An appliance system is provided having a plurality of appliances. A master controller includes the user-operable appliance controls as well as associated logic controls for controlling the operating components of the appliances. An interface control is physically associated with each controlled appliance and receives control signals for the various operating components from the master controller by way of power line transmission. The master controller effects a repeating sequence of transmitting and receiving control signals in the form of first and second data packages while the interface control effects a repeating sequence of receiving first data packages and transmitting second data packages. The interface control and the master controller will each interrupt operation of the appliances responsive to the absence of either first or second data packages.