Source code for qcodes.instrument_drivers.oxford.MercuryiPS_VISA

import logging
import time
from functools import partial
from typing import Any, Callable, Dict, List, Optional, Union, cast

import numpy as np
from packaging import version

from qcodes.instrument.channel import InstrumentChannel
from qcodes.instrument.visa import VisaInstrument
from qcodes.math_utils.field_vector import FieldVector

log = logging.getLogger(__name__)
visalog = logging.getLogger('qcodes.instrument.visa')


def _response_preparser(bare_resp: str) -> str:
    """
    Pre-parse response from the instrument
    """
    return bare_resp.replace(':', '')


def _signal_parser(our_scaling: float, response: str) -> float:
    """
    Parse a response string into a correct SI value.

    Args:
        our_scaling: Whatever scale we might need to apply to get from
            e.g. A/min to A/s.
        response: What comes back from instrument.ask
    """

    # there might be a scale before the unit. We only want to deal in SI
    # units, so we translate the scale
    scale_to_factor = {'n': 1e-9, 'u': 1e-6, 'm': 1e-3,
                       'k': 1e3, 'M': 1e6}

    numchars = ['0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.', '-']

    response = _response_preparser(response)
    digits = "".join(d for d in response if d in numchars)
    scale_and_unit = response[len(digits) :]
    if scale_and_unit == "":
        their_scaling: float = 1
    elif scale_and_unit[0] in scale_to_factor.keys():
        their_scaling = scale_to_factor[scale_and_unit[0]]
    else:
        their_scaling = 1

