diff --git a/cfg/main/jtccr.cfg b/cfg/main/jtccr.cfg
index baf8a1e..ddf2631 100644
--- a/cfg/main/jtccr.cfg
+++ b/cfg/main/jtccr.cfg
@@ -12,6 +12,7 @@ service = main
 class = secop_psi.sea.SeaDrivable
 io = sea_main
 sea_object = tt
+rel_paths = . tt
 
 [T_ccr]
 class = secop_psi.sea.SeaReadable
diff --git a/cfg/main/ma6.cfg b/cfg/main/ma6.cfg
index 7d61d60..9cd10b9 100644
--- a/cfg/main/ma6.cfg
+++ b/cfg/main/ma6.cfg
@@ -63,5 +63,5 @@ uri = ma6-ts.psi.ch:3003
 description = stick rotation, typically used for omega
 class = secop_psi.phytron.Motor
 io = om_io
-encoder_mode = CHECK
+encoder_mode = NO
 
diff --git a/cfg/sea/ma6.config.json b/cfg/sea/ma6.config.json
index 0ebe15e..d2ca2a3 100644
--- a/cfg/sea/ma6.config.json
+++ b/cfg/sea/ma6.config.json
@@ -1,50 +1,50 @@
 {"tt": {"base": "/tt", "params": [
 {"path": "", "type": "float", "readonly": false, "cmd": "run tt", "description": "tt", "kids": 18},
 {"path": "send", "type": "text", "readonly": false, "cmd": "tt send", "visibility": 3},
-{"path": "status", "type": "text", "visibility": 3},
+{"path": "status", "type": "text", "readonly": false, "cmd": "run tt", "visibility": 3},
 {"path": "is_running", "type": "int", "readonly": false, "cmd": "tt is_running", "visibility": 3},
 {"path": "mainloop", "type": "text", "readonly": false, "cmd": "tt mainloop", "visibility": 3},
-{"path": "target", "type": "float"},
-{"path": "running", "type": "int"},
+{"path": "target", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "running", "type": "int", "readonly": false, "cmd": "run tt"},
 {"path": "tolerance", "type": "float", "readonly": false, "cmd": "tt tolerance"},
 {"path": "maxwait", "type": "float", "readonly": false, "cmd": "tt maxwait"},
 {"path": "settle", "type": "float", "readonly": false, "cmd": "tt settle"},
 {"path": "log", "type": "text", "readonly": false, "cmd": "tt log", "visibility": 3, "kids": 4},
-{"path": "log/mean", "type": "float", "visibility": 3},
-{"path": "log/m2", "type": "float", "visibility": 3},
-{"path": "log/stddev", "type": "float", "visibility": 3},
-{"path": "log/n", "type": "float", "visibility": 3},
+{"path": "log/mean", "type": "float", "readonly": false, "cmd": "run tt", "visibility": 3},
+{"path": "log/m2", "type": "float", "readonly": false, "cmd": "run tt", "visibility": 3},
+{"path": "log/stddev", "type": "float", "readonly": false, "cmd": "run tt", "visibility": 3},
+{"path": "log/n", "type": "float", "readonly": false, "cmd": "run tt", "visibility": 3},
 {"path": "dblctrl", "type": "bool", "readonly": false, "cmd": "tt dblctrl", "kids": 9},
 {"path": "dblctrl/tshift", "type": "float", "readonly": false, "cmd": "tt dblctrl/tshift"},
 {"path": "dblctrl/mode", "type": "enum", "enum": {"disabled": -1, "inactive": 0, "stable": 1, "up": 2, "down": 3}, "readonly": false, "cmd": "tt dblctrl/mode"},
-{"path": "dblctrl/shift_up", "type": "float"},
-{"path": "dblctrl/shift_lo", "type": "float"},
-{"path": "dblctrl/t_min", "type": "float"},
-{"path": "dblctrl/t_max", "type": "float"},
+{"path": "dblctrl/shift_up", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "dblctrl/shift_lo", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "dblctrl/t_min", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "dblctrl/t_max", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "dblctrl/int2", "type": "float", "readonly": false, "cmd": "tt dblctrl/int2"},
 {"path": "dblctrl/prop_up", "type": "float", "readonly": false, "cmd": "tt dblctrl/prop_up"},
 {"path": "dblctrl/prop_lo", "type": "float", "readonly": false, "cmd": "tt dblctrl/prop_lo"},
-{"path": "tm", "type": "float", "kids": 4},
+{"path": "tm", "type": "float", "readonly": false, "cmd": "run tt", "kids": 4},
 {"path": "tm/curve", "type": "text", "readonly": false, "cmd": "tt tm/curve", "kids": 1},
 {"path": "tm/curve/points", "type": "floatvarar", "readonly": false, "cmd": "tt tm/curve/points", "visibility": 3},
 {"path": "tm/alarm", "type": "float", "readonly": false, "cmd": "tt tm/alarm"},
-{"path": "tm/stddev", "type": "float"},
-{"path": "tm/raw", "type": "float"},
-{"path": "ts", "type": "float", "kids": 4},
+{"path": "tm/stddev", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "tm/raw", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "ts", "type": "float", "readonly": false, "cmd": "run tt", "kids": 4},
 {"path": "ts/curve", "type": "text", "readonly": false, "cmd": "tt ts/curve", "kids": 1},
 {"path": "ts/curve/points", "type": "floatvarar", "readonly": false, "cmd": "tt ts/curve/points", "visibility": 3},
 {"path": "ts/alarm", "type": "float", "readonly": false, "cmd": "tt ts/alarm"},
-{"path": "ts/stddev", "type": "float"},
-{"path": "ts/raw", "type": "float"},
-{"path": "ts_2", "type": "float", "kids": 4},
+{"path": "ts/stddev", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "ts/raw", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "ts_2", "type": "float", "readonly": false, "cmd": "run tt", "kids": 4},
 {"path": "ts_2/curve", "type": "text", "readonly": false, "cmd": "tt ts_2/curve", "kids": 1},
 {"path": "ts_2/curve/points", "type": "floatvarar", "readonly": false, "cmd": "tt ts_2/curve/points", "visibility": 3},
 {"path": "ts_2/alarm", "type": "float", "readonly": false, "cmd": "tt ts_2/alarm"},
-{"path": "ts_2/stddev", "type": "float"},
-{"path": "ts_2/raw", "type": "float"},
+{"path": "ts_2/stddev", "type": "float", "readonly": false, "cmd": "run tt"},
+{"path": "ts_2/raw", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "set", "type": "float", "readonly": false, "cmd": "tt set", "kids": 18},
 {"path": "set/mode", "type": "enum", "enum": {"disabled": -1, "off": 0, "controlling": 1, "manual": 2}, "readonly": false, "cmd": "tt set/mode"},
-{"path": "set/reg", "type": "float"},
+{"path": "set/reg", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "set/ramp", "type": "float", "readonly": false, "cmd": "tt set/ramp", "description": "maximum ramp in K/min (0: ramp off)"},
 {"path": "set/wramp", "type": "float", "readonly": false, "cmd": "tt set/wramp"},
 {"path": "set/smooth", "type": "float", "readonly": false, "cmd": "tt set/smooth", "description": "smooth time (minutes)"},
@@ -53,17 +53,17 @@
 {"path": "set/resist", "type": "float", "readonly": false, "cmd": "tt set/resist"},
 {"path": "set/maxheater", "type": "text", "readonly": false, "cmd": "tt set/maxheater", "description": "maximum heater limit, units should be given without space: W, mW, A, mA"},
 {"path": "set/linearpower", "type": "float", "readonly": false, "cmd": "tt set/linearpower", "description": "when not 0, it is the maximum effective power, and the power is linear to the heater output"},
-{"path": "set/maxpowerlim", "type": "float", "description": "the maximum power limit (before any booster or converter)"},
+{"path": "set/maxpowerlim", "type": "float", "readonly": false, "cmd": "run tt", "description": "the maximum power limit (before any booster or converter)"},
 {"path": "set/maxpower", "type": "float", "readonly": false, "cmd": "tt set/maxpower", "description": "maximum power [W]"},
-{"path": "set/maxcurrent", "type": "float", "description": "the maximum current before any booster or converter"},
+{"path": "set/maxcurrent", "type": "float", "readonly": false, "cmd": "run tt", "description": "the maximum current before any booster or converter"},
 {"path": "set/manualpower", "type": "float", "readonly": false, "cmd": "tt set/manualpower"},
-{"path": "set/power", "type": "float"},
+{"path": "set/power", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "set/prop", "type": "float", "readonly": false, "cmd": "tt set/prop", "description": "bigger means more gain"},
 {"path": "set/integ", "type": "float", "readonly": false, "cmd": "tt set/integ", "description": "bigger means faster"},
 {"path": "set/deriv", "type": "float", "readonly": false, "cmd": "tt set/deriv"},
 {"path": "setsamp", "type": "float", "readonly": false, "cmd": "tt setsamp", "kids": 18},
 {"path": "setsamp/mode", "type": "enum", "enum": {"disabled": -1, "off": 0, "controlling": 1, "manual": 2}, "readonly": false, "cmd": "tt setsamp/mode"},
-{"path": "setsamp/reg", "type": "float"},
+{"path": "setsamp/reg", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "setsamp/ramp", "type": "float", "readonly": false, "cmd": "tt setsamp/ramp", "description": "maximum ramp in K/min (0: ramp off)"},
 {"path": "setsamp/wramp", "type": "float", "readonly": false, "cmd": "tt setsamp/wramp"},
 {"path": "setsamp/smooth", "type": "float", "readonly": false, "cmd": "tt setsamp/smooth", "description": "smooth time (minutes)"},
@@ -72,16 +72,16 @@
 {"path": "setsamp/resist", "type": "float", "readonly": false, "cmd": "tt setsamp/resist"},
 {"path": "setsamp/maxheater", "type": "text", "readonly": false, "cmd": "tt setsamp/maxheater", "description": "maximum heater limit, units should be given without space: W, mW, A, mA"},
 {"path": "setsamp/linearpower", "type": "float", "readonly": false, "cmd": "tt setsamp/linearpower", "description": "when not 0, it is the maximum effective power, and the power is linear to the heater output"},
-{"path": "setsamp/maxpowerlim", "type": "float", "description": "the maximum power limit (before any booster or converter)"},
+{"path": "setsamp/maxpowerlim", "type": "float", "readonly": false, "cmd": "run tt", "description": "the maximum power limit (before any booster or converter)"},
 {"path": "setsamp/maxpower", "type": "float", "readonly": false, "cmd": "tt setsamp/maxpower", "description": "maximum power [W]"},
-{"path": "setsamp/maxcurrent", "type": "float", "description": "the maximum current before any booster or converter"},
+{"path": "setsamp/maxcurrent", "type": "float", "readonly": false, "cmd": "run tt", "description": "the maximum current before any booster or converter"},
 {"path": "setsamp/manualpower", "type": "float", "readonly": false, "cmd": "tt setsamp/manualpower"},
-{"path": "setsamp/power", "type": "float"},
+{"path": "setsamp/power", "type": "float", "readonly": false, "cmd": "run tt"},
 {"path": "setsamp/prop", "type": "float", "readonly": false, "cmd": "tt setsamp/prop", "description": "bigger means more gain"},
 {"path": "setsamp/integ", "type": "float", "readonly": false, "cmd": "tt setsamp/integ", "description": "bigger means faster"},
 {"path": "setsamp/deriv", "type": "float", "readonly": false, "cmd": "tt setsamp/deriv"},
 {"path": "display", "type": "text", "readonly": false, "cmd": "tt display"},
-{"path": "remote", "type": "bool"}]},
+{"path": "remote", "type": "bool", "readonly": false, "cmd": "run tt"}]},
 
