If you have Windows XP, right click on My Computer and select Properties. The click the Hardware tab and click on Device Manager. Open up the Ports item by clicking the plus sign in front of it. You may see Communications Port and Printer Port, look for one that says USB Serial Port. In parenthesis after it will be COMx, that's the COM port number you'll need for JMRI.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
If you haven't already you need to go into preferences and let JMRI know what you are using as a command station as well what comm port you are using. The comm port might take a couple of tries when using USB to get the right one.
I have down loaded the most current version of JMR, have connected Digitrak Zephyr and computer using LocoBuffer-USB. How do you set up a rooster and program the decoders? I tried it and the computer doesn't seem to read the decorder in the locomotive.