c# - "System.UnauthorizedAccessException" error when opening second serial port -

i need open second serialport in visual c# program read data arduino. worked fine, in case see below not work..

using system; using system.collections.generic; using system.componentmodel; using system.data; using system.drawing; using system.linq; using system.text; using system.threading.tasks; using system.windows.forms; using system.io.ports; using commandspd4i;   namespace csharpexample { public partial class csharpexample : form {     public commotorcommands motor1;      public csharpexample()     {         initializecomponent();          motor1 = new commotorcommands();         motor1.setsteps(convert.toint32(numericschritte.value));     }     serialport arduino;     delegate void invokelb(string data);     invokelb lbrecieveddelegate;     int xpos = 0;       private void startbtn_click(object sender, eventargs e)     {         // set comm settings motor 1         motor1.selectedport = comportbox1.text;         motor1.baudrate = convert.toint32(baudratebox1.text);          // set motor address         motor1.motoraddresse = convert.toint32(motor1id.value);         // set relative positioning mode         motor1.setpositiontype(1);          // start travel profile         if (motor1.errorflag)         {             statuslabel1.text = "status 1: " + motor1.errormessagestring;         }         else         {             statuslabel1.text = "status 1: ok";         }     }      private void stopbtn_click(object sender, eventargs e)     {         // stop travel profile         motor1.stoptravelprofile();     }      private void timer1_tick(object sender, eventargs e)     {         lblposition.text = convert.tostring(motor1.getposition());         lblstatus.text = motor1.errormessagestring;        // this.chart1.series["kraft"].points.addxy(xpos, convert.todouble(lblkraft.text));        // xpos++;**strong text**     }      private void btnhoch_click(object sender, eventargs e)     {         motor1.setdirection(0);         motor1.setpositiontype(1);         motor1.starttravelprofile();     }      private void btnrunter_click(object sender, eventargs e)     {         motor1.setdirection(1);         motor1.setpositiontype(1);         motor1.starttravelprofile();     }      private void numericschritte_valuechanged(object sender, eventargs e)     {         motor1.setsteps(convert.toint32(numericschritte.value));     }      private void numericgeschwindigkeit_valuechanged(object sender, eventargs e)     {         motor1.setmaxfrequency(convert.toint32(numericgeschwindigkeit.value));      }      private void btndiagramm_click(object sender, eventargs e)     {         if (timer1.enabled)         {             timer1.stop();         }         else         {             timer1.start();         }     }      private void btnresetdiagramm_click(object sender, eventargs e)     {         this.chart1.series["kraft"].points.clear();         xpos = 0;     }      private void arduino_datareceived(object sender, serialdatareceivedeventargs e)     {         string recievedline = " ";         while (recievedline != "")         {             recievedline = arduino.readline();             lblkraft.invoke(lbrecieveddelegate, new object[] { recievedline });          }     }      void invokelabel1(string data)     {         label1.text = data;         this.chart1.series["kraft"].points.addxy(xpos, convert.todouble(lblkraft.text));         xpos++;     }      private void btnarduino_click(object sender, eventargs e)     {         //hier erstellen wir unseren serialport und legen die einstellungen fest         arduino = new serialport("com7", 9600);          if (!arduino.isopen)          {             arduino.open();             if (arduino.isopen)             {                 lblarduino.forecolor = system.drawing.color.fromargb(((int)(((byte)(0)))), ((int)(((byte)(200)))), ((int)(((byte)(0)))));                 lblarduino.text = "verbunden mit " + arduino.portname;             }          }         lbrecieveddelegate = new invokelb(invokelabel1);         arduino.datareceived += new serialdatareceivedeventhandler(arduino_datareceived); //datarecieved event abonnieren     }    } } 

when leave out this:

motor1.selectedport = comportbox1.text; motor1.baudrate = convert.toint32(baudratebox1.text); 

then works..

i hope can :)