private void listServices() throws Exception
    {
        final ListServices list_services = new ListServices();
		connection.execute(list_services);
		
		final Service[] services = list_services.getServices();
		if (services == null  ||  services.length < 1)
			throw new Exception("Device does not support EtherIP services");
		logger.log(Level.FINE, "Service: {0}", services[0].getName());
		if (! services[0].getName().toLowerCase().startsWith("comm"))
				throw new Exception("Expected EtherIP communication service, got " + services[0].getName());
    }