Automatic onboard logging

My project isn’t anything that flies or moves, but I am using arducopter to measure movements at the tops of trees. So when I power on my project, I want arducopter to start logging its sensor data. Is that possible or do I have to have mission planner connected to gather data over the telemetry link? My project is using rfd900+ units in multi point mode.

Setting LOG_DISARMED parameter to 1 will make Pixhawk start logging at power on.

Will logging take place without an SD card slot? Is there enough space onboad? Im using the omnibus f4 nano v6.