tomazas

Thanks. Unfortunately I do not have the possibility to test this.

Same as in #5, the problem is in native RXTX library (at least where it crashes). Sorry, but I don't know any workarounds. Since RXTX is dead (almost) and not...

Are you sure you're running this app via sudo to have access to hardware ports? What about sharing some logs not just a statement?

First, there should be some output (failure reason/text) printed in console after you run the "sudo java -jar ATCommandTester.jar" command and try to find (connect to) port.

Try some serial tool such as RealTerm to verify the port is working before using this software.