DMM Drivers - NPLC and Min/Max/Avg support

src/fixate/drivers/dmm/fluke_8846a.py

@@ -42,6 +42,16 @@ def __init__(self, instrument, *args, **kwargs):
             "continuity": "CONF:CONTinuity",
             "diode": "CONF:DIODe",
         }
+        self._nplc_modes = [
+            "resistance",
+            "fresistance",
+            "voltage_dc",
+            "current_dc",
+            "temperature",
+            "ftemperature",
+        ]
+        self._nplc_settings = [0.02, 0.2, 1, 10, 100]
+        self._default_nplc = 10  # Default NPLC setting as per Fluke 8846A manual
         self._init_string = ""  # Unchanging
 
     @property
@@ -101,6 +111,25 @@ def measurements(self):
         with self.lock:
             return self._read_measurements()
 
+    def min_avg_max(self, samples=1, sample_time=1):
+        """
+        automatically samples the DMM for a given number of samples and returns the min, max, and average values
+        :param samples: number of samples to take
+        :param sample_time: time to wait for the DMM to take the samples
+        return: min, avg, max values as floats
+        """
+
+        self._write(f"SAMP:COUN {samples}")
+        self._write("CALC:FUNC AVER")
+        self._write("CALC:STAT ON")
+        self._write("INIT")
+        time.sleep(sample_time)
+        _min = self.instrument.query_ascii_values("CALC:AVER:MIN?")[0]
+        _avg = self.instrument.query_ascii_values("CALC:AVER:AVER?")[0]
+        _max = self.instrument.query_ascii_values("CALC:AVER:MAX?")[0]
+
+        return _min, _avg, _max
+
     def reset(self):
         """
         Checks for errors and then returns DMM to power up state
@@ -222,6 +251,22 @@ def _set_measurement_mode(self, mode, _range=None, suffix=None):
         )
         self._is_error()
 
+    def set_nplc(self, nplc=None, reset=False):
+        if reset is True or nplc is None:
+            nplc = self._default_nplc
+        elif nplc not in self._nplc_settings:
+            raise ParameterError(f"Invalid NPLC setting {nplc}")
+
+        if self._mode not in self._nplc_modes:
+            raise ParameterError(f"NPLC setting not available for mode {self._mode}")
+
+        mode_str = f"{self._modes[self._mode]}"
+
+        # Remove the CONF: from the start of the string
+        mode_str = mode_str.replace("CONF:", "")
+
+        self._write(f"{mode_str}:NPLC {nplc}")  # e.g. VOLT:DC:NPLC 10
+
     def voltage_ac(self, _range=None):
         self._set_measurement_mode("voltage_ac", _range)
 

src/fixate/drivers/dmm/keithley_6500.py

@@ -40,7 +40,16 @@ def __init__(self, instrument, *args, **kwargs):
             "continuity": "CONT",
             "diode": "DIOD",
         }
-
+        self._nplc_modes = [
+            "voltage_dc",
+            "current_dc",
+            "resistance",
+            "fresistance",
+            "diode",
+            "temperature",
+        ]
+        self._nplc_min = 0.0005  # Minimum NPLC setting for the DMM
+        self._nplc_max = 12  # Maximum NPLC setting for the DMM
         self._init_string = ""  # Unchanging
 
     # Adapted for different DMM behaviour
@@ -138,6 +147,31 @@ def measurements(self):
         with self.lock:
             return self._read_measurements()
 
+    def min_avg_max(self, samples=1, sample_time=1):
+        """
+        automatically samples the DMM for a given number of samples and returns the min, max, and average values
+        :param samples: number of samples to take
+        :param sample_time: time to wait for the DMM to take the samples
+        return: min, avg, max values as floats
+        """
+
+        self._write(f'TRAC:MAKE "TempTable", {samples}')
+        self._write(f"SENS:COUNt {samples}")
+
+        # we don't actually want the results, this is just to tell the DMM to start sampling
+        _tmp = self.instrument.query_ascii_values('READ? "TempTable"')[0]
+        time.sleep(sample_time)
+
+        _avg = self.instrument.query_ascii_values('TRAC:STAT:AVER? "TempTable"')[0]
+        _min = self.instrument.query_ascii_values('TRAC:STAT:MIN? "TempTable"')[0]
+        _max = self.instrument.query_ascii_values('TRAC:STAT:MAX? "TempTable"')[0]
+
+        # cleanup
+        self._write("SENS:COUNt 1")
+        self._write('TRAC:DEL "TempTable"')
+
+        return _min, _avg, _max
+
     def reset(self):
         """
         Checks for errors and then returns DMM to power up state
@@ -255,6 +289,18 @@ def _set_measurement_mode(self, mode, _range=None, suffix=None):
         self._write(f":COUN {self.samples}")
         self._is_error()
 
+    def set_nplc(self, nplc=None, reset=False):
+        if reset is True or nplc is None:
+            nplc = "DEF"  # keithley supports sending the "DEF" string to reset the NPLC value
+        elif nplc <= self._nplc_min or nplc >= self._nplc_max:
+            raise ParameterError(f"NPLC setting out of range for Keithley 6500")
+
+        if self._mode not in self._nplc_modes:
+            raise ParameterError(f"NPLC setting not available for mode {self._mode}")
+
+        mode_str = f"{self._modes[self._mode]}"
+        self._write(f":SENS:{mode_str}:NPLC {nplc}")
+
     def voltage_ac(self, _range=None):
         self._set_measurement_mode("voltage_ac", _range)