    return float(digits)*their_scaling*our_scaling


[docs]class MercuryWorkerPS(InstrumentChannel): """ Class to hold a worker power supply for the MercuryiPS """ def __init__(self, parent: VisaInstrument, name: str, UID: str) -> None: """ Args: parent: The Instrument instance of the MercuryiPS name: The 'colloquial' name of the PS UID: The UID as used internally by the MercuryiPS, e.g. 'GRPX' """ if ':' in UID: raise ValueError('Invalid UID. Must be axis group name or device ' 'name, e.g. "GRPX" or "PSU.M1"') super().__init__(parent, name) self.uid = UID # The firmware update from 2.5 -> 2.6 changed the command # syntax slightly if version.parse(self.root_instrument.firmware) >= version.parse("2.6"): self.psu_string = "SPSU" else: self.psu_string = "PSU" self.add_parameter('voltage', label='Output voltage', get_cmd=partial(self._param_getter, 'SIG:VOLT'), unit='V', get_parser=partial(_signal_parser, 1)) self.add_parameter('current', label='Output current', get_cmd=partial(self._param_getter, 'SIG:CURR'), unit='A', get_parser=partial(_signal_parser, 1)) self.add_parameter('current_persistent', label='Output persistent current', get_cmd=partial(self._param_getter, 'SIG:PCUR'), unit='A', get_parser=partial(_signal_parser, 1)) self.add_parameter('current_target', label='Target current', get_cmd=partial(self._param_getter, 'SIG:CSET'), unit='A', get_parser=partial(_signal_parser, 1)) self.add_parameter('field_target', label='Target field', get_cmd=partial(self._param_getter, 'SIG:FSET'), set_cmd=partial(self._param_setter, 'SIG:FSET'), unit='T', get_parser=partial(_signal_parser, 1)) # NB: The current ramp rate follows the field ramp rate # (converted via the ATOB param) self.add_parameter('current_ramp_rate', label='Ramp rate (current)', unit='A/s', get_cmd=partial(self._param_getter, 'SIG:RCST'), get_parser=partial(_signal_parser, 1/60)) self.add_parameter('field_ramp_rate', label='Ramp rate (field)', unit='T/s', set_cmd=partial(self._param_setter, 'SIG:RFST'), get_cmd=partial(self._param_getter, 'SIG:RFST'), get_parser=partial(_signal_parser, 1/60), set_parser=lambda x: x*60) self.add_parameter('field', label='Field strength', unit='T', get_cmd=partial(self._param_getter, 'SIG:FLD'), get_parser=partial(_signal_parser, 1)) self.add_parameter('field_persistent', label='Persistent field strength', unit='T', get_cmd=partial(self._param_getter, 'SIG:PFLD'), get_parser=partial(_signal_parser, 1)) self.add_parameter('ATOB', label='Current to field ratio', unit='A/T', get_cmd=partial(self._param_getter, 'ATOB'), get_parser=partial(_signal_parser, 1), set_cmd=partial(self._param_setter, 'ATOB')) self.add_parameter('ramp_status', label='Ramp status', get_cmd=partial(self._param_getter, 'ACTN'), set_cmd=self._ramp_status_setter, get_parser=_response_preparser, val_mapping={'HOLD': 'HOLD', 'TO SET': 'RTOS', 'CLAMP': 'CLMP', 'TO ZERO': 'RTOZ'})
[docs] def ramp_to_target(self) -> None: """ Unconditionally ramp this PS to its target """ status = self.ramp_status() if status == 'CLAMP': self.ramp_status('HOLD') self.ramp_status('TO SET')
def _ramp_status_setter(self, cmd: str) -> None: status_now = self.ramp_status() if status_now == 'CLAMP' and cmd == 'RTOS': raise ValueError(f'Error in ramping unit {self.uid}: ' 'Can not ramp to target value; power supply is ' 'clamped. Unclamp first by setting ramp status ' 'to HOLD.') else: partial(self._param_setter, 'ACTN')(cmd) def _param_getter(self, get_cmd: str) -> str: """ General getter function for parameters Args: get_cmd: raw string for the command, e.g. 'SIG:VOLT' Returns: The response. Cf. MercuryiPS.ask for how much is returned """ dressed_cmd = f"READ:DEV:{self.uid}:{self.psu_string}:{get_cmd}" resp = self._parent.ask(dressed_cmd) return resp def _param_setter(self, set_cmd: str, value: Union[float, str]) -> None: """ General setter function for parameters Args: set_cmd: raw string for the command, e.g. 'SIG:FSET' """ dressed_cmd = f"SET:DEV:{self.uid}:{self.psu_string}:{set_cmd}:{value}" # the instrument always very verbosely responds # the return value of `ask` # holds the value reported back by the instrument self._parent.ask(dressed_cmd)
# TODO: we could use the opportunity to check that we did set/achieve # the intended value
[docs]class MercuryiPS(VisaInstrument): """ Driver class for the QCoDeS Oxford Instruments MercuryiPS magnet power supply """ def __init__(self, name: str, address: str, visalib: Optional[str] = None, field_limits: Optional[Callable[[float, float, float], bool]] = None, **kwargs: Any) -> None: """ Args: name: The name to give this instrument internally in QCoDeS address: The VISA resource of the instrument. Note that a socket connection to port 7020 must be made visalib: The VISA library to use. Leave blank if not in simulation mode. field_limits: A function describing the allowed field range (T). The function shall take (x, y, z) as an input and return a boolean describing whether that field value is acceptable. """ if field_limits is not None and not(callable(field_limits)): raise ValueError('Got wrong type of field_limits. Must be a ' 'function from (x, y, z) -> Bool. Received ' f'{type(field_limits)} instead.') if visalib: visabackend = visalib.split('@')[1] else: visabackend = 'NI' # ensure that a socket is used unless we are in simulation mode if not address.endswith('SOCKET') and visabackend != 'sim': raise ValueError('Incorrect VISA resource name. Must be of type ' 'TCPIP0::XXX.XXX.XXX.XXX::7020::SOCKET.') super().