Problem identifying USB

Hello everyone. I'm having a problem with my code. I'm using a YEI 3 Space Embedded for head tracking. I've found a code here on UnityAnswers for using this device and adapted for what I need. In the code I tell in which port the device is connected. I tried to use WMI to make the code automatically look for the port where the device is connected, but I'm getting the error:

NullReferenceException: Object reference not set to an instance of an object System.Management.MTAHelper.WorkerThread () System.Management.ManagementPath.SetWbemPath (IWbemPath wbemPath, System.String path) System.Management.ManagementPath.CreateWbemPath (System.String path) System.Management.ManagementPath..ctor (System.String path) System.Management.ManagementPath..cctor () Rethrow as TypeInitializationException: An exception was thrown by the type initializer for System.Management.ManagementPath System.Management.ManagementScope._Clone (System.Management.ManagementScope scope, System.Management.IdentifierChangedEventHandler handler) System.Management.ManagementScope._Clone (System.Management.ManagementScope scope) System.Management.ManagementObjectSearcher..ctor (System.Management.ManagementScope scope, System.Management.ObjectQuery query, System.Management.EnumerationOptions options) System.Management.ManagementObjectSearcher..ctor (System.String queryString) (wrapper remoting-invoke-with-check) System.Management.ManagementObjectSearcher:.ctor (string) YEIHeadTracking.SetPort () (at Assets/YEIHeadTracking.cs:149) YEIHeadTracking.Start () (at Assets/YEIHeadTracking.cs:79)

Also, Unity chashes when I execute the scene through play button. If I use the option Run with Unity Debugger through the MonoDevelop the error described above happens.

Does anyone know how I can fix this?

Here is the code:

 using UnityEngine;
 using System;
 using System.Collections;
 using System.IO.Ports;
 using System.Management;
  
  
 public class YEIHeadTracking : MonoBehaviour{
  
     public static SerialPort sp = new SerialPort();
  
     // Command packet for getting the filtered tared orientation as a quaternion
     // {header byte, command byte, [data bytes], checksum byte}
     // checksum = (command byte + data bytes) % 256
     public static byte[] send_bytes = {0xf7, 0x00, 0x00};
     public static byte[] button_bytes = {0xf7, 0xfa, 0xfa};
     public static byte[] tare_bytes = {0xf7, 0x60, 0x60};
  
     public int counter = 0;
  
     // Use this for initialization
  
  
     void Start(){
  
        SetPort ();
  
        sp.WriteTimeout = 100;
        sp.ReadTimeout = 100;
  
        sp.Open();
  
  
        sp.Write(send_bytes,0,3);
     }
  
     // Helper function for taking the bytes read from the 3-Space Sensor and converting them into a float
     float bytesToFloat(byte[] raw_bytes, int offset){
        byte[] big_bytes = new byte[4];
        big_bytes[0] = raw_bytes[offset+3];
        big_bytes[1] = raw_bytes[offset+2];
        big_bytes[2] = raw_bytes[offset+1];
        big_bytes[3] = raw_bytes[offset+0];
        return BitConverter.ToSingle(big_bytes,0);
     }
  
  
     //private SerialPort port;
     private void SetPort()
     {
        string[] portNames = SerialPort.GetPortNames();
        string spCaption = string.Empty;
        string spName = string.Empty;
        bool portFound = false;
  
        for (int y = 0; y < portNames.Length; y++)
        {
          ManagementObjectSearcher searcher = new ManagementObjectSearcher("SELECT * FROM Win32_SerialPort");
          foreach (ManagementObject queryObj in searcher.Get())
          {
           spCaption = queryObj["Caption"].ToString();
  
           if (spCaption.Contains("3 Space Embedded"))
           {
               spName = queryObj["DeviceID"].ToString();
               sp = new SerialPort(spName, 115200, Parity.None, 8, StopBits.One);
               portFound = true;
               break;
           }
          }
  
          if (portFound)
           break;
        }
     }