Adding Measure Frequency in NI-DMM

CHANGELOG.md

@@ -799,6 +799,7 @@
 #### [nidmm] Unreleased
 - Added
   - Added the `nidmm_measure_ac_volts.py` example.
+  - Added the `nidmm_measure_frequency.py` example.
   - (Common) Added `nitlsconfig[grpc]>=1.0.0a2` to the optional gRPC dependencies.
 - Changed
 - Removed

docs/nidmm/examples.rst

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

src/nidmm/examples/nidmm_measure_frequency.py

@@ -0,0 +1,56 @@
+#!/usr/bin/python
+
+import argparse
+import nidmm
+import sys
+import warnings
+
+# NIDMM_WARN_UNDERRANGE; reported by read() when the input is under range and used here to indicate "signal not detected"
+SIGNAL_NOT_DETECTED_WARNING_CODE = 0x3FFA4F80
+# Required by configure_measurement_digits(); 5.5 is the driver's documented default
+RESOLUTION_DIGITS = 5.5
+
+
+def example(resource_name, options, function, range, max_amplitude):
+    with nidmm.Session(resource_name=resource_name, options=options) as session:
+        session.configure_measurement_digits(measurement_function=nidmm.Function[function], range=range, resolution_digits=RESOLUTION_DIGITS)
+        session.freq_voltage_range = max_amplitude
+        # The driver reports warnings through Python's warnings module; the warning code is included in the message.
+        with warnings.catch_warnings(record=True) as caught:
+            warnings.simplefilter('always')
+            measurement = session.read()
+        signal_not_detected = any(f'Warning {SIGNAL_NOT_DETECTED_WARNING_CODE} occurred' in str(word.message) for word in caught)
+        units = 'Hz' if function == 'FREQ' else 's'
+        print(f'Measurement ({units}): {measurement}')
+        print(f'Signal not Detected: {signal_not_detected}')
+
+
+def _main(argsv):
+    parser = argparse.ArgumentParser(description='Performs a single frequency or period measurement using the NI-DMM API.', formatter_class=argparse.ArgumentDefaultsHelpFormatter)
+    parser.add_argument('-n', '--resource-name', default='PXI1Slot2', help='Contains the resource_name of the device to initialize.')
+    parser.add_argument('-f', '--function', default='FREQ', choices=['FREQ', 'PERIOD'], type=str.upper, help='Specifies the measurement_function used to acquire the measurement.')
+    parser.add_argument('-r', '--range', default=20, type=float, help='Specifies the range for the measurement function. For FREQ, the minimum frequency expected in Hz; for PERIOD, the maximum period expected in seconds.')
+    parser.add_argument('--max-amplitude', default=50, type=float, help='Specifies the maximum amplitude of the input signal for frequency measurements.')
+    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.resource_name, args.option_string, args.function, args.range, args.max_amplitude)
+
+
+def main():
+    _main(sys.argv[1:])
+
+
+def test_example():
+    options = {'simulate': True, 'driver_setup': {'Model': '4082', 'BoardType': 'PXIe', }, }
+    example('PXI1Slot2', options, 'FREQ', 100, 10)
+    example('PXI1Slot2', options, 'PERIOD', 0.01, 10)
+
+
+def test_main():
+    cmd_line = ['--option-string', 'Simulate=1, DriverSetup=Model:4082; BoardType:PXIe', ]
+    _main(cmd_line)
+    _main(cmd_line + ['--function', 'period', '--range', '0.02'])
+
+
+if __name__ == '__main__':
+    main()