diff --git a/config/settings.properties b/config/settings.properties
index 30724a6..c416f22 100644
--- a/config/settings.properties
+++ b/config/settings.properties
@@ -1,10 +1,10 @@
-#Wed Jan 22 08:53:02 CET 2020
+#Tue Feb 04 09:33:51 CET 2020
 dry_mount_counter=0
 room_temperature_enabled=false
 pin_offset=0.0
 puck_types=true
 imaging_enabled=false
-dry_timestamp=1.579679582092E9
+dry_timestamp=1.580771768364E9
 roi_h=1000
 led_level=0.0
 beamline_status_enabled=false
diff --git a/config/variables.properties b/config/variables.properties
index d457b07..f17ab80 100644
--- a/config/variables.properties
+++ b/config/variables.properties
@@ -1,2 +1,2 @@
-#Tue Jan 21 14:03:38 CET 2020
-FileSequentialNumber=138
+#Mon Feb 03 09:28:54 CET 2020
+FileSequentialNumber=149
diff --git a/devices/A1.properties b/devices/A1.properties
index 0d37ef0..d9b32f1 100644
--- a/devices/A1.properties
+++ b/devices/A1.properties
@@ -1,3 +1,3 @@
-#Thu Jun 06 15:40:21 CEST 2019
+#Fri Jan 31 16:58:30 CET 2020
 detection=Mechanical
 disabled=false
diff --git a/script/devices/LaserDistance.py b/script/devices/LaserDistance.py
index 97efea4..086a508 100644
--- a/script/devices/LaserDistance.py
+++ b/script/devices/LaserDistance.py
@@ -1,17 +1,27 @@
 class LaserDistance(ReadonlyRegisterBase):
     def __init__(self):
         ReadonlyRegisterBase.__init__(self, "laser_distance")
+        
     def doRead(self):
         ret = ue.readable.read()
-        ret = 0.0 if math.isnan(ret) else ret
+        ret = None if ret is None else (0.0 if math.isnan(ret) else ret)
         return ret
 
 class ListenerAI (DeviceListener):
-    def onValueChanged(self, device, value, former):
-        laser_distance.setCache( 0.0 if math.isnan(value) else value, None)
+    def onValueChanged(self, device, value, former):        
+        if laser_distance is not None:                    
+            value = None if value is None else (0.0 if math.isnan(value) else value)                        
+            laser_distance.setCache(value, None)            
+
+
+for l in ue.listeners:
+    if Nameable.getShortClassName(l.getClass()) == "ListenerAI":
+        ue.removeListener(l)
+
 
 listenerAI = ListenerAI()
 ue.addListener(listenerAI)
         
 laser_distance=LaserDistance()   
 add_device(laser_distance, True)
+laser_distance.update()