Adding Max DC Reading rate at 7.5 digits example in NI-DMM

CHANGELOG.md

@@ -800,6 +800,7 @@
 #### [nidmm] Unreleased
 - Added
   - Added the `nidmm_measure_ac_volts.py` example.
+  - Added the `nidmm_max_dc_reading_rate_at_7_5_digits.py` example.
   - Added the `nidmm_diode_test.py` example.
   - Added the `nidmm_measure_capacitance.py` example.
   - Added the `nidmm_measure_temperature_rtd.py` example.

build/templates/tox-system_tests.ini.mako

@@ -76,6 +76,9 @@ deps =
 % endif
 % if module_name == 'nidigital':
     ${module_name}-system_tests: nisync
+% endif
+% if module_name == 'nidmm':
+    ${module_name}-system_tests: matplotlib; sys_platform != "win32"
 % endif
     ${module_name}-system_tests: pytest
     ${module_name}-system_tests: coverage

docs/nidmm/examples.rst

@@ -21,6 +21,15 @@ nidmm_fetch_waveform.py
    :encoding: utf8
    :caption: `(nidmm_fetch_waveform.py) <https://github.com/ni/nimi-python/blob/master/src/nidmm/examples/nidmm_fetch_waveform.py>`_
 
+nidmm_max_dc_reading_rate_at_7_5_digits.py
+------------------------------------------
+
+.. literalinclude:: ../../src/nidmm/examples/nidmm_max_dc_reading_rate_at_7_5_digits.py
+   :language: python
+   :linenos:
+   :encoding: utf8
+   :caption: `(nidmm_max_dc_reading_rate_at_7_5_digits.py) <https://github.com/ni/nimi-python/blob/master/src/nidmm/examples/nidmm_max_dc_reading_rate_at_7_5_digits.py>`_
+
 nidmm_measure_ac_volts.py
 -------------------------
 

generated/nidmm/tox-system_tests.ini

@@ -32,6 +32,7 @@ commands =
     nidmm-coverage: coverage report --rcfile=../../tools/coverage_system_tests.rc
 
 deps =
+    nidmm-system_tests: matplotlib; sys_platform != "win32"
     nidmm-system_tests: pytest
     nidmm-system_tests: coverage
     nidmm-system_tests: numpy

