Patent ID: 7359812

Claim:
An automation device, with which a multiplicity of physically distributed functional units communicate with each other by means of a common transmission protocol, the automation device comprising: a microcontroller, which is assigned at least one clock generator and one memory unit, and which is connected at least to one data source, which is designed to output a received data bit-stream, and to which is input an FSK-modulated line signal in which a first frequency represents a first bit value and a second frequency represents a second value, a cascade circuit connected between a communications line ( 200 ) and the microcontroller, said cascade circuit comprising means ( 182 ) for detecting the zero crossover of the line signal ( 201 ), means ( 183 ) for determining the time between two consecutive zero crossovers of the line signal ( 201 ), means ( 184 ) for evaluating the determined time between two consecutive zero crossovers of the line signal ( 201 ) by comparing the determined time to a measurement time, the measurement time being derived from a half-period of the first frequency and a half-period of the second frequency, and means ( 185 ) for outputting the first bit value if the determined time is within the measurement time and outputting the second bit value if the determined time is not within the measurement time.