Abstract: The subject of this invention is a method for testing the data and control interface of individual machines intended for interconnection in an inline system for solar cell production. Furthermore, an Interface-Tester suitable for executing the testing method is disclosed. The method for testing comprises the steps of feeding a dummy workpiece to the tested machine and connecting the interface tester to the standard interface of the machine. Consecutively the interface tester sends controlling signals to the machine and receives the signals from the tested machine. The received signals are compared to reference signals and evaluated. The interface tester comprises a standard interface for coupling the machines in an inline system for solar cell production. Furthermore, the interface tester is equipped with at least one CPU, a volatile and/or non-volatile memory, communication modules, couplers and connectors and at least one human-machine interface.