diff --git a/.pylintrc b/.pylintrc
index daa9688..21527bf 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -162,7 +162,7 @@ max-line-length=132
 no-space-check=trailing-comma,dict-separator
 
 # Maximum number of lines in a module
-max-module-lines=1200
+max-module-lines=1000
 
 # String used as indentation unit. This is usually " " (4 spaces) or "\t" (1
 # tab).
diff --git a/doc/source/reference.rst b/doc/source/reference.rst
index 9326ba2..77491e6 100644
--- a/doc/source/reference.rst
+++ b/doc/source/reference.rst
@@ -7,7 +7,7 @@ Module Base Classes
 .. autodata:: secop.modules.Done
 
 .. autoclass:: secop.modules.Module
-    :members: earlyInit, initModule, startModule, pollerClass
+    :members: earlyInit, initModule, startModule
 
 .. autoclass:: secop.modules.Readable
     :members: Status
diff --git a/secop/core.py b/secop/core.py
index be3d338..1da4370 100644
--- a/secop/core.py
+++ b/secop/core.py
@@ -31,7 +31,7 @@ from secop.datatypes import ArrayOf, BLOBType, BoolType, EnumType, \
 from secop.iohandler import IOHandler, IOHandlerBase
 from secop.lib.enum import Enum
 from secop.modules import Attached, Communicator, \
-    Done, Drivable, Module, Readable, Writable
+    Done, Drivable, Module, Readable, Writable, HasAccessibles
 from secop.params import Command, Parameter
 from secop.properties import Property
 from secop.proxy import Proxy, SecNode, proxy_class
@@ -39,3 +39,8 @@ from secop.io import HasIO, StringIO, BytesIO, HasIodev  # TODO: remove HasIodev
 from secop.persistent import PersistentMixin, PersistentParam
 from secop.rwhandler import ReadHandler, WriteHandler, CommonReadHandler, \
     CommonWriteHandler, nopoll
+
+ERROR = Drivable.Status.ERROR
+WARN = Drivable.Status.WARN
+BUSY = Drivable.Status.BUSY
+IDLE = Drivable.Status.IDLE
diff --git a/secop/datatypes.py b/secop/datatypes.py
index 12ce4ec..f5c31c1 100644
--- a/secop/datatypes.py
+++ b/secop/datatypes.py
@@ -22,7 +22,7 @@
 # *****************************************************************************
 """Define validated data types."""
 
-# pylint: disable=abstract-method
+# pylint: disable=abstract-method, too-many-lines
 
 
 import sys
@@ -454,7 +454,10 @@ class EnumType(DataType):
         super().__init__()
         if members is not None:
             kwds.update(members)
-        self._enum = Enum(enum_or_name, **kwds)
+        if isinstance(enum_or_name, str):
+            self._enum = Enum(enum_or_name, kwds)  # allow 'self' as name
+        else:
+            self._enum = Enum(enum_or_name, **kwds)
         self.default = self._enum[self._enum.members[0]]
 
     def copy(self):
diff --git a/secop/lib/statemachine.py b/secop/lib/statemachine.py
index f24f00e..1742ff8 100644
--- a/secop/lib/statemachine.py
+++ b/secop/lib/statemachine.py
@@ -178,7 +178,9 @@ class StateMachine:
                 if self.stop_exc:
                     raise self.stop_exc
             except Exception as e:
-                self.log.info('%r raised in state %r', e, self.status_string)
+                # Stop and Restart are not unusual -> no warning
+                log = self.log.debug if isinstance(e, Stop) else self.log.warning
+                log('%r raised in state %r', e, self.status_string)
                 self.last_error = e
                 ret = self.cleanup(self)
                 self.log.debug('cleanup %r %r %r', self.cleanup, self.last_error, ret)
diff --git a/secop/modules.py b/secop/modules.py
index 6a7f2d9..322fd0e 100644
--- a/secop/modules.py
+++ b/secop/modules.py
@@ -161,8 +161,8 @@ class HasAccessibles(HasProperties):
                 new_rfunc.wrapped = True  # indicate to subclasses that no more wrapping is needed
                 setattr(cls, 'read_' + pname, new_rfunc)
 
