diff --git a/frappy/client/__init__.py b/frappy/client/__init__.py
index b3bcc6f..59fb20f 100644
--- a/frappy/client/__init__.py
+++ b/frappy/client/__init__.py
@@ -250,16 +250,9 @@ class ProxyClient:
         return bool(cblist)
 
     def updateValue(self, module, param, value, timestamp, readerror):
-        entry = CacheItem(value, timestamp, readerror,
-                          self.modules[module]['parameters'][param]['datatype'])
-        self.cache[(module, param)] = entry
-        self.callback(None, 'updateItem', module, param, entry)
-        self.callback(module, 'updateItem', module, param, entry)
-        self.callback((module, param), 'updateItem', module, param, entry)
-        # TODO: change clients to use updateItem instead of updateEvent
-        self.callback(None, 'updateEvent', module, param, *entry)
-        self.callback(module, 'updateEvent', module, param, *entry)
-        self.callback((module, param), 'updateEvent', module, param, *entry)
+        self.callback(None, 'updateEvent', module, param, value, timestamp, readerror)
+        self.callback(module, 'updateEvent', module, param, value, timestamp, readerror)
+        self.callback((module, param), 'updateEvent', module, param,value, timestamp, readerror)
 
 
 class SecopClient(ProxyClient):
@@ -651,6 +644,16 @@ class SecopClient(ProxyClient):
             data = datatype.import_value(data)
         return data, qualifiers
 
+    def updateValue(self, module, param, value, timestamp, readerror):
+        entry = CacheItem(value, timestamp, readerror,
+                          self.modules[module]['parameters'][param]['datatype'])
+        self.cache[(module, param)] = entry
+        self.callback(None, 'updateItem', module, param, entry)
+        self.callback(module, 'updateItem', module, param, entry)
+        self.callback((module, param), 'updateItem', module, param, entry)
+        # TODO: change clients to use updateItem instead of updateEvent
+        super().updateValue(module, param, value, timestamp, readerror)
+
     # the following attributes may be/are intended to be overwritten by a subclass
 
     PREDEFINED_NAMES = set(frappy.params.PREDEFINED_ACCESSIBLES)
diff --git a/frappy/config.py b/frappy/config.py
index b8b645e..c19cc6a 100644
--- a/frappy/config.py
+++ b/frappy/config.py
@@ -126,13 +126,15 @@ class Config(dict):
                 self.modules.append(mod)
 
 
-def process_file(config_text):
+def process_file(filename):
+    with open(filename, 'rb') as f:
+        config_text = f.read()
     node = NodeCollector()
     mods = Collector(Mod)
     ns = {'Node': node.add, 'Mod': mods.add, 'Param': Param, 'Command': Param, 'Group': Group}
 
     # pylint: disable=exec-used
-    exec(config_text, ns)
+    exec(compile(config_text, filename, 'exec'), ns)
     return Config(node, mods)
 
 
@@ -175,9 +177,7 @@ def load_config(cfgfiles, log):
     for cfgfile in cfgfiles.split(','):
         filename = to_config_path(cfgfile, log)
         log.debug('Parsing config file %s...', filename)
-        with open(filename, 'rb') as f:
-            config_text = f.read()
-        cfg = process_file(config_text)
+        cfg = process_file(filename)
         if config:
             config.merge_modules(cfg)
         else:
diff --git a/frappy/datatypes.py b/frappy/datatypes.py
index 49a91c7..28dad55 100644
--- a/frappy/datatypes.py
+++ b/frappy/datatypes.py
@@ -274,9 +274,8 @@ class FloatRange(HasUnit, DataType):
     def compatible(self, other):
         if not isinstance(other, (FloatRange, ScaledInteger)):
             raise WrongTypeError('incompatible datatypes')
-        # avoid infinity
-        other.validate(max(sys.float_info.min, self.min))
-        other.validate(min(sys.float_info.max, self.max))
+        other.validate(self.min)
+        other.validate(self.max)
 
 
 class IntRange(DataType):
diff --git a/frappy/lib/__init__.py b/frappy/lib/__init__.py
index 81fc108..827ac03 100644
--- a/frappy/lib/__init__.py
+++ b/frappy/lib/__init__.py
@@ -396,3 +396,13 @@ class UniqueObject:
 
     def __repr__(self):
         return self.name
+
+
+def merge_status(*args):
+    """merge status
+
+    the status with biggest code wins
+    texts matching maximal code are joined with ', '
+    """
+    maxcode = max(a[0] for a in args)
+    return maxcode, ', '.join([a[1] for a in args if a[0] == maxcode and a[1]])
diff --git a/frappy/mixins.py b/frappy/mixins.py
index c353ad4..8bfad2c 100644
--- a/frappy/mixins.py
+++ b/frappy/mixins.py
@@ -21,16 +21,17 @@
 # *****************************************************************************
 
 from frappy.datatypes import BoolType, EnumType, Enum
-from frappy.core import Parameter, Writable, Attached
+from frappy.core import Parameter, Attached
 
 
-class HasControlledBy(Writable):
+class HasControlledBy:
     """mixin for modules with controlled_by
 
     in the :meth:`write_target` the hardware action to switch to own control should be done
     and in addition self.self_controlled() should be called
     """
     controlled_by = Parameter('source of target value', EnumType(members={'self': 0}), default=0)
+    target = Parameter()  # make sure target is a parameter
     inputCallbacks = ()
 
     def register_input(self, name, deactivate_control):
@@ -57,7 +58,7 @@ class HasControlledBy(Writable):
                 deactivate_control(self.name)
 
 
-class HasOutputModule(Writable):
+class HasOutputModule:
     """mixin for modules having an output module
 
     in the :meth:`write_target` the hardware action to switch to own control should be done
@@ -66,6 +67,7 @@ class HasOutputModule(Writable):
     # mandatory=False: it should be possible to configure a module with fixed control
     output_module = Attached(HasControlledBy, mandatory=False)
     control_active = Parameter('control mode', BoolType(), default=False)
+    target = Parameter()  # make sure target is a parameter
 
     def initModule(self):
         super().initModule()
@@ -85,8 +87,8 @@ class HasOutputModule(Writable):
             out.controlled_by = self.name
         self.control_active = True
 
-    def deactivate_control(self, switched_by):
+    def deactivate_control(self, source):
         """called when an other module takes over control"""
         if self.control_active:
             self.control_active = False
-            self.log.warning(f'switched to manual mode by {switched_by}')
+            self.log.warning(f'switched to manual mode by {source}')
diff --git a/frappy/modules.py b/frappy/modules.py
index fafd3b4..0105c51 100644
--- a/frappy/modules.py
+++ b/frappy/modules.py
@@ -245,7 +245,6 @@ class Feature(HasAccessibles):
     a mixin with Feature as a direct base class is recognized as a SECoP feature
     and reported in the module property 'features'
     """
-    featureName = None
 
 
 class PollInfo:
@@ -377,10 +376,10 @@ class Module(HasAccessibles):
         #    b.__name__ for b in mycls.__mro__ if b.__module__.startswith('frappy.modules')]
         # list of only the 'highest' secop module class
         self.interface_classes = [
-            b.__name__ for b in mycls.__mro__ if issubclass(Drivable, b)][0:1]
+            b.__name__ for b in mycls.__mro__ if b in SECoP_BASE_CLASSES][:1]
 
         # handle Features
-        self.features = [b.featureName or b.__name__ for b in mycls.__mro__ if Feature in b.__bases__]
+        self.features = [b.__name__ for b in mycls.__mro__ if Feature in b.__bases__]
 
         # handle accessibles
         # 1) make local copies of parameter objects
@@ -898,6 +897,7 @@ class Communicator(HasComlog, Module):
         """
         raise NotImplementedError()
 
+SECoP_BASE_CLASSES = {Readable, Writable, Drivable, Communicator}
 
 class Attached(Property):
     """a special property, defining an attached module
diff --git a/frappy_psi/convergence.py b/frappy_psi/convergence.py
index 0a34a95..6a079c4 100644
--- a/frappy_psi/convergence.py
+++ b/frappy_psi/convergence.py
@@ -21,11 +21,11 @@
 # *****************************************************************************
 
 from frappy.core import Parameter, FloatRange, BUSY, IDLE, WARN
-from frappy.states import HasStates
 from frappy.lib.statemachine import StateMachine, Retry, Stop
+from frappy.lib import merge_status
 
 
-class HasConvergence(HasStates):
+class HasConvergence:
     """mixin for convergence checks
 
     Implementation based on tolerance, settling time and timeout.
@@ -33,6 +33,8 @@ class HasConvergence(HasStates):
     fly. However, the full history is not considered, which means for example
     that the spent time inside tolerance stored already is not altered when
     changing tolerance.
+
+    does not inherit from HasStates (own state machine!)
     """
     tolerance = Parameter('absolute tolerance', FloatRange(0, unit='$'), readonly=False, default=0)
     settling_time = Parameter(
@@ -51,118 +53,131 @@ class HasConvergence(HasStates):
         As soon as the value is the first time within tolerance, the timeout criterium is changed:
         then the timeout event happens after this time + <settling_time> + <timeout>.
         ''', FloatRange(0, unit='sec'), readonly=False, default=3600)
-    status = Parameter('status determined from convergence checks', default=(IDLE, ''))
-    convergence_state = None
+    status = Parameter()  # make sure status is a parameter
+    convergence_state = None  # the state machine
 
     def earlyInit(self):
         super().earlyInit()
-        self.convergence_state = StateMachine(threaded=False, logger=self.log,
-                                              cleanup=self.cleanup, spent_inside=0)
+        self.convergence_state = StateMachine(
+            threaded=False, logger=self.log, cleanup=self.convergence_cleanup,
+            status=(IDLE, ''), spent_inside=0, stop_status=(IDLE, 'stopped'))
 
