Unable to find serial ports

Question

Using Rxtx API.

I am 100% sure there is a serial port available. On Debian, I can see /dev/ttyUSB3 exists when the device is connected.

Tried running getPortIdentifiers() and got nothing when I tried iterating over the hashset

CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier("/dev/ttyUSB3");

Also did not work. I got:

Exception Caused by: gnu.io.NoSuchPortException

What am I doing wrong? I am fairly sure rxtx was set up correctly.

Answer 1

The problem here is with how RXTX defines ports. By default, it will only look for certain serial ports(on Linux, /dev/ttySX ). There are several options you have to fix this:

1. Set the gnu.io.rxtx.SerialPorts property when you start Java(either on the command line, or through code. See the Rxtx documentation for more details)
2. Use a different serial port library that lets you select serial ports manually.

For #2, the following are libraries that I know of:

• RXTX
• JSSC
• PureJavaComm
• JavaSerial (disclaimer: this is my library)