jMAVLink pre - flight checks

Hey! Currently I am running jMAVSim with the PX4 serially following instructions mentioned in jMAVSim/HIL.

My team and I are interested in verifying a quadcopter mathematical model written in Modelica by connecting it to PX4 via serial MAVLink and viewing the same in QGCS. We could send data using HIL_SENSOR, HIL_GPS and receive controller output using HIL_ACTUATOR_CONTROLS, but the controller output we are receiving is an array of zeros. We think pre-flight checks are not being satisfied for the PX4 in order for it to return proper control output data. I looked into the jMAVSim code to identify these checks, unfortunately I couldn’t find something concrete w.r.t the checks.

Please let me know what these pre-flight checks are or where I could find them or the variable values that need to set in order for the receive valid actuator values.