Chuck,
For rotary feedback, the RMC supports quadrature (A+,A-,B+,B-,Z+,Z-), SSI, or resolver. The RMC does not support rotary analog feedback.
For absolute rotary feedback, we recommend using an SSI encoder. For incremental feedback, we recommend quadrature encoder feedback.
For rugged transducers and small form factors, resolvers work as well, although the Resolver module on the RMC150 is more expensive than the other modules, and there are some velocity limitations with resolvers (3000 rpm for 14-bit resolution, 600 rpm for 16 bit resolution).