src/nidmm/examples/nidmm_max_dc_reading_rate_at_7_5_digits.py

@@ -0,0 +1,119 @@
+#!/usr/bin/python
+
+import argparse
+import collections
+import nidmm
+import pytest
+import sys
+import time
+
+
+SUPPORTED_MODELS = ('4071', '4081')
+
+CHART_HISTORY_SIZE = 250
+
+
+def _create_chart(plt):
+    figure, axes = plt.subplots()
+    (line,) = axes.plot([])
+    axes.set_xlabel('Sample Number')
+    axes.set_ylabel('Reading Value')
+    axes.grid(True)
+    return figure, axes, line
+
+
+def _update_chart(plt, figure, axes, line, measurements, new_samples, samples_fetched, reads_per_sec):
+    if new_samples:
+        measurements.extend(new_samples)
+        samples_fetched += len(new_samples)
+        # Offset X values to account for readings removed from the history buffer
+        first_sample = samples_fetched - len(measurements)
+        line.set_data(range(first_sample, samples_fetched), measurements)
+        axes.set_title(f'Reads/sec: {reads_per_sec:.0f}')
+        axes.relim()
+        axes.autoscale_view()
+    plt.pause(0.001)
+    return samples_fetched, plt.fignum_exists(figure.number)
+
+
+def example(device_name, options, powerline_frequency, measurement_range, aperture_time, adc_calibration, auto_zero, number_of_averages, total_samples):
+    # Imported lazily because matplotlib is unavailable on some platforms (e.g. 32-bit Python)
+    import matplotlib.pyplot as plt
+
+    with nidmm.Session(resource_name=device_name, reset_device=True, options=options) as session:
+        if not session.instrument_model.endswith(SUPPORTED_MODELS):
+            raise ValueError(f'{session.instrument_model} is not supported. This example requires an NI PXI-4071 or NI PXIe-4081.')
+
+        # Powerline frequency defines the timebase for aperture values in PLCs.
+        session.powerline_freq = powerline_frequency
+        session.configure_measurement_digits(measurement_function=nidmm.Function.DC_VOLTS, range=measurement_range, resolution_digits=7.5)
+        # A sample count of zero selects continuous acquisition.
+        session.configure_multi_point(trigger_count=1, sample_count=0)
+        session.aperture_time_units = nidmm.ApertureTimeUnits.POWER_LINE_CYCLES
+        session.aperture_time = aperture_time
+        session.number_of_averages = number_of_averages
+        session.auto_zero = nidmm.AutoZero[auto_zero]
+        # Disabling ADC calibration avoids the gain-reference measurement and increases reading rate.
+        session.adc_calibration = nidmm.ADCCalibration[adc_calibration]
+
+        figure, axes, line = _create_chart(plt)
+        measurements = collections.deque(maxlen=CHART_HISTORY_SIZE)
+        samples_fetched = 0
+        start_time = time.perf_counter()
+        try:
+            with session.initiate():
+                chart_open = True
+                while chart_open and (total_samples is None or samples_fetched < total_samples):
+                    backlog, _ = session.read_status()
+                    if total_samples is not None:
+                        backlog = min(backlog, total_samples - samples_fetched)
+                    new_samples = session.fetch_multi_point(array_size=backlog) if backlog > 0 else ()
+                    reads_per_sec = (samples_fetched + len(new_samples)) / (time.perf_counter() - start_time)
+                    samples_fetched, chart_open = _update_chart(
+                        plt, figure, axes, line, measurements, new_samples, samples_fetched, reads_per_sec,
+                    )
+
+            # The acquisition has stopped; keep the final chart on screen until its window is closed
+            if total_samples is not None and plt.fignum_exists(figure.number):
+                plt.show()
+        except KeyboardInterrupt:
+            pass
+        finally:
+            plt.close(figure)
+
+
+def _main(argsv):
+    parser = argparse.ArgumentParser(description='Achieves the higher DC voltage reading rate at 7.5 digits of resolution with a PXI-4071 or PXIe-4081 and charts the readings.', formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument('-n', '--device-name', default='PXI1Slot2', help='Contains the resource_name of the device to initialize.')
+    parser.add_argument('-p', '--powerline-frequency', default=60.0, type=float, choices=[50.0, 60.0], help='Specifies the powerline frequency.')
+    parser.add_argument('-r', '--range', default=10.0, type=float, help='Specifies the range for the function specified in the Measurement_Function parameter.')
+    parser.add_argument('-a', '--aperture-time', default=1.0, type=float, help='Specifies the measurement aperture time for the current configuration, in powerline cycles (PLCs).')
+    parser.add_argument('-c', '--adc-calibration', default='OFF', choices=nidmm.ADCCalibration.__members__.keys(), type=str.upper, help='Specifies the ADC calibration mode.')
+    parser.add_argument('-z', '--auto-zero', default='ON', choices=nidmm.AutoZero.__members__.keys(), type=str.upper, help='Specifies the AutoZero mode.')
+    parser.add_argument('-v', '--number-of-averages', default=4, type=int, help='Specifies the number of averages to perform in a measurement.')
+    parser.add_argument('--total-samples', default=None, type=int, help='Stops fetching after this many samples and keeps the chart open until its window is closed; omit to run until the chart window is closed.')
+    parser.add_argument('-op', '--option-string', default='', type=str, help='Sets the initial value of certain attributes for the session.')
+    args = parser.parse_args(argsv)
+    example(args.device_name, args.option_string, args.powerline_frequency, args.range, args.aperture_time, args.adc_calibration, args.auto_zero, args.number_of_averages, args.total_samples)
+
+
+def main():
+    _main(sys.argv[1:])
+
+
+def test_example():
+    plt = pytest.importorskip('matplotlib.pyplot')
+    plt.switch_backend('Agg')  # Avoid opening a chart window during the test
+    options = {'simulate': True, 'driver_setup': {'Model': '4081', 'BoardType': 'PXIe', }, }
+    example('PXI1Slot2', options, 60.0, 10.0, 1.0, 'OFF', 'ON', 4, 100)
+
+
+def test_main():
+    plt = pytest.importorskip('matplotlib.pyplot')
+    plt.switch_backend('Agg')  # Avoid opening a chart window during the test
+    cmd_line = ['--option-string', 'Simulate=1, DriverSetup=Model:4081; BoardType:PXIe', '--total-samples', '100', ]
+    _main(cmd_line)
+
+
+if __name__ == '__main__':
+    main()