I'm trying to get a Fanuc AC servo running using EMC2, the bldc component for EMC2, and an AMC brushless servo drive. The basic idea is that EMC2 takes the C1,C2,C4 and C8 commutation signals from the Fanuc encoder and outputs hall signals to the AMC drive. It can also take incremental encoder signals (but that's still down the road). The AMC drive takes +/-10V analog input, so I've built a pwm to analog circuit so EMC2 can give the drive an input signal. This sort of works and I've made a motor spin. However I currently only have it spinning in one direction whether I give it a positive or negative analog input voltage. So that is my question: Do I need to feed a positive voltage into the + input on the AMC drive for rotation in one direction and a negative voltage into the - input on the AMC drive for rotation in the other direction?
I ask because I can make the motor rotate the other way by putting a positive voltage into the - input on the drive, but that doesn't make sense to me... Simulating the input circuit in the AMC drive, I'd think I'd need positive and negative signals on their respective inputs to get reversing motor rotation.