It has since been replaced by the DLP-2232M-G module. Unfortunately FTDI no longer supply this product. After reading the documentation, it appeared that the DLP-2232M was ideal for my application, so I ordered one from Mouser (part #626-DLP2232M). Their DLP-2232M evaluation kit is an integrated module featuring their FT2232C Dual USB UART/FIFO.

FTDI make USB > Serial interface chips and supply Virtual Comm Port (VCP) device drivers for Microsoft and Linux Operating Systems. Whilst surfing the web, I found FTDI's website. To my way of thinking, it doesn't seem too elegant to convert from USB to RS232 then to Icom's logic bus, so I wanted a more direct solution. Now that modern PC's have either one or no Serial ports, one has to either use a collection of USB > Serial converters or find another solution to interface to the Icom CI-V bus. G3VGR's USB CI-V and Winkey Interface G3VGR