I am using a BX 10 PLC with two axis. The high-speed configuration tool automatically selected Y0 and Y1 when I was configuring the first axis and then it selected Y2 and Y3 for the second axis. Seemed logical and I didn't give it a second look. It took quite a few hours of debugging before I noticed the little "HS" and "Std" labels next to the outputs and found the problem.
Just a little feedback...you might want to modify the tool so it selects Y0 (step) and Y2 (direction) for the first axis. The tool should give you a warning if you select both HS outputs for a single axis since that makes it impossible to use a second axis. Or don't even list the Std outputs as a selectable option for the Step signal.