The IEC 62386 series specifies a bus system for control by digital signals of electronic lighting equipment. Typically, a bus unit according IEC 62386 contains firmware. There are circumstances where it might be necessary to change the firmware after production or shipping of the product. For example if the bus unit does not operate as intended. In such a case, a firmware update of a bus unit via the interface is beneficial. This firmware update process is primarily designed to be a bug fix process not a feature extension process. NOTE 1: Nevertheless the firmware update process may be used for feature extensions. But the risk of negative effects to the complete system should be considered in detail. NOTE 2: Annex B provides a Firmware Update Management Check Sheet to support risk estimation.