diff --git a/startup/15-optics.py b/startup/15-optics.py
index 5aaca30..5b95d4e 100644
--- a/startup/15-optics.py
+++ b/startup/15-optics.py
@@ -26,8 +26,20 @@ class SideBounceMono(Device):
     twist = Cpt(EpicsMotor, "Twist}Mtr")
 
 sbm = SideBounceMono("XF:28ID1A-OP{Mono:SBM-Ax:", name='sbm')
+
+
+class PDFShutter(EpicsSignal):
+
+    def stop(self):
+        self.set(0)
+
+    def resume(self):
+        self.set(1)
+
+
 # Shutters:
-fs = EpicsSignal('XF:28ID1B-OP{PSh:1-Det:2}Cmd', name='fs')  # fast shutter
+fs = PDFShutter('XF:28ID1B-OP{PSh:1-Det:2}Cmd', name='fs')  # fast shutter
+
 
 class Mirror(Device):
     y_upstream = Cpt(EpicsMotor, 'YU}Mtr')