Why is there an error that the port is open?

hanweiaaa

procedure TForm1.FormActivate(Sender: TObject);
begin

     MSComm1.CommPort:=1;
     MSComm1.Settings:='9600,n,8,1';
     MSComm1.InBufferSize:=32;
     MSComm1.OutBufferSize:=2;
     MSComm1.InputMode:=comInputModeBinary;//Set the receiving data mode to binary form
     MSComm1.InputLen := 1; //Set the number of bytes that Input reads from the receive buffer at a time to 1
     MSComm1.InputLen:=1; //Set the number of bytes that Input reads from the receive buffer at a time to 1
     MSComm1.SThreshold:=1; //Set Output to read the number of bytes from the sending buffer at one time to 1
     MSComm1.InBufferCount:=0; //Clear the receive buffer
     MSComm1.OutBufferCount:=0; //Clear the sending buffer
     MSComm1.PortOpen:=true; //Open serial port 1
     
end;

procedure TForm1.ComboBox1Change(Sender: TObject);
begin

     MSComm1.CommPort:=2;
     MSComm1.Settings:='9600,n,8,1';
     MSComm1.InBufferSize:=32;
     MSComm1.OutBufferSize:=2;
     MSComm1.InputMode:=comInputModeBinary;//Set the receiving data mode to binary form
     MSComm1.InputLen := 1; //Set the number of bytes that Input reads from the receive buffer at a time to 1
     MSComm1.InputLen:=1; //Set the number of bytes that Input reads from the receive buffer at a time to 1
     MSComm1.SThreshold:=1; //Set Output to read the number of bytes from the sending buffer at one time to 1
     MSComm1.InBufferCount:=0; //Clear the receive buffer
     MSComm1.OutBufferCount:=0; //Clear the sending buffer
     MSComm1.PortOpen:=true; //Open serial port 1
end;


When I change the drop-down box (ComboBox1Change),
The error that appears is:
Port is open
But I only opened serial port 1 when I initialized.
ComboBox1Change
Is to open the serial port 2

Why not?
Thank you!

jk66255

Is ComboBox1Change already called when it is created?

Guderian

procedure TForm1.ComboBox1Change(Sender: TObject);
begin
     MSComm1.PortOpen := False; //<<First turn it off and have a look
     MSComm1.CommPort:=2;
//...
     MSComm1.PortOpen:=true; //Open serial port 1
end;

gmwyj

Thank you! Thank you!