-    def cleanup(self, state):
+    def convergence_cleanup(self, state):
         state.default_cleanup(state)
         if state.stopped:
             if state.stopped is Stop:  # and not Restart
-                self.status = WARN, 'stopped'
+                self.__set_status(WARN, 'stopped')
         else:
-            self.status = WARN, repr(state.last_error)
+            self.__set_status(WARN, repr(state.last_error))
 
     def doPoll(self):
         super().doPoll()
         state = self.convergence_state
         state.cycle()
 
-    def get_min_slope(self, dif):
+    def __set_status(self, *status):
+        if status != self.convergence_state.status:
+            self.convergence_state.status = status
+            self.read_status()
+
+    def read_status(self):
+        return merge_status(super().read_status(), self.convergence_state.status)
+        #self.log.warn('inner %r conv %r merged %r', super().read_status(), self.convergence_state.status, merged)
+        #return merged
+
+    def convergence_min_slope(self, dif):
+        """calculate minimum expected slope"""
         slope = getattr(self, 'workingramp', 0) or getattr(self, 'ramp', 0)
         if slope or not self.timeout:
             return slope
         return dif / self.timeout  # assume exponential decay of dif, with time constant <tolerance>
 
-    def get_dif_tol(self):
-        value = self.read_value()
+    def convergence_dif(self):
+        """get difference target - value and tolerance"""
         tol = self.tolerance
         if not tol:
-            tol = 0.01 * max(abs(self.target), abs(value))
-        dif = abs(self.target - value)
+            tol = 0.01 * max(abs(self.target), abs(self.value))
+        dif = abs(self.target - self.value)
         return dif, tol
 
-    def start_state(self):
+    def convergence_start(self):
         """to be called from write_target"""
-        self.convergence_state.start(self.state_approach)
+        self.__set_status(BUSY, 'changed_target')
+        self.convergence_state.start(self.convergence_approach)
 
-    def state_approach(self, state):
+    def convergence_approach(self, state):
         """approaching, checking progress (busy)"""
         state.spent_inside = 0
-        dif, tol = self.get_dif_tol()
+        dif, tol = self.convergence_dif()
         if dif < tol:
             state.timeout_base = state.now
-            return self.state_inside
+            return self.convergence_inside
         if not self.timeout:
             return Retry
         if state.init:
             state.timeout_base = state.now
             state.dif_crit = dif  # criterium for resetting timeout base
-            self.status = BUSY, 'approaching'
-        state.dif_crit -= self.get_min_slope(dif) * state.delta()
+        self.__set_status(BUSY, 'approaching')
+        state.dif_crit -= self.convergence_min_slope(dif) * state.delta()
         if dif < state.dif_crit:  # progress is good: reset timeout base
             state.timeout_base = state.now
         elif state.now > state.timeout_base + self.timeout:
-            self.status = WARN, 'convergence timeout'
-            return self.state_instable
+            self.__set_status(WARN, 'convergence timeout')
+            return self.convergence_instable
         return Retry
 
-    def state_inside(self, state):
+    def convergence_inside(self, state):
         """inside tolerance, still busy"""
-        dif, tol = self.get_dif_tol()
+        dif, tol = self.convergence_dif()
         if dif > tol:
-            return self.state_outside
+            return self.convergence_outside
         state.spent_inside += state.delta()
         if state.spent_inside > self.settling_time:
-            self.status = IDLE, 'reached target'
-            return self.state_stable
+            self.__set_status(IDLE, 'reached target')
+            return self.convergence_stable
         if state.init:
-            self.status = BUSY, 'inside tolerance'
+            self.__set_status(BUSY, 'inside tolerance')
         return Retry
 
-    def state_outside(self, state):
+    def convergence_outside(self, state):
         """temporarely outside tolerance, busy"""
-        dif, tol = self.get_dif_tol()
+        dif, tol = self.convergence_dif()
         if dif < tol:
-            return self.state_inside
+            return self.convergence_inside
         if state.now > state.timeout_base + self.settling_time + self.timeout:
-            self.status = WARN, 'settling timeout'
-            return self.state_instable
+            self.__set_status(WARN, 'settling timeout')
+            return self.convergence_instable
         if state.init:
-            self.status = BUSY, 'outside tolerance'
+            self.__set_status(BUSY, 'outside tolerance')
         # do not reset the settling time on occasional outliers, count backwards instead
         state.spent_inside = max(0.0, state.spent_inside - state.delta())
         return Retry
 
-    def state_stable(self, state):
+    def convergence_stable(self, state):
         """stable, after settling_time spent within tolerance, idle"""
-        dif, tol = self.get_dif_tol()
+        dif, tol = self.convergence_dif()
         if dif <= tol:
             return Retry
-        self.status = WARN, 'instable'
+        self.__set_status(WARN, 'instable')
         state.spent_inside = max(self.settling_time, state.spent_inside)
-        return self.state_instable
+        return self.convergence_instable
 
-    def state_instable(self, state):
+    def convergence_instable(self, state):
         """went outside tolerance from stable, warning"""
-        dif, tol = self.get_dif_tol()
+        dif, tol = self.convergence_dif()
         if dif <= tol:
             state.spent_inside += state.delta()
             if state.spent_inside > self.settling_time:
-                self.status = IDLE, 'stable'  # = recovered from instable
-                return self.state_stable
+                self.__set_status(IDLE, 'stable')  # = recovered from instable
+                return self.convergence_stable
         else:
             state.spent_inside = max(0, state.spent_inside - state.delta())
         return Retry
 
-    def state_interrupt(self, state):
+    def convergence_interrupt(self, state):
         """stopping"""
-        self.status = IDLE, 'stopped'  # stop called
-        return self.state_instable
+        self.__set_status(state.stop_status)  # stop called
+        return self.convergence_instable
 
     def stop(self):
         """set to idle when busy
@@ -170,4 +185,14 @@ class HasConvergence(HasStates):
         does not stop control!
         """
         if self.isBusy():
-            self.convergence_state.start(self.state_interrupt)
+            self.convergence_state.start(self.convergence_interrupt)
+
+    def write_settling_time(self, value):
+        if self.pollInfo:
+            self.pollInfo.trigger(True)
+        return value
+
+    def write_tolerance(self, value):
+        if self.pollInfo:
+            self.pollInfo.trigger(True)
+        return value
diff --git a/frappy_psi/ips_mercury.py b/frappy_psi/ips_mercury.py
index 978bc58..467f9eb 100644
--- a/frappy_psi/ips_mercury.py
+++ b/frappy_psi/ips_mercury.py
@@ -21,7 +21,7 @@
 """oxford instruments mercury IPS power supply"""
 
 import time
-from frappy.core import Parameter, EnumType, FloatRange, BoolType, IntRange, StringType, Property, BUSY
+from frappy.core import Parameter, EnumType, FloatRange, BoolType, IntRange, Property, Module
 from frappy.lib.enum import Enum
 from frappy.errors import BadValueError, HardwareError
 from frappy_psi.magfield import Magfield, SimpleMagfield, Status
@@ -41,16 +41,16 @@ class SimpleField(MercuryChannel, SimpleMagfield):
     voltage = Parameter('leads voltage', FloatRange(unit='V'), default=0)
     atob = Parameter('field to amp', FloatRange(0, unit='A/T'), default=0)
     working_ramp = Parameter('effective ramp', FloatRange(0, unit='T/min'), default=0)
-    channel_type = 'PSU'
+    kind = 'PSU'
     slave_currents = None
     classdict = {}
 
-    def __new__(cls, name, logger, cfgdict, srv):
-        base = cls.__bases__[1]
+    def __new__(cls, name, logger, cfgdict, srv):  # pylint: disable=arguments-differ
         nunits = cfgdict.get('nunits', 1)
+        if isinstance(nunits, dict):
+            nunits = nunits['value']
         if nunits == 1:
-            obj = object.__new__(cls)
-            return obj
+            return Module.__new__(cls, name, logger, cfgdict, srv)
         classname = cls.__name__ + str(nunits)
         newclass = cls.classdict.get(classname)
         if not newclass:
@@ -62,8 +62,7 @@ class SimpleField(MercuryChannel, SimpleMagfield):
 
             newclass = type(classname, (cls,), attrs)
             cls.classdict[classname] = newclass
-        obj = object.__new__(newclass)
-        return obj
+        return Module.__new__(newclass, name, logger, cfgdict, srv)
 
     def initModule(self):
         super().initModule()
@@ -73,34 +72,34 @@ class SimpleField(MercuryChannel, SimpleMagfield):
             self.log.error('can not set to hold %r', e)
 
     def read_value(self):
-        return self.query('PSU:SIG:FLD')
+        return self.query('DEV::PSU:SIG:FLD')
 
     def read_ramp(self):
-        return self.query('PSU:SIG:RFST')
+        return self.query('DEV::PSU:SIG:RFST')
 
     def write_ramp(self, value):
-        return self.change('PSU:SIG:RFST', value)
+        return self.change('DEV::PSU:SIG:RFST', value)
 
     def read_action(self):
-        return self.query('PSU:ACTN', hold_rtoz_rtos_clmp)
+        return self.query('DEV::PSU:ACTN', hold_rtoz_rtos_clmp)
 
     def write_action(self, value):
-        return self.change('PSU:ACTN', value, hold_rtoz_rtos_clmp)
+        return self.change('DEV::PSU:ACTN', value, hold_rtoz_rtos_clmp)
 
     def read_atob(self):
-        return self.query('PSU:ATOB')
+        return self.query('DEV::PSU:ATOB')
 
     def read_voltage(self):
-        return self.query('PSU:SIG:VOLT')
+        return self.query('DEV::PSU:SIG:VOLT')
 
     def read_working_ramp(self):
-        return self.query('PSU:SIG:RFLD')
+        return self.query('DEV::PSU:SIG:RFLD')
 
     def read_setpoint(self):
-        return self.query('PSU:SIG:FSET')
+        return self.query('DEV::PSU:SIG:FSET')
 
     def set_and_go(self, value):
-        self.setpoint = self.change('PSU:SIG:FSET', value)
+        self.setpoint = self.change('DEV::PSU:SIG:FSET', value)
         assert self.write_action(Action.hold) == Action.hold
         assert self.write_action(Action.run_to_set) == Action.run_to_set
 
