Unity - IOException: SerialPort.Open()

So I am trying to open a Serial Port on unity so I can read data.

However, the new USB device I'm trying to read from has been giving me issues unlike previous.

IOException: Invalid argument

 System.IO.Ports.SerialPortStream.ThrowIOException () (at <aa976c2104104b7ca9e1785715722c9d>:0)
 System.IO.Ports.SerialPortStream..ctor (System.String portName, System.Int32 baudRate, System.Int32 dataBits, System.IO.Ports.Parity parity, System.IO.Ports.StopBits stopBits, System.Boolean dtrEnable, System.Boolean rtsEnable, System.IO.Ports.Handshake handshake, System.Int32 readTimeout, System.Int32 writeTimeout, System.Int32 readBufferSize, System.Int32 writeBufferSize) (at <aa976c2104104b7ca9e1785715722c9d>:0)
 (wrapper remoting-invoke-with-check)System.IO.Ports.SerialPortStream..ctor(string,int,int,System.IO.Ports.Parity,System.IO.Ports.StopBits,bool,bool,System.IO.Ports.Handshake,int,int,int,int)
 System.IO.Ports.SerialPort.Open () (at <aa976c2104104b7ca9e1785715722c9d>:0)
 (wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort.Open()

Never got this error before when opening other USB serial ports.

 using System.IO.Ports;

 void Start()
 {
       stream = new SerialPort("/dev/usb/hiddev0",256000,Parity.None, 8 ,StopBits.One);
       stream.WriteTimeout = 300;
       stream.ReadTimeout = 5000;
       stream.DtrEnable = true;
       stream.RtsEnable = true;
       stream.Open()
 }

I tried to change syntax but haven't gotten a successful open().

EDIT: turns out Hiddev aren't readable serial. I have all core information about device, but no matter what I try, I can not get the data to Unity.