diff --git a/frappy_psi/ccu4.py b/frappy_psi/ccu4.py
index 19bccf0..4fb4176 100644
--- a/frappy_psi/ccu4.py
+++ b/frappy_psi/ccu4.py
@@ -22,6 +22,7 @@
 """drivers for CCU4, the cryostat control unit at SINQ"""
 import time
 import math
+from frappy.lib.enum import Enum
 # the most common Frappy classes can be imported from frappy.core
 from frappy.core import HasIO, Parameter, Command, Readable, Writable, Drivable, \
     Property, StringIO, BUSY, IDLE, WARN, ERROR, DISABLED, Attached
@@ -32,6 +33,10 @@ from frappy.errors import CommunicationFailedError
 from frappy.states import HasStates, status_code, Retry
 
 
+M = Enum(idle=0, opening=1, closing=2, opened=3, closed=5, no_motor=6)
+A = Enum(disabled=0, manual=1, auto=2)
+
+
 class CCU4IO(StringIO):
     """communication with CCU4"""
     # for completeness: (not needed, as it is the default)
@@ -43,25 +48,34 @@ class CCU4IO(StringIO):
 class CCU4Base(HasIO):
     ioClass = CCU4IO
 
-    def command(self, *args, **kwds):
+    def command(self, **kwds):
         """send a command and get the response
 
-        :param args: the name of the parameters to query
-        :param kwds: <parameter>=<value> for changing a parameter
+        :param kwds: <parameter>=<value> for changing a parameter <parameter>=<type> for querying a parameter
         :returns: the (new) values of the parameters
         """
-        cmds = [f'{k}={v:g}' for k, v in kwds.items()] + list(args)
+        types = {}
+        cmds = []
+        for key, value in kwds.items():
+            if isinstance(value, type):
+                types[key] = value
+                cmds.append(key)
+            elif isinstance(value, str):
+                types[key] = str
+                cmds.append(f'{key}={value}')
+            else:
+                types[key] = float
+                cmds.append(f'{key}={value:g}')
         reply = self.io.communicate(' '.join(cmds)).split()
-        names = list(args) + list(kwds)
-        if len(reply) != len(names):
+        if len(reply) != len(types):
             raise CommunicationFailedError('number of reply items does not match')
         result = []
-        for given, item in zip(names, reply):
-            name, txtvalue = item.split('=')
+        for (given, typ), res in zip(types.items(), reply):
+            name, txtvalue = res.split('=')
             if given != name:
                 raise CommunicationFailedError('result keys do not match given keys')
-            result.append(float(txtvalue))
-        if len(result) == 1:
+            result.append(typ(txtvalue))
+        if len(kwds) == 1:
             return result[0]
         return result
 
@@ -89,13 +103,13 @@ class HeLevel(CCU4Base, Readable):
     }
 
     def read_value(self):
-        return self.command('h')
+        return self.command(h=float)
 
     def read_status(self):
-        return self.STATUS_MAP[int(self.command('hsf'))]
+        return self.STATUS_MAP[int(self.command(hsf=int))]
 
     def read_sample_rate(self):
-        value, self.empty_length, self.full_length = self.command('hf', 'hem', 'hfu')
+        value, self.empty_length, self.full_length = self.command(hf=int, hem=float, hfu=float)
         return value
 
     def write_sample_rate(self, value):
@@ -138,13 +152,13 @@ class Valve(CCU4Base, Writable):
 class HeFillValve(Valve):
     _open_command = {'hcd': 1, 'hf': 1}
     _close_command = {'hcd': 0,  'hf': 0}
-    _query_state = 'hv'
+    _query_state = {'hv': int}
 
 
 class N2FillValve(Valve):
     _open_command = {'nc': 1}
     _close_command = {'nc': 0}
-    _query_state = 'nv'
+    _query_state = {'nv': int}
 
 
 class AuxValve(Valve):
@@ -153,7 +167,7 @@ class AuxValve(Valve):
     def initModule(self):
         self._open_command = {f'vc{self.channel}': 1}
         self._close_command = {f'vc{self.channel}': 0}
-        self._query_state = f'v{self.channel}'
+        self._query_state = {f'v{self.channel}': int}
 
 
 class N2TempSensor(Readable):
@@ -167,7 +181,7 @@ class N2Level(CCU4Base, Pinata, Readable):
 
     value = Parameter('vessel state', EnumType(empty=0, ok=1, full=2))
     status = Parameter(datatype=StatusType(Readable, 'BUSY'))
-    mode = Parameter('auto mode', EnumType(disabled=0, manual=1, auto=2), readonly=False)
+    mode = Parameter('auto mode', EnumType(A), readonly=False)
 
     threshold = Parameter('threshold triggering start/stop filling',
                           FloatRange(unit='K'), readonly=False)
@@ -206,17 +220,17 @@ class N2Level(CCU4Base, Pinata, Readable):
         super().initialReads()
 