 "cc": {"base": "/cc", "params": [
 {"path": "", "type": "bool", "kids": 96},
@@ -239,16 +239,16 @@
 {"path": "", "type": "enum", "enum": {"xds35_auto": 0, "xds35_manual": 1, "sv65": 2, "other": 3, "no": -1}, "readonly": false, "cmd": "hepump", "description": "xds35: scroll pump, sv65: leybold", "kids": 10},
 {"path": "send", "type": "text", "readonly": false, "cmd": "hepump send", "visibility": 3},
 {"path": "status", "type": "text", "visibility": 3},
-{"path": "running", "type": "bool", "readonly": false, "cmd": "hepump running", "visibility": 3},
-{"path": "eco", "type": "bool", "readonly": false, "cmd": "hepump eco", "visibility": 3},
-{"path": "auto", "type": "bool", "readonly": false, "cmd": "hepump auto", "visibility": 3},
-{"path": "valve", "type": "enum", "enum": {"closed": 0, "closing": 1, "opening": 2, "opened": 3, "undefined": 4}, "readonly": false, "cmd": "hepump valve", "visibility": 3},
-{"path": "eco_t_lim", "type": "float", "readonly": false, "cmd": "hepump eco_t_lim", "description": "switch off eco mode when T_set < eco_t_lim and T < eco_t_lim * 2", "visibility": 3},
+{"path": "running", "type": "bool", "readonly": false, "cmd": "hepump running"},
+{"path": "eco", "type": "bool", "readonly": false, "cmd": "hepump eco"},
+{"path": "auto", "type": "bool", "readonly": false, "cmd": "hepump auto"},
+{"path": "valve", "type": "enum", "enum": {"closed": 0, "closing": 1, "opening": 2, "opened": 3, "undefined": 4}, "readonly": false, "cmd": "hepump valve"},
+{"path": "eco_t_lim", "type": "float", "readonly": false, "cmd": "hepump eco_t_lim", "description": "switch off eco mode when T_set < eco_t_lim and T < eco_t_lim * 2"},
 {"path": "calib", "type": "float", "readonly": false, "cmd": "hepump calib", "visibility": 3},
 {"path": "health", "type": "float"}]},
 
 "hemot": {"base": "/hepump/hemot", "params": [
-{"path": "", "type": "float", "readonly": false, "cmd": "run hemot", "visibility": 3, "kids": 30},
+{"path": "", "type": "float", "readonly": false, "cmd": "run hemot", "kids": 30},
 {"path": "send", "type": "text", "readonly": false, "cmd": "hemot send", "visibility": 3},
 {"path": "status", "type": "text", "visibility": 3},
 {"path": "is_running", "type": "int", "readonly": false, "cmd": "hemot is_running", "visibility": 3},
@@ -280,6 +280,16 @@
 {"path": "customadr", "type": "text", "readonly": false, "cmd": "hemot customadr"},
 {"path": "custompar", "type": "float", "readonly": false, "cmd": "hemot custompar"}]},
 
+"nvflow": {"base": "/nvflow", "params": [
+{"path": "", "type": "float", "kids": 7},
+{"path": "send", "type": "text", "readonly": false, "cmd": "nvflow send", "visibility": 3},
+{"path": "status", "type": "text", "visibility": 3},
+{"path": "stddev", "type": "float"},
+{"path": "nsamples", "type": "int", "readonly": false, "cmd": "nvflow nsamples"},
+{"path": "offset", "type": "float", "readonly": false, "cmd": "nvflow offset"},
+{"path": "scale", "type": "float", "readonly": false, "cmd": "nvflow scale"},
+{"path": "save", "type": "bool", "readonly": false, "cmd": "nvflow save", "description": "unchecked: current calib is not saved. set checked: save calib"}]},
+
 "ln2fill": {"base": "/ln2fill", "params": [
 {"path": "", "type": "enum", "enum": {"watching": 0, "fill": 1, "inactive": 2}, "readonly": false, "cmd": "ln2fill", "kids": 14},
 {"path": "send", "type": "text", "readonly": false, "cmd": "ln2fill send", "visibility": 3},
@@ -317,32 +327,32 @@
 {"path": "vext", "type": "float"}]},
 
 "mf": {"base": "/mf", "params": [
-{"path": "", "type": "float", "kids": 26},
+{"path": "", "type": "float", "readonly": false, "cmd": "run mf", "kids": 26},
 {"path": "persmode", "type": "int", "readonly": false, "cmd": "mf persmode"},
-{"path": "perswitch", "type": "int"},
+{"path": "perswitch", "type": "int", "readonly": false, "cmd": "run mf"},
 {"path": "nowait", "type": "int", "readonly": false, "cmd": "mf nowait"},
-{"path": "maxlimit", "type": "float", "visibility": 3},
+{"path": "maxlimit", "type": "float", "readonly": false, "cmd": "run mf", "visibility": 3},
 {"path": "limit", "type": "float", "readonly": false, "cmd": "mf limit"},
 {"path": "ramp", "type": "float", "readonly": false, "cmd": "mf ramp"},
 {"path": "perscurrent", "type": "float", "readonly": false, "cmd": "mf perscurrent"},
 {"path": "perslimit", "type": "float", "readonly": false, "cmd": "mf perslimit"},
 {"path": "perswait", "type": "int", "readonly": false, "cmd": "mf perswait"},
 {"path": "persdelay", "type": "int", "readonly": false, "cmd": "mf persdelay"},
-{"path": "current", "type": "float"},
-{"path": "measured", "type": "float"},
-{"path": "voltage", "type": "float"},
-{"path": "lastfield", "type": "float", "visibility": 3},
-{"path": "ampRamp", "type": "float", "visibility": 3},
-{"path": "inductance", "type": "float", "visibility": 3},
+{"path": "current", "type": "float", "readonly": false, "cmd": "run mf"},
+{"path": "measured", "type": "float", "readonly": false, "cmd": "run mf"},
+{"path": "voltage", "type": "float", "readonly": false, "cmd": "run mf"},
+{"path": "lastfield", "type": "float", "readonly": false, "cmd": "run mf", "visibility": 3},
+{"path": "ampRamp", "type": "float", "readonly": false, "cmd": "run mf", "visibility": 3},
+{"path": "inductance", "type": "float", "readonly": false, "cmd": "run mf", "visibility": 3},
 {"path": "trainedTo", "type": "float", "readonly": false, "cmd": "mf trainedTo"},
-{"path": "trainMode", "type": "int"},
+{"path": "trainMode", "type": "int", "readonly": false, "cmd": "run mf"},
 {"path": "external", "type": "int", "readonly": false, "cmd": "mf external"},
 {"path": "startScript", "type": "text", "readonly": false, "cmd": "mf startScript", "visibility": 3},
-{"path": "is_running", "type": "int", "visibility": 3},
+{"path": "is_running", "type": "int", "readonly": false, "cmd": "run mf", "visibility": 3},
 {"path": "verbose", "type": "int", "readonly": false, "cmd": "mf verbose", "visibility": 3},
-{"path": "driver", "type": "text", "visibility": 3},
-{"path": "creationCmd", "type": "text", "visibility": 3},
-{"path": "targetValue", "type": "float"},
+{"path": "driver", "type": "text", "readonly": false, "cmd": "run mf", "visibility": 3},
+{"path": "creationCmd", "type": "text", "readonly": false, "cmd": "run mf", "visibility": 3},
+{"path": "targetValue", "type": "float", "readonly": false, "cmd": "run mf"},
 {"path": "status", "type": "text", "readonly": false, "cmd": "mf status", "visibility": 3}]},
 
