What type of RS232 converter can I use ?

There are different manufacturers that have a USB to RS232 converter. We have different clients already working with the Keyspan USA-28XG from TrippLite.

http://www.tripplite.com/en/products/model.cfm?txtSeriesID=849&txtModelID=3915

Be aware that most devices require drivers to be installed. Once correctly installed, it will show up in the list of available Serial Port (for example, the Keyspan will show up as USA28X)