fix read issue with multiple channel types in a single task (#196)

* fix read issue with multiple channel types in a single task

* update changelog

* updated issue name

* remove duplicated test

Author: zhindes

CHANGELOG.md

@@ -21,7 +21,7 @@ All notable changes to this project will be documented in this file.
 * ### Merged Pull Requests
     * ...
 * ### Resolved Issues
-    * ...
+    * [194: Multiple Voltage Measurement Types in the same task causes errors on Read](https://github.com/ni/nidaqmx-python/pull/194)
 * ### Major Changes
     * ...
 

nidaqmx/task.py

@@ -620,8 +620,14 @@ def read(self, number_of_samples_per_channel=NUM_SAMPLES_UNSET,
 
         # Analog Input
         if read_chan_type == ChannelType.ANALOG_INPUT:
-            meas_type = channels_to_read.ai_meas_type
-            if meas_type == UsageTypeAI.POWER:
+            has_power_chan = False
+            for chan in channels_to_read:
+                meas_type = chan.ai_meas_type
+                has_power_chan = meas_type == UsageTypeAI.POWER
+                if has_power_chan:
+                    break
+
+            if has_power_chan:
                 voltages = numpy.zeros(array_shape, dtype=numpy.float64)
                 currents = numpy.zeros(array_shape, dtype=numpy.float64)
 

nidaqmx/tests/fixtures.py

@@ -78,34 +78,50 @@ def bridge_device():
 
 
 @pytest.fixture(scope="module")
-def sim_power_device():
+def sim_ts_power_device():
     system = nidaqmx.system.System.local()
 
     for device in system.devices:
-        if device.dev_is_simulated and UsageTypeAI.POWER in device.ai_meas_types:
+        if device.dev_is_simulated and device.product_category == ProductCategory.TEST_SCALE_MODULE and UsageTypeAI.POWER in device.ai_meas_types:
             return device
 
     pytest.skip(
-        "Could not detect a device that meets the requirements to be a simulated power device. "
+        "Could not detect a device that meets the requirements to be a TestScale simulated power device. "
         "Cannot proceed to run tests. Import the NI MAX configuration file located at "
         "nidaqmx\\tests\\max_config\\nidaqmxMaxConfig.ini to create these devices."
     )
     return None
 
 
 @pytest.fixture(scope="module")
-def sim_power_devices():
+def sim_ts_voltage_device():
+    system = nidaqmx.system.System.local()
+
+    for device in system.devices:
+        if device.dev_is_simulated and device.product_category == ProductCategory.TEST_SCALE_MODULE and UsageTypeAI.VOLTAGE in device.ai_meas_types:
+            return device
+
+    pytest.skip(
+        "Could not detect a device that meets the requirements to be a TestScale simulated voltage device. "
+        "Cannot proceed to run tests. Import the NI MAX configuration file located at "
+        "nidaqmx\\tests\\max_config\\nidaqmxMaxConfig.ini to create these devices."
+    )
+    return None
+
+
+@pytest.fixture(scope="module")
+def sim_ts_power_devices():
     system = nidaqmx.system.System.local()
 
     devices = []
     for device in system.devices:
-        if device.dev_is_simulated and UsageTypeAI.POWER in device.ai_meas_types:
+        if device.dev_is_simulated and device.product_category == ProductCategory.TEST_SCALE_MODULE and UsageTypeAI.POWER in device.ai_meas_types:
             devices.append(device)
             if len(devices) == 2:
                 return devices
 
     pytest.skip(
-        "Could not detect two or more devices that meets the requirements to be a simulated power "
+        "Could not detect two or more devices that meets the requirements to be a TestScale simulated power "
         "device. Cannot proceed to run tests. Import the NI MAX configuration file located at "
         "nidaqmx\\tests\\max_config\\nidaqmxMaxConfig.ini to create these devices."
     )

nidaqmx/tests/max_config/nidaqmxMaxConfig.ini

@@ -87,3 +87,10 @@ DevIsSimulated = 1
 CompactDAQ.ChassisDevName = tsChassisTester
 CompactDAQ.SlotNum = 2
 
