Hello JTH,
You can use the same +5V power supply you are using for the UMI to power the optoisolators. The negative terminal of this power supply is referenced to the controller digital ground. The STEP/DIR lines (PULSE/DIR in the SS2000D6 manual) are open collector like the middle diagram in Figure 4.2. They will sink up to 64ma which is plenty for the drive. AWO should be connected to the INHOUTx line and you will need to set the INHOUT polarity switch on the UMI to the correct setting. RDCE/BOOST could be connected to unused Breakpoint lines (optional), which can be used as general purpose digital output, if you want this functionality.
Regards,
Brent R.
Applcations Engineer
National Instruments