 "lev": {"base": "/lev", "params": [
@@ -350,4 +360,9 @@
 {"path": "send", "type": "text", "readonly": false, "cmd": "lev send", "visibility": 3},
 {"path": "status", "type": "text", "visibility": 3},
 {"path": "mode", "type": "enum", "enum": {"slow": 0, "fast (switches to slow automatically after filling)": 1}, "readonly": false, "cmd": "lev mode"},
-{"path": "n2", "type": "float"}]}}
+{"path": "n2", "type": "float"}]},
+
+"prep0": {"base": "/prep0", "params": [
+{"path": "", "type": "text", "readonly": false, "cmd": "prep0", "kids": 2},
+{"path": "send", "type": "text", "readonly": false, "cmd": "prep0 send", "visibility": 3},
+{"path": "status", "type": "text", "visibility": 3}]}}
diff --git a/cfg/uniax.cfg b/cfg/uniax.cfg
index c1cbf18..1d8d755 100644
--- a/cfg/uniax.cfg
+++ b/cfg/uniax.cfg
@@ -42,10 +42,15 @@ digits = 2
 scale_factor = 0.0156
 offset = 15
 
+[res_io]
+description = io to lakeshore
+class = secop_psi.ls340res.LscIO
+uri = tcp://192.168.127.254:3003
+
 [res]
 description = temperature on uniax stick
 class = secop_psi.ls340res.ResChannel
-uri = tcp://192.168.127.254:3003
+io = res_io
 channel = A
 
 [T]
diff --git a/debian/changelog b/debian/changelog
index 2b822a0..a2d2e8c 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -1,3 +1,77 @@
+secop-core (0.13.1) focal; urgency=medium
+
+  [ Markus Zolliker ]
+  * an enum with value 0 should be interpreted as False
+  * make startup faster in case of errors
+
+  [ Enrico Faulhaber ]
+  * secop_mlz: minor rework entangle client
+
+ -- Markus Zolliker <jenkins@jenkins02.admin.frm2.tum.de>  Tue, 02 Aug 2022 15:31:52 +0200
+
+secop-core (0.13.0) focal; urgency=medium
+
+  [ Georg Brandl ]
+  * debian: fix email addresses in changelog
+
+  [ Markus Zolliker ]
+  * various small changes
+  * automatic saving of persistent parameters
+  * add more tests and fixes for command inheritance
+  * entangle.AnalogOutput: fix window mechanism
+  * remote logging (issue 46)
+  * add timeouts to MultiEvents
+  * introduce general config file
+  * improve handling of module init methods
+  * check for bad read_* and write_* methods
+  * change name of read_hw_status method in sequencer mixin
+  * fix doc (stringio - > io)
+  * enhance logging
+  * UniqueObject
+  * ReadHandler and WriteHandler decorators
+  * do not convert string to float
+  * check for problematic value range
+  * unify name and module on Attached property
+  * ppms: replace IOHandler by Read/WriteHandler
+  * fix handling commands
+  * common read/write handlers
+  * implement a state machine
+  * proper return value in handler read_* methods
+  * new poll mechanism
+  * support for fast poll when busy
+  * various small fixes
+  * reset connection on identification
+  * improve softcal
+  * move markdown to requirements-dev.txt
+  * improve k2601b driver
+  * fix and improved Attached
+  * fix error in write wrapper and more
+  * support write_ method on readonly param and more
+  * init generalConfig.defaults only in secop-server
+  * HasConvergence mixin
+  * avoid race conditions in read_*/write_* methods
+  * reintroduced individual init of generalConfig.defaults
+  * fix statemachine
+  * use a common poller thread for modules sharing io
+  * motor valve using trinamic motor
+  * improved trinamic driver
+  * fix error in secop.logging
+  * avoid deadlock in proxy
+  * improve poller error handling
+  * support for OI mercury series
+  * add 'ts' to the ppms simulation
+  * allow a configfile path as single argument to secop-server
+  * fix keithley 2601b after tests
+  * channel switcher for Lakeshore 370 with scanner
+  * feature implementation
+  * allow to convert numpy arrays to ArrayOf
+  * remove IOHandler stuff
+
+  [ Enrico Faulhaber ]
+  * default unit to UTF8
+
+ -- Georg Brandl <jenkins@frm2.tum.de>  Tue, 02 Aug 2022 09:47:06 +0200
+
 secop-core (0.12.4) focal; urgency=medium
 
   * fix command inheritance
diff --git a/secop/client/__init__.py b/secop/client/__init__.py
index 346179e..e01522a 100644
--- a/secop/client/__init__.py
+++ b/secop/client/__init__.py
@@ -356,7 +356,7 @@ class SecopClient(ProxyClient):
         except ConnectionClosed:
             pass
         except Exception as e:
-            self.log.error('rxthread ended with %s' % e)
+            self.log.error('rxthread ended with %r', e)
         self._rxthread = None
         self.disconnect(False)
         if self._shutdown:
@@ -490,7 +490,7 @@ class SecopClient(ProxyClient):
 
     def _unhandled_message(self, action, ident, data):
         if not self.callback(None, 'unhandledMessage', action, ident, data):
-            self.log.warning('unhandled message: %s %s %r' % (action, ident, data))
+            self.log.warning('unhandled message: %s %s %r', action, ident, data)
 
     def _set_state(self, online, state=None):
         # remark: reconnecting is treated as online
diff --git a/secop/client/interactive.py b/secop/client/interactive.py
index 85d6428..28d8b61 100644
--- a/secop/client/interactive.py
+++ b/secop/client/interactive.py
@@ -23,10 +23,11 @@
 
 import sys
 import time
-import json
+import re
 from queue import Queue
 from secop.client import SecopClient
 from secop.errors import SECoPError
+from secop.datatypes import get_datatype
 
 USAGE = """
 Usage:
@@ -58,10 +59,15 @@ class Logger:
             if lev == loglevel:
                 func = self.emit
             setattr(self, lev, func)
+        self._minute = 0
 
-    @staticmethod
-    def emit(fmt, *args, **kwds):
-        print(str(fmt) % args)
+    def emit(self, fmt, *args, **kwds):
+        now = time.time()
+        minute = now // 60
+        if minute != self._minute:
+            self._minute = minute
+            print(time.strftime('--- %H:%M:%S ---', time.localtime(now)))
+        print('%6.3f' % (now % 60.0), str(fmt) % args)
 
     @staticmethod
     def noop(fmt, *args, **kwds):
@@ -77,6 +83,8 @@ class PrettyFloat(float):
 
 
 class Module:
+    _log_pattern = re.compile('.*')
+
     def __init__(self, name, secnode):
         self._name = name
         self._secnode = secnode
@@ -89,15 +97,12 @@ class Module:
 
     def _one_line(self, pname, minwid=0):
         """return <module>.<param> = <value> truncated to one line"""
+        param = getattr(type(self), pname)
         try:
             value = getattr(self, pname)
-            # make floats appear with 7 digits only
-            r = repr(json.loads(json.dumps(value), parse_float=PrettyFloat))
+            r = param.format(value)
         except Exception as e:
             r = repr(e)
-        unit = getattr(type(self), pname).unit
-        if unit:
-            r += ' %s' % unit
         pname = pname.ljust(minwid)
         vallen = 113 - len(self._name) - len(pname)
         if len(r) > vallen:
@@ -174,13 +179,21 @@ class Module:
             '\n'.join(self._one_line(k, wid) for k in self._parameters),
             ', '.join(k + '()' for k in self._commands))
 
+    def logging(self, level='comlog', pattern='.*'):
+        self._log_pattern = re.compile(pattern)
+        self._secnode.request('logging', self._name, level)
+
+    def handle_log_message_(self, data):
+        if self._log_pattern.match(data):
+            self._secnode.log.info('%s: %r', self._name, data)
+
 
 class Param:
-    def __init__(self, name, unit=None):
+    def __init__(self, name, datainfo):
         self.name = name
         self.prev = None
         self.prev_time = 0
-        self.unit = unit
+        self.datatype = get_datatype(datainfo)
 
     def __get__(self, obj, owner):
         if obj is None:
@@ -198,6 +211,9 @@ class Param:
         except SECoPError as e:
             obj._secnode.log.error(repr(e))
 
+    def format(self, value):
+        return self.datatype.format_value(value)
+
 
 class Command:
     def __init__(self, name, modname, secnode):
@@ -250,14 +266,24 @@ class Client(SecopClient):
                 self.log.info('overwrite module %s', modname)
             attrs = {}
             for pname, pinfo in moddesc['parameters'].items():
-                unit = pinfo['datainfo'].get('unit')
-                attrs[pname] = Param(pname, unit)
+                attrs[pname] = Param(pname, pinfo['datainfo'])
             for cname in moddesc['commands']:
                 attrs[cname] = Command(cname, modname, self)
             mobj = type('M_%s' % modname, (Module,), attrs)(modname, self)
             if 'status' in mobj._parameters:
                 self.register_callback((modname, 'status'), updateEvent=mobj._status_value_update)
                 self.register_callback((modname, 'value'), updateEvent=mobj._status_value_update)
-
             setattr(main, modname, mobj)
+        self.register_callback(None, self.unhandledMessage)
         self.log.info('%s', USAGE)
+
+    def unhandledMessage(self, action, ident, data):
+        """handle logging messages"""
+        if action == 'log':
+            modname = ident.split(':')[0]
+            modobj = getattr(main, modname, None)
+            if modobj:
+                modobj.handle_log_message_(data)
+                return
+            self.log.info('module %s not found', modname)
+        self.log.info('unhandled: %s %s %r', action, ident, data)
diff --git a/secop/datatypes.py b/secop/datatypes.py
index 5da9a99..8296c2f 100644
--- a/secop/datatypes.py
+++ b/secop/datatypes.py
@@ -124,6 +124,9 @@ class DataType(HasProperties):
         """
         raise NotImplementedError
 
