Updated output voltage with custom visa dmm driver (#447)

* Updated output voltage with custom visa dmm driver

* Fixed lint errors

examples/output_voltage_measurement/OutputVoltageMeasurement.pinmap

@@ -4,7 +4,7 @@
 		<NIDCPowerInstrument name="DCPower1" numberOfChannels="4">
 			<ChannelGroup name="CommonDCPowerChannelGroup" />
 		</NIDCPowerInstrument>
-		<Instrument name="GPIB0::3::INSTR" instrumentTypeId="DigitalMultimeterSimulator">
+		<Instrument name="GPIB0::3::INSTR" instrumentTypeId="VisaDmm">
 			<Channel id="0" />
 		</Instrument>
 	</Instruments>

examples/output_voltage_measurement/README.md

@@ -1,6 +1,6 @@
 ## Output Voltage Measurement
 
-This is a MeasurementLink example that sources DC voltage as input to the DUT with an NI SMU and measures the DUT output with DMM using NI-VISA.
+This is a MeasurementLink example that sources DC voltage as input to the DUT with an NI SMU and measures the DUT output with a DMM that supports SCPI commands using NI-VISA.
 
 ### Features
 
@@ -27,21 +27,24 @@ This is a MeasurementLink example that sources DC voltage as input to the DUT wi
 - NI-VISA
 - Optional: NI Instrument Simulator software
 
-Note: there is no Python instrument driver for the NI Instrument Simulator, so
-this example directly performs low-level, device-specific commands and queries.
+> **Note:**
+>
+> This example uses the custom instrument driver `_visa_dmm.py` to perform the device-specific commands and queries.
 
 ### Required Hardware
 
-By default, this example does not require hardware; it uses a simulated instrument and PyVISA-sim to simulate NI-DCPower and NI-VISA DMM instruments in software. [`NIInstrumentSimulatorV2_0.yaml`](./NIInstrumentSimulatorV2_0.yaml) defines the behavior of the simulated NI-VISA DMM instrument.
+By default, this example does not require hardware; it uses a simulated instrument and PyVISA-sim to simulate NI-DCPower and NI-VISA DMM instruments in software. [`_visa_dmm_sim.yaml`](./_visa_dmm_sim.yaml) defines the behavior of the simulated NI-VISA DMM instrument.
 
-This example requires an NI SMU that is supported by NI-DCPower (e.g. PXIe-4141).
+Supported instrument models:
+- NI Instrument Simulator v2.0
+- HP/Agilent/Keysight 34401A DMM
 
-By default, this example uses simulated instruments. To use physical instruments, edit
-`_constants.py` to specify `USE_SIMULATION = False`.
-
-To use NI Instrument Simulator hardware:
 
-- Connect the NI Instrument Simulator over GPIB or serial.
+To use a physical instrument:
+- This example requires an NI SMU that is supported by NI-DCPower (e.g. PXIe-4141).
+- By default, this example uses simulated instruments. To use physical instruments, edit
+`_constants.py` to specify `USE_SIMULATION = False`.
+- Connect the instrument to a supported interface, such as GPIB or serial.
 - By default, the pin map included with this example uses the resource name
   `GPIB0::3::INSTR`, which matches the NI Instrument Simulator's factory default
   settings when connected via GPIB.
@@ -53,4 +56,4 @@ To use NI Instrument Simulator hardware:
     the NI Instrument Simulator software.
 
 To use a 3rd party DMM, such as a Keysight 34401A:
-  - Verify the driver specific commands in `_visa_helpers.py` and update them if required.
+  - Verify the driver specific commands in `_visa_dmm.py` and update them if required.