@@ -133,7 +132,7 @@ class SimpleField(MercuryChannel, SimpleMagfield):
 
 class Field(SimpleField, Magfield):
     persistent_field = Parameter(
-        'persistent field', FloatRange(unit='$'), readonly=False)
+        'persistent field at last switch off', FloatRange(unit='$'), readonly=False)
     wait_switch_on = Parameter(
         'wait time to ensure switch is on', FloatRange(0, unit='s'), readonly=True, default=60)
     wait_switch_off = Parameter(
@@ -142,7 +141,7 @@ class Field(SimpleField, Magfield):
         'manual indication that persistent field is bad', BoolType(), readonly=False, default=False)
 
     _field_mismatch = None
-    __init = True
+    __persistent_field = None  # internal value of persistent field
     __switch_fixed_until = 0
 
     def doPoll(self):
@@ -154,33 +153,41 @@ class Field(SimpleField, Magfield):
         # will complain and this will be handled in start_ramp_to_field
         self.switch_on_time = 0
         self.switch_off_time = 0
-        self.switch_heater = self.query('PSU:SIG:SWHT', off_on)
+        self.switch_heater = self.query('DEV::PSU:SIG:SWHT', off_on)
         super().startModule(start_events)
 
     def read_value(self):
-        current = self.query('PSU:SIG:FLD')
-        pf = self.query('PSU:SIG:PFLD')
-        if self.__init:
-            self.__init = False
-            self.persistent_field = pf
-        if self.switch_heater == self.switch_heater.on or self._field_mismatch is None:
+        current = self.query('DEV::PSU:SIG:FLD')
+        if self.switch_heater == self.switch_heater.on:
+            self.__persistent_field = current
             self.forced_persistent_field = False
-            self._field_mismatch = False
             return current
-        self._field_mismatch = abs(self.persistent_field - pf) > self.tolerance
-        return pf
+        pf = self.query('DEV::PSU:SIG:PFLD')
+        if self.__persistent_field is None:
+            self.__persistent_field = pf
+            self._field_mismatch = False
+        else:
+            self._field_mismatch = abs(self.__persistent_field - pf) > self.tolerance * 10
+        self.persistent_field = self.__persistent_field
+        return self.__persistent_field
+
+    def _check_adr(self, adr):
+        """avoid complains about bad slot"""
+        if adr.startswith('DEV:PSU.M'):
+            return
+        super()._check_adr(adr)
 
     def read_current(self):
         if self.slave_currents is None:
             self.slave_currents = [[] for _ in range(self.nunits + 1)]
         if self.nunits > 1:
             for i in range(1, self.nunits + 1):
-                curri = self.query('DEV:PSU.M%d:PSU:SIG:CURR' % i)
-                volti = self.query('DEV:PSU.M%d:PSU:SIG:VOLT' % i)
-                setattr(self, 'I%d' % i, curri)
-                setattr(self, 'V%d' % i, volti)
+                curri = self.query(f'DEV:PSU.M{i}:PSU:SIG:CURR')
+                volti = self.query(f'DEV:PSU.M{i}:PSU:SIG:VOLT')
+                setattr(self, f'I{i}', curri)
+                setattr(self, f'V{i}', volti)
                 self.slave_currents[i].append(curri)
-            current = self.query('PSU:SIG:CURR')
+            current = self.query('DEV::PSU:SIG:CURR')
             self.slave_currents[0].append(current)
             min_ = min(self.slave_currents[0]) / self.nunits
             max_ = max(self.slave_currents[0]) / self.nunits
@@ -194,14 +201,15 @@ class Field(SimpleField, Magfield):
                     if min_i - 0.1 > max_ or min_ > max_i + 0.1:  # use an arbitrary 0.1 A tolerance
                         self.log.warning('individual currents mismatch %r', self.slave_currents)
         else:
-            current = self.query('PSU:SIG:CURR')
+            current = self.query('DEV::PSU:SIG:CURR')
         if self.atob:
             return current / self.atob
         return 0
 
     def write_persistent_field(self, value):
-        if self.forced_persistent_field:
+        if self.forced_persistent_field or abs(self.__persistent_field - value) <= self.tolerance * 10:
             self._field_mismatch = False
+            self.__persistent_field = value
             return value
         raise BadValueError('changing persistent field needs forced_persistent_field=True')
 
@@ -212,7 +220,7 @@ class Field(SimpleField, Magfield):
         return super().write_target(target)
 
     def read_switch_heater(self):
-        value = self.query('PSU:SIG:SWHT', off_on)
+        value = self.query('DEV::PSU:SIG:SWHT', off_on)
         now = time.time()
         if value != self.switch_heater:
             if now < self.__switch_fixed_until:
@@ -226,10 +234,10 @@ class Field(SimpleField, Magfield):
         return value
 
     def read_wait_switch_on(self):
-        return self.query('PSU:SWONT') * 0.001
+        return self.query('DEV::PSU:SWONT') * 0.001
 
     def read_wait_switch_off(self):
-        return self.query('PSU:SWOFT') * 0.001
+        return self.query('DEV::PSU:SWOFT') * 0.001
 
     def write_switch_heater(self, value):
         if value == self.read_switch_heater():
@@ -238,20 +246,20 @@ class Field(SimpleField, Magfield):
             return value
         self.__switch_fixed_until = time.time() + 10
         self.log.debug('switch time fixed for 10 sec')
-        result = self.change('PSU:SIG:SWHT', value, off_on, n_retry=0)  # no readback check
+        result = self.change('DEV::PSU:SIG:SWHT', value, off_on, n_retry=0)  # no readback check
         return result
 
     def start_ramp_to_field(self, sm):
-        if abs(self.current - self.persistent_field) <= self.tolerance:
-            self.log.info('leads %g are already at %g', self.current, self.persistent_field)
+        if abs(self.current - self.__persistent_field) <= self.tolerance:
+            self.log.info('leads %g are already at %g', self.current, self.__persistent_field)
             return self.ramp_to_field
         try:
-            self.set_and_go(self.persistent_field)
+            self.set_and_go(self.__persistent_field)
         except (HardwareError, AssertionError) as e:
             if self.switch_heater:
                 self.log.warn('switch is already on!')
                 return self.ramp_to_field
-            self.log.warn('wait first for switch off current=%g pf=%g %r', self.current, self.persistent_field, e)
+            self.log.warn('wait first for switch off current=%g pf=%g %r', self.current, self.__persistent_field, e)
             sm.after_wait = self.ramp_to_field
             return self.wait_for_switch
         return self.ramp_to_field
@@ -274,7 +282,7 @@ class Field(SimpleField, Magfield):
             sm.try_cnt -= 1
             if sm.try_cnt < 0:
                 raise
-            self.set_and_go(sm.persistent_field)
+            self.set_and_go(self.__persistent_field)
             return Retry
 
     def wait_for_switch(self, sm):
@@ -283,14 +291,14 @@ class Field(SimpleField, Magfield):
         try:
             self.log.warn('try again')
             # try again
-            self.set_and_go(self.persistent_field)
-        except (HardwareError, AssertionError) as e:
+            self.set_and_go(self.__persistent_field)
+        except (HardwareError, AssertionError):
             return Retry
         return sm.after_wait
 
     def wait_for_switch_on(self, sm):
         self.read_switch_heater()  # trigger switch_on/off_time
-        if self.switch_heater == self.switch_heater.OFF:
+        if self.switch_heater == self.switch_heater.off:
             if sm.init:  # avoid too many states chained
                 return Retry
             self.log.warning('switch turned off manually?')
@@ -299,7 +307,7 @@ class Field(SimpleField, Magfield):
 
     def wait_for_switch_off(self, sm):
         self.read_switch_heater()
-        if self.switch_heater == self.switch_heater.ON:
+        if self.switch_heater == self.switch_heater.on:
             if sm.init:  # avoid too many states chained
                 return Retry
             self.log.warning('switch turned on manually?')
@@ -307,6 +315,9 @@ class Field(SimpleField, Magfield):
         return super().wait_for_switch_off(sm)
 
     def start_ramp_to_zero(self, sm):
+        pf = self.query('DEV::PSU:SIG:PFLD')
+        if abs(pf - self.value) > self.tolerance * 10:
+            self.log.warning('persistent field %g does not match %g after switch off', pf, self.value)
         try:
             assert self.write_action(Action.hold) == Action.hold
             assert self.write_action(Action.run_to_zero) == Action.run_to_zero
diff --git a/frappy_psi/magfield.py b/frappy_psi/magfield.py
index ae58ffc..71f128b 100644
--- a/frappy_psi/magfield.py
+++ b/frappy_psi/magfield.py
@@ -20,12 +20,11 @@
 """generic persistent magnet driver"""
 
 import time
-from frappy.core import Drivable, Parameter, Done, IDLE, BUSY, ERROR
-from frappy.datatypes import FloatRange, EnumType, ArrayOf, TupleOf, StatusType
-from frappy.features import HasTargetLimits
-from frappy.errors import ConfigError, ProgrammingError, HardwareError, BadValueError
+from frappy.core import Drivable, Parameter, BUSY, Limit
+from frappy.datatypes import FloatRange, EnumType, TupleOf, StatusType
+from frappy.errors import ConfigError, HardwareError, DisabledError
 from frappy.lib.enum import Enum
-from frappy.states import Retry, HasStates, status_code, Start
+from frappy.states import Retry, HasStates, status_code
 