+    def set_main_unit(self, unit):
+        """replace $ in unit by argument"""
+
 
 class Stub(DataType):
     """incomplete datatype, to be replaced with a proper one later during module load
@@ -155,9 +158,17 @@ class Stub(DataType):
                         prop.datatype = globals()[stub.name](*stub.args, **stub.kwds)
 
 
+class HasUnit:
+    unit = Property('physical unit', Stub('StringType', isUTF8=True), extname='unit', default='')
+
+    def set_main_unit(self, unit):
+        if '$' in self.unit:
+            self.setProperty('unit', self.unit.replace('$', unit))
+
+
 # SECoP types:
 
-class FloatRange(DataType):
+class FloatRange(HasUnit, DataType):
     """(restricted) float type
 
     :param minval: (property **min**)
@@ -166,7 +177,6 @@ class FloatRange(DataType):
     """
     min = Property('low limit', Stub('FloatRange'), extname='min', default=-sys.float_info.max)
     max = Property('high limit', Stub('FloatRange'), extname='max', default=sys.float_info.max)
-    unit = Property('physical unit', Stub('StringType', isUTF8=True), extname='unit', default='')
     fmtstr = Property('format string', Stub('StringType'), extname='fmtstr', default='%g')
     absolute_resolution = Property('absolute resolution', Stub('FloatRange', 0),
                                    extname='absolute_resolution', default=0.0)
@@ -331,7 +341,7 @@ class IntRange(DataType):
         raise BadValueError('incompatible datatypes')
 
 
-class ScaledInteger(DataType):
+class ScaledInteger(HasUnit, DataType):
     """scaled integer (= fixed resolution float) type
 
     :param minval: (property **min**)
@@ -344,7 +354,6 @@ class ScaledInteger(DataType):
     scale = Property('scale factor', FloatRange(sys.float_info.min), extname='scale', mandatory=True)
     min = Property('low limit', FloatRange(), extname='min', mandatory=True)
     max = Property('high limit', FloatRange(), extname='max', mandatory=True)
-    unit = Property('physical unit', Stub('StringType', isUTF8=True), extname='unit', default='')
     fmtstr = Property('format string', Stub('StringType'), extname='fmtstr', default='%g')
     absolute_resolution = Property('absolute resolution', FloatRange(0),
                                    extname='absolute_resolution', default=0.0)
@@ -806,6 +815,9 @@ class ArrayOf(DataType):
         except AttributeError:
             raise BadValueError('incompatible datatypes') from None
 
+    def set_main_unit(self, unit):
+        self.members.set_main_unit(unit)
+
 
 class TupleOf(DataType):
     """data structure with fields of inhomogeneous type
@@ -872,6 +884,10 @@ class TupleOf(DataType):
         for a, b in zip(self.members, other.members):
             a.compatible(b)
 
+    def set_main_unit(self, unit):
+        for member in self.members:
+            member.set_main_unit(unit)
+
 
 class ImmutableDict(dict):
     def _no(self, *args, **kwds):
@@ -961,6 +977,10 @@ class StructOf(DataType):
         except (AttributeError, TypeError, KeyError):
             raise BadValueError('incompatible datatypes') from None
 
+    def set_main_unit(self, unit):
+        for member in self.members.values():
+            member.set_main_unit(unit)
+
 
 class CommandType(DataType):
     """command
diff --git a/secop/io.py b/secop/io.py
index 0ff9359..a5431c3 100644
--- a/secop/io.py
+++ b/secop/io.py
@@ -71,14 +71,6 @@ class HasIO(Module):
         elif not io:
             raise ConfigError("Module %s needs a value for either 'uri' or 'io'" % name)
 
-    def initModule(self):
-        try:
-            self.io.read_is_connected()
-        except (CommunicationFailedError, AttributeError):
-            # AttributeError: read_is_connected is not required for an io object
-            pass
-        super().initModule()
-
     def communicate(self, *args):
         return self.io.communicate(*args)
 
@@ -118,6 +110,7 @@ class IOBase(Communicator):
     _conn = None
     _last_error = None
     _lock = None
+    _last_connect_attempt = 0
 
     def earlyInit(self):
         super().earlyInit()
@@ -169,6 +162,17 @@ class IOBase(Communicator):
             return False
         return self.read_is_connected()
 
+    def check_connection(self):
+        """called before communicate"""
+        if not self.is_connected:
+            now = time.time()
+            if now >= self._last_connect_attempt + self.pollinterval:
+                # we do not try to reconnect more often than pollinterval
+                _last_connect_attempt = now
+                if self.read_is_connected():
+                    return
+            raise SilentError('disconnected') from None
+
     def registerReconnectCallback(self, name, func):
         """register reconnect callback
 
@@ -250,11 +254,7 @@ class StringIO(IOBase):
         wait_before is respected for end_of_lines within a command.
         """
         command = command.encode(self.encoding)
-        if not self.is_connected:
-            # do not try to reconnect here
-            # read_is_connected is doing this when called by its poller
-            self.read_is_connected()  # try to reconnect
-            raise SilentError('disconnected') from None
+        self.check_connection()
         try:
             with self._lock:
                 # read garbage and wait before send
@@ -359,11 +359,7 @@ class BytesIO(IOBase):
     @Command((BLOBType(), IntRange(0)), result=BLOBType())
     def communicate(self, request, replylen):  # pylint: disable=arguments-differ
         """send a request and receive (at least) <replylen> bytes as reply"""
-        if not self.is_connected:
-            # do not try to reconnect here
-            # read_is_connected is doing this when called by its poller
-            self.read_is_connected()  # try to reconnect
-            raise SilentError('disconnected') from None
+        self.check_connection()
         try:
             with self._lock:
                 # read garbage and wait before send
diff --git a/secop/lib/statemachine.py b/secop/lib/statemachine.py
index 309cabf..9fe6271 100644
--- a/secop/lib/statemachine.py
+++ b/secop/lib/statemachine.py
@@ -132,7 +132,8 @@ class StateMachine:
         :return: None (for custom cleanup functions this might be a new state)
         """
         if state.stopped:  # stop or restart
-            state.log.debug('%sed in state %r', repr(state.stopped).lower(), state.status_string)
+            verb = 'stopped' if state.stopped is Stop else 'restarted'
+            state.log.debug('%s in state %r', verb, state.status_string)
         else:
             state.log.warning('%r raised in state %r', state.last_error, state.status_string)
 
@@ -196,7 +197,7 @@ class StateMachine:
                     self.log.debug('called %r %sexc=%r', self.cleanup,
                                    'ret=%r ' % ret if ret else '', e)
                 if ret is None:
-                    self.log.debug('state: None')
+                    self.log.debug('state: None after cleanup')
                     self.state = None
                     self._idle_event.set()
                     return None
@@ -270,8 +271,8 @@ class StateMachine:
                 if self.stopped:  # cleanup is not yet done
                     self.last_error = self.stopped
                     self.cleanup(self)  # ignore return state on restart
-                    self.stopped = False
-                    self._start(state, **kwds)
+                self.stopped = False
+                self._start(state, **kwds)
         else:
             self._start(state, **kwds)
 
diff --git a/secop/modules.py b/secop/modules.py
index 3806302..db6d296 100644
--- a/secop/modules.py
+++ b/secop/modules.py
@@ -30,7 +30,7 @@ from functools import wraps
 
 from secop.datatypes import ArrayOf, BoolType, EnumType, FloatRange, \
     IntRange, StatusType, StringType, TextType, TupleOf, DiscouragedConversion
-from secop.errors import BadValueError, ConfigError, \
+from secop.errors import BadValueError, CommunicationFailedError, ConfigError, \
     ProgrammingError, SECoPError, secop_error
 from secop.lib import formatException, mkthread, UniqueObject, generalConfig
 from secop.lib.enum import Enum
@@ -476,10 +476,12 @@ class Module(HasAccessibles):
             aobj.finish()
 
         # Modify units AFTER applying the cfgdict
-        for pname, pobj in self.parameters.items():
-            dt = pobj.datatype
-            if '$' in dt.unit:
-                dt.setProperty('unit', dt.unit.replace('$', self.parameters['value'].datatype.unit))
+        mainvalue = self.parameters.get('value')
+        if mainvalue:
+            mainunit = mainvalue.datatype.unit
+            if mainunit:
+                for pname, pobj in self.parameters.items():
+                    pobj.datatype.set_main_unit(mainunit)
 
         # 6) check complete configuration of * properties
         if not errors:
@@ -639,7 +641,7 @@ class Module(HasAccessibles):
             self.pollInfo.interval = fast_interval if flag else self.pollinterval
             self.pollInfo.trigger()
 
