daq: fixed dtecetor min and max bug if llm or hlm si missing in epics

src/aare/daq/daq.py

@@ -3195,10 +3195,19 @@ class AareDAQ:
             dtz_min = self.__cfg.cached_dtz_low
             dtz_max = self.__cfg.cached_dtz_high
 
-            if dtz_min is None or dtz_max is None:
+            if (
+                    dtz_min is None or dtz_max is None
+                    or (dtz_min > dtz_max)
+                    or (dtz_min == dtz_max)
+                    or (dtz_min == 0 and dtz_max == 0)
+            ):
                 logger.warning("DTZ limits missing from cache, using conservative defaults in beamline_status")
-                dtz_min = 20.0
-                dtz_max = 1000.0
+                dtz_min = cfg_get('daq.hardware.default_detector_distance_minimum', 100)
+                dtz_max = cfg_get('daq.hardware.default_detector_distance_maximum', 1000)
+                logger.warning(
+                    f"using dtz_min {dtz_min} and dtz_max {dtz_max}"
+                )
+
             return BeamlineStatus(
                 ring_current_mA=ring_current,
                 front_light=front_light,