SPCOM 串口?

unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, SPComm;type
  TForm1 = class(TForm)
    Comm1: TComm;
    Memo1: TMemo;
    Button1: TButton;
    procedure FormShow(Sender: TObject);
    procedure FormClose(Sender: TObject; var Action: TCloseAction);
    procedure Button1Click(Sender: TObject);
    procedure Comm1ReceiveData(Sender: TObject; Buffer: Pointer;
      BufferLength: Word);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;
  viewstring:string;
  i:integer;
  rbuf,sbuf:array[1..6] of byte;
implementation{$R *.dfm}procedure TForm1.FormShow(Sender: TObject);
begin
comm1.StartComm;
end;procedure TForm1.FormClose(Sender: TObject; var Action: TCloseAction);
begin
comm1.StopComm;
end;//自定义发送数据过程　
procedure senddata;
var
i:integer;
commflg:boolean;
begin
viewstring:='' ;
commflg:=true;
for i:=1 to 6 do
begin
if not form1.comm1.writecommdata(@sbuf,1) then
begin
commflg:=false;
break;
end;
//发送时字节间的延时　
sleep(2);
viewstring:=viewstring+inttohex(sbuf[i],2)+'';
end;
viewstring:='发送'+viewstring;
form1.memo1.lines.add(viewstring);
form1.memo1.lines.add('' );
if not commflg then messagedlg('发送失败 !' ,mterror,[mbyes],0);
end;procedure TForm1.Button1Click(Sender: TObject);   //发送按钮
begin
sbuf[1]:=byte($f0); //帧头　
sbuf[2]:=byte($01); //命令号　
sbuf[3]:=byte($ff);
sbuf[4]:=byte($ff);
sbuf[5]:=byte($01);
sbuf[6]:=byte($f0); //帧尾　
senddata;//调用发送函数　
end;procedure TForm1.Comm1ReceiveData(Sender: TObject; Buffer: Pointer;
  BufferLength: Word);
var
i:integer;
begin
viewstring:='' ;
move(Buffer^,(@rbuf)^,BufferLength);
for i:=1 to bufferlength do
viewstring:=viewstring+inttohex(rbuf[i],2)+'';
viewstring:='接收'+viewstring;
memo1.lines.add(viewstring);
memo1.lines.add('' );
end;end.
在memo1上只是显示发送F0 01 FF FF 0F ,但没有显示接受F0 01 FF FF 0F,应该是接收不成功吧,请问哪里出错啦,帮忙看看