diff --git a/secop_psi/triton.py b/secop_psi/triton.py
index f7bf713..533f5ee 100644
--- a/secop_psi/triton.py
+++ b/secop_psi/triton.py
@@ -20,11 +20,13 @@
 # *****************************************************************************
 """oxford instruments triton (kelvinoxjt dil)"""
 
-from math import sqrt
-from secop.core import Writable, Parameter, Readable, Drivable, IDLE, WARN, BUSY, ERROR, Done
-from secop.datatypes import EnumType, FloatRange
+from math import sqrt, log10
+from secop.core import Writable, Parameter, Readable, Drivable, IDLE, WARN, BUSY, ERROR, \
+    Done, Property
+from secop.datatypes import EnumType, FloatRange, StringType
 from secop.lib.enum import Enum
 from secop_psi.mercury import MercuryChannel, Mapped, off_on, HasInput, SELF
+from secop.lib import clamp
 import secop_psi.mercury as mercury
 
 actions = Enum(none=0, condense=1, circulate=2, collect=3)
@@ -35,6 +37,7 @@ actions_map.mapping['NONE'] = actions.none  # when writing, STOP is used instead
 
 class Action(MercuryChannel, Writable):
     channel_type = 'ACTN'
+    cooldown_channel = Property('cool down channel', StringType(), 'T5')
     value = Parameter('running action', EnumType(actions))
     target = Parameter('action to do', EnumType(none=0, condense=1, collect=3), readonly=False)
     _target = 0
@@ -47,6 +50,7 @@ class Action(MercuryChannel, Writable):
 
     def write_target(self, value):
         self._target = value
+        self.change('SYS:DR:CHAN:COOL', self.cooldown_channel, str)
         return self.change('SYS:DR:ACTN', value, actions_map)
 
     # actions:
@@ -245,10 +249,14 @@ class TemperatureLoop(ScannerChannel, mercury.TemperatureLoop):
     ENABLE = 'TEMP:LOOP:MODE'
     ENABLE_RAMP = 'TEMP:LOOP:RAMP:ENAB'
     RAMP_RATE = 'TEMP:LOOP:RAMP:RATE'
+
     enable_pid_table = None  # remove, does not work on triton
+    ctrlpars = Parameter('pid (gain, integral (inv. time), differential time')
+    system_channel = Property('system channel name', StringType(), 'MC')
 
     def write_control_active(self, value):
-        self.change('SYS:DR:CHAN:MC', 'T5', str)
+        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)
             if self.output_module:
@@ -260,7 +268,7 @@ class TemperatureLoop(ScannerChannel, mercury.TemperatureLoop):
 class HeaterOutput(HasInput, MercuryChannel, Writable):
     """heater output"""
     channel_type = 'HTR'
-    value = Parameter('heater output', FloatRange(unit='W'))
+    value = Parameter('heater output', FloatRange(unit='uW'))
     target = Parameter('heater output', FloatRange(0, unit='$'), readonly=False)
     resistivity = Parameter('heater resistivity', FloatRange(unit='Ohm'))
 
@@ -268,7 +276,7 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
         return self.query('HTR:RES')
 
     def read_value(self):
-        return self.query('HTR:SIG:POWR') * 1e-6
+        return round(self.query('HTR:SIG:POWR'), 3)
 
     def read_target(self):
         if self.controlled_by != 0:
@@ -277,24 +285,33 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
 
     def write_target(self, value):
         self.write_controlled_by(SELF)
-        return self.change('HTR:SIG:POWR', value * 1e6)
+        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)
 
 
 class HeaterOutputWithRange(HeaterOutput):
     """heater output with heater range"""
     channel_type = 'HTR,TEMP'
 
-    limit = Parameter('max. heater power', FloatRange(unit='W'), readonly=False)
+    limit = Parameter('max. heater power', FloatRange(unit='uW'), readonly=False)
 
     def read_limit(self):
-        maxcur = self.query('TEMP:LOOP:RANGE') * 0.001  # mA -> A
-        return self.read_resistivity() * maxcur ** 2
+        maxcur = self.query('TEMP:LOOP:RANGE')  # mA
+        return self.read_resistivity() * maxcur ** 2  # uW
 
     def write_limit(self, value):
         if value is None:
-            maxcur = 0.1  # max. allowed current 100mA
+            maxcur = 100  # max. allowed current 100mA
         else:
             maxcur = sqrt(value / self.read_resistivity())
-        self.change('TEMP:LOOP:RANGE', maxcur * 1000)
+        for cur in 0.0316, 0.1, 0.316, 1, 3.16, 10, 31.6, 100:
+            if cur > maxcur * 0.999:
+                maxcur = cur
+                break
+        else:
+            maxcur = cur
+        self.change('TEMP:LOOP:RANGE', maxcur)
         return self.read_limit()