The process of synchronizing matching circuits of a communication system having modules connected with each other by serial data lines includes providing a transmitter and a receiver in each module as an interface between the serial data lines and a matching circuit; synchronizing at least one other matching circuit with a synchronizing matching circuit and transmitting the required synchronizing signals over the serial data lines; supplying parallel signals from the synchronizing matching circuit to the transmitter connected thereto and converting those parallel signals into serial signals in that transmitter; feeding the serial signals over the serial data lines to the receivers connected with the at least one other matching circuit, converting the serial signals into other parallel signals in those receivers and supplying the other parallel signals to the at least one other matching circuit connected with the receivers; generating an error signal in each receiver on detection of a transmission error; and resetting the at least one other matching circuit connected to each receiver producing the error signal when at least two error signals are generated within a predetermined time interval.