What Is This Multi-Protocol Interface? The Controller Area Network (CAN) has become the standard of choice for most automotive manufacturers. Approved for use as an ISO and EPA diagnostic network, its usage continues to grow. Shown in Figure 1, this interface is designed to act as a bridge between those On-Board Diagnostics (OBD) ports and standard RS232 PC ports. It uses ELM327 IC chip which builds on improved versions of the proven ELM320, ELM 322, and ELM 323 OBD interfaces by adding four CAN protocols to them. The IC chip can automatically sense and convert the nine most common protocols in use today, which makes such an interface capable of working with almost all vehicles. Here are some key characteristics and improvements offered by this interface and ELM327 chip: ?An interface set of a direct plug-in device and a serial cable configuration for convenience. ?When plugged in the direct uses, it requires PC with 9-pin serial port. ?In serial port connectivity, it is able to be converted for USB connection if needed. ?Slim design on the OBD-II plug-in end allows the maximum vehicle fit-ability by the interface. ?Supports J1850 VPW and PWM, ISO 9141-2, ISO 14230-4 as well as ISO 15765-4 (CAN-bus). ?Supports J1939 (CAN-bus) through software switch setting. ?Auto protocol search. ?Uses the same simple ASCII command interface. ?RS232 pins? polarities are compatible with standard COM interface IC. ?Internal EEPROM can remember the last protocol. ?Voltage input monitors your vehicle battery. ?Low power CMOS design. What Exactly Can You Do with This Multi-Protocol Interface and the Software? With v1.10, this interface can work with all vehicles regardless of their makes as long as they are newer than model year 1996 in the US. As a typical example, it lets you perform the following operati Read diagnostic trouble codes, both generic and manufacturer-specific, and display their meaning (over 3000 generic code definitions in the database). Clear trouble codes and turn off the MIL ("Check Engine" light) Display current sensor data, including: o Engine RPM o Calculated Load Value o Coolant Temperature o Fuel System Status o Vehicle Speed o Short Term Fuel Tri