de.rkjava.serial.j3964r-package:
For direct data exchange in form of a byte array via serial interface with 3964R protocol
It uses the Communication API 2.0 from Sun, which you must have installed. E.g. for Windows:
Sun provides the Communication API 2.0 for Windows and Solaris. For Linux there is a backend to the Solaris-Communication-API: www.rxtx.org. (I got the best experience with version rxtx-1.4.16pre2)