-    def callPollFunc(self, rfunc):
+    def callPollFunc(self, rfunc, raise_com_failed=False):
         """call read method with proper error handling"""
         try:
             rfunc()
@@ -656,6 +658,8 @@ class Module(HasAccessibles):
                 else:
                     # uncatched error: this is more serious
                     self.log.error('%s: %s', name, formatException())
+            if raise_com_failed and isinstance(e, CommunicationFailedError):
+                raise
 
     def __pollThread(self, modules, started_callback):
         """poll thread body
@@ -680,7 +684,7 @@ class Module(HasAccessibles):
                 trg.set()
             self.registerReconnectCallback('trigger_polls', trigger_all)
 
-        # collect and call all read functions a first time
+        # collect all read functions
         for mobj in modules:
             pinfo = mobj.pollInfo = PollInfo(mobj.pollinterval, self.triggerPoll)
             # trigger a poll interval change when self.pollinterval changes.
@@ -691,7 +695,16 @@ class Module(HasAccessibles):
                 rfunc = getattr(mobj, 'read_' + pname)
                 if rfunc.poll:
                     pinfo.polled_parameters.append((mobj, rfunc, pobj))
-                    mobj.callPollFunc(rfunc)
+        # call all read functions a first time
+        try:
+            for m in modules:
+                for mobj, rfunc, _ in m.pollInfo.polled_parameters:
+                    mobj.callPollFunc(rfunc, raise_com_failed=True)
+        except CommunicationFailedError as e:
+            # when communication failed, probably all parameters and may be more modules are affected.
+            # as this would take a lot of time (summed up timeouts), we do not continue
+            # trying and let the server accept connections, further polls might success later
+            self.log.error('communication failure on startup: %s', e)
         started_callback()
         to_poll = ()
         while True:
diff --git a/secop/persistent.py b/secop/persistent.py
index 0e7aebd..2d0f12f 100644
--- a/secop/persistent.py
+++ b/secop/persistent.py
@@ -129,7 +129,7 @@ class PersistentMixin(HasAccessibles):
                 if getattr(v, 'persistent', False)}
         if data != self.persistentData:
             self.persistentData = data
-            persistentdir = os.path.basename(self.persistentFile)
+            persistentdir = os.path.dirname(self.persistentFile)
             tmpfile = self.persistentFile + '.tmp'
             if not os.path.isdir(persistentdir):
                 os.makedirs(persistentdir, exist_ok=True)
diff --git a/secop_mlz/entangle.py b/secop_mlz/entangle.py
index ba97125..df20938 100644
--- a/secop_mlz/entangle.py
+++ b/secop_mlz/entangle.py
@@ -28,6 +28,9 @@ Here we support devices which fulfill the official
 MLZ TANGO interface for the respective device classes.
 """
 
+# pylint: disable=too-many-lines
+
+
 import re
 import threading
 from time import sleep
@@ -173,7 +176,7 @@ class PyTangoDevice(Module):
     tango_status_mapping = {
         PyTango.DevState.ON:     Drivable.Status.IDLE,
         PyTango.DevState.ALARM:  Drivable.Status.WARN,
-        PyTango.DevState.OFF:    Drivable.Status.ERROR,
+        PyTango.DevState.OFF:    Drivable.Status.DISABLED,
         PyTango.DevState.FAULT:  Drivable.Status.ERROR,
         PyTango.DevState.MOVING: Drivable.Status.BUSY,
     }
@@ -504,6 +507,9 @@ class AnalogOutput(PyTangoDevice, Drivable):
         return stable and at_target
 
     def read_status(self):
+        _st, _sts = super().read_status()
+        if _st == Readable.Status.DISABLED:
+            return _st, _sts
         if self._isAtTarget():
             self._timeout = None
             self._moving = False
diff --git a/secop_psi/ips_mercury.py b/secop_psi/ips_mercury.py
index 6020359..4c14ccf 100644
--- a/secop_psi/ips_mercury.py
+++ b/secop_psi/ips_mercury.py
@@ -20,11 +20,13 @@
 # *****************************************************************************
 """oxford instruments mercury IPS power supply"""
 
+import time
 from secop.core import Parameter, EnumType, FloatRange, BoolType
 from secop.lib.enum import Enum
-from secop.errors import BadValueError
+from secop.errors import BadValueError, HardwareError
 from secop_psi.magfield import Magfield
 from secop_psi.mercury import MercuryChannel, off_on, Mapped
+from secop.lib.statemachine import Retry
 
 Action = Enum(hold=0, run_to_set=1, run_to_zero=2, clamped=3)
 hold_rtoz_rtos_clmp = Mapped(HOLD=Action.hold, RTOS=Action.run_to_set,
@@ -37,6 +39,12 @@ class Field(MercuryChannel, Magfield):
     setpoint = Parameter('field setpoint', FloatRange(unit='T'), default=0)
     voltage = Parameter('leads voltage', FloatRange(unit='V'), default=0)
     atob = Parameter('field to amp', FloatRange(0, unit='A/T'), default=0)
+    I1 = Parameter('master current', FloatRange(unit='A'), default=0)
+    I2 = Parameter('slave 2 current', FloatRange(unit='A'), default=0)
+    I3 = Parameter('slave 3 current', FloatRange(unit='A'), default=0)
+    V1 = Parameter('master voltage', FloatRange(unit='V'), default=0)
+    V2 = Parameter('slave 2 voltage', FloatRange(unit='V'), default=0)
+    V3 = Parameter('slave 3 voltage', FloatRange(unit='V'), default=0)
     forced_persistent_field = Parameter(
         'manual indication that persistent field is bad', BoolType(), readonly=False, default=False)
 
@@ -46,13 +54,17 @@ class Field(MercuryChannel, Magfield):
     slave_currents = None
     __init = True
 
+    def doPoll(self):
+        super().doPoll()
+        self.read_current()
+
     def read_value(self):
         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 != 0 or self._field_mismatch is None:
+        if self.switch_heater == self.switch_heater.on or self._field_mismatch is None:
             self.forced_persistent_field = False
             self._field_mismatch = False
             return self.current
@@ -84,7 +96,13 @@ class Field(MercuryChannel, Magfield):
         return self.change('PSU:ACTN', value, hold_rtoz_rtos_clmp)
 
     def read_switch_heater(self):
-        return self.query('PSU:SIG:SWHT', off_on)
+        value = self.query('PSU:SIG:SWHT', off_on)
+        now = time.time()
+        if value != self.switch_heater:
+            if now < (self.switch_time[self.switch_heater] or 0) + 10:
+                # probably switch heater was changed, but IPS reply is not yet updated
+                return self.switch_heater
+        return value
 
     def write_switch_heater(self, value):
         return self.change('PSU:SIG:SWHT', value, off_on)
@@ -104,7 +122,11 @@ class Field(MercuryChannel, Magfield):
         current = self.query('PSU:SIG:CURR')
         for i in range(self.nslaves + 1):
             if i:
-                self.slave_currents[i].append(self.query('DEV:PSU.M%d:PSU:SIG:CURR' % i))
+                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)
+                self.slave_currents[i].append(curri)
             else:
                 self.slave_currents[i].append(current)
             min_i = min(self.slave_currents[i])
@@ -128,16 +150,22 @@ class Field(MercuryChannel, Magfield):
         try:
             self.set_and_go(self.persistent_field)
         except (HardwareError, AssertionError):
-            state.switch_undef = self.switch_on_time or state.now
+            state.switch_undef = self.switch_time[self.switch_heater.on] or state.now
             return self.wait_for_switch
         return self.ramp_to_field
 
+    def ramp_to_field(self, state):
+        if self.action != 'run_to_set':
+            self.status = Status.PREPARING, 'restart ramp to field'
+            return self.start_ramp_to_field
+        return super().ramp_to_field(state)
+
     def wait_for_switch(self, state):
-        if self.now - self.switch_undef < self.wait_switch_on:
+        if state.now - state.switch_undef < self.wait_switch_on:
             return Retry()
         self.set_and_go(self.persistent_field)
         return self.ramp_to_field
-        
+
     def start_ramp_to_target(self, state):
         self.set_and_go(self.target)
         return self.ramp_to_target
diff --git a/secop_psi/magfield.py b/secop_psi/magfield.py
index 1d800b2..b7d42f6 100644
--- a/secop_psi/magfield.py
+++ b/secop_psi/magfield.py
@@ -44,6 +44,9 @@ Status = Enum(
     FINALIZING=390,
 )
 
+OFF = 0
+ON = 1
+
 
 class Magfield(HasLimits, Drivable):
     value = Parameter('magnetic field', datatype=FloatRange(unit='T'))
@@ -52,7 +55,7 @@ class Magfield(HasLimits, Drivable):
         'persistent mode', EnumType(Mode), readonly=False, default=Mode.PERSISTENT)
     tolerance = Parameter(
         'tolerance', FloatRange(0, unit='$'), readonly=False, default=0.0002)
-    switch_heater = Parameter('switch heater', EnumType(off=0, on=1),
+    switch_heater = Parameter('switch heater', EnumType(off=OFF, on=ON),
                               readonly=False, default=0)
     persistent_field = Parameter(
         'persistent field', FloatRange(unit='$'), readonly=False)
@@ -73,34 +76,23 @@ class Magfield(HasLimits, Drivable):
     #     ArrayOf(TupleOf(FloatRange(unit='$'), FloatRange(unit='$/min'))), readonly=False)
     # TODO: the following parameters should be changed into properties after tests
     wait_switch_on = Parameter(
-        'wait time to ensure switch is on', FloatRange(0, unit='s'), readonly=False, default=61)
+        'wait time to ensure switch is on', FloatRange(0, unit='s'), readonly=False, default=60)
     wait_switch_off = Parameter(
-        'wait time to ensure switch is off', FloatRange(0, unit='s'), readonly=False, default=61)
+        'wait time to ensure switch is off', FloatRange(0, unit='s'), readonly=False, default=60)
     wait_stable_leads = Parameter(
         'wait time to ensure current is stable', FloatRange(0, unit='s'), readonly=False, default=6)
     wait_stable_field = Parameter(
-        'wait time to ensure field is stable', FloatRange(0, unit='s'), readonly=False, default=31)
+        'wait time to ensure field is stable', FloatRange(0, unit='s'), readonly=False, default=30)
     persistent_limit = Parameter(
         'above this limit, lead currents are not driven to 0',
         FloatRange(0, unit='$'), readonly=False, default=99)
 
