After installed Java CD, one could find there are 6 demo projects included, RS232Demo is one of them.

If you are using BGS5 for Java development, and happened to run RS232Demo project,  you'll find the following error message from the console:

 RS232Demo: Constructor
 Available COM-Ports: COM0,USB0
 javax.microedition.io.ConnectionNotFoundException: com0 port not found!
 MIDlet:RS232Demo.RS232Demo exited 

For this case, actually the 2nd line of debug message already gives you hint of solution

 Available COM-Ports: COM0,USB0 

It’s the output of

 System.out.println("Available COM-Ports: " + System.getProperty("microedition.commports")); 

My advice is changing the strCOM, replacing the port identifier “com0” from lower case to “COM0”, this will fix the issue:

     try {
      String strCOM = "comm:COM0;blocking=on;baudrate=115200";