SITL simulation

Hi, in SITL simulation how I can access the code during simualtion? or changes to the code have to be made before simulation?

Depends on which “code” you are going to change. If you change the firmware, you have to restart the process, that is running the firmware. If it is some code, that is external to the firmware (say, some code, that interfaces with the firmware via mavlink), then neither the firmware nor the simulation don’t need to be restarted.