 UNLIMITED = FloatRange()
 
@@ -48,8 +47,10 @@ OFF = 0
 ON = 1
 
 
-class SimpleMagfield(HasStates, HasTargetLimits, Drivable):
+class SimpleMagfield(HasStates, Drivable):
     value = Parameter('magnetic field', datatype=FloatRange(unit='T'))
+    target_min = Limit()
+    target_max = Limit()
     ramp = Parameter(
         'wanted ramp rate for field', FloatRange(unit='$/min'), readonly=False)
     # export only when different from ramp:
@@ -68,6 +69,22 @@ class SimpleMagfield(HasStates, HasTargetLimits, Drivable):
         FloatRange(0, unit='s'), readonly=False, default=30)
 
     _last_target = None
+    _symmetric_limits = False
+
+    def earlyInit(self):
+        super().earlyInit()
+        # when limits are symmetric at init, we want auto symmetric limits
+        self._symmetric_limits = self.target_min == -self.target_max
+
+    def write_target_max(self, value):
+        if self._symmetric_limits:
+            self.target_min = -value
+        return value
+
+    def write_target_min(self, value):
+        """when modified to other than a symmetric value, we assume the user does not want auto symmetric limits"""
+        self._symmetric_limits = value == -self.target_max
+        return value
 
     def checkProperties(self):
         dt = self.parameters['target'].datatype
@@ -76,6 +93,9 @@ class SimpleMagfield(HasStates, HasTargetLimits, Drivable):
             raise ConfigError('target.max not configured')
         if dt.min == UNLIMITED.min:  # not given: assume bipolar symmetric
             dt.min = -max_
+            self.target_min = max(dt.min, self.target_min)
+            if 'target_max' in self.writeDict:
+                self.writeDict.setdefault('target_min', -self.writeDict['target_max'])
         super().checkProperties()
 
     def stop(self):
@@ -101,7 +121,6 @@ class SimpleMagfield(HasStates, HasTargetLimits, Drivable):
         return last
 
     def write_target(self, target):
-        self.check_limits(target)
         self.start_machine(self.start_field_change, target=target)
         return target
 
@@ -147,8 +166,7 @@ class SimpleMagfield(HasStates, HasTargetLimits, Drivable):
 
 class Magfield(SimpleMagfield):
     status = Parameter(datatype=StatusType(Status))
-    mode = Parameter(
-        'persistent mode', EnumType(Mode), readonly=False, initwrite=False, default=Mode.PERSISTENT)
+    mode = Parameter('persistent mode', EnumType(Mode), readonly=False, default=Mode.PERSISTENT)
     switch_heater = Parameter('switch heater', EnumType(off=OFF, on=ON),
                               readonly=False, default=0)
     current = Parameter(
@@ -180,6 +198,9 @@ class Magfield(SimpleMagfield):
     def doPoll(self):
         if self.init_persistency:
             if self.read_switch_heater() and self.mode != Mode.DRIVEN:
+                # switch heater is on on startup: got to persistent mode
+                # do this after some delay, so the user might continue
+                # driving without delay after a restart
                 self.start_machine(self.go_persistent_soon, mode=self.mode)
             self.init_persistency = False
         super().doPoll()
@@ -207,9 +228,7 @@ class Magfield(SimpleMagfield):
         if self.mode == Mode.DISABLED:
             if target == 0:
                 return 0
-            self.log.info('raise error %r', target)
-            raise BadValueError('disabled')
-        self.check_limits(target)
+            raise DisabledError('disabled')
         self.start_machine(self.start_field_change, target=target, mode=self.mode)
         return target
 
diff --git a/frappy_psi/mercury.py b/frappy_psi/mercury.py
index 2ffade5..bdb5227 100644
--- a/frappy_psi/mercury.py
+++ b/frappy_psi/mercury.py
@@ -25,12 +25,13 @@ import math
 import re
 import time
 
-from frappy.core import Drivable, HasIO, Writable, \
-    Parameter, Property, Readable, StringIO, Attached, IDLE, nopoll
+from frappy.core import Drivable, HasIO, Writable, StatusType, \
+    Parameter, Property, Readable, StringIO, Attached, IDLE, RAMPING, nopoll
 from frappy.datatypes import EnumType, FloatRange, StringType, StructOf, BoolType, TupleOf
-from frappy.errors import HardwareError, ProgrammingError, ConfigError
+from frappy.errors import HardwareError, ProgrammingError, ConfigError, RangeError
 from frappy_psi.convergence import HasConvergence
-from frappy.lib.enum import Enum
+from frappy.states import Retry, Finish
+from frappy.mixins import HasOutputModule, HasControlledBy
 
 
 VALUE_UNIT = re.compile(r'(.*\d|inf)([A-Za-z/%]*)$')
@@ -126,7 +127,7 @@ class MercuryChannel(HasIO):
                 msg = f'invalid reply {reply!r} to cmd {cmd!r}'
         raise HardwareError(msg) from None
 
-    def multichange(self, adr, values, convert=as_float, tolerance=0, n_retry=3):
+    def multichange(self, adr, values, convert=as_float, tolerance=0, n_retry=3, lazy=False):
         """set parameter(s) in mercury syntax
 
         :param adr: as in multiquery method. SET: is added automatically
@@ -134,6 +135,7 @@ class MercuryChannel(HasIO):
         :param convert: a converter function (converts given value to string and replied string to value)
         :param tolerance: tolerance for readback check
         :param n_retry: number of retries or 0 for no readback check
+        :param lazy: check direct reply only (no additional query)
         :return:  the values as tuple
 
         Example (kind=TEMP, slot=DB6.T1:
@@ -145,6 +147,7 @@ class MercuryChannel(HasIO):
         adr = self._complete_adr(adr)
         params = [f'{k}:{convert(v)}' for k, v in values]
         cmd = f"SET:{adr}:{':'.join(params)}"
+        givenkeys = tuple(v[0] for v in values)
         for _ in range(max(1, n_retry)):  # try n_retry times or until readback result matches
             reply = self.communicate(cmd)
             head = f'STAT:SET:{adr}:'
@@ -153,29 +156,35 @@ class MercuryChannel(HasIO):
                 replyiter = iter(reply[len(head):].split(':'))
                 # reshuffle reply=(k1, r1, v1, k2, r2, v1) --> keys = (k1, k2), result = (r1, r2), valid = (v1, v2)
                 keys, result, valid = zip(*zip(replyiter, replyiter, replyiter))
-                assert keys == tuple(k for k, _ in values)
+                assert keys == givenkeys
                 assert any(v == 'VALID' for v in valid)
                 result = tuple(convert(r) for r in result)
             except (AssertionError, AttributeError, ValueError) as e:
                 time.sleep(0.1)  # in case of missed replies this might help to skip garbage
                 raise HardwareError(f'invalid reply {reply!r} to cmd {cmd!r}') from e
             if n_retry == 0:
-                return [v[1] for v in values]  # no readback check
-            keys = [v[0] for v in values]
-            debug = []
-            readback = self.multiquery(adr, keys, convert, debug)
-            for k, r, b in zip(keys, result, readback):
+                return [v for _, v in values]
+            if lazy:
+                debug = [reply]
+                readback = [v for _, v in values]
+            else:
+                debug = []
+                readback = list(self.multiquery(adr, givenkeys, convert, debug))
+            failed = False
+            for i, ((k, v), r, b) in enumerate(zip(values, result, readback)):
                 if convert is as_float:
                     tol = max(abs(r) * 1e-3, abs(b) * 1e-3, tolerance)
-                    if abs(r - b) > tol:
-                        break
-                elif r != b:
-                    break
-            else:
+                    if abs(b - v) > tol or abs(r - v) > tol:
+                        readback[i] = None
+                        failed = True
+                elif b != v or r != v:
+                    readback[i] = None
+                    failed = True
+            if not failed:
                 return readback
-            self.log.warning('sent: %s', cmd)
-            self.log.warning('got: %s', debug[0])
-        return readback
+        self.log.warning('sent: %s', cmd)
+        self.log.warning('got: %s', debug[0])
+        return tuple(v[1] if b is None else b for b, v in zip(readback, values))
 
     def query(self, adr, convert=as_float):
         """query a single parameter
@@ -185,9 +194,9 @@ class MercuryChannel(HasIO):
         adr, _, name = adr.rpartition(':')
         return self.multiquery(adr, [name], convert)[0]
 
-    def change(self, adr, value, convert=as_float, tolerance=0, n_retry=3):
+    def change(self, adr, value, convert=as_float, tolerance=0, n_retry=3, lazy=False):
         adr, _, name = adr.rpartition(':')
-        return self.multichange(adr, [(name, value)], convert, tolerance, n_retry)[0]
+        return self.multichange(adr, [(name, value)], convert, tolerance, n_retry, lazy)[0]
 
 
 class TemperatureSensor(MercuryChannel, Readable):
@@ -202,38 +211,14 @@ class TemperatureSensor(MercuryChannel, Readable):
         return self.query('DEV::TEMP:SIG:RES')
 
 
-class HasInput(MercuryChannel):
-    controlled_by = Parameter('source of target value', EnumType(members={'self': SELF}), default=0)
-    # do not know why this? target = Parameter(readonly=False)
-    input_callbacks = ()
-
-    def register_input(self, name, control_off):
-        """register input
-
-        :param name: the name of the module (for controlled_by enum)
-        :param control_off: a method on the input module to switch off control
-        """
-        if not self.input_callbacks:
-            self.input_callbacks = []
-        self.input_callbacks.append(control_off)
-        prev_enum = self.parameters['controlled_by'].datatype._enum
-        # add enum member, using autoincrement feature of Enum
-        self.parameters['controlled_by'].datatype = EnumType(Enum(prev_enum, **{name: None}))
-
-    def write_controlled_by(self, value):
-        if self.controlled_by == value:
-            return value
-        self.controlled_by = value
-        if value == SELF:
-            for control_off in self.input_callbacks:
-                control_off()
-        return value
+class HasInput(HasControlledBy, MercuryChannel):
+    pass
 
