Quite common .... I use "Keyspan USB Twin Serial Adapter"
www.keyspan.com


In article . com,
larry wrote:

For the last four years and three computers, I've had two serial
periphals to interface with ship's laptop. A GPS and a PTC IIe Pactor
modem. The first two of the laptops had a DB-9 input and I used a
belkin serial to USB adaptor. XP seems to have a habit of not
recognizing a device and requires the driver to be re-installed. At
times I have had a "memory mini dump" - "blue screen" crash as a result
of a failure of interface with the GPS and nav pgm. I thought it to be
the OS and installed 2000 on my last laptop and it was no more stable
in terms of crashing than XP. I am considering getting a USB port
replicator as I tried to run two different serial to USB converted
devices at once and had major crash and config problems. Any advice on
units and ARE THER ANY units with 2 DB-9 serial plug-ports? TIA, Larry