title: Serial Input in Ubuntu, Usb to serial converter (Pl2303 - Prolific) not working in ubuntu 18.04
body: <p>I am trying to read input from a Electronic weighing scale (Weigh sensor) connected to Ubuntu enabled UDOO board using a Prolific PL2303 serial converter cable (CA-US9), but am unable to read any input from the sensor. To monitor the input I have tried using (Coolterm &amp; GTKTerm), assuming an issue with the driver I have referred and tried updating the DTR line as the solutions suggested in the following stack overflow resources <a href="https://ubuntuforums.org/showthread.php?t=1716756" rel="nofollow noreferrer">Reference 1</a>,<a href="https://askubuntu.com/questions/465628/my-prolific-technology-inc-pl2303-serial-port-adapter-doesnt-work-in-either-u">Reference 2</a>,<a href="https://stackoverflow.com/questions/17000078/prolific-pl2303-serial-port-to-250000bps">Reference 3</a>.</p>
  
  <p>I have tied the same on the ubuntu based computer too but the issue remain the same. Using the <code>dmesg</code> command i was able to check that the device has been detected properly when connected. The output to the command executed as <code>dmesg | tail</code> is as follows :</p>
  
  <pre><code>[ 7365.393110] usb 1-3: new full-speed USB device number 53 using xhci_hcd
  [ 7365.542407] usb 1-3: New USB device found, idVendor=067b, idProduct=2303, bcdDevice= 4.00
  [ 7365.542424] usb 1-3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
  [ 7365.542437] usb 1-3: Product: USB-Serial Controller D
  [ 7365.542448] usb 1-3: Manufacturer: Prolific Technology Inc. 
  [ 7365.545546] pl2303 1-3:1.0: pl2303 converter detected
  [ 7365.552313] usb 1-3: pl2303 converter now attached to ttyUSB0
  [ 7373.296214] usb 1-3: USB disconnect, device number 53
  [ 7373.297492] pl2303 ttyUSB0: pl2303 converter now disconnected from ttyUSB0
  [ 7373.297644] pl2303 1-3:1.0: device disconnected
  </code></pre>
  
  <p>The device remains connected physically but seems disconnected by the command output, Also please suggest how to find the port id for the serial port connected.</p>