Uggh.
Due to a similar drive question that came up in this thread: Control motor with Arduino via "isolated 0-5 V DC signal" - Project Guidance - Arduino Forum
I re-read the Minarik drive manual (this time on my pc, not an ipad) and see they do specifically call for an analog input that is isolated from ground. I apologize that I did not see this for what it really was - trouble for an Arduino.
The digital pot can withstand +/-18 volts to the same common as the pot's digital common but the real problem is the Arduino. If the drive's common terminal (RB1) isn't grounded, and it's clear from the manual it's not, there is really no way to know what potential exists between earth ground and the drive common.
The problem will really appear when you plug a USB cable into the Arduino, especially on a desktop because the metal shell and the DC (-) of the USB connector is usually tied directly to case and then to earth through the standard three wire plug. It's not as big an issue with a laptop since they usually have two wire cord sets but there's no guarantee of that. Depending upon what voltage (and its source) are present on the drives' common terminal, that voltage will be taken to ground through the USB cable or worse, through your body if you come into contact with it.
Since we don't know what voltage may be lurking on the common of the drive, I think it would be far safer to use an opto-isolated pwm to analog convertor. The other thread had a reference to this design:
Which is an okay circuit, I've tested it and works fine with the exception that it inverts the signal. That's easy to fix when you call the analogWrite routine with the map function. All that would be needed for your application would be few easy tweaks to make it 0 to 10 rather than 0 to 5 volts out per this changed version.
