Add Counter Input examples (#581)

* Add Counter Input examples

* reworked as per comments

* reworked on comments part 2

examples/counter_in/cnt_dig_event.py

@@ -0,0 +1,32 @@
+"""Example of counter input edge count operation.
+
+This example demonstrates how to count digital events on a
+Counter Input Channel. The Initial Count, Count Direction, and
+Edge are all configurable.
+"""
+
+import nidaqmx
+from nidaqmx.constants import CountDirection, Edge
+
+with nidaqmx.Task() as task:
+    channel = task.ci_channels.add_ci_count_edges_chan(
+        "Dev1/ctr0",
+        edge=Edge.RISING,
+        initial_count=0,
+        count_direction=CountDirection.COUNT_UP,
+    )
+    channel.ci_count_edges_term = "/Dev1/PFI8"
+
+    print("Continuously polling. Press Ctrl+C to stop.")
+    task.start()
+
+    try:
+        edge_counts = 0
+        while True:
+            edge_counts = task.read()
+            print(f"Acquired count: {edge_counts:n}", end="\r")
+    except KeyboardInterrupt:
+        pass
+    finally:
+        task.stop()
+        print(f"\nAcquired {edge_counts:n} total counts.")

examples/counter_in/cont_cnt_buff_event_ext_clk.py

@@ -0,0 +1,36 @@
+"""Example of counter input edge count operation.
+
+This example demonstrates how to count buffered digital events
+on a Counter Input Channel. The Initial Count, Count Direction,
+Edge, and Sample Clock Source are all configurable.
+"""
+
+import nidaqmx
+from nidaqmx.constants import AcquisitionType, CountDirection, Edge
+
+with nidaqmx.Task() as task:
+    channel = task.ci_channels.add_ci_count_edges_chan(
+        "Dev1/ctr0",
+        edge=Edge.RISING,
+        initial_count=0,
+        count_direction=CountDirection.COUNT_UP,
+    )
+    task.timing.cfg_samp_clk_timing(
+        1000, source="/Dev1/PFI9", sample_mode=AcquisitionType.CONTINUOUS
+    )
+    channel.ci_count_edges_term = "/Dev1/PFI8"
+
+    print("Continuously polling. Press Ctrl+C to stop.")
+    task.start()
+
+    try:
+        total_read = 0
+        while True:
+            edge_counts = task.read(number_of_samples_per_channel=1000)
+            total_read += len(edge_counts)
+            print(f"Acquired data: {len(edge_counts)} samples. Total {total_read}.", end="\r")
+    except KeyboardInterrupt:
+        pass
+    finally:
+        task.stop()
+        print(f"\nAcquired {total_read} total samples.")

examples/counter_in/cont_read_buff_freq.py

@@ -0,0 +1,36 @@
+"""Example of counter input frequency acquisition.
+
+This example demonstrates how to continuously measure buffered frequency
+using one counter on a Counter Input Channel. The Edge, Minimum Value
+and Maximum Value are all configurable.
+"""
+
+import nidaqmx
+from nidaqmx.constants import AcquisitionType, Edge, FrequencyUnits
+
+
+with nidaqmx.Task() as task:
+    channel = task.ci_channels.add_ci_freq_chan(
+        "Dev1/ctr0",
+        min_val=2.0,
+        max_val=100000.0,
+        units=FrequencyUnits.HZ,
+        edge=Edge.RISING,
+    )
+    channel.ci_freq_term = "/Dev1/PFI8"
+    task.timing.cfg_implicit_timing(sample_mode=AcquisitionType.CONTINUOUS)
+
+    print("Continuously polling. Press Ctrl+C to stop.")
+    task.start()
+
+    try:
+        total_read = 0
+        while True:
+            frequencies = task.read(number_of_samples_per_channel=1000)
+            total_read += len(frequencies)
+            print(f"Acquired data: {len(frequencies)} samples. Total {total_read}.", end="\r")
+    except KeyboardInterrupt:
+        pass
+    finally:
+        task.stop()
+        print(f"\nAcquired {total_read} total samples.")

examples/counter_in/read_freq.py

@@ -0,0 +1,27 @@
+"""Example of counter input frequency acquisition.
+
+This example demonstrates how to measure frequency using one
+counter on a Counter Input Channel. The Edge, Minimum Value and
+Maximum Value are all configurable.
+"""
+
+import nidaqmx
+from nidaqmx.constants import Edge, FrequencyUnits
+
+
+with nidaqmx.Task() as task:
+    channel = task.ci_channels.add_ci_freq_chan(
+        "Dev1/ctr0",
+        min_val=2.0,
+        max_val=100000.0,
+        units=FrequencyUnits.HZ,
+        edge=Edge.RISING,
+    )
+    channel.ci_freq_term = "/Dev1/PFI8"
+
+    task.start()
+
+    data = task.read()
+    print(f"Acquired frequency: {data:.2f} Hz")
+
+    task.stop()

examples/counter_in/read_pulse_freq.py

@@ -0,0 +1,22 @@
+"""Example of CI pulse frequency operation.
+
+This example demonstrates how to configure a pulse measurement to acquire frequency and duty cycle.
+"""
+
+import nidaqmx
+from nidaqmx.constants import FrequencyUnits
+
+with nidaqmx.Task() as task:
+    channel = task.ci_channels.add_ci_pulse_chan_freq(
+        "Dev1/ctr0", "", min_val=2.0, max_val=100000.0, units=FrequencyUnits.HZ
+    )
+    channel.ci_pulse_freq_term = "/Dev1/PFI8"
+
+    task.start()
+
+    data = task.read()
+    print(f"Acquired data:")
+    print(f"Frequency: {data.freq:.2f} Hz")
+    print(f"Duty cycle: {(data.duty_cycle * 100):.2f}%")
+
+    task.stop()

tests/acceptance/test_examples.py

@@ -27,7 +27,7 @@ def test___shipping_example___run___no_errors(example_path: Path, system):
                 pytest.skip(
                     f"Device {device_name} does not have physical channel {physical_channel_name}"
                 )
-    if example_path.name == "ci_pulse_freq.py":
+    if example_path.name == "read_pulse_freq.py":
         pytest.skip("Example times out if there is no signal.")
     if re.search(r"\binput\(|\bKeyboardInterrupt\b", example_source):
         pytest.skip("Example waits for keyboard input.")