I had a number of controllers that would not connect using the Curtis 1314-4401 Software. Some were used so I figured they were bad, I had them rebuilt by FSIP and they still would not connect. I had other controllers that would connect without problems using straight serial, or a USB to serial adapter from Staples. I breadboarded this adapter and every controller worked flawlessly from that point on using either straight serial or the USB to serial adapter above. This adapter also works with Excel Controllers which use Enhanced Serial Protocol.