K+CAN Commander 1.4 also known as VAG-K+CAN is simple, reliable and very inexpensive diagnostic adapter.

It can be used to diagnose a wide variety of vehicles via K-line and CAN-bus. K+CAN Commander 1.4 uses L9637 or L339 chip as the bus driver for K-line interface and uses USB as the power supply, allowing this adapter to be used on trucks and commercial vehicles with 24 volt electrical systems. This adapter has been successfully tested on Hino, Tata and Hyundai trucks.

K+CAN Commander 1.4 is based on FT232 chip and in K-line mode allows the diagnostic program to communicate directly with the Control Unit using any initialization sequence and communication speed required by the protocol. It uses a PIC18F2580 or PIC18F25K80 microcontroller for CAN bus communication. It does not have a K-line multiplexer, but K+CAN Commander 1.4 can be easily modified for custom use, as shown in this example.

Due to the lack of a K-line multiplexer, you may need a K-line switch or an OBD2 breakout box.

DAP4CS also supports adapters for OEM protocols based on FT232 chip, such as Nissan Consult 14 pin USB.

ELM327 probably is the most widely used diagnostic adapter in the world due to its low cost, but it has some limitations.

It supports CAN, K-line, J1850 PWM/VPW modes, but ELM327 has some limitations, so it cannot be used for some special purpose procedures, such as ECU variant coding or injector coding if they are performed in K-line mode. For diagnostics of modern cars, where the CAN network has a Central Gateway, this adapter is also not entirely suitable.

It also does not have a K-line multiplexer. Read about the limitations of ELM327 before you use it.

Adapters based on STN chips STN11xx/21xx (OBDLink, ELS27) are devoid of ELM327's drawbacks, but also do not have a K-line multiplexer.

They allow to send data packets up to several kilobytes in size, have flexible timings control, adjustable K-line speed settings in a wide range from 4 baud to several megabauds, and have a lower response delays. Most STN adapters additionally support MS_CAN bus (for Ford / Mazda / Land Rover / Volvo diagnostics) and SW_CAN bus (for GM / Opel / Chevrolet diagnostics). With DAP4CS, STN adapters can be used not only for diagnostics using standard ISO/SAE protocols, but also for diagnostics using some OEM protocols, for example, KWP 1281, Honda HDS, MMC SCI.

vLinker adapters are based on MIC331x/MIC3322 controllers. They do not have all the capabilities of STN adapters.

There are many diagnostic adapters that support J2534 API, such as SM2-PRO, CHIPSOFT Pro, Tactrix OpenPort 2.0, etc.

J2534 describes a Windows API for communication between ECU and PC. J2534 adapters from different manufacturers have different hardware capabilities.

Some advanced models have a full featured K-line multiplexer, support multiple CAN bus, Single Wire CAN bus (SW CAN), support 5V protocols, Tx/Rx protocols such as Chrysler SCI, and support 24V on-board systems.

SM2-PRO is one of the most advanced adapters that supports all of the above. 👍

See information about J2534 adapters that have been tested with DAP4CS.