Based on the m2ms_incomingSAL.vi, there should be a user event (SAL_Command) to decide the M2 control system can accept the SAL command or not. In the case structure inside, a enum of SAL_InterfaceCommandEnum.ctl is used.
The PublishOnlySubstate class has the systemReady.vi to send the SAL_Command event to allow the SAL command. This is triggered by the exec.vi of SystemReady class.
The createCommand.vi in CommandFactory class issues the SystemReady command. There is a SystemNotReady command as well.
The SystemMonitor class has the check_for_system_ready.vi to send the SystemReady command.