__init__(name, address, terminator='\n', visalib=visalib, **kwargs) # to ensure a correct snapshot, we must wrap the get function self.IDN.get = self.IDN._wrap_get(self._idn_getter) self.firmware = self.IDN()['firmware'] # TODO: Query instrument to ensure which PSUs are actually present for grp in ['GRPX', 'GRPY', 'GRPZ']: psu_name = grp psu = MercuryWorkerPS(self, psu_name, grp) self.add_submodule(psu_name, psu) self._field_limits = (field_limits if field_limits else lambda x, y, z: True) self._target_vector = FieldVector(x=self.GRPX.field(), y=self.GRPY.field(), z=self.GRPZ.field()) for coord, unit in zip( ['x', 'y', 'z', 'r', 'theta', 'phi', 'rho'], ['T', 'T', 'T', 'T', 'degrees', 'degrees', 'T']): self.add_parameter(name=f'{coord}_target', label=f'{coord.upper()} target field', unit=unit, get_cmd=partial(self._get_component, coord), set_cmd=partial(self._set_target, coord)) self.add_parameter(name=f'{coord}_measured', label=f'{coord.upper()} measured field', unit=unit, get_cmd=partial(self._get_measured, [coord])) self.add_parameter(name=f'{coord}_ramp', label=f'{coord.upper()} ramp field', unit=unit, docstring='A safe ramp for each coordinate', get_cmd=partial(self._get_component, coord), set_cmd=partial(self._set_target_and_ramp, coord, 'safe')) if coord in ['r', 'theta', 'phi', 'rho']: self.add_parameter(name=f'{coord}_simulramp', label=f'{coord.upper()} ramp field', unit=unit, docstring='A simultaneous blocking ramp for' ' a combined coordinate', get_cmd=partial(self._get_component, coord), set_cmd=partial(self._set_target_and_ramp, coord, 'simul_block')) # FieldVector-valued parameters # self.add_parameter(name="field_target", label="target field", unit="T", get_cmd=self._get_target_field, set_cmd=self._set_target_field) self.add_parameter(name="field_measured", label="measured field", unit="T", get_cmd=self._get_field) self.add_parameter(name="field_ramp_rate", label="ramp rate", unit="T/s", get_cmd=self._get_ramp_rate, set_cmd=self._set_ramp_rate) self.connect_message() def _get_component(self, coordinate: str) -> float: return self._target_vector.get_components(coordinate)[0] def _get_target_field(self) -> FieldVector: return FieldVector( **{ coord: self._get_component(coord) for coord in 'xyz' } ) def _get_ramp_rate(self) -> FieldVector: return FieldVector( x=self.GRPX.field_ramp_rate(), y=self.GRPY.field_ramp_rate(), z=self.GRPZ.field_ramp_rate(), ) def _set_ramp_rate(self, rate: FieldVector) -> None: self.GRPX.field_ramp_rate(rate.x) self.GRPY.field_ramp_rate(rate.y) self.GRPZ.field_ramp_rate(rate.z) def _get_measured(self, coordinates: List[str]) -> Union[float, List[float]]: """ Get the measured value of a coordinate. Measures all three fields and computes whatever coordinate we asked for. """ meas_field = FieldVector(x=self.GRPX.field(), y=self.GRPY.field(), z=self.GRPZ.field()) if len(coordinates) == 1: return meas_field.get_components(*coordinates)[0] else: return meas_field.get_components(*coordinates) def _get_field(self) -> FieldVector: return FieldVector( x=self.x_measured(), y=self.y_measured(), z=self.z_measured() ) def _set_target(self, coordinate: str, target: float) -> None: """ The function to set a target value for a coordinate, i.e. the set_cmd for the XXX_target parameters """ # first validate the new target valid_vec = FieldVector() valid_vec.copy(self._target_vector) valid_vec.set_component(**{coordinate: target}) components = valid_vec.get_components('x', 'y', 'z') if not self._field_limits(*components): raise ValueError(f'Cannot set {coordinate} target to {target}, ' 'that would violate the field_limits. ') # update our internal target cache self._target_vector.set_component(**{coordinate: target}) # actually assign the target on the workers cartesian_targ = self._target_vector.get_components('x', 'y', 'z') for targ, worker in zip(cartesian_targ, self.submodules.values()): if not isinstance(worker, MercuryWorkerPS): raise RuntimeError(f"Expected a MercuryWorkerPS but got " f"{type(worker)}") worker.field_target(targ) def _set_target_field(self, field: FieldVector) -> None: for coord in 'xyz': self._set_target(coord, field[coord]) def _idn_getter(self) -> Dict[str, str]: """ Parse the raw non-SCPI compliant IDN string into an IDN dict Returns: The normal IDN dict """ raw_idn_string = self.ask('*IDN?') resps = raw_idn_string.split(':') idn_dict = {'model': resps[2], 'vendor': resps[1], 'serial': resps[3], 'firmware': resps[4]} return idn_dict def _ramp_simultaneously(self) -> None: """ Ramp all three fields to their target simultaneously at their given ramp rates. NOTE: there is NO