Are you wanting the heads to run synchronously? Is there a way to assign G54 to the X and G55 to the U? I did some programming for a Fagor control with X and U for the tables. I did not run both tables at the same time though. There was an M-code that automatically read X's and applied them to the U axis. Oh, and there also was an M-code to link the tables together to operate as one.