-            if not pobj.readonly:
-                wfunc = getattr(cls, 'write_' + pname, None)
+            wfunc = getattr(cls, 'write_' + pname, None)
+            if not pobj.readonly or wfunc:  # allow write_ method even when pobj is not readonly
                 wrapped = getattr(wfunc, 'wrapped', False)  # meaning: wrapped or auto generated
                 if (wfunc is None or wrapped) and pobj.handler:
                     # ignore the handler, if a write function is present
@@ -392,9 +392,8 @@ class Module(HasAccessibles):
                 continue
 
             if pname in cfgdict:
-                if not pobj.readonly and pobj.initwrite is not False:
+                if pobj.initwrite is not False and hasattr(self, 'write_' + pname):
                     # parameters given in cfgdict have to call write_<pname>
-                    # TODO: not sure about readonly (why not a parameter which can only be written from config?)
                     try:
                         pobj.value = pobj.datatype(cfgdict[pname])
                         self.writeDict[pname] = pobj.value
@@ -417,10 +416,8 @@ class Module(HasAccessibles):
                     except BadValueError as e:
                         # this should not happen, as the default is already checked in Parameter
                         raise ProgrammingError('bad default for %s:%s: %s' % (name, pname, e)) from None
-                    if pobj.initwrite and not pobj.readonly:
+                    if pobj.initwrite and hasattr(self, 'write_' + pname):
                         # we will need to call write_<pname>
-                        # if this is not desired, the default must not be given
-                        # TODO: not sure about readonly (why not a parameter which can only be written from config?)
                         pobj.value = value
                         self.writeDict[pname] = value
                     else:
diff --git a/secop/persistent.py b/secop/persistent.py
index 0360b84..63ce5a1 100644
--- a/secop/persistent.py
+++ b/secop/persistent.py
@@ -75,7 +75,7 @@ class PersistentMixin(HasAccessibles):
         self.initData = {}
         for pname in self.parameters:
             pobj = self.parameters[pname]
-            if not pobj.readonly and getattr(pobj, 'persistent', 0):
+            if hasattr(self, 'write_' + pname) and getattr(pobj, 'persistent', 0):
                 self.initData[pname] = pobj.value
                 if pobj.persistent == 'auto':
                     def cb(value, m=self):
diff --git a/secop/proxy.py b/secop/proxy.py
index 7189fa8..2c25838 100644
--- a/secop/proxy.py
+++ b/secop/proxy.py
@@ -23,8 +23,7 @@
 
 from secop.client import SecopClient, decode_msg, encode_msg_frame
 from secop.datatypes import StringType
-from secop.errors import BadValueError, \
-    CommunicationFailedError, ConfigError, make_secop_error
+from secop.errors import BadValueError, CommunicationFailedError, ConfigError
 from secop.lib import get_class
 from secop.modules import Drivable, Module, Readable, Writable
 from secop.params import Command, Parameter
@@ -47,8 +46,6 @@ class ProxyModule(HasIO, Module):
         if parameter not in self.parameters:
             return  # ignore unknown parameters
         # should be done here: deal with clock differences
-        if readerror:
-            readerror = make_secop_error(*readerror)
         self.announceUpdate(parameter, value, readerror, timestamp)
 
     def initModule(self):
@@ -201,7 +198,7 @@ def proxy_class(remote_class, name=None):
                 def wfunc(self, value, pname=aname):
                     value, _, readerror = self._secnode.setParameter(self.name, pname, value)
                     if readerror:
-                        raise make_secop_error(*readerror)
+                        raise readerror
                     return value
 
                 attrs['write_' + aname] = wfunc
diff --git a/secop_psi/ccu4.py b/secop_psi/ccu4.py
index e263537..e1b4801 100644
--- a/secop_psi/ccu4.py
+++ b/secop_psi/ccu4.py
@@ -72,7 +72,7 @@ class HeLevel(HasIO, Readable):
         """
         name, txtvalue = self.communicate(cmd).split('=')
         assert name == cmd.split('=')[0]  # check that we got a reply to our command
-        return txtvalue  # Frappy will automatically convert the string to the needed data type
+        return float(txtvalue)
 
     def read_value(self):
         return self.query('h')
diff --git a/test/test_lib_enum.py b/test/test_lib_enum.py
index 78016fa..97228e1 100644
--- a/test/test_lib_enum.py
+++ b/test/test_lib_enum.py
@@ -64,6 +64,7 @@ def test_EnumMember():
     assert a != 3
     assert a == 1
 
+
 def test_Enum():
     e1 = Enum('e1')
     e2 = Enum('e2', e1, a=1, b=3)
@@ -75,3 +76,4 @@ def test_Enum():
     assert e2.b > e3.a
     assert e3.c >= e2.a
     assert e3.b <= e2.b
+    assert Enum({'self': 0, 'other': 1})('self') == 0