Convention for adding parameters to instrument driver + intellisense problems

[fishyvishy]

Hello,

I noticed that in the Creating Drivers page, the VisaInstrument example with the Weinschel8320 binds the attenuation parameter to the instrument using the self.add_parameter method and assigns the output to an identically named attribute. However, in the source code for the driver here, I see that the parameter is instantiated with the Parameter class directly and then assigned to self.attenuation.

When I tried using the self.add_parameter approach, I noticed that the driver breaks, which seems to be because self.add_parameter returns NoneType as per its definition in the InstrumentBase class. I switched to the second approach, directly instantiating with the Parameter class and everything seems fine.

As I understand, the purpose of assigning the parameter to an attribute is to allow intellisense to recognize the instrument parameters, but, in both approaches, my intellisense isn't recognizing any of the parameters of my instrument.

What is the recommended approach for binding instrument parameters, and are there any fixes to the intellisense problem? For reference, I've attached the current implementation of my instrument driver below.

Thanks

import qcodes.validators as vals
import logging

from time import sleep
from typing import Any, Optional
from functools import partial
from qcodes.instrument import InstrumentChannel, VisaInstrument
from qcodes.parameters import ( Parameter )
from qcodes.validators import Ints, Numbers

log = logging.getLogger(__name__)


class BarreraDCDAC5764Channel(InstrumentChannel):
    """
    Class to hold one of the 8 DC DAC Channels
    """

    def __init__(self, parent: "BarreraDCDAC5764", name: str, channel: str) -> None:
        """
        Args:
            parent: The YokogawaGS820 instance to which the channel is
                to be attached.
            name: The 'colloquial' name of the channel
            channel: The name used by the Yokogawa, i.e. either
                'channel1' or 'channel2'
        """
        valid_chnls = [f"channel{i}" for i in range(1, 9)]
        if channel not in valid_chnls:
            raise ValueError(f'{channel} not in channel1, ..., channel8')

        super().__init__(parent, name)
        self.channel = channel
        self._extra_visa_timeout = 5000

        self.voltage = Parameter(
            name="voltage",
            unit="V",
            label="Voltage",
            get_parser=float,
            get_cmd=partial(self._get_set_voltage),
            set_cmd=partial(self._get_set_voltage),
            vals=Numbers(-10, 10),
            instrument=self
        )
        "Voltage level parameter"

        self.offset = Parameter(
            name = "offset",
            label="Offset",
            get_cmd=None,
            set_cmd=f"{self.channel}:OFFSET {{}}",
            # signed 8 bit integer
            vals=Ints(-128, 127), 
            instrument=self
        )
        "Offset level settable parameter"

        self.step = Parameter(
            name="step",
            label="Step",
            get_cmd=None,
            set_cmd=f"{self.channel}:STEP {{}}",
            # signed 6 bit integer 
            vals=Ints(-32, 31),
            instrument=self
        )
        "Step size settable parameter"

    def _get_set_voltage(self, voltage: Optional[float] = None) -> Optional[float]:
        """
        Get or set the voltage level.

        Args:
            voltage: If missing, we assume that we are getting the 
            current level. Else we are setting it
        """
        if voltage is not None:
            self.write(f'{self.channel}:VOLTAGE {voltage}')
        else:
            return self.ask(f'{self.channel}:VOLTAGE?')
        
        self.add_parameter



class BarreraDCDAC5764(VisaInstrument):
    """
    QCoDeS driver for custom made DC-DAC AD55706 DC generator
    Args:
      name: What this instrument is called locally.
      address: The GPIB or USB address of this instrument
      kwargs: kwargs to be passed to VisaInstrument class
      terminator: read terminator for reads/writes to the instrument.
    """

    def __init__(self, name: str, address: str, terminator: str = "\n", **kwargs: Any
    ) -> None:
        super().__init__(name, address, terminator=terminator, **kwargs)

        self.channels: list[BarreraDCDAC5764Channel] = []
        for ch in range(1, 9):
            ch_name = f"channel{ch}"
            channel = BarreraDCDAC5764Channel(self, ch_name, ch_name)
            self.add_submodule(ch_name, channel)
            self.channels.append(channel)

        # Required as Arduino takes around 2 seconds to setup serial
        sleep(3)
        self.connect_message()


    def reset(self) -> None:
        """
        Reset DAC to 0V on each channel, and sets offsets/steps to 0
        """
        self.write("*RST")
        for channel_num in range(8):
            inst_chnl = self.channels[channel_num]
            inst_chnl.offset(0)
            inst_chnl.step(0)
        log.debug("Reset Instrument. Re-querying settings...")
        self.snapshot(update=True)

[jenshnielsen]

When I tried using the self.add_parameter approach, I noticed that the driver breaks, which seems to be because self.add_parameter returns NoneType as per its definition in the InstrumentBase class. I switched to the second approach, directly instantiating with the Parameter class and everything seems fine.

Which version of qcodes are you using. The return from add_parameter was added in 0.46.0

[fishyvishy]

I see, I was using version 0.45. I just upgraded and the first method works fine now.