Well... I'm on a T+ control, that may be the difference. M21 thru M29, are robot commands according to my books. All I'm going by are all the programs left in the machine from the previous owner. They left me all their programs, and their programs in the gantry control box. I've been sifting and studying my way through them. All the programs in the machine pretty much start with a MNP that does an airblast on the chuck, and orients the chuck, then has a M20 (Robot Command 1)... All of them end with the same air blast, orient, and then an M21 (Robot Command 2) to remove the part from head 2 at the end of the program...
I'm setting up my first gantry job probably late next week so I'll be learning a bit here as we go.
I'd like to see if you get this worked out... I have more than a few jobs where I would like to just stuck a bar in there and bar pull... and let the gantry put the part back on the table...
I have a really sharp Mazak applications guy that I've talked to a few times... but he's pretty tied up right now with the IMTS around the corner