Write data 

const
	DataToWrite = 'String data';
begin
	try
		FTSPCControl1.Write(PChar(DataToWrite), length(DataToWrite));
	except
		on e:FTSPCException do
		begin
			application.MessageBox(PChar('Error: ' + inttostr(e.ErrorCode) + 
				' - ' + e.ErrorSource), 'Error!', MB_OK + MB_ICONERROR);
		end;
	end;
end;