Abstract: An interface adapter for use in combination with a commercial installation having a central refrigeration system with multiple compressors and refrigerated units and also having environmental apparatus for regulating the heating, ventilating and air conditioning of such installation. The refrigeration system has a local control apparatus for operating the system in response to local status signals and has remote control input ports for remote control of the system. A remote electronic controller adapted to receive the local status signals and to override at least part of said local control means operates the refrigeration system by generating an electrical control signal and a switchback signal indicating that the electrical control signal should be recognized. The interface adapter electronically isolates and interfaces the refrigeration system and the remote controller.