 
-class Loop(HasConvergence, MercuryChannel, Drivable):
+class Loop(HasOutputModule, MercuryChannel, Drivable):
     """common base class for loops"""
-    control_active = Parameter('control mode', BoolType())
     output_module = Attached(HasInput, mandatory=False)
+    control_active = Parameter(readonly=False)
     ctrlpars = Parameter(
         'pid (proportional band, integral time, differential time',
         StructOf(p=FloatRange(0, unit='$'), i=FloatRange(0, unit='min'), d=FloatRange(0, unit='min')),
@@ -241,35 +226,15 @@ class Loop(HasConvergence, MercuryChannel, Drivable):
     )
     enable_pid_table = Parameter('', BoolType(), readonly=False)
 
-    def initModule(self):
-        super().initModule()
-        if self.output_module:
-            self.output_module.register_input(self.name, self.control_off)
-
-    def control_off(self):
-        if self.control_active:
-            self.log.warning('switch to manual mode')
-            self.write_control_active(False)
-
-    def set_output(self, active):
+    def set_output(self, active, source='HW'):
         if active:
-            if self.output_module and self.output_module.controlled_by != self.name:
-                self.output_module.write_controlled_by(self.name)
+            self.activate_control()
         else:
-            if self.output_module and self.output_module.controlled_by != SELF:
-                self.output_module.write_controlled_by(SELF)
-            status = IDLE, 'control inactive'
-            if self.status != status:
-                self.status = status
+            self.deactivate_control(source)
 
     def set_target(self, target):
-        if self.control_active:
-            self.set_output(True)
-        else:
-            self.log.warning('switch loop control on')
-        self.write_control_active(True)
+        self.set_output(True)
         self.target = target
-        self.start_state()
 
     def read_enable_pid_table(self):
         return self.query(f'DEV::{self.kinds[0]}:LOOP:PIDT', off_on)
@@ -286,8 +251,24 @@ class Loop(HasConvergence, MercuryChannel, Drivable):
         pid = self.multichange(f'DEV::{self.kinds[0]}:LOOP', [(k, value[k.lower()]) for k in 'PID'])
         return {k.lower(): v for k, v in zip('PID', pid)}
 
+    def read_status(self):
+        return IDLE, ''
 
-class HeaterOutput(HasInput, MercuryChannel, Writable):
+
+class ConvLoop(HasConvergence, Loop):
+    def deactivate_control(self, source):
+        if self.control_active:
+            super().deactivate_control(source)
+            self.convergence_state.start(self.inactive_state)
+            if self.pollInfo:
+                self.pollInfo.trigger(True)
+
+    def inactive_state(self, state):
+        self.convergence_state.status = IDLE, 'control inactive'
+        return Finish
+
+
+class HeaterOutput(HasInput, Writable):
     """heater output
 
     Remark:
@@ -324,7 +305,7 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
         if self._last_target is not None:
             if not self.true_power:
                 self._volt_target = math.sqrt(self._last_target * self.resistivity)
-            self.change('DEV::HTR:SIG:VOLT', self._volt_target)
+            self.change('DEV::HTR:SIG:VOLT', self._volt_target, tolerance=2e-4)
         return self.resistivity
 
     def read_status(self):
@@ -344,7 +325,7 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
                 self.write_resistivity(round(res, 1))
                 if self.controlled_by == 0:
                     self._volt_target = math.sqrt(self._last_target * self.resistivity)
-                    self.change('DEV::HTR:SIG:VOLT', self._volt_target)
+                    self.change('DEV::HTR:SIG:VOLT', self._volt_target, tolerance=2e-4)
         return volt * current
 
     def read_target(self):
@@ -362,23 +343,25 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
         might be used by a software loop
         """
         self._volt_target = math.sqrt(target * self.resistivity)
-        self.change('DEV::HTR:SIG:VOLT', self._volt_target)
+        self.change('DEV::HTR:SIG:VOLT', self._volt_target, tolerance=2e-4)
         self._last_target = target
         return target
 
     def write_target(self, value):
-        self.write_controlled_by(SELF)
+        self.self_controlled()
         return self.set_target(value)
 
 
-class TemperatureLoop(TemperatureSensor, Loop, Drivable):
+class TemperatureLoop(TemperatureSensor, ConvLoop):
     kind = 'TEMP'
     output_module = Attached(HasInput, mandatory=False)
     ramp = Parameter('ramp rate', FloatRange(0, unit='$/min'), readonly=False)
     enable_ramp = Parameter('enable ramp rate', BoolType(), readonly=False)
     setpoint = Parameter('working setpoint (differs from target when ramping)', FloatRange(0, unit='$'))
+    status = Parameter(datatype=StatusType(Drivable, 'RAMPING'))  # add ramping status
     tolerance = Parameter(default=0.1)
     _last_setpoint_change = None
+    __status = IDLE, ''
     # overridden in subclass frappy_psi.triton.TemperatureLoop
     ENABLE = 'TEMP:LOOP:ENAB'
     ENABLE_RAMP = 'TEMP:LOOP:RENA'
@@ -394,7 +377,9 @@ class TemperatureLoop(TemperatureSensor, Loop, Drivable):
         return active
 
     def write_control_active(self, value):
-        self.set_output(value)
+        if value:
+            raise RangeError('write to target to switch control on')
+        self.set_output(value, 'user')
         return self.change(f'DEV::{self.ENABLE}', value, off_on)
 
     @nopoll  # polled by read_setpoint
@@ -407,43 +392,65 @@ class TemperatureLoop(TemperatureSensor, Loop, Drivable):
     def read_setpoint(self):
         setpoint = self.query('DEV::TEMP:LOOP:TSET')
         if self.enable_ramp:
-            if setpoint == self.setpoint:
+            if setpoint == self.target:
+                self.__ramping = False
+            elif setpoint == self.setpoint:
                 # update target when working setpoint does no longer change
-                if setpoint != self.target and self._last_setpoint_change is not None:
+                if self._last_setpoint_change is not None:
                     unchanged_since = time.time() - self._last_setpoint_change
                     if unchanged_since > max(12.0, 0.06 / max(1e-4, self.ramp)):
+                        self.__ramping = False
                         self.target = self.setpoint
                 return setpoint
             self._last_setpoint_change = time.time()
         else:
+            self.__ramping = False
             self.target = setpoint
         return setpoint
 
+    def set_target(self, target):
+        self.change(f'DEV::{self.ENABLE}', True, off_on)
+        super().set_target(target)
+
+    def deactivate_control(self, source):
+        if self.__ramping:
+            self.__ramping = False
+            # stop ramping setpoint
+            self.change('DEV::TEMP:LOOP:TSET', self.read_setpoint(), lazy=True)
+        super().deactivate_control(source)
+
+    def ramping_state(self, state):
+        self.read_setpoint()
+        if self.__ramping:
+            return Retry
+        return self.convergence_approach
+
     def write_target(self, value):
-        target = self.change('DEV::TEMP:LOOP:TSET', value)
+        target = self.change('DEV::TEMP:LOOP:TSET', value, lazy=True)
         if self.enable_ramp:
             self._last_setpoint_change = None
+            self.__ramping = True
             self.set_target(value)
+            self.convergence_state.status = RAMPING, 'ramping'
+            self.read_status()
+            self.convergence_state.start(self.ramping_state)
         else:
             self.set_target(target)
+            self.convergence_start()
+        self.read_status()
         return self.target
 
     def read_enable_ramp(self):
         return self.query(f'DEV::{self.ENABLE_RAMP}', off_on)
 
     def write_enable_ramp(self, value):
-        return self.change(f'DEV::{self.ENABLE_RAMP}', value, off_on)
-
-    def set_output(self, active):
-        if active:
-            if self.output_module and self.output_module.controlled_by != self.name:
-                self.output_module.write_controlled_by(self.name)
-        else:
-            if self.output_module and self.output_module.controlled_by != SELF:
-                self.output_module.write_controlled_by(SELF)
-            status = IDLE, 'control inactive'
-            if self.status != status:
-                self.status = status
+        if self.enable_ramp < value:  # ramp_enable was off: start from current value
+            self.change('DEV::TEMP:LOOP:TSET', self.value, lazy=True)
+        result = self.change(f'DEV::{self.ENABLE_RAMP}', value, off_on)
+        if self.isDriving() and value != self.enable_ramp:
+            self.enable_ramp = value
+            self.write_target(self.target)
+        return result
 
     def read_ramp(self):
         result = self.query(f'DEV::{self.RAMP_RATE}')
@@ -470,7 +477,7 @@ class PressureSensor(MercuryChannel, Readable):
         return self.query('DEV::PRES:SIG:PRES')
 
 
-class ValvePos(HasInput, MercuryChannel, Drivable):
+class ValvePos(HasInput, Drivable):
     kind = 'PRES,AUX'
     value = Parameter('value pos', FloatRange(unit='%'), readonly=False)
     target = Parameter('valve pos target', FloatRange(0, 100, unit='$'), readonly=False)
@@ -491,11 +498,11 @@ class ValvePos(HasInput, MercuryChannel, Drivable):
         return self.query('DEV::PRES:LOOP:FSET')
 
     def write_target(self, value):
-        self.write_controlled_by(SELF)
+        self.self_controlled()
         return self.change('DEV::PRES:LOOP:FSET', value)
 
