diff --git a/py25/bacpypes/service/detect.py b/py25/bacpypes/service/detect.py
index 4b743e8..2de5929 100755
--- a/py25/bacpypes/service/detect.py
+++ b/py25/bacpypes/service/detect.py
@@ -37,6 +37,7 @@ class DetectionMonitor:
         # if the algorithm is already triggered, don't bother checking for more
         if self.algorithm._triggered:
             if _debug: DetectionMonitor._debug("    - already triggered")
+            self.algorithm._triggered = False
             return
 
         # if there is a special filter, use it, otherwise use !=
diff --git a/py27/bacpypes/service/detect.py b/py27/bacpypes/service/detect.py
index 0be0551..9ff8829 100755
--- a/py27/bacpypes/service/detect.py
+++ b/py27/bacpypes/service/detect.py
@@ -38,6 +38,7 @@ class DetectionMonitor:
         # if the algorithm is already triggered, don't bother checking for more
         if self.algorithm._triggered:
             if _debug: DetectionMonitor._debug("    - already triggered")
+            self.algorithm._triggered = False
             return
 
         # if there is a special filter, use it, otherwise use !=
diff --git a/py34/bacpypes/service/detect.py b/py34/bacpypes/service/detect.py
index 0be0551..9ff8829 100755
--- a/py34/bacpypes/service/detect.py
+++ b/py34/bacpypes/service/detect.py
@@ -38,6 +38,7 @@ class DetectionMonitor:
         # if the algorithm is already triggered, don't bother checking for more
         if self.algorithm._triggered:
             if _debug: DetectionMonitor._debug("    - already triggered")
+            self.algorithm._triggered = False
             return
 
         # if there is a special filter, use it, otherwise use !=