The right KKL-Interface: USB or RS232 ?

[alexander]

We recommend using a USB KKL-interface based on the USB-serial converter chip from FTDI with CarPort car diagnostics software. Most of the available USB KKL-interfaces use this kind of converter chip (if in doubt, ask the dealer).

 

The FTDI-chip allows a more stable connection to ECUs that communicate at custom baudrates. Additionally the latencies are lower with the FTDI-chip. Even though, when using a RS232 KKL-interface, the converted signal is immediately available at the RS232 connector, the time it takes till this information is available in windows is typically around 5ms. When using the FTDI-chip the time is around 2ms. Although this difference might seem small, it can have some impact to the very timing sensitive KWP1281 protocol.