from typing import Any
from qcodes.instrument import VisaInstrument
from qcodes.parameters import create_on_off_val_mapping
from qcodes.validators import Enum, Strings
[docs]
class Keithley2400(VisaInstrument):
"""
QCoDeS driver for the Keithley 2400 voltage source.
"""
def __init__(self, name: str, address: str, **kwargs: Any):
super().__init__(name, address, terminator="\n", **kwargs)
self.add_parameter(
"rangev",
get_cmd="SENS:VOLT:RANG?",
get_parser=float,
set_cmd="SOUR:VOLT:RANG {:f}",
label="Voltage range",
)
self.add_parameter(
"rangei",
get_cmd="SENS:CURR:RANG?",
get_parser=float,
set_cmd="SOUR:CURR:RANG {:f}",
label="Current range",
)
self.add_parameter(
"compliancev",
get_cmd="SENS:VOLT:PROT?",
get_parser=float,
set_cmd="SENS:VOLT:PROT {:f}",
label="Voltage Compliance",
)
self.add_parameter(
"compliancei",
get_cmd="SENS:CURR:PROT?",
get_parser=float,
set_cmd="SENS:CURR:PROT {:f}",
label="Current Compliance",
)
self.add_parameter(
"volt",
get_cmd=self._get_read_output_protected,
get_parser=self._volt_parser,
set_cmd=":SOUR:VOLT:LEV {:.8f}",
label="Voltage",
unit="V",
docstring="Sets voltage in 'VOLT' mode. "
"Get returns measured voltage if "
"sensing 'VOLT' otherwise it returns "
"setpoint value. "
"Note that it is an error to read voltage with "
"output off",
)
self.add_parameter(
"curr",
get_cmd=self._get_read_output_protected,
get_parser=self._curr_parser,
set_cmd=":SOUR:CURR:LEV {:.8f}",
label="Current",
unit="A",
docstring="Sets current in 'CURR' mode. "
"Get returns measured current if "
"sensing 'CURR' otherwise it returns "
"setpoint value. "
"Note that it is an error to read current with "
"output off",
)
self.add_parameter(
"mode",
vals=Enum("VOLT", "CURR"),
get_cmd=":SOUR:FUNC?",
set_cmd=self._set_mode_and_sense,
label="Mode",
)
self.add_parameter(
"sense",
vals=Strings(),
get_cmd=":SENS:FUNC?",
set_cmd=':SENS:FUNC "{:s}"',
label="Sense mode",
)
self.add_parameter(
"output",
set_cmd=":OUTP:STAT {}",
get_cmd=":OUTP:STAT?",
val_mapping=create_on_off_val_mapping(on_val="1", off_val="0"),
)
self.add_parameter(
"nplcv",
get_cmd="SENS:VOLT:NPLC?",
get_parser=float,
set_cmd="SENS:VOLT:NPLC {:f}",
label="Voltage integration time",
)
self.add_parameter(
"nplci",
get_cmd="SENS:CURR:NPLC?",
get_parser=float,
set_cmd="SENS:CURR:NPLC {:f}",
label="Current integration time",
)
self.add_parameter(
"resistance",
get_cmd=self._get_read_output_protected,
get_parser=self._resistance_parser,
label="Resistance",
unit="Ohm",
docstring="Measure resistance from current and voltage "
"Note that it is an error to read current "
"and voltage with output off",
)
self.write(":TRIG:COUN 1;:FORM:ELEM VOLT,CURR")
# This line sends 2 commands to the instrument:
# ":TRIG:COUN 1" sets the trigger count to 1 so that each READ? returns
# only 1 measurement result.
# ":FORM:ELEM VOLT,CURR" sets the output string formatting of the the
# Keithley 2400 to return "{voltage}, {current}".
# Default value on instrument reset is "VOLT, CURR, RES, TIME, STATUS";
# however, resistance, status, and time are unused in this driver and
# so are omitted.
# These commands do not reset the instrument but do the minimal amount
# to ensure that voltage and current parameters can be read from the
# instrument, in the event that output formatting of the instrument was
# previously changed to some other unknown state.
self.connect_message()
def _get_read_output_protected(self) -> str:
"""
This wrapper function around ":READ?" exists because calling
":READ?" on an instrument with output disabled is an error.
So first we check that output is on and if not we return
nan for volt, curr etc.
"""
output = self.output.get_latest()
if output is None:
# if get_latest returns None we have
# to ask the instrument for the status of output
output = self.output.get()
if output == 1:
msg = self.ask(":READ?")
else:
raise RuntimeError("Cannot perform read with output off")
return msg
def _set_mode_and_sense(self, msg: str) -> None:
# This helps set the correct read out curr/volt
if msg == "VOLT":
self.sense("CURR")
elif msg == "CURR":
self.sense("VOLT")
else:
raise AttributeError("Mode does not exist")
self.write(f":SOUR:FUNC {msg:s}")
[docs]
def reset(self) -> None:
"""
Reset the instrument. When the instrument is reset, it performs the
following actions.
Returns the SourceMeter to the GPIB default conditions.
Cancels all pending commands.
Cancels all previously send `*OPC` and `*OPC?`
"""
self.write(":*RST")
def _volt_parser(self, msg: str) -> float:
fields = [float(x) for x in msg.split(",")]
return fields[0]
def _curr_parser(self, msg: str) -> float:
fields = [float(x) for x in msg.split(",")]
return fields[1]
def _resistance_parser(self, msg: str) -> float:
fields = [float(x) for x in msg.split(",")]
res = fields[0] / fields[1]
return res