如何在Linux中读取/ dev / ttyUSB0设备？

I have connected a USB RFID in serial port and use to read RFID tags. So I need to read the data from the device and process the output. I am getting the data with screen command from Linux command line but I was not able to take the value from screen and cannot pass to my application. Is there any other way to read from /dev/ttyUSB0? I have used the code shown below but it shows currently the resource is unavailable (even though I have given chmod permissions)I have connected a USB RFID in serial port and