DAQ: when __set_state is called check to see if beamline is busy otherwise raise an exception

daq/src/aaredaq/daq.py

@@ -1219,6 +1219,9 @@ class AareDAQ:
         #
         curr_state = self.__cfg.state
 
+        if not self.__cfg.state_busy:
+            raise Exception("Beamline should be busy")
+
         if target == BeamlineStateEnum.Maintenance:
             self.__cfg.state = BeamlineStateEnum.Maintenance
         elif target != curr_state: