diff --git a/secop_psi/dpm.py b/secop_psi/dpm.py
index 4069c6c..d1b34b5 100644
--- a/secop_psi/dpm.py
+++ b/secop_psi/dpm.py
@@ -48,20 +48,20 @@ def float2hex(value, digits):
 class DPM3(HasIodev, Drivable):
     OFFSET = 0x8f
     SCALE = 0x8c
-    
+
     MAGNITUDE = {'1': 1, '2': 10, '3': 100, '4': 1e3, '5': 1e4, '6': 1e5,
              '9':-1, 'A':-10, 'B':-100, 'C':-1e3, 'D':-1e4, 'E':-1e5}
-    
+
     iodevClass = DPM3IO
-    
+
     motor = Attached()
     digits = Parameter('number of digits for value', IntRange(0, 5), initwrite=True, readonly=False)
-    value = Parameter(unit='N')
-    target = Parameter(unit='N')
+    value = Parameter(datatype=FloatRange(unit='N'))
+    target = Parameter(datatype=FloatRange(unit='N'))
     step = Parameter('maximum motor step', FloatRange(unit='deg'), default=5, readonly=False)
 
     offset = Parameter('', FloatRange(-1e5, 1e5), readonly=False, poll=True)
-    
+
     #Note: we have tro treat the units properly.
     """ We got an output of 150 for 10N. The maximal force we want to deal with is 100N,
         thus a maximl output of 1500. 10=150/f 
@@ -69,7 +69,7 @@ class DPM3(HasIodev, Drivable):
     scale_factor  = Parameter('', FloatRange(-1e5, 1e5, unit='input_units/N'), readonly=False, poll=True)
     _target = None
     fast_pollfactor = 0.01
-    
+
     def query(self, adr, value=None):
         if value is not None:
             if adr == self.SCALE:
@@ -109,11 +109,11 @@ class DPM3(HasIodev, Drivable):
         self.write_scale_factor(self.scale_factor)
         self.write_offset(self.offset)
         return Done
-    
+
     def read_digits(self):
         back_value = self._iodev.communicate('*1G135')
         return int(back_value,16) - 1
- 
+
     def read_value(self):
         value = float(self._iodev.communicate('*1B1'))
         mot = self._motor
@@ -135,10 +135,9 @@ class DPM3(HasIodev, Drivable):
                 self.stop()
                 self.status = self.Status.IDLE, 'target reached'
         return value
-    
+
     def write_target(self, target):
         self._target = target
-        self._started = True
         if target - self.value > 0:
             self._direction = 1
         else:
@@ -158,7 +157,7 @@ class DPM3(HasIodev, Drivable):
     def read_offset(self):
         reply = self.query(self.OFFSET)
         return reply
-            
+
     def write_offset(self, value):
         return self.query(self.OFFSET, value)
 
@@ -169,20 +168,20 @@ class DPM3(HasIodev, Drivable):
     def write_scale_factor(self, value):
         reply = self.query(self.SCALE, value * 10 ** self.digits)
         return float(reply) / 10 ** self.digits
-      
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diff --git a/secop_psi/softcal.py b/secop_psi/softcal.py
index e1ddf3a..cbcacec 100644
--- a/secop_psi/softcal.py
+++ b/secop_psi/softcal.py
@@ -27,7 +27,7 @@ from os.path import basename, exists, join
 import numpy as np
 from scipy.interpolate import splev, splrep  # pylint: disable=import-error
 
-from secop.core import Attached, BoolType, Parameter, Readable, StringType
+from secop.core import Attached, BoolType, Parameter, Readable, StringType, FloatRange
 
 
 def linear(x):
@@ -174,7 +174,7 @@ class Sensor(Readable):
 
     calib = Parameter('calibration name', datatype=StringType(), readonly=False)
     abs = Parameter('True: take abs(raw) before calib', datatype=BoolType(), readonly=False, default=True)
-    value = Parameter(unit='K')
+    value = Parameter(datatype=FloatRange(unit='K'))
     pollinterval = Parameter(export=False)
     status = Parameter(default=(Readable.Status.ERROR, 'unintialized'))