examples/output_voltage_measurement/_visa_dmm.py

@@ -0,0 +1,145 @@
+"""Custom instrument driver for MeasurementLink NI-VISA DMM examples."""
+from __future__ import annotations
+
+import pathlib
+import sys
+from enum import Enum
+from types import TracebackType
+from typing import (
+    TYPE_CHECKING,
+    Optional,
+    Type,
+)
+
+import pyvisa
+import pyvisa.resources
+import pyvisa.typing
+
+
+if TYPE_CHECKING:
+    if sys.version_info >= (3, 11):
+        from typing import Self
+    else:
+        from typing_extensions import Self
+
+
+# Pin map instrument type constant for VISA DMM
+INSTRUMENT_TYPE_VISA_DMM = "VisaDmm"
+
+_SIMULATION_YAML_PATH = pathlib.Path(__file__).resolve().parent / "_visa_dmm_sim.yaml"
+
+_RESOLUTION_DIGITS_TO_VALUE = {"3.5": 0.001, "4.5": 0.0001, "5.5": 1e-5, "6.5": 1e-6}
+
+# Supported NI-VISA DMM instrument IDs, both real and simulated, can be added here
+_SUPPORTED_INSTRUMENT_IDS = [
+    # Keysight/Agilent/HP 34401A
+    "34401",
+    "34410",
+    "34411",
+    "L4411",
+    # NI Instrument Simulator v2.0
+    "Instrument Simulator",  # single instrument
+    "Waveform Generator Simulator",  # multi-instrument
+]
+
+
+class Function(Enum):
+    """Enum that represents the measurement function."""
+
+    DC_VOLTS = 0
+    AC_VOLTS = 1
+
+
+_FUNCTION_TO_VALUE = {
+    Function.DC_VOLTS: "VOLT:DC",
+    Function.AC_VOLTS: "VOLT:AC",
+}
+
+
+class Session:
+    """An NI-VISA DMM session."""
+
+    def __init__(
+        self,
+        resource_name: str,
+        id_query: bool = True,
+        reset_device: bool = True,
+        simulate: bool = False,
+    ) -> None:
+        """Open NI-VISA DMM session."""
+        # Create a real or simulated VISA resource manager."""
+        visa_library = f"{_SIMULATION_YAML_PATH}@sim" if simulate else ""
+        resource_manager = pyvisa.ResourceManager(visa_library)
+
+        session = resource_manager.open_resource(
+            resource_name, read_termination="\n", write_termination="\n"
+        )
+
+        if not isinstance(session, pyvisa.resources.MessageBasedResource):
+            raise TypeError("The 'session' object must be an instance of MessageBasedResource.")
+        self._session = session
+
+        if id_query:
+            self._validate_id()
+
+        if reset_device:
+            self._reset()
+
+    def close(self) -> None:
+        """Close the session."""
+        self._session.close()
+
+    def __enter__(self) -> Self:
+        """Context management protocol. Returns self."""
+        return self
+
+    def __exit__(
+        self,
+        exc_type: Optional[Type[BaseException]],
+        exc_val: Optional[BaseException],
+        traceback: Optional[TracebackType],
+    ) -> None:
+        """Context management protocol. Calls close()."""
+        self.close()
+
+    def configure_measurement_digits(
+        self, function: Function, range: float, resolution_digits: float
+    ) -> None:
+        """Configure the common properties of the measurement.
+
+        These properties include function, range, and resolution_digits.
+        """
+        function_enum = _FUNCTION_TO_VALUE[function]
+        resolution_value = _RESOLUTION_DIGITS_TO_VALUE[str(resolution_digits)]
+
+        self._session.write("CONF:%s %.g,%.g" % (function_enum, range, resolution_value))
+        self._check_error()
+
+    def read(self) -> float:
+        """Acquires a single measurement and returns the measured value."""
+        response = self._session.query("READ?")
+        self._check_error()
+        return float(response)
+
+    def _check_error(self) -> None:
+        """Query the instrument's error queue."""
+        response = self._session.query("SYST:ERR?")
+        fields = response.split(",", maxsplit=1)
+        assert len(fields) >= 1
+        if int(fields[0]) != 0:
+            raise RuntimeError("Instrument returned error %s: %s" % (fields[0], fields[1]))
+
+    def _validate_id(self) -> None:
+        """Check the selected instrument is proper and responding.."""
+        instrument_id = self._session.query("*IDN?")
+        if not any(id_check in instrument_id for id_check in _SUPPORTED_INSTRUMENT_IDS):
+            raise RuntimeError(
+                "The ID query failed. This may mean that you selected the wrong instrument, your instrument did not respond, "
+                f"or you are using a model that is not officially supported by this driver. Instrument ID: {instrument_id}"
+            )
+
+    def _reset(self) -> None:
+        """Reset the instrument to a known state."""
+        self._session.write("*CLS")
+        self._session.write("*RST")
+        self._check_error()

examples/output_voltage_measurement/_visa_dmm_sim.yaml

@@ -0,0 +1,32 @@
+spec: "1.1"
+devices:
+  VisaDmm:
+    eom:
+      GPIB INSTR:
+        q: "\n"
+        r: "\n"
+    dialogues:
+      - q: "*CLS"
+      - q: "*IDN?"
+        r: "National Instruments,Waveform Generator Simulator (simulated with pyvisa-sim),00000000,2.0.1"
+      - q: "*RST"
+      - q: "READ?"
+        r: "1.23456"
+    error:
+      error_queue:
+        - q: 'SYST:ERR?'
+          default: '0,No Error'
+          command_error: '-100,Command Error'
+          query_error: '-400,Query Error'
+    properties:
+      configuration:
+        default: "VOLT:DC 5.000000,0.001000"
+        getter:
+          q: "CONF?"
+          r: "{:s}"
+        setter:
+          q: "CONF:{:s}"
+
+resources:
+  GPIB0::3::INSTR:
+    device: VisaDmm