winforms - Caller ID using SerialPort C# -

i using serialport caller id when rings landline. i've tested using putty software , works fine.

my c# code throws invalidoperation exception , says that: cross-thread operation not valid: control lblcalleridtitle accessed thread other thread created on. error occurs when try do: lblcalleridtitle.text = readdata;

how can fix this? below code:

using system; using system.collections.generic; using system.componentmodel; using system.data; using system.drawing; using system.linq; using system.text; using system.windows.forms; using system.io.ports;  namespace callerid {     public partial class callerid : form     {         public callerid()         {             initializecomponent();             port.open();             watchmodem();             setmodem();         }      protected override void onpaint(painteventargs e)     {         base.onpaint(e);         watchmodem();     }      private serialport port = new serialport("com3");     string callname;     string callnumber;     string readdata;      private void setmodem()     {         port.writeline("at+vcid=1\n");         port.rtsenable = true;     }      private void watchmodem()     {         port.datareceived += new serialdatareceivedeventhandler(port_datareceived);     }      private void port_datareceived(object sender, serialdatareceivedeventargs e)     {         readdata = port.readexisting();         //add code split up/decode incoming data         lblcalleridtitle.text = readdata;         console.writeline(readdata);     }      private void callerid_load(object sender, eventargs e)     {      }   } } 

i want label show incoming data. thanks

your user controls (such label) have updated on ui thread, , serial data coming in on thread.

your 2 options either push control update main ui thread invoke(), or have serial thread update variable, , use timer control check variable update label.

the code first (better) option, should this:

private void port_datareceived(object sender, serialdatareceivedeventargs e) {     readdata = port.readexisting();     //add code split up/decode incoming data     if (lblcalleridtitle.invokerequired)         lblcalleridtitle.invoke(() => lblcalleridtitle.text = readdata);     else         lblcalleridtitle.text = readdata;     console.writeline(readdata); } 

the label updated on main ui thread.