Where is the place in the code or in the configuration files of PX4/firwmare to enable, disable or change the frequency of selected mavlink messages?
I am working with the Pixhawk (px4fmu-v2).
Are you talking about the stream rate in a groundstation or onboard logging?
For the groundstation, (as far as I know), it is located in mavlink_main.cpp, under configure_stream()
configure_stream("SYS_STATUS", 1.0f);
configure_stream("EXTENDED_SYS_STATE", 1.0f);
configure_stream("HIGHRES_IMU", 1.5f);
configure_stream("ATTITUDE", 20.0f);
configure_stream("RC_CHANNELS", 5.0f);
configure_stream("SERVO_OUTPUT_RAW_0", 1.0f);
configure_stream("ALTITUDE", 1.0f);
configure_stream("GPS_RAW_INT", 1.0f);
configure_stream("ADSB_VEHICLE", 2.0f);
configure_stream("DISTANCE_SENSOR", 0.5f);
configure_stream("OPTICAL_FLOW_RAD", 1.0f);
configure_stream("VISION_POSITION_NED", 1.0f);
configure_stream("ESTIMATOR_STATUS", 0.5f);
configure_stream("NAV_CONTROLLER_OUTPUT", 1.5f);
configure_stream("GLOBAL_POSITION_INT", 5.0f);
configure_stream("LOCAL_POSITION_NED", 1.0f);
configure_stream("POSITION_TARGET_GLOBAL_INT", 1.5f);
configure_stream("ATTITUDE_TARGET", 2.0f);
configure_stream("HOME_POSITION", 0.5f);
configure_stream("NAMED_VALUE_FLOAT", 1.0f);
configure_stream("VFR_HUD", 4.0f);
configure_stream("WIND_COV", 1.0f);
break;
For the onboard logging itself, it can be set via QGC (params tab) or in init.d
See also How to increase sdlog2 logging rate?
Thanks pziyiang 