 
-class PressureLoop(HasInput, PressureSensor, Loop, Drivable):
+class PressureLoop(PressureSensor, HasControlledBy, ConvLoop):
     kind = 'PRES'
     output_module = Attached(ValvePos, mandatory=False)
     tolerance = Parameter(default=0.1)
@@ -506,7 +513,7 @@ class PressureLoop(HasInput, PressureSensor, Loop, Drivable):
         return active
 
     def write_control_active(self, value):
-        self.set_output(value)
+        self.set_output(value, 'user')
         return self.change('DEV::PRES:LOOP:FAUT', value, off_on)
 
     def read_target(self):
@@ -521,7 +528,7 @@ class PressureLoop(HasInput, PressureSensor, Loop, Drivable):
         super().set_target(target)
 
     def write_target(self, value):
-        self.write_controlled_by(SELF)
+        self.self_controlled()
         self.set_target(value)
         return value
 
@@ -548,14 +555,13 @@ class HasAutoFlow:
             self.needle_valve.register_input(self.name, self.auto_flow_off)
 
     def write_auto_flow(self, value):
-        if value:
-            if self.needle_valve and self.needle_valve.controlled_by != self.name:
-                self.needle_valve.write_controlled_by(self.name)
-        else:
-            if self.needle_valve and self.needle_valve.controlled_by != SELF:
-                self.needle_valve.write_controlled_by(SELF)
-            _, (fmin, _) = self.flowpars
-            self.needle_valve.write_target(fmin)
+        if self.needle_valve:
+            if value:
+                self.needle_valve.controlled_by = self.name
+            else:
+                if self.needle_valve.controlled_by != SELF:
+                    self.needle_valve.controlled_by = SELF
+                self.needle_valve.write_target(self.flowpars[1][0])  # flow min
         return value
 
     def auto_flow_off(self):
diff --git a/frappy_psi/sea.py b/frappy_psi/sea.py
index c73b1be..c78b6f0 100644
--- a/frappy_psi/sea.py
+++ b/frappy_psi/sea.py
@@ -40,9 +40,8 @@ from os.path import expanduser, join, exists
 from frappy.client import ProxyClient
 from frappy.datatypes import ArrayOf, BoolType, \
     EnumType, FloatRange, IntRange, StringType
-from frappy.errors import ConfigError, HardwareError, secop_error, NoSuchModuleError, \
-    CommunicationFailedError
-from frappy.lib import generalConfig, mkthread, formatExtendedStack
+from frappy.errors import ConfigError, HardwareError, secop_error, CommunicationFailedError
+from frappy.lib import generalConfig, mkthread
 from frappy.lib.asynconn import AsynConn, ConnectionClosed
 from frappy.modules import Attached, Command, Done, Drivable, \
     Module, Parameter, Property, Readable, Writable
@@ -62,7 +61,7 @@ Mod(%(seaconn)r,
 """
 
 CFG_MODULE = """Mod(%(module)r,
-    'frappy_psi.sea.%(modcls)s',
+    'frappy_psi.sea.%(modcls)s', '',
     io = %(seaconn)r,
     sea_object = %(module)r,
 )
@@ -75,18 +74,18 @@ SERVICE_NAMES = {
 }
 
 SEA_DIR = expanduser('~/sea')
-for confdir in generalConfig.confdir.split(os.pathsep):
-    seaconfdir = join(confdir, 'sea')
-    if exists(seaconfdir):
-        break
-else:
-    seaconfdir = os.environ.get('FRAPPY_SEA_DIR')
+seaconfdir = os.environ.get('FRAPPY_SEA_DIR')
+if not exists(seaconfdir):
+    for confdir in generalConfig.confdir.split(os.pathsep):
+        seaconfdir = join(confdir, 'sea')
+        if exists(seaconfdir):
+            break
 
 
 def get_sea_port(instance):
     for filename in ('sea_%s.tcl' % instance, 'sea.tcl'):
         try:
-            with open(join(SEA_DIR, filename)) as f:
+            with open(join(SEA_DIR, filename), encoding='utf-8') as f:
                 for line in f:
                     linesplit = line.split()
                     if len(linesplit) == 3:
@@ -115,18 +114,21 @@ class SeaClient(ProxyClient, Module):
     _instance = None
 
     def __init__(self, name, log, opts, srv):
-        instance = srv.node_cfg['name'].rsplit('_', 1)[0]
+        nodename = srv.node_cfg.get('name') or srv.node_cfg.get('equipment_id')
+        instance = nodename.rsplit('_', 1)[0]
         if 'uri' not in opts:
             self._instance = instance
             port = get_sea_port(instance)
             if port is None:
                 raise ConfigError('missing sea port for %s' % instance)
-            opts['uri'] = 'tcp://localhost:%s' % port
+            opts['uri'] = {'value': 'tcp://localhost:%s' % port}
         self.objects = set()
         self.shutdown = False
         self.path2param = {}
         self._write_lock = threading.Lock()
         config = opts.get('config')
+        if isinstance(config, dict):
+            config = config['value']
         if config:
             self.default_json_file[name] = config.split()[0] + '.json'
         self.syncio = None
@@ -147,14 +149,17 @@ class SeaClient(ProxyClient, Module):
     def _connect(self, started_callback):
         if self._instance:
             if not self._service_manager:
-                from servicemanager import SeaManager
-                self._service_manager = SeaManager()
-            self._service_manager.do_start(self._instance)
+                if self._service_manager is None:
+                    try:
+                        from servicemanager import SeaManager  # pylint: disable=import-outside-toplevel
+                        self._service_manager = SeaManager()
+                    except ImportError:
+                        self._service_manager = False
+            if self._service_manager:
+                self._service_manager.do_start(self._instance)
         if '//' not in self.uri:
             self.uri = 'tcp://' + self.uri
         self.asynio = AsynConn(self.uri)
-        # print('CONNECT', self.uri, self.asynio)
-        # print(formatExtendedStack())
         reply = self.asynio.readline()
         if reply != b'OK':
             raise CommunicationFailedError('reply %r should be "OK"' % reply)
@@ -184,13 +189,11 @@ class SeaClient(ProxyClient, Module):
                         pass
                     self._connect(None)
                 self.syncio = AsynConn(self.uri)
-                # print('SYNCIO', self.uri)
                 assert self.syncio.readline() == b'OK'
                 self.syncio.writeline(b'seauser seaser')
                 assert self.syncio.readline() == b'Login OK'
-                print('connected to %s' % self.uri)
+                self.log.info('connected to %s', self.uri)
             self.syncio.flush_recv()
-            # print('> %s' % command)
             ft = 'fulltransAct' if quiet else 'fulltransact'
             self.syncio.writeline(('%s %s' % (ft, command)).encode())
             result = None
@@ -203,19 +206,18 @@ class SeaClient(ProxyClient, Module):
                 except ConnectionClosed:
                     break
                 reply = reply.decode()
-                # print('< %s' % reply)
                 if reply.startswith('TRANSACTIONSTART'):
                     result = []
                     continue
                 if reply == 'TRANSACTIONFINISHED':
                     if result is None:
-                        print('missing TRANSACTIONSTART on: %s' % command)
+                        self.log.info('missing TRANSACTIONSTART on: %s', command)
                         return ''
                     if not result:
                         return ''
                     return '\n'.join(result)
                 if result is None:
-                    print('swallow: %s' % reply)
+                    self.log.info('swallow: %s', reply)
                     continue
                 if not result:
                     result = [reply.split('=', 1)[-1]]
@@ -234,7 +236,7 @@ class SeaClient(ProxyClient, Module):
             try:
                 msg = json.loads(reply)
             except Exception as e:
-                print(repr(e), reply)
+                self.log.warn('bad reply %r %r', e, reply)
                 continue
             if isinstance(msg, str):
                 if msg.startswith('_E '):
@@ -259,12 +261,12 @@ class SeaClient(ProxyClient, Module):
                 continue
             if flag != 'hdbevent':
                 if obj not in ('frappy_async_client', 'get_all_param'):
-                    print('SKIP', msg)
+                    self.log.debug('skip %r', msg)
                 continue
             if not data:
                 continue
             if not isinstance(data, dict):
-                print('what means %r' % msg)
+                self.log.debug('what means %r', msg)
                 continue
             now = time.time()
             for path, value in data.items():
@@ -318,7 +320,7 @@ class SeaClient(ProxyClient, Module):
 
 
 class SeaConfigCreator(SeaClient):
-    def startModule(self, started_callback):
+    def startModule(self, start_events):
         """save objects (and sub-objects) description and exit"""
         self._connect(None)
         reply = self.request('describe_all')
@@ -343,20 +345,20 @@ class SeaConfigCreator(SeaClient):
             service = SERVICE_NAMES[ext]
             seaconn = 'sea_' + service
             cfgfile = join(seaconfdir, stripped + '_cfg.py')
-            with open(cfgfile, 'w') as fp:
-                fp.write(CFG_HEADER % dict(config=filename, seaconn=seaconn, service=service,
-                                           nodedescr=description.get(filename, filename)))
+            with open(cfgfile, 'w', encoding='utf-8') as fp:
+                fp.write(CFG_HEADER % {'config': filename, 'seaconn': seaconn, 'service': service,
+                                       'nodedescr': description.get(filename, filename)})
                 for obj in descr:
-                    fp.write(CFG_MODULE % dict(modcls=modcls[obj], module=obj, seaconn=seaconn))
+                    fp.write(CFG_MODULE % {'modcls': modcls[obj], 'module': obj, 'seaconn': seaconn})
             content = json.dumps(descr).replace('}, {', '},\n{').replace('[{', '[\n{').replace('}]}, ', '}]},\n\n')
             result.append('%s\n' % cfgfile)
-            with open(join(seaconfdir, filename + '.json'), 'w') as fp:
+            with open(join(seaconfdir, filename + '.json'), 'w', encoding='utf-8') as fp:
                 fp.write(content + '\n')
             result.append('%s: %s' % (filename, ','.join(n for n in descr)))
         raise SystemExit('; '.join(result))
 
