procedure TForm1.SpeedButton1Click(Sender: TObject);
var
Buf: Array[1..10] of Byte;
i:integer;
begin
Buf[1]:=66;
set a signal to identify in onreceive event;
comm1.WriteCommData(@buf[1],1);
end;
onreceive:
...
if signaled then
if received then
send next command (67,68, etc),
if finished then set off signal.
...