c# - External class handler interacting with UI -

i working on class communicate external device through serialport class, need update ui according messages device send back.

i tried following code not work:

using system.io.ports;  namespace learningsteps {     /// <summary>     /// interaction logic comm.xaml     /// </summary>     ///       public class teste     {         private serialport _myport;          public teste(serialport p) { _myport = p; }          public void funcao(serialdatareceivedeventhandler h)         {             _myport.datareceived += h;             byte[] vetor = new byte[] { 0x24, 0x24, 0xcf, 0x00, 0x01, 0x02, 0x25, 0x33, 0x7e };             _myport.write(vetor, 0, 9);         }     }      public partial class comm : window     {         serialport port;         teste t;          public delegate void atualizacallback(string message);         system.text.asciiencoding encoding = new system.text.asciiencoding();          public comm()         {             initializecomponent();             port = new serialport("com5",115200,parity.none,8,stopbits.one);             port.rtsenable = false;             port.dtrenable = false;             port.handshake = handshake.none;             port.newline = "~";             port.open();             t = new teste(port);          }          private void recebido(object sender, serialdatareceivedeventargs e)         {             serialport sp = (serialport)sender;             string indata = sp.readexisting();              my_label.dispatcher.invoke(new atualizacallback(this.atualiza),new object[]{indata});          }          private void bt_click(object sender, routedeventargs e)         {             t.funcao(recebido);         }          private void atualiza(string s)         {             byte[] vet = encoding.getbytes(s);             my_label.content = bitconverter.tostring(vet);         }      } } 

i error when try compile, think because i'm trying send internal serialdatareceivedeventhandler argument. don't know how use t.funcao , update ui otherwise.

the error says: "an unhandled exception of type 'system.window.markup.xamlparseexception' occurred in presentationframework.dll

additional information: 'the invocation of constructor type 'learningsteps.comm' matches specified binding constraints threw exception.' line number '3' , line position '9'.

if there handler exception, program may safely continued."

can me please?