     _state = None
-    __init = True
     _last_target = None
-    switch_on_time = None
-    switch_off_time = None
+    switch_time = None, None
 
     def doPoll(self):
-        if self.__init:
-            self.__init = False
-            if self.read_switch_heater() and self.mode == Mode.PERSISTENT:
-                self.read_value()  # check for persistent field mismatch
-                # switch off heater from previous live or manual intervention
-                self.write_target(self.persistent_field)
-            else:
-                self._last_target = self.persistent_field
-        else:
-            self.read_value()
+        self.read_value()
         self._state.cycle()
 
     def checkProperties(self):
@@ -117,6 +109,19 @@ class Magfield(HasLimits, Drivable):
         self.registerCallbacks(self)  # for update_switch_heater
         self._state = StateMachine(logger=self.log, threaded=False, cleanup=self.cleanup_state)
 
+    def startModule(self, start_events):
+        start_events.queue(self.startupCheck)
+        super().startModule(start_events)
+
+    def startupCheck(self):
+        if self.read_switch_heater() and self.mode == Mode.PERSISTENT:
+            self.read_value()  # check for persistent field mismatch
+            # switch off heater from previous live or manual intervention
+            self.write_mode(self.mode)
+            self.write_target(self.persistent_field)
+        else:
+            self._last_target = self.persistent_field
+
     def write_target(self, target):
         self.check_limits(target)
         self.target = target
@@ -185,14 +190,11 @@ class Magfield(HasLimits, Drivable):
 
     def update_switch_heater(self, value):
         """is called whenever switch heater was changed"""
-        if value != 0:
-            self.switch_off_time = None
-            if self.switch_on_time is None:
-                self.switch_on_time = time.time()
-        else:
-            self.switch_on_time = None
-            if self.switch_off_time is None:
-                self.switch_off_time = time.time()
+        switch_time = self.switch_time[value]
+        if switch_time is None:
+            switch_time = time.time()
+        self.switch_time = [None, None]
+        self.switch_time[value] = switch_time
 
     def start_switch_on(self, state):
         """switch heater on"""
@@ -213,12 +215,10 @@ class Magfield(HasLimits, Drivable):
                 abs(self.target - self.persistent_field) <= self.tolerance):  # short cut
             return self.check_switch_off
         self.read_switch_heater()
-        if self.switch_on_time is None:
-            if state.now - self.switch_off_time > 10:
-                 self.log.warning('switch turned off manually?')
-                 return self.start_switch_on
-            return Retry()
-        if state.now - self.switch_on_time < self.wait_switch_on:
+        if self.switch_time[ON] is None:
+            self.log.warning('switch turned off manually?')
+            return self.start_switch_on
+        if state.now - self.switch_time[ON] < self.wait_switch_on:
             return Retry()
         self._last_target = self.target
         return self.start_ramp_to_target
@@ -279,12 +279,10 @@ class Magfield(HasLimits, Drivable):
             return self.start_switch_on
         self.persistent_field = self.value
         self.read_switch_heater()
-        if self.switch_off_time is None:
-            if state.now - self.switch_on_time > 10:
-                 self.log.warning('switch turned on manually?')
-                 return self.start_switch_off
-            return Retry()
-        if state.now - self.switch_off_time < self.wait_switch_off:
+        if self.switch_time[OFF] is None:
+            self.log.warning('switch turned on manually?')
+            return self.start_switch_off
+        if state.now - self.switch_time[OFF] < self.wait_switch_off:
             return Retry()
         if abs(self.value) > self.persistent_limit:
             self.status = Status.IDLE, 'leads current at field, switch off'
diff --git a/secop_psi/mercury.py b/secop_psi/mercury.py
index deb4a9e..0aebc82 100644
--- a/secop_psi/mercury.py
+++ b/secop_psi/mercury.py
@@ -345,7 +345,7 @@ class HeaterOutput(HasInput, MercuryChannel, Writable):
 class TemperatureLoop(TemperatureSensor, Loop, Drivable):
     channel_type = 'TEMP'
     output_module = Attached(HasInput, mandatory=False)
-    ramp = Parameter('ramp rate', FloatRange(0, unit='K/min'), readonly=False)
+    ramp = Parameter('ramp rate', FloatRange(0, unit='$/min'), readonly=False)
     enable_ramp = Parameter('enable ramp rate', BoolType(), readonly=False)
     setpoint = Parameter('working setpoint (differs from target when ramping)', FloatRange(0, unit='$'))
     tolerance = Parameter(default=0.1)
diff --git a/secop_psi/phytron.py b/secop_psi/phytron.py
index 614814d..66899e5 100644
--- a/secop_psi/phytron.py
+++ b/secop_psi/phytron.py
@@ -35,7 +35,9 @@ class PhytronIO(StringIO):
     identification = [('0IVR', 'MCC Minilog .*')]
 
     def communicate(self, command):
-        for ntry in range(5, 0, -1):
+        ntry = 5
+        warn = None
+        for itry in range(ntry):
             try:
                 _, _, reply = super().communicate('\x02' + command).partition('\x02')
                 if reply[0] == '\x06':  # ACK
@@ -43,9 +45,12 @@ class PhytronIO(StringIO):
                 raise CommunicationFailedError('missing ACK %r (cmd: %r)'
                                                % (reply, command))
             except Exception as e:
-                if ntry == 1:
+                if itry < ntry - 1:
+                    warn = e
+                else:
                     raise
-                self.log.warning('%s - retry', e)
+        if warn:
+            self.log.warning('needed %d retries after %r', itry, warn)
         return reply[1:]
 
 
diff --git a/secop_psi/softcal.py b/secop_psi/softcal.py
index 530c7be..45b385c 100644
--- a/secop_psi/softcal.py
+++ b/secop_psi/softcal.py
@@ -27,7 +27,8 @@ from os.path import basename, dirname, 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, FloatRange
+from secop.core import Attached, BoolType, Parameter, Readable, StringType, \
+    FloatRange, Done
 
 
 def linear(x):
@@ -182,7 +183,6 @@ class Sensor(Readable):
 
     description = 'a calibrated sensor value'
     _value_error = None
-    enablePoll = False
 
     def checkProperties(self):
         if 'description' not in self.propertyValues:
@@ -196,6 +196,9 @@ class Sensor(Readable):
         if self.description == '_':
             self.description = '%r calibrated with curve %r' % (self.rawsensor, self.calib)
 
+    def doPoll(self):
+        self.read_status()
+
     def write_calib(self, value):
         self._calib = CalCurve(value)
         return value
@@ -221,3 +224,8 @@ class Sensor(Readable):
 
     def read_value(self):
         return self._calib(self.rawsensor.read_value())
+
+    def read_status(self):
+        self.update_status(self.rawsensor.status)
+        return Done
+        
diff --git a/secop_psi/uniax.py b/secop_psi/uniax.py
index 22443be..e4e0813 100644
--- a/secop_psi/uniax.py
+++ b/secop_psi/uniax.py
@@ -25,7 +25,12 @@ import time
 import math
 from secop.core import Drivable, Parameter, FloatRange, Done, \
     Attached, Command, PersistentMixin, PersistentParam, BoolType
-from secop.errors import BadValueError
+from secop.errors import BadValueError, SECoPError
+from secop.lib.statemachine import Retry, StateMachine, Restart
+
+
+class Error(SECoPError):
+    pass
 
 
 class Uniax(PersistentMixin, Drivable):
@@ -33,11 +38,11 @@ class Uniax(PersistentMixin, Drivable):
     motor = Attached()
     transducer = Attached()
     limit = Parameter('abs limit of force', FloatRange(0, 190, unit='N'), readonly=False, default=150)
-    tolerance = Parameter('force tolerance', FloatRange(0, 10, unit='N'), readonly=False, default=0.1)
+    tolerance = Parameter('force tolerance', FloatRange(0, 10, unit='N'), readonly=False, default=0.2)
     slope = PersistentParam('spring constant', FloatRange(unit='deg/N'), readonly=False,
                             default=0.5, persistent='auto')
     pid_i = PersistentParam('integral', FloatRange(), readonly=False, default=0.5, persistent='auto')
-    filter_interval = Parameter('filter time', FloatRange(0, 60, unit='s'), readonly=False, default=1)
+    filter_interval = Parameter('filter time', FloatRange(0, 60, unit='s'), readonly=False, default=5)
     current_step = Parameter('', FloatRange(unit='deg'), default=0)
     force_offset = PersistentParam('transducer offset', FloatRange(unit='N'), readonly=False, default=0,
                                    initwrite=True, persistent='auto')
@@ -52,8 +57,11 @@ class Uniax(PersistentMixin, Drivable):
                                    default=0.2, persistent='auto')
     low_pos = Parameter('max. position for positive forces', FloatRange(unit='deg'), readonly=False, needscfg=False)
     high_pos = Parameter('min. position for negative forces', FloatRange(unit='deg'), readonly=False, needscfg=False)
+    substantial_force = Parameter('min. force change expected within motor play', FloatRange(), default=1)
+    motor_play = Parameter('acceptable motor play within hysteresis', FloatRange(), readonly=False, default=10)
+    motor_max_play = Parameter('acceptable motor play outside hysteresis', FloatRange(), readonly=False, default=90)
+    timeout = Parameter('driving finishes when no progress within this delay', FloatRange(), readonly=False, default=300)
     pollinterval = 0.1
-    fast_pollfactor = 1
 
