ELM327 is the latest PC-based scan tool. It supports all OBD-II protocols and is dispatched with a number of compatible programs. The processor is an ELM327. The output protocol (connection to laptop) is RS232.
Processor: ELM327

OBD-II Protocols:
ISO15765-4 (CAN)
ISO14230-4 (KWP2000)
ISO9141-2
J1850 VPW
J1850 PWM
Output protocol: RS232
Baud rate: 9600 or 38400
Indicator LEDs: OBD Tx/Rx, RS232 Tx/Rx, Power
Operating voltage: 12V, internal protection from short circuits/overvoltages
Nominal idle current: 45 mA

Description:
OBD-II Software for ELM327 is a free program that allows you to use your PC and a hardware interface to get the information from your car's computer.
The program is very user-friendly, and easy to learn. It is also very easy to install:
Simply extract the files into a folder on your computer's hard drive, and you're ready to go. To uninstall the program, simply delete the entire contents of the folder where the program resides.
The software supports two platforms - DOS and Windows.