improvements in magfiels/ips_mercury

- read voltage
- fix a bug with ._init name conflict

cfg/main/mb11.cfg

@@ -161,6 +161,7 @@ class = secop_psi.ips_mercury.Field
 description = magnetic field
 slot = GRPZ
 io = ips
+tolerance = 0.001
 target.max = 11
 
 [om_io]

secop_psi/convergence.py

@@ -89,6 +89,10 @@ class HasConvergence:
         """to be called from write_target"""
         self.convergence_state.start(self.state_approach)
 
+    def interrupt_state(self):
+        """to be called from stop"""
+        self.convergence_state.start(self.state_instable)
+
     def state_approach(self, state):
         """approaching, checking progress (busy)"""
         state.spent_inside = 0
@@ -157,3 +161,10 @@ class HasConvergence:
         else:
             state.spent_inside = max(0, state.spent_inside - state.delta())
         return Retry()
+
+    def state_interrupt(self, state):
+        self.status = IDLE, 'stopped'  # stop called
+        return self.state_instable
+
+    def stop(self):
+        self.convergence_state.start(self.state_interrupt)

secop_psi/ips_mercury.py

@@ -35,6 +35,7 @@ CURRENT_CHECK_SIZE = 2
 class Field(MercuryChannel, Magfield):
     action = Parameter('action', EnumType(Action), readonly=False)
     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)
     forced_persistent_field = Parameter(
         'manual indication that persistent field is bad', BoolType(), readonly=False, default=False)
@@ -43,13 +44,13 @@ class Field(MercuryChannel, Magfield):
     _field_mismatch = None
     nslaves = 3
     slave_currents = None
-    _init = True
+    __init = True
 
     def read_value(self):
         self.current = self.query('PSU:SIG:FLD')
         pf = self.query('PSU:SIG:PFLD')
-        if self._init:
-            self._init = False
+        if self.__init:
+            self.__init = False
             self.persistent_field = pf
         if self.switch_heater != 0 or self._field_mismatch is None:
             self.forced_persistent_field = False
@@ -92,6 +93,9 @@ class Field(MercuryChannel, Magfield):
     def read_atob(self):
         return self.query('PSU:ATOB')
 
+    def read_voltage(self):
+        return self.query('PSU:SIG:VOLT')
+
     def read_setpoint(self):
         return self.query('PSU:SIG:FSET')
 

secop_psi/magfield.py

@@ -82,19 +82,21 @@ class Magfield(HasLimits, Drivable):
         'wait time to ensure field is stable', FloatRange(0, unit='s'), readonly=False, default=31)
 
     _state = None
-    _init = True
+    __init = True
     _super_sw_check = False
     _last_target = None
     switch_time = None
 
     def doPoll(self):
-        if self._init:
-            self._init = False
+        if self.__init:
+            self.__init = False
             self.switch_time = time.time()
             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_value)
+                self.write_target(self.persistent_field)
+            else:
+                self._last_target = self.persistent_field
         else:
             self.read_value()
         self._state.cycle()