     _mot_target = None  # for detecting manual motor manipulations
     _filter_start = 0
@@ -61,19 +69,21 @@ class Uniax(PersistentMixin, Drivable):
     _sum = 0
     _cnt_rderr = 0
     _cnt_wrerr = 0
-    _action = None
-    _last_force = 0
-    _expected_step = 1
-    _fail_cnt = 0
-    _in_cnt = 0
-    _init_action = False
     _zero_pos_tol = None
-    _find_target = 0
+    _state = None
+    _force = None  # raw force
 
     def earlyInit(self):
         super().earlyInit()
         self._zero_pos_tol = {}
-        self._action = self.idle
+
+    def initModule(self):
+        super().initModule()
+        self._state = StateMachine(logger=self.log, threaded=False, cleanup=self.cleanup)
+
+    def doPoll(self):
+        self.read_value()
+        self._state.cycle()
 
     def drive_relative(self, step, ntry=3):
         """drive relative, try 3 times"""
@@ -84,7 +94,12 @@ class Uniax(PersistentMixin, Drivable):
         self.current_step = step
         for _ in range(ntry):
             try:
-                self._mot_target = self.motor.write_target(mot.value + step)
+                if abs(mot.value - mot.target) < mot.tolerance:
+                    # make sure rounding erros do not suppress small steps
+                    newpos = mot.target + step
+                else:
+                    newpos = mot.value + step
+                self._mot_target = self.motor.write_target(newpos)
                 self._cnt_wrerr = max(0, self._cnt_wrerr - 1)
                 return True
             except Exception as e:
@@ -96,39 +111,52 @@ class Uniax(PersistentMixin, Drivable):
                 self.motor.reset()
         return False
 
-    def reset_filter(self, now=0.0):
-        self._sum = self._cnt = 0
-        self._filter_start = now or time.time()
-
     def motor_busy(self):
         mot = self.motor
         if mot.isBusy():
             if mot.target != self._mot_target:
-                self.action = self.idle
+                raise Error('control stopped - motor moved directly')
             return True
         return False
 
-    def next_action(self, action):
-        """call next action
+    def read_value(self):
+        try:
+            self._force = force = self.transducer.read_value()
+            self._cnt_rderr = max(0, self._cnt_rderr - 1)
+        except Exception as e:
+            self._cnt_rderr += 1
+            if self._cnt_rderr > 10:
+                self.stop()
+                self.status = 'ERROR', 'too many read errors: %s' % e
+                self.log.error(self.status[1])
+                self.read_target()
+            return Done
 
-        :param action: function to be called next time
-        :param do_now: do next action in the same cycle
-        """
-        self._action = action
-        self._init_action = True
-        self.log.info('action %r', action.__name__)
+        now = time.time()
+        self._sum += force
+        self._cnt += 1
+        if now < self._filter_start + self.filter_interval:
+            return Done
+        force = self._sum / self._cnt
+        self.reset_filter(now)
+        if abs(force) > self.limit + self.hysteresis:
+            self.motor.stop()
+            self.status = 'ERROR', 'above max limit'
+            self.log.error(self.status[1])
+            self.read_target()
+            return Done
+        if self.zero_pos(force) is None and abs(force) > self.hysteresis:
+            self.set_zero_pos(force, self.motor.read_value())
+        return force
 
-    def init_action(self):
-        """return true when called the first time after next_action"""
-        if self._init_action:
-            self._init_action = False
-            return True
-        return False
+    def reset_filter(self, now=0.0):
+        self._sum = self._cnt = 0
+        self._filter_start = now or time.time()
 
-    def zero_pos(self, value,):
+    def zero_pos(self, value):
         """get high_pos or low_pos, depending on sign of value
 
-        :param force: when not 0, return an estimate for a good starting position
+        :param value: return an estimate for a good starting position
         """
 
         name = 'high_pos' if value > 0 else 'low_pos'
@@ -155,207 +183,233 @@ class Uniax(PersistentMixin, Drivable):
         self._zero_pos_tol[name] = tol
         self.log.info('set %s = %.1f +- %.1f (@%g N)' % (name, pos, tol, force))
         setattr(self, name, pos)
-        return pos
 
-    def find(self, force, target):
-        """find active (engaged) range"""
-        sign = math.copysign(1, target)
-        if force * sign > self.hysteresis or force * sign > target * sign:
-            if self.motor_busy():
-                self.log.info('motor stopped - substantial force detected: %g', force)
-                self.motor.stop()
-            elif self.init_action():
-                self.next_action(self.adjust)
-                return
-            if abs(force) > self.hysteresis:
-                self.set_zero_pos(force, self.motor.read_value())
-            self.next_action(self.adjust)
-            return
-        if force * sign < -self.hysteresis:
-            self._previous_force = force
-            self.next_action(self.free)
-            return
-        if self.motor_busy():
-            if sign * self._find_target < 0:  # target sign changed
-                self.motor.stop()
-                self.next_action(self.find)  # restart find
+    def cleanup(self, state):
+        """in case of error, set error status"""
+        if state.stopped:  # stop or restart
+            if state.stopped is Restart:
                 return
+            self.status = 'IDLE', 'stopped'
+            self.log.warning('stopped')
         else:
-            self._find_target = target
-            zero_pos = self.zero_pos(target)
-            side_name = 'positive' if target > 0 else 'negative'
-            if not self.init_action():
-                if abs(self.motor.target - self.motor.value) > self.motor.tolerance:
-                    # no success on last find try, try short and strong step
-                    self.write_adjusting(True)
-                    self.log.info('one step to %g', self.motor.value + self.safe_step)
-                    self.drive_relative(sign * self.safe_step)
-                    return
-            if zero_pos is not None:
-                self.status = 'BUSY', 'change to %s side' % side_name
-                zero_pos += sign * (self.hysteresis * self.slope - self.motor.tolerance)
-                if (self.motor.value - zero_pos) * sign < -self.motor.tolerance:
-                    self.write_adjusting(False)
-                    self.log.info('change side to %g', zero_pos)
-                    self.drive_relative(zero_pos - self.motor.value)
-                    return
-                # we are already at or beyond zero_pos
-                self.next_action(self.adjust)
-                return
-            self.write_adjusting(False)
-            self.status = 'BUSY', 'find %s side' % side_name
-            self.log.info('one turn to %g', self.motor.value + sign * 360)
-            self.drive_relative(sign * 360)
+            self.status = 'ERROR', str(state.last_error)
+            if isinstance(state.last_error, Error):
+                self.log.error('%s', state.last_error)
+            else:
+                self.log.error('%r raised in state %r', str(state.last_error), state.status_string)
+        self.read_target()  # make target invalid
+        self.motor.stop()
+        self.write_adjusting(False)
 
-    def free(self, force, target):
-        """free from high force at other end"""
-        if self.motor_busy():
-            return
-        if abs(force) > abs(self._previous_force) + self.tolerance:
-            self.stop()
-            self.status = 'ERROR', 'force increase while freeing'
-            self.log.error(self.status[1])
-            return
-        if abs(force) < self.hysteresis:
-            self.next_action(self.find)
-            return
-        if self.init_action():
-            self._free_way = 0
-            self.log.info('free from high force %g', force)
-            self.write_adjusting(True)
-        sign = math.copysign(1, target)
-        if self._free_way > (abs(self._previous_force) + self.hysteresis) * self.slope:
-            self.stop()
-            self.status = 'ERROR', 'freeing failed'
-            self.log.error(self.status[1])
-            return
-        self._free_way += self.safe_step
-        self.drive_relative(sign * self.safe_step)
+    def reset_progress(self, state):
+        state.prev_force = self.value
+        state.prev_pos = self.motor.value
+        state.prev_time = time.time()
 
-    def within_tolerance(self, force, target):
-        """within tolerance"""
-        if self.motor_busy():
-            return
-        if abs(target - force) > self.tolerance:
-            self.next_action(self.adjust)
-        elif self.init_action():
-            self.status = 'IDLE', 'within tolerance'
+    def check_progress(self, state):
+        force_step = self.target - self.value
+        direction = math.copysign(1, force_step)
+        try:
+            force_progress = direction * (self.value - state.prev_force)
+        except AttributeError:  # prev_force undefined?
+            self.reset_progress(state)
+            return True
+        if force_progress >= self.substantial_force:
+            self.reset_progress(state)
+        else:
+            motor_dif = abs(self.motor.value - state.prev_pos)
+            if motor_dif > self.motor_play:
+                if motor_dif > self.motor_max_play:
+                    raise Error('force seems not to change substantially %g %g (%g %g)' % (self.value, self.motor.value, state.prev_force, state.prev_pos))
+                return False
+        return True
 