+[DAQmxCDAQModule tsVoltageTester1]
+ProductType = TS-15100
+DevSerialNum = 0x0
+DevIsSimulated = 1
+CompactDAQ.ChassisDevName = tsChassisTester
+CompactDAQ.SlotNum = 3
+

nidaqmx/tests/test_channel_creation.py

@@ -9,7 +9,7 @@
     CurrentShuntResistorLocation, TemperatureUnits, RTDType,
     ResistanceConfiguration, ExcitationSource, ResistanceUnits, StrainUnits,
     StrainGageBridgeType, BridgeConfiguration)
-from nidaqmx.tests.fixtures import sim_power_device, any_x_series_device
+from nidaqmx.tests.fixtures import sim_ts_power_device, any_x_series_device
 from nidaqmx.tests.helpers import generate_random_seed
 
 
@@ -268,11 +268,11 @@ def test_create_ai_voltage_chan_with_excit(self, any_x_series_device, seed):
             assert not ai_channel.ai_excit_use_for_scaling
 
     @pytest.mark.parametrize('seed', [generate_random_seed()])
-    def test_create_ai_power_chan(self, sim_power_device, seed):
+    def test_create_ai_power_chan(self, sim_ts_power_device, seed):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
-        pwr_phys_chan = f"{sim_power_device.name}/power"
+        pwr_phys_chan = f"{sim_ts_power_device.name}/power"
         voltage_setpoint = random.random() * 6.0
         current_setpoint = random.random() * 3.0
         output_enable = random.choice([True, False])

nidaqmx/tests/test_read_write.py

@@ -11,7 +11,7 @@
 from nidaqmx.constants import (
     Edge, TriggerType, AcquisitionType, LineGrouping, Level, TaskMode)
 from nidaqmx.utils import flatten_channel_string
-from nidaqmx.tests.fixtures import sim_power_device, sim_power_devices, real_x_series_device
+from nidaqmx.tests.fixtures import sim_ts_power_device, sim_ts_power_devices, sim_ts_voltage_device, sim_x_series_device, real_x_series_device
 from nidaqmx.tests.helpers import generate_random_seed, POWER_ABS_EPSILON
 
 
@@ -613,7 +613,7 @@ class TestPowerRead(TestDAQmxIOBase):
             (generate_random_seed(), False)
         ]
     )
-    def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
+    def test_power_1_chan_1_samp(self, sim_ts_power_device, seed, output_enable):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -622,7 +622,7 @@ def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
 
         with nidaqmx.Task() as read_task:
             read_task.ai_channels.add_ai_power_chan(
-                f"{sim_power_device.name}/power",
+                f"{sim_ts_power_device.name}/power",
                 voltage_setpoint, current_setpoint, output_enable)
 
             read_task.start()
@@ -644,15 +644,15 @@ def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
             (generate_random_seed(), [False, False])
         ]
     )
-    def test_power_n_chan_1_samp(self, sim_power_devices, seed, output_enables):
+    def test_power_n_chan_1_samp(self, sim_ts_power_devices, seed, output_enables):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
         voltage_setpoint = 0.0
         current_setpoint = 0.03
 
         with nidaqmx.Task() as read_task:
-            for device, output_enable in zip(sim_power_devices, output_enables):
+            for device, output_enable in zip(sim_ts_power_devices, output_enables):
                 read_task.ai_channels.add_ai_power_chan(
                     f"{device.name}/power",
                     voltage_setpoint, current_setpoint, output_enable)
@@ -675,7 +675,7 @@ def test_power_n_chan_1_samp(self, sim_power_devices, seed, output_enables):
             (generate_random_seed(), False)
         ]
     )
-    def test_power_1_chan_n_samp(self, sim_power_device, seed, output_enable):
+    def test_power_1_chan_n_samp(self, sim_ts_power_device, seed, output_enable):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -684,7 +684,7 @@ def test_power_1_chan_n_samp(self, sim_power_device, seed, output_enable):
 
         with nidaqmx.Task() as read_task:
             read_task.ai_channels.add_ai_power_chan(
-                f"{sim_power_device.name}/power",
+                f"{sim_ts_power_device.name}/power",
                 voltage_setpoint, current_setpoint, output_enable)
 
             read_task.start()
@@ -706,15 +706,15 @@ def test_power_1_chan_n_samp(self, sim_power_device, seed, output_enable):
             (generate_random_seed(), [False, False])
         ]
     )
-    def test_power_n_chan_n_samp(self, sim_power_devices, seed, output_enables):
+    def test_power_n_chan_n_samp(self, sim_ts_power_devices, seed, output_enables):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
         voltage_setpoint = 0.0
         current_setpoint = 0.03
 
