use orb_advertise_multi:

- subscribe to actuator controls after topic has been advertised

src/drivers/hil/hil.cpp

@@ -348,9 +348,9 @@ HIL::task_main()
 	actuator_outputs_s outputs;
 	memset(&outputs, 0, sizeof(outputs));
 	/* advertise the mixed control outputs */
-	//int dummy;
-	_t_outputs = orb_advertise(ORB_ID(actuator_outputs),
-				   &outputs);
+	int dummy;
+	_t_outputs = orb_advertise_multi(ORB_ID(actuator_outputs),
+	&outputs, &dummy, ORB_PRIO_LOW);
 
 	px4_pollfd_struct_t fds[2];
 	fds[0].fd = _t_actuators;

src/modules/simulator/simulator_mavlink.cpp

@@ -310,9 +310,6 @@ void Simulator::updateSamples()
 	struct mag_report mag;
 	memset(&mag, 0 ,sizeof(mag));
 
-	// subscribe to topics
-	_actuator_outputs_sub = orb_subscribe(ORB_ID(actuator_outputs));
-
 	// try to setup udp socket for communcation with simulator
 	memset((char *)&_myaddr, 0, sizeof(_myaddr));
 	_myaddr.sin_family = AF_INET;
@@ -381,6 +378,9 @@ void Simulator::updateSamples()
 		send_controls();
 	}
 
+	// subscribe to topics
+	_actuator_outputs_sub = orb_subscribe_multi(ORB_ID(actuator_outputs), 0);
+
 	// got data from simulator, now activate the sending thread
 	pthread_create(&sender_thread, &sender_thread_attr, Simulator::sending_trampoline, NULL);
 	pthread_attr_destroy(&sender_thread_attr);