-    def adjust(self, force, target):
+    def adjust(self, state):
         """adjust force"""
+        if state.init:
+            state.phase = 0  # just initialized
+            state.in_since = 0
+            state.direction = math.copysign(1, self.target - self.value)
+            state.pid_fact = 1
         if self.motor_busy():
-            return
-        if abs(target - force) < self.tolerance:
-            self._in_cnt += 1
-            if self._in_cnt >= 3:
-                self.next_action(self.within_tolerance)
-                return
+            return Retry()
+        self.value = self._force
+        force_step = self.target - self.value
+        if abs(force_step) < self.tolerance:
+            if state.in_since == 0:
+                state.in_since = state.now
+            if state.now > state.in_since + 10:
+                return self.within_tolerance
         else:
-            self._in_cnt = 0
-        if self.init_action():
-            self._fail_cnt = 0
+            if force_step * state.direction < 0:
+                if state.pid_fact == 1:
+                    self.log.info('overshoot -> adjust with reduced pid_i')
+                state.pid_fact = 0.1
+            state.in_since = 0
+        if state.phase == 0:
+            state.phase = 1
+            self.reset_progress(state)
             self.write_adjusting(True)
             self.status = 'BUSY', 'adjusting force'
-        elif not self._filtered:
-            return
-        else:
-            force_step = force - self._last_force
-            if self._expected_step:
-                # compare detected / expected step
-                q = force_step / self._expected_step
-                if q < 0.1:
-                    self._fail_cnt += 1
-                elif q > 0.5:
-                    self._fail_cnt = max(0, self._fail_cnt - 1)
-                if self._fail_cnt >= 10:
-                    if force < self.hysteresis:
-                        self.log.warning('adjusting failed - try to find zero pos')
-                        self.set_zero_pos(target, None)
-                        self.next_action(self.find)
-                    elif self._fail_cnt > 20:
-                        self.stop()
-                        self.status = 'ERROR', 'force seems not to change substantially'
-                        self.log.error(self.status[1])
-                        return
-        self._last_force = force
-        force_step = (target - force) * self.pid_i
-        if abs(target - force) < self.tolerance * 0.5:
-            self._expected_step = 0
-            return
-        self._expected_step = force_step
-        step = force_step * self.slope
-        self.drive_relative(step)
+        elif not self.check_progress(state):
+            if abs(self.value) < self.hysteresis:
+                if motor_dif > self.motor_play:
+                    self.log.warning('adjusting failed - try to find zero pos')
+                    self.set_zero_pos(self.target, None)
+                    return self.find
+            elif time.time() > state.prev_time + self.timeout:
+                if state.phase == 1:
+                   state.phase = 2
+                   self.log.warning('no substantial progress since %d sec', self.timeout)
+                   self.status = 'IDLE', 'adjusting timeout'
+        self.drive_relative(force_step * self.slope * self.pid_i * min(1, state.delta()) * state.pid_fact)
+        return Retry()
 
-    def idle(self, *args):
-        if self.init_action():
-            self.write_adjusting(False)
-            if self.status[0] == 'BUSY':
-                self.status = 'IDLE', 'stopped'
-
-    def read_value(self):
-        try:
-            force = self.transducer.read_value()
-            self._cnt_rderr = max(0, self._cnt_rderr - 1)
-        except Exception as e:
-            self._cnt_rderr += 1
-            if self._cnt_rderr > 10:
-                self.stop()
-                self.status = 'ERROR', 'too many read errors: %s' % e
-                self.log.error(self.status[1])
-            return Done
-
-        now = time.time()
+    def within_tolerance(self, state):
+        """within tolerance"""
+        if state.init:
+            self.status = 'IDLE', 'within tolerance'
+            return Retry()
         if self.motor_busy():
-            # do not filter while driving
-            self.value = force
-            self.reset_filter()
-            self._filtered = False
+            return Retry()
+        force_step = self.target - self.value
+        if abs(force_step) < self.tolerance * 0.5:
+            self.current_step = 0
         else:
-            self._sum += force
-            self._cnt += 1
-            if now < self._filter_start + self.filter_interval:
-                return Done
-            force = self._sum / self._cnt
-            self.value = force
-            self.reset_filter(now)
-            self._filtered = True
-        if abs(force) > self.limit + self.hysteresis:
-            self.status = 'ERROR', 'above max limit'
-            self.log.error(self.status[1])
-            return Done
-        if self.zero_pos(force) is None and abs(force) > self.hysteresis and self._filtered:
-            self.set_zero_pos(force, self.motor.read_value())
-        self._action(self.value, self.target)
-        return Done
+            self.check_progress(state)
+            self.drive_relative(force_step * self.slope * self.pid_i * min(1, state.delta()) * 0.1)
+        if abs(force_step) > self.tolerance:
+            return self.out_of_tolerance
+        return Retry()
+
+    def out_of_tolerance(self, state):
+        """out of tolerance"""
+        if state.init:
+            self.status = 'WARN', 'out of tolerance'
+            state.in_since = 0
+            return Retry()
+        if self.motor_busy():
+            return Retry()
+        force_step = self.target - self._force
+        if abs(force_step) < self.tolerance:
+            if state.in_since == 0:
+                state.in_since = state.now
+            if state.now > state.in_since + 10:
+                return self.within_tolerance
+            if abs(force_step) < self.tolerance * 0.5:
+                return Retry()
+        self.check_progress(state)
+        self.drive_relative(force_step * self.slope * self.pid_i * min(1, state.delta()) * 0.1)
+        return Retry()
+
+    def find(self, state):
+        """find active (engaged) range"""
+        if state.init:
+            state.prev_direction = 0  # find not yet started
+            self.reset_progress(state)
+        direction = math.copysign(1, self.target)
+        self.value = self._force
+        abs_force = self.value * direction
+        if abs_force > self.hysteresis or abs_force > self.target * direction:
+            if self.motor_busy():
+                self.log.info('motor stopped - substantial force detected: %g', self.value)
+                self.motor.stop()
+            elif state.prev_direction == 0:
+                return self.adjust
+            if abs_force > self.hysteresis:
+                self.set_zero_pos(self.value, self.motor.read_value())
+            return self.adjust
+        if abs_force < -self.hysteresis:
+            state.force_before_free = self.value
+            return self.free
+        if self.motor_busy():
+            if direction == -state.prev_direction:  # target direction changed
+                self.motor.stop()
+                state.init_find = True   # restart find
+            return Retry()
+        zero_pos = self.zero_pos(self.target)
+        if state.prev_direction:  # find already started
+            if abs(self.motor.target - self.motor.value) > self.motor.tolerance:
+                # no success on last find try, try short and strong step
+                self.write_adjusting(True)
+                self.log.info('one step to %g', self.motor.value + self.safe_step)
+                self.drive_relative(direction * self.safe_step)
+                return Retry()
+        else:
+            state.prev_direction = math.copysign(1, self.target)
+        side_name = 'negative' if direction == -1 else 'positive'
+        if zero_pos is not None:
+            self.status = 'BUSY', 'change to %s side' % side_name
+            zero_pos += direction * (self.hysteresis * self.slope - self.motor.tolerance)
+            if (self.motor.value - zero_pos) * direction < -self.motor.tolerance:
+                self.write_adjusting(False)
+                self.log.info('change side to %g', zero_pos)
+                self.drive_relative(zero_pos - self.motor.value)
+                return Retry()
+            # we are already at or beyond zero_pos
+            return self.adjust
+        self.write_adjusting(False)
+        self.status = 'BUSY', 'find %s side' % side_name
+        self.log.info('one turn to %g', self.motor.value + direction * 360)
+        self.drive_relative(direction * 360)
+        return Retry()
+
+    def free(self, state):
+        """free from high force at other end"""
+        if state.init:
+            state.free_way = None
+            self.reset_progress(state)
+        if self.motor_busy():
+            return Retry()
+        self.value = self._force
+        if abs(self.value) > abs(state.force_before_free) + self.hysteresis:
+            raise Error('force increase while freeing')
+        if abs(self.value) < self.hysteresis:
+            return self.find
+        if state.free_way is None:
+            state.free_way = 0
+            self.log.info('free from high force %g', self.value)
+            self.write_adjusting(True)
+        direction = math.copysign(1, self.target)
+        if state.free_way > abs(state.force_before_free + self.hysteresis) * self.slope + self.motor_max_play:
+            raise Error('freeing failed')
+        state.free_way += self.safe_step
+        self.drive_relative(direction * self.safe_step)
+        return Retry()
 
     def write_target(self, target):
         if abs(target) > self.limit:
             raise BadValueError('force above limit')
         if abs(target - self.value) <= self.tolerance:
-            if self.isBusy():
-                self.stop()
-                self.next_action(self.within_tolerance)
-            else:
+            if not self.isBusy():
                 self.status = 'IDLE', 'already at target'
-                self.next_action(self.within_tolerance)
-                return target
+            self._state.start(self.within_tolerance)
+            return target
         self.log.info('new target %g', target)
         self._cnt_rderr = 0
         self._cnt_wrerr = 0
         self.status = 'BUSY', 'changed target'
+        self.target = target
         if self.value * math.copysign(1, target) > self.hysteresis:
-            self.next_action(self.adjust)
+            self._state.start(self.adjust)
         else:
-            self.next_action(self.find)
-        return target
+            self._state.start(self.find)
+        return Done
+
+    def read_target(self):
+        if self._state.state is None:
+            if self.status[1]:
+                raise Error(self.status[1])
+            raise Error('inactive')
+        return self.target
 
     @Command()
     def stop(self):
-        self._action = self.idle
         if self.motor.isBusy():
             self.log.info('stop motor')
             self.motor.stop()
-        self.next_action(self.idle)
+        self.status = 'IDLE', 'stopped'
+        self._state.stop()
 
     def write_force_offset(self, value):
         self.force_offset = value