A-B Rockwell Automation 847H-DN2D-AE00500. Incremental Encoder, 2.5" Diameter, Solid Shaft, Standard Square Flange, 3/8 Diameter Shaft with Flat, 8 30 V DC, 8 30V Open Collector, Axial Exit, MS 7 Pin w/ Mating Connector, B leads A, CW, Z gated with BN, 500 PPR