     def read_status(self):
-        auto, nstate = self.command('na', 'ns')
+        auto, nstate = self.command(na=int, ns=int)
         if not self.valve or not auto:
-            if self.mode == 'auto':
+            if self.mode == A.auto:
                 # no valve assigned
-                self.mode = 'manual'
-        if self.mode == 'disabled':
+                self.mode = A.manual
+        if self.mode == A.disabled:
             return DISABLED, ''
         status = self.STATUS_MAP[nstate]
         if status[0] // 100 != IDLE // 100:
             return status
-        if self.mode == 'manual':
+        if self.mode == A.manual:
             return IDLE, ''
         vstatus = self.valve.status
         if vstatus[0] // 100 == WARN // 100:
@@ -229,7 +243,7 @@ class N2Level(CCU4Base, Pinata, Readable):
 
     def read_value(self):
         # read sensors
-        lower, upper = self.command('nl', 'nu')
+        lower, upper = self.command(nl=float, nu=float)
         if self.lower:
             self.lower.value = lower
         if self.upper:
@@ -241,7 +255,7 @@ class N2Level(CCU4Base, Pinata, Readable):
         return 'empty'
 
     def write_mode(self, mode):
-        if mode == 'auto':
+        if mode == A.auto:
             if self.isBusy():
                 return mode
             # set to watching
@@ -252,7 +266,7 @@ class N2Level(CCU4Base, Pinata, Readable):
         return mode
 
     def read_threshold(self):
-        value, self.cool_delay, self.fill_timeout = self.command('nth', 'ntc', 'ntm')
+        value, self.cool_delay, self.fill_timeout = self.command(nth=float, ntc=float, ntm=float)
         return value
 
     def write_threshold(self, value):
@@ -266,12 +280,12 @@ class N2Level(CCU4Base, Pinata, Readable):
 
     @Command()
     def fill(self):
-        self.mode = 'auto'
+        self.mode = A.auto
         self.io.write(nc=1)
 
     @Command()
     def stop(self):
-        if self.mode == 'auto':
+        if self.mode == A.auto:
             # set to watching
             self.command(nc=3)
         else:
@@ -285,7 +299,7 @@ class FlowPressure(CCU4Base, Readable):
     pollinterval = Parameter(default=0.25)
 
     def read_value(self):
-        return self.filter(self.command('f')) - self.mbar_offset
+        return self.filter(self.command(f=float)) - self.mbar_offset
 
 
 class NeedleValve(HasStates, CCU4Base, Drivable):
@@ -298,9 +312,7 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
     lnm_per_mbar = Parameter(unit='ln/min/mbar', default=0.6, readonly=False)
     use_pressure = Parameter('use flow from pressure', BoolType(),
                              default=False, readonly=False)
-    motor_state = Parameter('motor_state',
-                            EnumType(idle=0, opening=1, closing=2,
-                                     opened=3, closed=5, no_motor=6))
+    motor_state = Parameter('motor_state', EnumType(M))
     tolerance = Parameter('tolerance', FloatRange(0), value=0.25, readonly=False)
     tolerance2 = Parameter('tolerance limit above 2 lnm', FloatRange(0), value=0.5, readonly=False)
     prop = Parameter('proportional term', FloatRange(unit='s/lnm'), readonly=False)
@@ -341,12 +353,12 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
     def update_flow(self, value):
         if not self.use_pressure:
             self.value = value
-            self.doPoll()
+            self.cycle_machine()
 
     def update_flow_pressure(self, value):
         if self.use_pressure:
             self.value = value * self.lnm_per_mbar
-            self.doPoll()
+            self.cycle_machine()
 
     def write_target(self, value):
         self.start_machine(self.controlling, in_tol_time=0,
@@ -354,7 +366,7 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
 
     @status_code(BUSY)
     def unblock_from_open(self, state):
-        self.motor_state = self.command('fm')
+        self.motor_state = self.command(fm=int)
         if self.motor_state == 'opened':
             self.command(mp=-60)
             return Retry
@@ -372,7 +384,7 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
 
     @status_code(BUSY)
     def unblock_open(self, state):
-        self.motor_state = self.command('fm')
+        self.motor_state = self.command(fm=int)
         if self.value < state.flow_before:
             state.flow_before_open = self.value
         elif self.value > state.flow_before + 1:
@@ -393,7 +405,7 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
 
     @status_code(BUSY)
     def unblock_close(self, state):
-        self.motor_state = self.command('fm')
+        self.motor_state = self.command(fm=int)
         if self.value > state.flow_before:
             state.flow_before_open = self.value
         elif self.value < state.flow_before - 1:
@@ -435,7 +447,7 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
         dif = self.target - self.value
         difdif = dif - state.prev_dif
         state.prev_dif = dif
-        self.motor_state = self.command('fm')
+        self.motor_state = self.command(fm=int)
         if self.motor_state == 'closed':
             if dif < 0 or difdif < 0:
                 return Retry
@@ -467,5 +479,3 @@ class NeedleValve(HasStates, CCU4Base, Drivable):
             return Retry
         self.command(mp=state.step)
         return Retry
-
-