guarantee that this does not take you out of your safe region. Use with care. """ for worker in self.submodules.values(): if not isinstance(worker, MercuryWorkerPS): raise RuntimeError(f"Expected a MercuryWorkerPS but got " f"{type(worker)}") worker.ramp_to_target() def _ramp_simultaneously_blocking(self) -> None: """ Ramp all three fields to their target simultaneously at their given ramp rates. NOTE: there is NO guarantee that this does not take you out of your safe region. Use with care. This function is BLOCKING. """ self._ramp_simultaneously() for worker in self.submodules.values(): if not isinstance(worker, MercuryWorkerPS): raise RuntimeError(f"Expected a MercuryWorkerPS but got " f"{type(worker)}") # wait for the ramp to finish, we don't care about the order while worker.ramp_status() == 'TO SET': time.sleep(0.1) self.update_field() def _ramp_safely(self) -> None: """ Ramp all three fields to their target using the 'first-down-then-up' sequential ramping procedure. This function is BLOCKING. """ meas_vals = self._get_measured(['x', 'y', 'z']) targ_vals = self._target_vector.get_components('x', 'y', 'z') order = np.argsort(np.abs(np.array(targ_vals) - np.array(meas_vals))) for worker in np.array(list(self.submodules.values()))[order]: worker.ramp_to_target() # now just wait for the ramp to finish # (unless we are testing) if self.visabackend == 'sim': pass else: while worker.ramp_status() == 'TO SET': time.sleep(0.1) self.update_field()
[docs] def update_field(self) -> None: """ Update all the field components. """ coords = ['x', 'y', 'z', 'r', 'theta', 'phi', 'rho'] _ = self._get_field() [getattr(self, f'{i}_measured').get() for i in coords]
[docs] def is_ramping(self) -> bool: """ Returns True if any axis has a ramp status that is either 'TO SET' or 'TO ZERO' """ ramping_statuus = ['TO SET', 'TO ZERO'] is_x_ramping = self.GRPX.ramp_status() in ramping_statuus is_y_ramping = self.GRPY.ramp_status() in ramping_statuus is_z_ramping = self.GRPZ.ramp_status() in ramping_statuus return is_x_ramping or is_y_ramping or is_z_ramping
[docs] def set_new_field_limits(self, limit_func: Callable[[float, float, float], bool]) -> None: """ Assign a new field limit function to the driver Args: limit_func: must be a function mapping (Bx, By, Bz) -> True/False where True means that the field is INSIDE the allowed region """ # first check that the current target is allowed if not limit_func(*self._target_vector.get_components('x', 'y', 'z')): raise ValueError('Can not assign new limit function; present ' 'target is illegal. Please change the target ' 'and try again.') self._field_limits = limit_func
[docs] def ramp(self, mode: str = "safe") -> None: """ Ramp the fields to their present target value Args: mode: how to ramp, either 'simul', 'simul-block' or 'safe'. In 'simul' and 'simul-block' mode, the fields are ramping simultaneously in a non-blocking mode and blocking mode, respectively. There is no safety check that the safe zone is not exceeded. In 'safe' mode, the fields are ramped one-by-one in a blocking way that ensures that the total field stays within the safe region (provided that this region is convex). """ if mode not in ['simul', 'safe', 'simul_block']: raise ValueError('Invalid ramp mode. Please provide either "simul"' ', "safe" or "simul_block".') meas_vals = self._get_measured(['x', 'y', 'z']) # we asked for three coordinates, so we know that we got a list meas_vals = cast(List[float], meas_vals) for cur, worker in zip(meas_vals, self.submodules.values()): if not isinstance(worker, MercuryWorkerPS): raise RuntimeError(f"Expected a MercuryWorkerPS but got " f"{type(worker)}") if worker.field_target() != cur: if worker.field_ramp_rate() == 0: raise ValueError(f'Can not ramp {worker}; ramp rate set to' ' zero!') # then the actual ramp {'simul': self._ramp_simultaneously, 'safe': self._ramp_safely, 'simul_block': self._ramp_simultaneously_blocking}[mode]()
def _set_target_and_ramp(self, coordinate: str, mode: str, target: float) -> None: """Convenient method to combine setting target and ramping""" self._set_target(coordinate, target) self.ramp(mode)
[docs] def ask(self, cmd: str) -> str: """ Since Oxford Instruments implement their own version of a SCPI-like language, we implement our own reader. Note that this command is used for getting and setting (asking and writing) alike. Args: cmd: the command to send to the instrument """ visalog.debug(f"Writing to instrument {self.name}: {cmd}") resp = self.visa_handle.query(cmd) visalog.debug(f"Got instrument response: {resp}") if 'INVALID' in resp: log.error(f'Invalid command. Got response: {resp}') base_resp = resp # if the command was not invalid, it can either be a SET or a READ # SET: elif resp.endswith('VALID'): base_resp = resp.split(':')[-2] # READ: else: # For "normal" commands only (e.g. '*IDN?' is excepted): # the response of a valid command echoes back said command, # thus we remove that part base_cmd = cmd.replace('READ:', '') base_resp = resp.replace(f'STAT:{base_cmd}', '') return base_resp