Quote Originally Posted by dazp1976 View Post
The only real difference between the 2 is the secondary analog output and the way you install a 5th/6th axis. And of course the 300 needs bob's or equivelent.

1. Some servo's use 2 analog inputs for hybrid speed/torque mode. If required, use uc300.
Not exactly correct, I think you maybe don't understand how the Speed/Torque mode switching in servos works.?

You don't need 2 analog 0-10v OUTPUTS from the controller to use this feature on a servo. You just need Digital OUTPUTS which connect to Digital INPUTS on the servo drive to signal the mode change, you still use the same Analog speed reference output from the controller to command the speed or torque.
The Servo Drive just changes tuning parameters etc when it sees the Digital inputs change. The same is true when switching from High to Low-speed range on a servo spindle drive or going from Speed to Position mode for ridged tapping. All done using the same Speed reference input, whether that be digital or Analog, just controlled and switched using digital Inputs.

However, to the OP this isn't really relevant as he's using a stepper-based system and if he was it wouldn't be an issue provided he didn't need more I/O than the AXBB-E offers.
In fact, for the OP the AXBB-E is a better option than the UC300 + UCSB or UCBB combo because it comes with dedicated Analog Output built into the BOB which is protected, the UCSB and UCBB don't offer this so you need some external protection if you want to be safe. It's also upgradable with an additional BOB if more I/O is required.

I fit both the AXBB-E and UC300 to machines and to me for most stepper-based machines that don't run an ATC spindle or require lots of I/O then the AXBB-E wins hands down for its neatness and simplicity in one single board and it's not exactly short of I/O for most machines. The ratio I fit is at least 20:1 in favor of the AXBB-E.