The plug part (10) is connectable to a mating part (1), which is used as a connector of a device (50), to form a plug-in connection. The plug part (10) includes at least one non-volatile memory (13), a communication unit (15) and a microprocessor (14). A network having such plug parts (10) can be tested by means of a testing device, which is designed to generate test signals from information stored in the memory (13), which test signals can be laid on the cable wired leading out of the plug part (10) in order to generate measurement signals. The memory (13) preferably contains a list of permissible combinations of hardware and software versions, which can be compared with the current hardware and software combination of the device (50) in order to configure the device (50) and/or authorize the device (50) for normal operation.