The invention is an improved protocol adapter for in-vehicle networks for diagnostics, analysis and monitoring. The invention has a pass through feature (voltage translator)/smart mode that allows the protocol adapter to emulate older boxes. Visual indicators (LEDs) indicate the pass through feature is in operation. LEDs also indicate activity on the on the RS232 bus between the adapter and a PC. Single color and multiple color emitting LEDs indicate a program is being executed and identify the program that is being executed. The protocol adapter supports RP1202 and RP1210, J1708 and J1939 and J1939 Transport Layer. The improved protocol adapter has a Real Time Clock, Standard COMM port connection, 7 32 Volt Supply and is CE compliant. The adapter can be used wirelessly.