Abstract: In an industrial process control system, in which a plurality of remote stations interconnected by a communications link each control and manage a plurality of input/output devices, each remote station comprises a primary data processor and a back-up data processor. The primary data processor normally exercises control over and manages the input/output devices, but, should the primary data processor fail, the back-up processor takes over management and control of the input/output devices. Periodically, the primary data processor transfers status data relating to its operation in the control of the input/output devices to the back-up data processor via a dual ported memory connected between the two processors. The back-up processor maintains a record of the status data and updates its record of the status data with the periodically transferred copy of the status data.