diff --git a/script/local.py b/script/local.py
index 47760732..040e84e4 100644
--- a/script/local.py
+++ b/script/local.py
@@ -3,6 +3,9 @@ import ch.psi.pshell.device.Readable.ReadableArray as ReadableArray
 import ch.psi.pshell.device.Readable.ReadableCalibratedArray as ReadableCalibratedArray
 import ch.psi.pshell.device.ArrayCalibration as ArrayCalibration
 import ch.psi.utils.Str
+
+
+beam_ok = True
  
 class SimulatedOutput(Writable):
     def write(self, value):
@@ -208,7 +211,19 @@ def append_diag_datasets(parent = None):
         append_dataset(group+get_diag_name(f), x)
 
 
+def before_readout():
+    if not beam_ok:
+        print "Waiting for beam..."
+        while not beam_ok:
+            time.sleep(0.1)
+        print "Beam ok"
+    trig_scienta()
+
+
 def after_readout(rec):
+    if not beam_ok:
+        rec.invalidate()
+        return
     if get_context().persist:
         if rec.index == 0:
             create_diag_datasets()
diff --git a/script/scan_guard.py b/script/scan_guard.py
index ff1896cc..b2abb63d 100644
--- a/script/scan_guard.py
+++ b/script/scan_guard.py
@@ -678,6 +678,28 @@ class StationShutter(ControlledDevice):
             logging.error("failed to set station shutter (requested %g, actual %g)", newpos, curpos)
         return result
 
+
+###Global flag
+class GlobalFlag(ControlledDevice):
+
+    def __init__(self, name):
+        pass
+
+    def pause(self):
+        """
+        
+        """
+        global beam_ok
+        beam_ok = False
+
+    def resume(self):
+        """
+        Opens the shutter if it was open before the pause.
+        """
+        global beam_ok
+        beam_ok = True
+
+
 
 ##### ScanGuard class #####
 
@@ -743,6 +765,7 @@ class ScanGuard(object):
         self.devices.append(AreaDetector('X03DA-SCIENTA'))
         self.devices.append(AnalogChannels('X03DA-OP-10ADC'))
         self.devices.append(StationShutter('X03DA-OP-ST1'))
+        self.devices.append(GlobalFlag())
 
     @property
     def ringcurrent_trip_lo(self):