Update dmm current modes

docs/release-notes.rst

@@ -2,14 +2,27 @@
 Release Notes
 ==================================
 
+*************
+Version 0.6.5
+*************
+Release Date xx/xx/xx
+
+New Features
+############
+
+Improvements
+############
+- DMM current mode functions now raise an exception when an incompatible port and range combination is used. The range and port parameters are now required parameters.
+
+
 *************
 Version 0.6.4
 *************
 Release Date 14/01/25
 
 New Features
 ############
-- DMM drivers now have a new function to set NPLC (Number of Power Line Cycles) for the DMM.
+- DMM drivers now have a new function to set NPLC (Number of Powr Line Cycles) for the DMM.
 - DMM drivers now have a new function to use the DMM's internal statistics function to take multiple measurements and return the mean, minimum and maximum values.
 
 Improvements

src/fixate/drivers/dmm/fluke_8846a.py

@@ -2,6 +2,7 @@
 from fixate.core.exceptions import InstrumentError, ParameterError
 from fixate.drivers.dmm.helper import DMM
 import time
+from typing import Literal
 
 
 class Fluke8846A(DMM):
@@ -54,6 +55,10 @@ def __init__(self, instrument, *args, **kwargs):
         self._default_nplc = 10  # Default NPLC setting as per Fluke 8846A manual
         self._init_string = ""  # Unchanging
 
+        # High and low current port definition. Each definition encodes the maximum current able to
+        # be measured by the port (in amps)
+        self._current_ports = {"HIGH": 10, "LOW": 400e-3}
+
     @property
     def samples(self):
         return self._samples
@@ -268,10 +273,36 @@ def voltage_dc(self, _range=None, auto_impedance=False):
             command = "; :SENS:VOLT:DC:IMP:AUTO OFF"
         self._set_measurement_mode("voltage_dc", _range, suffix=command)
 
-    def current_ac(self, _range=None):
+    def current_ac(self, _range, port):
+        """
+        Set the measurement mode on the DMM to AC current.
+
+        If the range and port selection are not compatible, i.e. someone has requested to measure
+        1 A on the low range port with a maximum capability of 400 mA, an exception is raised.
+
+        If the range requested can be measured by the low port, but the high port is selected, an
+        exception is raised.
+        """
+
+        # Check the port and range combination is compatible for the instrument:
+        self._check_current_port_range(_range, port)
+
         self._set_measurement_mode("current_ac", _range)
 
-    def current_dc(self, _range=None):
+    def current_dc(self, _range, port: Literal["HIGH", "LOW"]):
+        """
+        Set the measurement mode on the DMM to DC current.
+
+        If the range and port selection are not compatible, i.e. someone has requested to measure
+        1A on the low range port with a maximum capability of 400 mA, an exception is raised.
+
+        If the range requested can be measured by the low port, but the high port is selected, an
+        exception is raised.
+        """
+
+        # Check the port and range combination is compatible for the instrument:
+        self._check_current_port_range(_range, port)
+
         self._set_measurement_mode("current_dc", _range)
 
     def resistance(self, _range=None):

src/fixate/drivers/dmm/helper.py

@@ -1,4 +1,5 @@
 from dataclasses import dataclass
+from typing import Literal
 
 
 class DMM:
@@ -60,13 +61,23 @@ def voltage_dc(self, _range=None, auto_impedance=False):
         """
         raise NotImplementedError
 
-    def current_ac(self, _range):
+    def current_ac(self, _range, port: Literal["HIGH", "LOW"]):
+        """
+        Sets the DMM in AC current measurement mode.
+
+        Args:
+            _range: The measurement range to set on the instrument.
+            port: Informs the driver what physical port on the DMM is intended to be used for the measurement
+        """
         raise NotImplementedError
 
-    def current_dc(self, _range):
+    def current_dc(self, _range, port: Literal["HIGH", "LOW"]):
         """
-        Sets the DMM in DC current measurement mode and puts it in the range given
-        by the argument _range. Signals expected to be measured must be < _range.
+        Sets the DMM in DC current measurement mode.
+
+        Args:
+            _range: The measurement range to set on the instrument.
+            port: Informs the driver what physical port on the DMM is intended to be used for the measurement
         """
         raise NotImplementedError
 
@@ -129,3 +140,23 @@ def __exit__(self, exc_type, exc_val, exc_tb):
 
     def nplc(self, nplc=None):
         return self._nplc_context_manager(self, nplc)
+
+    def _check_current_port_range(self, range, port):
+        """
+        Checks that the requested port and range are going to be compatible for the instrument.
+        Raises:
+            ValueError
+        Returns:
+        None
+        """
+        # Check the requested range is not more than the port capability:
+        if range > self._current_ports[port]:
+            raise ValueError(
+                "The selected port and range combination is not available for this instrument. Consider using a different multimeter"
+            )
+
+        # Raise an error if the high port is selected when the low port should be used:
+        if range < self._current_ports["LOW"] and port == "HIGH":
+            raise ValueError(
+                "High range port selected when the low range port should be used! Consider using a different multimeter."
+            )

src/fixate/drivers/dmm/keithley_6500.py

@@ -53,6 +53,10 @@ def __init__(self, instrument, *args, **kwargs):
         self._nplc_default = 1
         self._init_string = ""  # Unchanging
 
+        # High and low current port definition. Each definition encodes the maximum current able to
+        # be measured by the port (in amps)
+        self._current_ports = {"HIGH": 10, "LOW": 3}
+
     # Adapted for different DMM behaviour
     @property
     def display(self):
@@ -303,10 +307,34 @@ def voltage_dc(self, _range=None, auto_impedance=False):
             command = "; :SENS:VOLT:DC:INP MOHM10"
         self._set_measurement_mode("voltage_dc", _range, suffix=command)
 
-    def current_ac(self, _range=None):
+    def current_ac(self, _range, port):
+        """
+        Set the measurement mode on the DMM to AC current.
+
+        If the range and port selection are not compatible, i.e. someone has requested to measure
+        1A on the low range port with a maximum capability of 400 mA, an exception is raised.
+
+        If the range requested can be measured by the low port, but the high port is selected, an
+        exception is raised.
+        """
+        # Check the port and range combination is compatible for the instrument:
+        self._check_current_port_range(_range, port)
+
         self._set_measurement_mode("current_ac", _range)
 
-    def current_dc(self, _range=None):
+    def current_dc(self, _range, port):
+        """
+        Set the measurement mode on the DMM to DC current.
+
+        If the range and port selection are not compatible, i.e. someone has requested to measure
+        1A on the low range port with a maximum capability of 400 mA, an exception is raised.
+
+        If the range requested can be measured by the low port, but the high port is selected, an
+        exception is raised.
+        """
+        # Check the port and range combination is compatible for the instrument:
+        self._check_current_port_range(_range, port)
+
         self._set_measurement_mode("current_dc", _range)
 
     def resistance(self, _range=None):