diff --git a/frappy_psi/ionopimax.py b/frappy_psi/ionopimax.py
index 221c848..75e64d1 100644
--- a/frappy_psi/ionopimax.py
+++ b/frappy_psi/ionopimax.py
@@ -18,60 +18,59 @@
 #   Jael Celia Lorenzana <jael-celia.lorenzana@psi.ch>
 # *****************************************************************************
 
-import os
-from glob import glob
+"""support for iono pi max from Sfera Labs
+
+supports also the smaller model iono pi
+"""
+
+from pathlib import Path
 from frappy.core import Readable, Writable, Parameter, BoolType, StringType,\
     EnumType, FloatRange, Property, TupleOf, ERROR, IDLE
-from frappy.errors import ConfigError, OutOfRangeError
+from frappy.errors import ConfigError, OutOfRangeError, ProgrammingError
 from math import log
 
-basepaths = '/sys/class/ionopimax', '/sys/class/ionopi'
-
 
 class Base:
     addr = Property('address', StringType())
     _devpath = None
-    devclass = None
+    _devclass = None
+    _status = None
 
     def initModule(self):
         super().initModule()
-        # candidates = glob(f'/sys/class/iono*/*/{self.addr}')
-        # if not candidates:
-        #     raise ConfigError(f'can not find path for {self.addr}')
-        for basepath in basepaths:
-            for devclass in ([self.devclass] if isinstance(self.devclass, str) else self.devclass):
-                devpath = f'{basepath}/{devclass}'
-                if os.path.exists(f'{devpath}/{self.addr}'):
-                    self._devpath = devpath
-                    return
-                else:
-                    self.log.info('%s does not exist', devpath)
-        else:
-            raise ConfigError(f'device path for {self.devclass} not found {devpath}')
+        candidates = list(Path('/sys/class').glob(f'ionopi*/*/{self.addr}'))
+        if not candidates:
+            raise ConfigError(f'can not find path for {self.addr}')
+        if len(candidates) > 1:
+            raise ProgrammingError(f"ambiguous paths {','.join(candidates)}")
+        self._devpath = candidates[0].parent
+        self._devclass = candidates[0].parent.name
 
     def read(self, addr, scale=None):
-        with open(f'{self._devpath}/{addr}') as f:
+        with open(self._devpath / addr) as f:
             result = f.read()
         if scale:
             return float(result) / scale
-        return result
+        return result.strip()
 
     def write(self, addr, value, scale=None):
         value = str(round(value * scale)) if scale else str(value)
-        with open(f'{self._devpath}/{addr}', 'w') as f:
+        with open(self._devpath / addr, 'w') as f:
             f.write(value)
 
+    def read_status(self):
+        if self.status is None:
+            return IDLE, ''
+        return self._status
 
 class DigitalInput(Base, Readable):
     value = Parameter('input state', BoolType())
-    true_level = Property('level representig True', EnumType(low=0, high=1), default=1)
-    devclass = 'digital_in', 'digital_io'
+    true_level = Property('level representing True', EnumType(low=0, high=1), default=1)
 
     def initModule(self):
         super().initModule()
-        self.log.info('devpath %r', self._devpath)
-        if self.addr.startswith('dt'):
-            self.write(f'{self.addr}_mode','inp')
+        if self._devclass == 'digital_io'
+            self.write(f'{self.addr}_mode', 'inp')
 
     def read_value(self):
         return self.read(self.addr, 1) == self.true_level
@@ -79,7 +78,24 @@ class DigitalInput(Base, Readable):
 
 class DigitalOutput(DigitalInput, Writable):
     target = Parameter('output state', BoolType(), readonly=False)
-    devclass = 'digital_out', 'relay'
+
+    def read_value(self):
+        reply = self.read(self.addr)
+        try:
+            self._status = None
+            self.read_status()
+            value = int(reply)
+        except ValueError:
+            if reply == 'S':
+                if self.addr.startswith('oc'):
+                    self._status = ERROR, 'short circuit'
+                else:
+                    self._status = ERROR, 'fault while closed'
+                value = 0
+            else:
+                self._status = ERROR, 'fault while open'
+                value = 1
+        return value == self.true_level
 
     def write_target(self, value):
         self.write(self.addr, value == self.true_level, 1)
@@ -87,9 +103,8 @@ class DigitalOutput(DigitalInput, Writable):
 
 class AnalogInput(Base, Readable):
     value = Parameter('analog value', FloatRange())
-    rawrange = Property('raw range(electronic)', TupleOf(FloatRange(),FloatRange()))
-    valuerange = Property('value range(physical)', TupleOf(FloatRange(),FloatRange()))
-    devclass = 'analog_in'
+    rawrange = Property('raw range (electronic)', TupleOf(FloatRange(),FloatRange()))
+    valuerange = Property('value range (physical)', TupleOf(FloatRange(),FloatRange()))
 
     def read_value(self):
         x0, x1 = self.rawrange
@@ -127,15 +142,14 @@ class CurrentInput(AnalogInput):
     def read_value(self):
         result = super().read_value()
         if self.x > 0.021:
-            self.status = ERROR, 'sensor broken'
-            raise OutOfRangeError('sensor broken')
+            self.status = ERROR, 'sensor fault'
+            raise OutOfRangeError('sensor fault')
         self.status = IDLE, ''
         return result
 
 
 class AnalogOutput(AnalogInput, Writable):
     target = Parameter('outputvalue', FloatRange())
-    devclass = 'analog_out'
 
     def write_target(self, value):
         x0, x1 = self.rawrange
@@ -156,7 +170,6 @@ class VoltageOutput(AnalogOutput):
 
 
 class VoltagePower(Base, Writable):
-    devclass = 'power_out'
     target = Parameter(datatype=FloatRange(0, 24.5, unit='V'), default=12)
     addr = 'vso'