ELM323

Since the 1996 model year, North American automobiles have been required to provide an OBD (On Board Diagnostics) data port for the connection of test equipment. This port is used to obtain emissions-related diagnostics information, and in some cases can also be used to obtain real-time vehicle operating parameters.

The ELM323 is a 14 pin integrated circuit that, with only a few external components, is able to convert between the OBD data format and the standard RS232 serial data format. This allows virtually any personal computer or PDA to communicate with a vehicle using only a standard serial port and a terminal program. If desired, hobbyists can even create their own custom 'scan tool' by adding an interface program.

Please note that while this integrated circuit has undergone significant changes recently, it is still considered to be an experimenter's circuit. It does support a great many of the ISO9141 and ISO14230 (KWP2000) protocol vehicles, but not all of them, due to the many interpretations of these standards that are to be found in use.