Abstract: A event-driven portable data bus message logger includes an event message receiver for receiving an event message including an event field, an event message storage operably connected to the event message receiver for storing the event message, a data bus message receiver for receiving data bus messages including a data field and a data checksum, a comparator for comparing a current data field of a current data bus message to the event field; and a trigger operably connected to the comparator for storing the current data bus message, a preceding data bus message, and a subsequent data bus message in a snapshot storage if the current data field is substantially similar to the event field.