Spcomm串口控件的例程：

           //串口初始化

           procedure TForm1.BitBtn3Click(Sender: TObject);
            begin
               comm1.startcomm;
            end;
              //关闭串口
            procedure TForm1.BitBtn4Click(Sender: TObject);
            begin
               comm1.StopComm;
            end;
            //发送数据
            procedure TForm1.BitBtn1Click(Sender: TObject);{var str:string;
                ch1:char;
            begin
            comm1.WriteCommData(ch,1);
            end.
            //接收数据
            procedure TForm1.Comm1ReceiveData(Sender: TObject; Buffer: Pointer;
              BufferLength: Word);
            type   ss=array[1..500]of char ;
            var    str1:^ss;
                   i:integer;
                   s:array[0..15] of char ;
                   n:integer;
            begin
                   str1:=Buffer;
                 //s[]=('0','1','2','3'...'E')
                   for i:=0 to 9 do
                   s[i]:=chr(48+i);
                   for i:=10 to 15 do
                   s[i]:=chr(55+i);
                   for i:=1 to bufferlength do
                   begin
                   n:=ord(str1^[i]);
                   listbox1.Items.add(
                             inttostr(listbox1.Items.Count+1)
                             +' - '+s[n div 16]+s[n mod 16]);
                   end;
                   listbox1.Refresh;
                  if listbox1.Items.count > strtoint(form2.edit1.text)
                  then listbox1.Items.Clear;
            end;