You initiate a data stream by sending the string
Ser.WriteData(':,1'+#13);
In this case you should wait for 32 bytes in the serial port buffer. After the buffer filled by 32 bytes, read the data.
The most simple way of implementation is adding code to TTimer.OnTimer event.
I never use TLazSerial(as I know it use TBlockSerial from SynaSer library)
procedure TMainForm.Timer1Timer(Sender: TObject);
begin
memo1.Lines.add(BlockSerial.RecvTerminated(10, #13));
end;
Other way is a creation of TTheard to read data in the loop.