         with nidaqmx.Task() as read_task:
-            for device, output_enable in zip(sim_power_devices, output_enables):
+            for device, output_enable in zip(sim_ts_power_devices, output_enables):
                 read_task.ai_channels.add_ai_power_chan(
                     f"{device.name}/power",
                     voltage_setpoint, current_setpoint, output_enable)
@@ -731,3 +731,40 @@ def test_power_n_chan_n_samp(self, sim_power_devices, seed, output_enables):
                 else:
                     assert all(math.isnan(sample.voltage) for sample in channel_values)
                     assert all(math.isnan(sample.current) for sample in channel_values)
+
+    @pytest.mark.parametrize('seed', [generate_random_seed()])
+    def test_mixed_chans(self, sim_x_series_device, seed):
+        # Reset the pseudorandom number generator with seed.
+        random.seed(seed)
+
+        with nidaqmx.Task() as read_task:
+            read_task.ai_channels.add_ai_voltage_chan(
+                f"{sim_x_series_device.name}/ai0", max_val=10, min_val=-10)
+            read_task.ai_channels.add_ai_current_chan(
+                f"{sim_x_series_device.name}/ai1", max_val=0.01, min_val=-0.01)
+
+            read_task.start()
+            # We aren't validating data, just assuring that it doesn't fail.
+            values_read = read_task.read(number_of_samples_per_channel=10)
+
+    @pytest.mark.parametrize('seed', [generate_random_seed()])
+    def test_mixed_chans_with_power(self, sim_ts_power_device, sim_ts_voltage_device, seed):
+        # Reset the pseudorandom number generator with seed.
+        random.seed(seed)
+
+        voltage_setpoint = 0.0
+        current_setpoint = 0.03
+        output_enable = False
+
+        with nidaqmx.Task() as read_task:
+            read_task.ai_channels.add_ai_power_chan(
+                f"{sim_ts_power_device.name}/power",
+                voltage_setpoint, current_setpoint, output_enable)
+            read_task.ai_channels.add_ai_voltage_chan(
+                f"{sim_ts_voltage_device.name}/ai0", max_val=10, min_val=-10)
+
+            read_task.start()
+            # We aren't validating data, just assuring that it fails. The error
+            # code is currently not very good, so we'll ignore that for now.
+            with pytest.raises(nidaqmx.errors.DaqReadError):
+                values_read = read_task.read(number_of_samples_per_channel=10)

nidaqmx/tests/test_stream_power_readers.py

@@ -10,7 +10,7 @@
 import nidaqmx
 from nidaqmx.stream_readers import (
     PowerSingleChannelReader, PowerMultiChannelReader, PowerBinaryReader)
-from nidaqmx.tests.fixtures import sim_power_device, sim_power_devices
+from nidaqmx.tests.fixtures import sim_ts_power_device, sim_ts_power_devices
 from nidaqmx.tests.helpers import generate_random_seed, POWER_ABS_EPSILON
 from nidaqmx.tests.test_read_write import TestDAQmxIOBase
 
@@ -31,7 +31,7 @@ class TestPowerSingleChannelReader(TestDAQmxIOBase):
             (generate_random_seed(), False)
         ]
     )
-    def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
+    def test_power_1_chan_1_samp(self, sim_ts_power_device, seed, output_enable):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -40,7 +40,7 @@ def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
 
         with nidaqmx.Task() as read_task:
             read_task.ai_channels.add_ai_power_chan(
-                f"{sim_power_device.name}/power",
+                f"{sim_ts_power_device.name}/power",
                 voltage_setpoint, current_setpoint, output_enable)
 
             reader = PowerSingleChannelReader(read_task.in_stream)
@@ -62,7 +62,7 @@ def test_power_1_chan_1_samp(self, sim_power_device, seed, output_enable):
             (generate_random_seed(), False)
         ]
     )
-    def test_power_1_chan_n_samp(self, sim_power_device, seed, output_enable):
+    def test_power_1_chan_n_samp(self, sim_ts_power_device, seed, output_enable):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -76,7 +76,7 @@ def test_power_1_chan_n_samp(self, sim_power_device, seed, output_enable):
 
         with nidaqmx.Task() as read_task:
             read_task.ai_channels.add_ai_power_chan(
-                f"{sim_power_device.name}/power",
+                f"{sim_ts_power_device.name}/power",
                 voltage_setpoint, current_setpoint, output_enable)
 
             reader = PowerSingleChannelReader(read_task.in_stream)
@@ -111,19 +111,19 @@ class TestPowerMultiChannelReader(TestDAQmxIOBase):
             (generate_random_seed(), [False, False])
         ]
     )
-    def test_power_n_chan_1_samp(self, sim_power_devices, seed, output_enables):
+    def test_power_n_chan_1_samp(self, sim_ts_power_devices, seed, output_enables):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
         voltage_setpoint = 0.0
         current_setpoint = 0.03
 
