Mitsubishi OSA104S2 Absolute Servo Motor Rotary Encoder

The Mitsubishi OSA104S2 is an absolute rotary encoder used as the motor-side feedback detector on select Mitsubishi HC and HC-R AC servo motors. Mitsubishi identifies it as detector code A42, with absolute-position detection and 100,000 pulses per revolution. Its feedback supports accurate closed-loop positioning and speed control in CNC and industrial motion systems.

OSA104S2 Product Details

Absolute Position Feedback Function

Installed at the servo motor, the OSA104S2 detects shaft position and sends feedback to the Mitsubishi servo control system. Absolute feedback helps retain machine-position information when the complete absolute-position circuit, battery and parameters are correctly configured. It is used in CNC feed axes and precision automated machinery where stable position feedback is essential.

Motor Compatibility and Replacement Matching

Match the complete code OSA104S2 before replacement. Mitsubishi documentation associates it with selected HC and HC-R motors carrying detector code A42. Confirm the motor nameplate, encoder label, connector, mounting pattern, shaft coupling and cable pinout. OSA104S2 is not automatically interchangeable with OSE104S2, which is incremental, or OSA105S2, which has a different resolution. OSA104S used on some HA-N motors is also a different full model code.

Testing, Installation and Protective Packing

Each available unit is inspected for label identity, housing condition, connector integrity, mounting surfaces and feedback performance on a compatible setup where applicable. Installation requires correct mechanical orientation and motor alignment; incorrect mounting can cause position deviation or servo alarms. Absolute-position data may require initialization or machine reference recovery under the machine builder's procedure.

REACO CNC Supply and Support

REACO CNC supplies tested Mitsubishi CNC and servo encoders for maintenance and replacement projects. Technical matching and Mitsubishi CNC parts repair support are available for legacy machine-tool systems.