I am having trouble getting serial port to work even with rxtx installed or another one I found which is SerialPort that was dated 2006. Still, neither works so I was wondering if I might be able to use the one in my Arduino IDE as it uses RXTX and it works. I was wondering if anyone might know how to do this and if someone might have a sample program to write to the serial port. I tried the examples on the RXTX site, but they did not work. All I need to do is send a command to device (UBW from SparkFun) which then turns on an LED. In C# this is simple, but I am having a lot of trouble in Java doing this same thing. I am new to Java, but the code structure is similar. I would not have thought it would be this difficult doing the same thing I did in C#.