Abstract: A digital computer control system is provided for operating a steam turbine in an electric power plant. The computer develops steam valve position signals to control turbine speed and load. Various turbine temperature, pressure and other process parameter signals are coupled to the computer which stores the parameter values along with other parameters such as control loop setpoints in its memory. Another computer at the plant level or at the system dispatch level is coupled to the turbine computer through a data link which includes data link programs in each computer and data transmitter and receiver circuitry connected to the two computers. The higher level computer is the controlling computer on the data link. Control words are used to identify data transmission modes and validity checks are made on transmitted words. Turbine computer core data is accessible and transmittable to either higher level computer.