     @Command(StringType(), result=StringType())
-    def query(self, cmd):
+    def query(self, cmd, quiet=False):
         """a request checking for errors and accepting 0 or 1 line as result"""
         errors = []
         reply = None
@@ -400,12 +402,18 @@ class SeaModule(Module):
     sea_object = None
     hdbpath = None  # hdbpath for main writable
 
+    # pylint: disable=too-many-statements,arguments-differ,too-many-branches
     def __new__(cls, name, logger, cfgdict, srv):
         if hasattr(srv, 'extra_sea_modules'):
             extra_modules = srv.extra_sea_modules
         else:
             extra_modules = {}
             srv.extra_sea_modules = extra_modules
+        for k, v in cfgdict.items():
+            try:
+                cfgdict[k] = v['value']
+            except (KeyError, TypeError):
+                pass
         json_file = cfgdict.pop('json_file', None) or SeaClient.default_json_file[cfgdict['io']]
         visibility_level = cfgdict.pop('visibility_level', 2)
 
@@ -416,25 +424,22 @@ class SeaModule(Module):
             paramdesc['key'] = 'value'
             if issubclass(cls, SeaWritable):
                 if paramdesc.get('readonly', True):
-                    raise ConfigError('%s/%s is not writable' % (sea_object, paramdesc['path']))
+                    raise ConfigError(f"{sea_object}/{paramdesc['path']} is not writable")
                 params.insert(0, paramdesc.copy())  # copy value
                 paramdesc['key'] = 'target'
                 paramdesc['readonly'] = False
             extra_module_set = ()
             if 'description' not in cfgdict:
-                cfgdict['description'] = '%s@%s' % (single_module, json_file)
+                cfgdict['description'] = f'{single_module}@{json_file}'
         else:
             sea_object = cfgdict.pop('sea_object')
             rel_paths = cfgdict.pop('rel_paths', '.')
             if 'description' not in cfgdict:
                 cfgdict['description'] = '%s@%s%s' % (
-                    name, json_file, '' if rel_paths == '.' else ' (rel_paths=%s)' % rel_paths)
+                    name, json_file, '' if rel_paths == '.' else f' (rel_paths={rel_paths})')
 
-            # with open(join(seaconfdir, json_file + '.json')) as fp:
-            #    sea_object, descr = json.load(fp)
-            with open(join(seaconfdir, json_file)) as fp:
+            with open(join(seaconfdir, json_file), encoding='utf-8') as fp:
                 content = json.load(fp)
-                # print(json_file, content.keys())
                 descr = content[sea_object]
             if rel_paths == '*' or not rel_paths:
                 # take all
@@ -478,7 +483,6 @@ class SeaModule(Module):
                         result.pop(0)
                 else:
                     logger.error('%s: no value found', name)
-                # logger.info('PARAMS %s %r', name, result)
             base = descr['base']
             params = descr['params']
             if issubclass(cls, SeaWritable):
@@ -486,14 +490,14 @@ class SeaModule(Module):
                 assert paramdesc['key'] == 'value'
                 params.append(paramdesc.copy())  # copy value?
                 if paramdesc.get('readonly', True):
-                    raise ConfigError('%s/%s is not writable' % (sea_object, paramdesc['path']))
+                    raise ConfigError(f"{sea_object}/{paramdesc['path']} is not writable")
                 paramdesc['key'] = 'target'
                 paramdesc['readonly'] = False
             extra_module_set = cfgdict.pop('extra_modules', ())
             if extra_module_set:
                 extra_module_set = set(extra_module_set.replace(',', ' ').split())
         path2param = {}
-        attributes = dict(sea_object=sea_object, path2param=path2param)
+        attributes = {'sea_object': sea_object, 'path2param': path2param}
 
         # some guesses about visibility (may be overriden in *_cfg.py):
         if sea_object in ('table', 'cc'):
@@ -504,12 +508,10 @@ class SeaModule(Module):
             path = paramdesc['path']
             readonly = paramdesc.get('readonly', True)
             dt = get_datatype(paramdesc)
-            #print('----', sea_object)
-            #print(dt, paramdesc)
-            kwds = dict(description=paramdesc.get('description', path),
-                        datatype=dt,
-                        visibility=paramdesc.get('visibility', 1),
-                        needscfg=False, readonly=readonly)
+            kwds = {'description': paramdesc.get('description', path),
+                    'datatype': dt,
+                    'visibility': paramdesc.get('visibility', 1),
+                    'needscfg': False, 'readonly': readonly}
             if kwds['datatype'] is None:
                 kwds.update(visibility=3, default='', datatype=StringType())
             pathlist = path.split('/') if path else []
@@ -555,10 +557,8 @@ class SeaModule(Module):
                 continue  # skip this parameter
             path2param.setdefault(hdbpath, []).append((name, key))
             attributes[key] = pobj
-            # if hasattr(cls, 'read_' + key):
-            #     print('override %s.read_%s' % (cls.__name__, key))
 
-            def rfunc(self, cmd='hval %s/%s' % (base, path)):
+            def rfunc(self, cmd=f'hval {base}/{path}'):
                 reply = self.io.query(cmd, True)
                 try:
                     reply = float(reply)
@@ -571,15 +571,13 @@ class SeaModule(Module):
             attributes['read_' + key] = rfunc
 
             if not readonly:
-                # if hasattr(cls, 'write_' + key):
-                #     print('override %s.write_%s' % (cls.__name__, key))
 
                 def wfunc(self, value, datatype=datatype, command=paramdesc['cmd']):
                     value = datatype.export_value(value)
                     if isinstance(value, bool):
                         value = int(value)
                         # TODO: check if more has to be done for valid tcl data (strings?)
-                    cmd = "%s %s" % (command, value)
+                    cmd = f'{command} {value}'
                     self.io.query(cmd)
                     return Done
 
@@ -596,7 +594,7 @@ class SeaModule(Module):
                 attributes[pname] = pobj
                 pobj.__set_name__(cls, pname)
 
-        classname = '%s_%s' % (cls.__name__, name)
+        classname = f'{cls.__name__}_{name}'
         newcls = type(classname, (cls,), attributes)
         result = Module.__new__(newcls)
         return result
@@ -609,11 +607,9 @@ class SeaModule(Module):
         try:
             pobj = self.parameters[parameter]
         except KeyError:
-            print(self.name, parameter)
+            self.log.error('do not know %s:%s', self.name, parameter)
             raise
         pobj.timestamp = timestamp
-        #if not pobj.readonly and pobj.value != value:
-        #    print('UPDATE', module, parameter, value)
         # should be done here: deal with clock differences
         if not readerror:
             try:
@@ -668,7 +664,7 @@ class SeaDrivable(SeaModule, Drivable):
     #    return self.target
 
     def write_target(self, value):
-        self.io.query('run %s %s' % (self.sea_object, value))
+        self.io.query(f'run {self.sea_object} {value}')
         # self.status = [self.Status.BUSY, 'driving']
         return value
 
@@ -701,4 +697,4 @@ class SeaDrivable(SeaModule, Drivable):
         - on stdsct drivables this will call the halt script
         - on EaseDriv this will set the stopped state
         """
-        self.io.query('%s is_running 0' % self.sea_object)
+        self.io.query(f'{self.sea_object} is_running 0')
diff --git a/frappy_psi/triton.py b/frappy_psi/triton.py
index 1feffd8..99f7f40 100644
--- a/frappy_psi/triton.py
+++ b/frappy_psi/triton.py
@@ -20,14 +20,13 @@
 # *****************************************************************************
 """oxford instruments triton (kelvinoxjt dil)"""
 
-from math import sqrt, log10
+from math import sqrt
 from frappy.core import Writable, Parameter, Readable, Drivable, IDLE, WARN, BUSY, ERROR, \
     Done, Property
 from frappy.datatypes import EnumType, FloatRange, StringType
 from frappy.lib.enum import Enum
 from frappy_psi.mercury import MercuryChannel, Mapped, off_on, HasInput, SELF
-from frappy.lib import clamp
-import frappy_psi.mercury as mercury
+from frappy_psi import mercury
 
 actions = Enum(none=0, condense=1, circulate=2, collect=3)
 open_close = Mapped(CLOSE=0, OPEN=1)
@@ -36,7 +35,7 @@ actions_map.mapping['NONE'] = actions.none  # when writing, STOP is used instead
 
 
 class Action(MercuryChannel, Writable):
-    channel_type = 'ACTN'
+    kind = 'ACTN'
     cooldown_channel = Property('cool down channel', StringType(), 'T5')
     mix_channel = Property('mix channel', StringType(), 'T5')
     value = Parameter('running action', EnumType(actions))
@@ -72,7 +71,7 @@ class Action(MercuryChannel, Writable):
 
 
 class Valve(MercuryChannel, Drivable):
-    channel_type = 'VALV'
+    kind = 'VALV'
     value = Parameter('valve state', EnumType(closed=0, opened=1))
     target = Parameter('valve target', EnumType(close=0, open=1))
 
