Add another USB to Mega R3

I would like to add another serial USB port to my Mega R3 board, so I can talk to the PC via 2 x USB ports (or more!) simultaneously.

My searching / the reference leads me to the fact that I need a USB to Serial adaptor.

Having googled for such devices, I have turned up cables and what not, but am not sure where to start. A shield would be nice, but I am happy to cobble something together if someone could point to a web page or schematic or...

Is this something unusual I want to do? I have not managed to find a single example of someone doing this to take advantage of the Mega's 4 serial ports.

mikroe-483 at
I think this is the lowest priced FTDI based USB/Serial module going - $8.75, dowm from $10.95 (which was also the lowest).
Connect Tx to Rx1, Rx to Tx1, Gnd to Gnd. Device is powered from PC. Your mega is powered from whatever.
Lots of other USB/Serial adapters out, any will do the same.
I build these into designs to skip the hassle of soldering that little part:
Space on lower right is for one of these, if offboard adapter is not used:

This board also uses one:

Brilliant, thank you.

I could solder in a header and plug it into the Mega's header directly for Rx/Tx, but access to ground from that position is going to be tricky - do you have any advice there?