Add multimeter simulator

Implement SCPI-based virtual DMM with DC voltage and current measurement.
Supports MEAS, CONF, and READ commands. Integrates with physics engine
for DUT output measurements.

src/py_dvt_ate/simulation/virtual/multimeter.py

@@ -0,0 +1,213 @@
+"""Virtual digital multimeter (DMM) simulator.
+
+This module implements a SCPI-based virtual multimeter that interfaces
+with the physics engine to measure DUT electrical parameters.
+"""
+
+from __future__ import annotations
+
+from enum import Enum
+from typing import TYPE_CHECKING
+
+from py_dvt_ate.instruments.scpi import SCPICommand
+from py_dvt_ate.simulation.virtual.base import BaseInstrument
+
+if TYPE_CHECKING:
+    from py_dvt_ate.simulation.physics.engine import PhysicsEngine
+
+
+class MeasurementFunction(Enum):
+    """Available measurement functions."""
+
+    VOLTAGE_DC = "VOLT:DC"
+    CURRENT_DC = "CURR:DC"
+
+
+class MultimeterSim(BaseInstrument):
+    """Virtual digital multimeter simulator.
+
+    Simulates a digital multimeter with SCPI control interface. The DMM
+    measures DUT output voltage and load current via the physics engine.
+
+    SCPI Commands:
+        MEAS:VOLT:DC?      - Measure DC voltage (shortcut)
+        MEAS:CURR:DC?      - Measure DC current (shortcut)
+        CONF:VOLT:DC       - Configure for DC voltage measurement
+        CONF:CURR:DC       - Configure for DC current measurement
+        CONF?              - Query current configuration
+        READ?              - Take measurement with current configuration
+
+    Attributes:
+        manufacturer: "PyDVTATE"
+        model: "DMM-SIM-001"
+    """
+
+    manufacturer = "PyDVTATE"
+    model = "DMM-SIM-001"
+    serial_number = "DMMSIM001"
+    firmware_version = "1.0.0"
+
+    def __init__(self, physics_engine: PhysicsEngine | None = None) -> None:
+        """Initialise the multimeter simulator.
+
+        Args:
+            physics_engine: Reference to physics engine for measurement values.
+        """
+        self._function = MeasurementFunction.VOLTAGE_DC
+        super().__init__(physics_engine)
+
+    def _setup_commands(self) -> None:
+        """Register multimeter SCPI commands."""
+        self.register_command("MEAS:VOLT:DC", self._handle_meas_volt_dc)
+        self.register_command("MEAS:CURR:DC", self._handle_meas_curr_dc)
+        self.register_command("CONF:VOLT:DC", self._handle_conf_volt_dc)
+        self.register_command("CONF:CURR:DC", self._handle_conf_curr_dc)
+        self.register_command("CONF", self._handle_conf)
+        self.register_command("READ", self._handle_read)
+
+    def reset(self) -> None:
+        """Reset multimeter to default state."""
+        self._function = MeasurementFunction.VOLTAGE_DC
+
+    def _handle_meas_volt_dc(self, command: SCPICommand) -> str:
+        """Handle MEAS:VOLT:DC? query.
+
+        Configures for DC voltage and takes measurement in one command.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured DC voltage.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:VOLT:DC is query only")
+
+        self._function = MeasurementFunction.VOLTAGE_DC
+        return self._measure_voltage_dc()
+
+    def _handle_meas_curr_dc(self, command: SCPICommand) -> str:
+        """Handle MEAS:CURR:DC? query.
+
+        Configures for DC current and takes measurement in one command.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured DC current.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("MEAS:CURR:DC is query only")
+
+        self._function = MeasurementFunction.CURRENT_DC
+        return self._measure_current_dc()
+
+    def _handle_conf_volt_dc(self, command: SCPICommand) -> str:
+        """Handle CONF:VOLT:DC command.
+
+        Configures multimeter for DC voltage measurement.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Empty string (no response for configuration).
+
+        Raises:
+            ValueError: If used as query.
+        """
+        if command.is_query:
+            raise ValueError("CONF:VOLT:DC is command only")
+
+        self._function = MeasurementFunction.VOLTAGE_DC
+        return ""
+
+    def _handle_conf_curr_dc(self, command: SCPICommand) -> str:
+        """Handle CONF:CURR:DC command.
+
+        Configures multimeter for DC current measurement.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Empty string (no response for configuration).
+
+        Raises:
+            ValueError: If used as query.
+        """
+        if command.is_query:
+            raise ValueError("CONF:CURR:DC is command only")
+
+        self._function = MeasurementFunction.CURRENT_DC
+        return ""
+
+    def _handle_conf(self, command: SCPICommand) -> str:
+        """Handle CONF? query.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Current measurement configuration.
+
+        Raises:
+            ValueError: If used as command without subcommand.
+        """
+        if not command.is_query:
+            raise ValueError("CONF requires a function (e.g., CONF:VOLT:DC)")
+
+        return f'"{self._function.value}"'
+
+    def _handle_read(self, command: SCPICommand) -> str:
+        """Handle READ? query.
+
+        Takes measurement using current configuration.
+
+        Args:
+            command: Parsed SCPI command.
+
+        Returns:
+            Measured value.
+
+        Raises:
+            ValueError: If used as command (not query).
+        """
+        if not command.is_query:
+            raise ValueError("READ is query only")
+
+        if self._function == MeasurementFunction.VOLTAGE_DC:
+            return self._measure_voltage_dc()
+        else:
+            return self._measure_current_dc()
+
+    def _measure_voltage_dc(self) -> str:
+        """Measure DC voltage from physics engine.
+
+        Returns:
+            Formatted voltage reading.
+        """
+        if self._physics_engine is None:
+            return "0.000000"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        return f"{electrical_state.output_voltage:.6f}"
+
+    def _measure_current_dc(self) -> str:
+        """Measure DC current from physics engine.
+
+        Returns:
+            Formatted current reading.
+        """
+        if self._physics_engine is None:
+            return "0.000000"
+
+        electrical_state = self._physics_engine.get_electrical_state()
+        return f"{electrical_state.load_current:.6f}"