based on which pallet was loaded. Continuous operation was achieved by running a main program that consisted of an M50 to perform a pallet change, the G188 to call the program for the loaded pallet, and an M99 to loop the whole process. The M50 loaded the next scheduled pallet, and the G188 called the program designated for that pallet.
With the G188, however, if you restarted your machining process in the middle of one of the pallet programs, it didn’t allow you to get back to the main program to continue uninterrupted machining. You had to wait for your restarted program to finish, select your main program again, and then start your continuous cycle.
We developed a new M-code to solve this problem. The M199 is used at the end of a program. When the program is started by pressing [CYCLE START] in Memory mode, the M199 acts exactly like an M30 (Program End and Reset). But if the program is started by pressing [INSERT] while the Pallet Schedule Table is displayed, the M199 will command a pallet change to load the next scheduled pallet, and then run the program associated with that pallet. This allows the user to start machining on any pallet, and continue uninterrupted machining, as long as pallets are scheduled.