Black box data reader for devices without communication interface

A data reader for a microcontroller based electronic device 1, such as an emergency light driver, which has no externally accessible data interface, includes an interface device 3 for communicating with the electronic device via a first interface 8. The interface device includes a transmitting means 12 configured to transmit a request signal to the electronic device and a receiving means 11 configured to receive a data signal. The transmitting means may transmit the request signal to a test switch connection 6.1, 6.2 of the electronic device and the receiving means receives the data signal transmitted via a status indicator light connection 7.1, 7.2 of the electronic device. The data signal may comprise event log data relating to operation of the electronic device. The interface device may be connected to a computer 2 to download and store the obtained log data.