@@ -82,7 +81,7 @@ class Valve(MercuryChannel, Drivable):
         self.read_status()
 
     def read_value(self):
-        return self.query('VALV:SIG:STATE', open_close)
+        return self.query('DEV::VALV:SIG:STATE', open_close)
 
     def read_status(self):
         pos = self.read_value()
@@ -92,41 +91,41 @@ class Valve(MercuryChannel, Drivable):
             # success
             if self._try_count:
                 # make sure last sent command was not opposite
-                self.change('VALV:SIG:STATE', self.target, open_close)
+                self.change('DEV::VALV:SIG:STATE', self.target, open_close)
             self._try_count = None
             self.setFastPoll(False)
             return IDLE, ''
         self._try_count += 1
         if self._try_count % 4 == 0:
             # send to opposite position in order to unblock
-            self.change('VALV:SIG:STATE', pos, open_close)
+            self.change('DEV::VALV:SIG:STATE', pos, open_close)
             return BUSY, 'unblock'
         if self._try_count > 9:
             # make sure system does not toggle later
-            self.change('VALV:SIG:STATE', pos, open_close)
+            self.change('DEV::VALV:SIG:STATE', pos, open_close)
             return ERROR, 'can not %s valve' % self.target.name
-        self.change('VALV:SIG:STATE', self.target, open_close)
+        self.change('DEV::VALV:SIG:STATE', self.target, open_close)
         return BUSY, 'waiting'
 
     def write_target(self, value):
         if value != self.read_value():
             self._try_count = 0
             self.setFastPoll(True, 0.25)
-            self.change('VALV:SIG:STATE', value, open_close)
+            self.change('DEV::VALV:SIG:STATE', value, open_close)
             self.status = BUSY, self.target.name
         return value
 
 
 class Pump(MercuryChannel, Writable):
-    channel_type = 'PUMP'
+    kind = 'PUMP'
     value = Parameter('pump state', EnumType(off=0, on=1))
     target = Parameter('pump target', EnumType(off=0, on=1))
 
     def read_value(self):
-        return self.query('PUMP:SIG:STATE', off_on)
+        return self.query('DEV::PUMP:SIG:STATE', off_on)
 
     def write_target(self, value):
-        return self.change('PUMP:SIG:STATE', value, off_on)
+        return self.change('DEV::PUMP:SIG:STATE', value, off_on)
 
     def read_status(self):
         return IDLE, ''
@@ -142,35 +141,35 @@ class TurboPump(Pump):
     electronics_temp = Parameter('temperature of electronics', FloatRange(unit='K'))
 
     def read_status(self):
-        status = self.query('PUMP:STATUS', str)
+        status = self.query('DEV::PUMP:STATUS', str)
         if status == 'OK':
             return IDLE, ''
         return WARN, status
 
     def read_power(self):
-        return self.query('PUMP:SIG:POWR')
+        return self.query('DEV::PUMP:SIG:POWR')
 
     def read_freq(self):
-        return self.query('PUMP:SIG:SPD')
+        return self.query('DEV::PUMP:SIG:SPD')
 
     def read_powerstage_temp(self):
-        return self.query('PUMP:SIG:PST')
+        return self.query('DEV::PUMP:SIG:PST')
 
     def read_motor_temp(self):
-        return self.query('PUMP:SIG:MT')
+        return self.query('DEV::PUMP:SIG:MT')
 
     def read_bearing_temp(self):
-        return self.query('PUMP:SIG:BT')
+        return self.query('DEV::PUMP:SIG:BT')
 
     def read_pumpbase_temp(self):
-        return self.query('PUMP:SIG:PBT')
+        return self.query('DEV::PUMP:SIG:PBT')
 
     def read_electronics_temp(self):
-        return self.query('PUMP:SIG:ET')
+        return self.query('DEV::PUMP:SIG:ET')
 
 
 # class PulseTubeCompressor(MercuryChannel, Writable):
-#     channel_type = 'PTC'
+#     kind = 'PTC'
 #     value = Parameter('compressor state', EnumType(closed=0, opened=1))
 #     target = Parameter('compressor target', EnumType(close=0, open=1))
 #     water_in_temp = Parameter('temperature of water inlet', FloatRange(unit='K'))
@@ -181,42 +180,42 @@ class TurboPump(Pump):
 #     motor_current = Parameter('motor current', FloatRange(unit='A'))
 #
 #     def read_value(self):
-#         return self.query('PTC:SIG:STATE', off_on)
+#         return self.query('DEV::PTC:SIG:STATE', off_on)
 #
 #     def write_target(self, value):
-#         return self.change('PTC:SIG:STATE', value, off_on)
+#         return self.change('DEV::PTC:SIG:STATE', value, off_on)
 #
 #     def read_status(self):
 #         # TODO: check possible status values
-#         return self.WARN, self.query('PTC:SIG:STATUS')
+#         return self.WARN, self.query('DEV::PTC:SIG:STATUS')
 #
 #     def read_water_in_temp(self):
-#         return self.query('PTC:SIG:WIT')
+#         return self.query('DEV::PTC:SIG:WIT')
 #
 #     def read_water_out_temp(self):
-#         return self.query('PTC:SIG:WOT')
+#         return self.query('DEV::PTC:SIG:WOT')
 #
 #     def read_helium_temp(self):
-#         return self.query('PTC:SIG:HT')
+#         return self.query('DEV::PTC:SIG:HT')
 #
 #     def read_helium_low_pressure(self):
-#         return self.query('PTC:SIG:HLP')
+#         return self.query('DEV::PTC:SIG:HLP')
 #
 #     def read_helium_high_pressure(self):
-#         return self.query('PTC:SIG:HHP')
+#         return self.query('DEV::PTC:SIG:HHP')
 #
 #     def read_motor_current(self):
-#         return self.query('PTC:SIG:MCUR')
+#         return self.query('DEV::PTC:SIG:MCUR')
 
 
 class FlowMeter(MercuryChannel, Readable):
-    channel_type = 'FLOW'
+    kind = 'FLOW'
 
     def read_value(self):
-        return self.query('FLOW:SIG:FLOW')
+        return self.query('DEV::FLOW:SIG:FLOW')
 
 
-class ScannerChannel:
+class ScannerChannel(MercuryChannel):
     # TODO: excitation, enable
     # TODO: switch on/off filter, check
     filter_time = Parameter('filter time', FloatRange(1, 200, unit='sec'), readonly=False)
@@ -224,24 +223,24 @@ class ScannerChannel:
     pause_time = Parameter('pause time', FloatRange(3, 200, unit='sec'), readonly=False)
 
     def read_filter_time(self):
-        return self.query('TEMP:FILT:TIME')
+        return self.query('DEV::TEMP:FILT:TIME')
 
     def write_filter_time(self, value):
-        self.change('TEMP:FILT:WIN', 80)
-        return self.change('TEMP:FILT:TIME', value)
+        self.change('DEV::TEMP:FILT:WIN', 80)
+        return self.change('DEV::TEMP:FILT:TIME', value)
 
     def read_dwell_time(self):
-        return self.query('TEMP:MEAS:DWEL')
+        return self.query('DEV::TEMP:MEAS:DWEL')
 
     def write_dwell_time(self, value):
-        self.change('TEMP:FILT:WIN', 80)
-        return self.change('TEMP:MEAS:DWEL', value)
+        self.change('DEV::TEMP:FILT:WIN', 80)
+        return self.change('DEV::TEMP:MEAS:DWEL', value)
 
     def read_pause_time(self):
-        return self.query('TEMP:MEAS:PAUS')
+        return self.query('DEV::TEMP:MEAS:PAUS')
 
     def write_pause_time(self, value):
-        return self.change('TEMP:MEAS:PAUS', value)
+        return self.change('DEV::TEMP:MEAS:PAUS', value)
 
 
 class TemperatureSensor(ScannerChannel, mercury.TemperatureSensor):
@@ -261,7 +260,7 @@ class TemperatureLoop(ScannerChannel, mercury.TemperatureLoop):
         if self.system_channel:
             self.change('SYS:DR:CHAN:%s' % self.system_channel, self.slot.split(',')[0], str)
         if value:
-            self.change('TEMP:LOOP:FILT:ENAB', 'ON', str)
+            self.change('DEV::TEMP:LOOP:FILT:ENAB', 'ON', str)
             if self.output_module:
                 limit = self.output_module.read_limit() or None  # None: max. limit
                 self.output_module.write_limit(limit)
@@ -270,16 +269,16 @@ class TemperatureLoop(ScannerChannel, mercury.TemperatureLoop):
 
 class HeaterOutput(HasInput, MercuryChannel, Writable):
     """heater output"""
-    channel_type = 'HTR'
+    kind = 'HTR'
     value = Parameter('heater output', FloatRange(unit='uW'))
     target = Parameter('heater output', FloatRange(0, unit='$'), readonly=False)
     resistivity = Parameter('heater resistivity', FloatRange(unit='Ohm'))
 
     def read_resistivity(self):
-        return self.query('HTR:RES')
+        return self.query('DEV::HTR:RES')
 
     def read_value(self):
-        return round(self.query('HTR:SIG:POWR'), 3)
+        return round(self.query('DEV::HTR:SIG:POWR'), 3)
 
     def read_target(self):
         if self.controlled_by != 0:
@@ -291,17 +290,17 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
         if self.resistivity:
             # round to the next voltage step
             value = round(sqrt(value * self.resistivity)) ** 2 / self.resistivity
-        return round(self.change('HTR:SIG:POWR', value), 3)
+        return round(self.change('DEV::HTR:SIG:POWR', value), 3)
 
 
 class HeaterOutputWithRange(HeaterOutput):
     """heater output with heater range"""
-    channel_type = 'HTR,TEMP'
+    kind = 'HTR,TEMP'
 
     limit = Parameter('max. heater power', FloatRange(unit='uW'), readonly=False)
 
     def read_limit(self):
-        maxcur = self.query('TEMP:LOOP:RANGE')  # mA
+        maxcur = self.query('DEV::TEMP:LOOP:RANGE')  # mA
         return self.read_resistivity() * maxcur ** 2  # uW
 
     def write_limit(self, value):
@@ -315,6 +314,5 @@ class HeaterOutputWithRange(HeaterOutput):
                 break
         else:
             maxcur = cur
-        self.change('TEMP:LOOP:RANGE', maxcur)
+        self.change('DEV::TEMP:LOOP:RANGE', maxcur)
         return self.read_limit()
-