Your client is using TIdIOHandler.WriteLn()
to send a request. On the server side, call TIdIOHandler.ReadLn()
to wait for the request before then calling TIdIOHandler.Write()
to send the response:
procedure TDummySign.OnExecute(AContext: TIdContext);
var
Req: string;
begin
Req := AContext.Connection.IOHandler.ReadLn;
...
AContext.Connection.IOHandler.Write(#6'01011234'#3#1'010101'#2'060100037908751531342CB30801010801000000000000D69A'#3);
...
end;