minimal example

minimal_example.py

from ophyd import PVPositionerPC, EpicsSignal, EpicsSignalRO, PseudoPositioner, PseudoSingle
from ophyd.pseudopos import (pseudo_position_argument,
                             real_position_argument)
from ophyd import Component as Cpt


class QuadEMDwellTime(PVPositionerPC):
    setpoint = Cpt(EpicsSignal, 'AveragingTime')
    readback = Cpt(EpicsSignalRO, 'AveragingTime_RBV')


class StruckDwellTime(PVPositionerPC):
    setpoint = Cpt(EpicsSignal, 'TP')
    readback = Cpt(EpicsSignalRO, 'TP')
    

class LockedDwellTimes(PseudoPositioner):
    "Sync QuadEM and Struck dwell times to one pseudo-axis dwell time."
    dwell_time = Cpt(PseudoSingle, kind='hinted')
    quadem_dwell_time = Cpt(QuadEMDwellTime, 'XF:06BM-BI{EM:1}EM180:', egu='seconds')
    struck_dwell_time = Cpt(StruckDwellTime, 'XF:06BM-ES:1{Sclr:1}.',  egu='seconds')

    @property
    def settle_time(self):
        return self.quadem_dwell_time.settle_time

    @settle_time.setter
    def settle_time(self, val):
        self.quadem_dwell_time.settle_time = val
        self.struck_dwell_time.settle_time = val

    @pseudo_position_argument
    def forward(self, pseudo_pos):
        pseudo_pos = self.PseudoPosition(*pseudo_pos)
        # logger.debug('forward %s', pseudo_pos)
        return self.RealPosition(quadem_dwell_time=pseudo_pos.dwell_time,
                                 struck_dwell_time=pseudo_pos.dwell_time)

    @real_position_argument
    def inverse(self, real_pos):
        real_pos = self.RealPosition(*real_pos)
        return self.PseudoPosition(dwell_time=real_pos.quadem_dwell_time)


_locked_dwell_time = LockedDwellTimes('', name='dwti')
dwell_time = _locked_dwell_time.dwell_time
dwell_time.name = 'inttime'

output.md

$ ipython -i minimal_example.py

In [1]: _locked_dwell_time.wait_for_connection()                                                                                  
---------------------------------------------------------------------------
TimeoutError                              Traceback (most recent call last)
<ipython-input-1-fc5bf05eae5a> in <module>
----> 1 _locked_dwell_time.wait_for_connection()
/tmp/new-stuff/lib/python3.7/site-packages/ophyd/device.py in wait_for_connection(self, all_signals, timeout)
   1141                                 for obj, description in funcs.items())
   1142             reasons.append(f'Pending operations: {pending}')
-> 1143         raise TimeoutError('; '.join(reasons))
   1144 
   1145     def get_instantiated_signals(self, *, attr_prefix=None):
TimeoutError: Pending operations: inttime readback subscription, dwti_quadem_dwell_time readback position