If these are quadrature encoders they should have A & B if differential then they would have A, /A & B, /B the / indicate the complements.
If using an external supply for the encoder then you only need the common and the A & B, no need to connect the +v.
I misunderstood your question, if you wish to set up a receiver for differential there are a few IC's if you Google RS422.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.