diff --git a/secop/params.py b/secop/params.py
index cd620fd..10ddf4d 100644
--- a/secop/params.py
+++ b/secop/params.py
@@ -139,9 +139,8 @@ class Parameter(Accessible):
             datatype.setProperty('unit', unit)
         super(Parameter, self).__init__(**kwds)
 
-        # note: auto-converts True/False to 1/0 which yield the expected
-        # behaviour...
-        self.properties['poll'] = int(self.poll)
+        if self.handler and not self.poll:
+            self.properties['poll'] = True
 
         if self.constant is not None:
             self.properties['readonly'] = True
diff --git a/secop/poller.py b/secop/poller.py
index 05f3a54..e1f49da 100644
--- a/secop/poller.py
+++ b/secop/poller.py
@@ -132,10 +132,11 @@ class Poller(PollerBase):
             self.startup_timeout = max(self.startup_timeout, module.startup_timeout)
         except AttributeError:
             pass
+        handlers = set()
         # at the beginning, queues are simple lists
         # later, they will be converted to heaps
         for pname, pobj in module.parameters.items():
-            polltype = int(pobj.poll)
+            polltype = pobj.poll
             rfunc = getattr(module, 'read_' + pname, None)
             if not polltype or not rfunc:
                 continue
@@ -149,6 +150,13 @@ class Poller(PollerBase):
                     polltype = REGULAR
                 else:
                     polltype = SLOW
+            if not polltype in factors:
+                raise ProgrammingError("unknown poll type %r for parameter '%s'"
+                                       % (polltype, pname))
+            if pobj.handler:
+                if pobj.handler in handlers:
+                    continue # only one poller per handler
+                handlers.add(pobj.handler)
             # placeholders 0 are used for due, lastdue and idx
             self.queues[polltype].append((0, 0,
                 (0, module, pobj, rfunc, factors[polltype])))
diff --git a/test/test_poller.py b/test/test_poller.py
index 07b0b5f..430e87b 100644
--- a/test/test_poller.py
+++ b/test/test_poller.py
@@ -87,6 +87,7 @@ class Parameter:
         self.readonly = readonly
         self.interval = interval
         self.timestamp = 0
+        self.handler = None
         self.reset()
 
     def reset(self):