USB to serial convertors are a little picky. For home use I use an Edgeport USB to 8 serial port (search for it on eBay for great deals) that has worked with everything I have thrown at it. The single port ones I have tried 1/2 work 1/2 don't work with specific hardware. I think there is a specific chip that seems to work best, just can't remember which one it is off the top.