Rockwell Automation 1746-HSCE2 Multi-Channel High Speed Counter Module - Manual (Page 124)

Publication 1746-UM002B-EN-P - August 2004
B-2 Connecting a Differential Encoder
4. Look at the A input signal and its complement A signal.
Whichever signal is low for at least part of the marker interval
should be wired to the A(+) terminal. If both signals meet this
condition, then either signal may be wired to the A(+) terminal.
Wire the remaining signal to the A(-) terminal.
5. Since the encoder may be mounted on either end of a motor
shaft, the encoder may spin clockwise or counter-clockwise for
a given shaft direction. As a result, the direction (phasing) of the
encoder may be backwards. If this is the case, exchange the
A(+) wire with the A(-) wire.