1756-RM2 is a ControlLogix redundant controller module manufactured Allen-Bradley. It is part of the Allen-Bradley ControlLogix family of programmable logic controllers (PLCs). The 6-RM2 module is used in applications that require high availability and fault tolerance. It provides redundant control processing and communication interfaces to ensure uninterrupted operation in critical systems. The module can be used as the primary and backup controller, and it supports synchronization between redundant controllers for seamless switchover in case of a failure.