Mot sure about the Bob, but The measured voltage was 3.3V, which is on the border line of working for the optos.
I have found that most support calls that end with the signal voltages being too low were on laptops.


Quote Originally Posted by irving2008 View Post
What breakout board is he using? The MDS drivers are optisolated so dont really need a sophisticated BOB and are pretty immune to cross-over noise on the signal lines due to the low impedance 'on' drive. Unless he has a very long cable from PC to BOB or the BOB is a old design with TTL rather than CMOS logic I'd be suprised that the use of a laptop was an issue.