Many generic USB<->Serial converters are unable to handle the baud rate and timing requirements that are demanded by some control modules using the VAG protocols. If you wish to use a USB<->Serial converter, we recommend that you get one with an FT232B or FT232R chipset. It is essential to configure the virtual COM port that it creates to be in the range of COM1 to COM4, and to set the Latency timer to 2. See this screen-shot as a guide to configuring these devices. Please understand, this is a recommendation only; if you purchase your own USB<->Serial converter, please do not expect us to support it.
For registered users with HEX-COM or HEX-COM+CAN interfaces, we can supply a modified FT232B based USB<->Serial converter, which is compatible with the "Direct" drivers provided with VCDS version 10.6 and newer, and is fully supported by us. Once "married" to your interface, these converters provide the exact same functionality as our HEX-USB or HEX-USB+CAN interfaces. However, this "marriage" requires a revised license to be loaded in the interface, so the initial installation is not just plug-an-play. This makes us reluctant to put them in our web-store. If you are registered user with a HEX-COM or HEX-COM+CAN interface and no longer have a PC with a serial port, please contact our Sales Department.