         # Fill with bad data to ensure its overwritten by read.
-        voltage_data = numpy.full(len(sim_power_devices), -1.0, dtype=numpy.float64)
-        current_data = numpy.full(len(sim_power_devices), -1.0, dtype=numpy.float64)
+        voltage_data = numpy.full(len(sim_ts_power_devices), -1.0, dtype=numpy.float64)
+        current_data = numpy.full(len(sim_ts_power_devices), -1.0, dtype=numpy.float64)
 
         with nidaqmx.Task() as read_task:
-            for device, output_enable in zip(sim_power_devices, output_enables):
+            for device, output_enable in zip(sim_ts_power_devices, output_enables):
                 read_task.ai_channels.add_ai_power_chan(
                     f"{device.name}/power",
                     voltage_setpoint, current_setpoint, output_enable)
@@ -150,7 +150,7 @@ def test_power_n_chan_1_samp(self, sim_power_devices, seed, output_enables):
             (generate_random_seed(), [False, False])
         ]
     )
-    def test_power_n_chan_n_samp(self, sim_power_devices, seed, output_enables):
+    def test_power_n_chan_n_samp(self, sim_ts_power_devices, seed, output_enables):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -159,11 +159,11 @@ def test_power_n_chan_n_samp(self, sim_power_devices, seed, output_enables):
         number_of_samples_per_channel = 10
 
         # Fill with bad data to ensure its overwritten by read.
-        voltage_data = numpy.full((len(sim_power_devices), number_of_samples_per_channel), -1.0, dtype=numpy.float64)
-        current_data = numpy.full((len(sim_power_devices), number_of_samples_per_channel), -1.0, dtype=numpy.float64)
+        voltage_data = numpy.full((len(sim_ts_power_devices), number_of_samples_per_channel), -1.0, dtype=numpy.float64)
+        current_data = numpy.full((len(sim_ts_power_devices), number_of_samples_per_channel), -1.0, dtype=numpy.float64)
 
         with nidaqmx.Task() as read_task:
-            for device, output_enable in zip(sim_power_devices, output_enables):
+            for device, output_enable in zip(sim_ts_power_devices, output_enables):
                 read_task.ai_channels.add_ai_power_chan(
                     f"{device.name}/power",
                     voltage_setpoint, current_setpoint, output_enable)
@@ -203,7 +203,7 @@ class TestPowerBinaryReader(TestDAQmxIOBase):
             (generate_random_seed(), False)
         ]
     )
-    def test_power_1_chan_n_samp_binary(self, sim_power_device, seed, output_enable):
+    def test_power_1_chan_n_samp_binary(self, sim_ts_power_device, seed, output_enable):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -217,7 +217,7 @@ def test_power_1_chan_n_samp_binary(self, sim_power_device, seed, output_enable)
 
         with nidaqmx.Task() as read_task:
             read_task.ai_channels.add_ai_power_chan(
-                f"{sim_power_device.name}/power",
+                f"{sim_ts_power_device.name}/power",
                 voltage_setpoint, current_setpoint, output_enable)
 
             reader = PowerBinaryReader(read_task.in_stream)
@@ -247,7 +247,7 @@ def test_power_1_chan_n_samp_binary(self, sim_power_device, seed, output_enable)
             (generate_random_seed(), [False, False])
         ]
     )
-    def test_power_n_chan_many_sample_binary(self, sim_power_devices, seed, output_enables):
+    def test_power_n_chan_many_sample_binary(self, sim_ts_power_devices, seed, output_enables):
         # Reset the pseudorandom number generator with seed.
         random.seed(seed)
 
@@ -256,11 +256,11 @@ def test_power_n_chan_many_sample_binary(self, sim_power_devices, seed, output_e
         number_of_samples_per_channel = 10
 
         # Fill with bad data to ensure its overwritten by read.
-        voltage_data = numpy.full((len(sim_power_devices), number_of_samples_per_channel), -32768, dtype=numpy.int16)
-        current_data = numpy.full((len(sim_power_devices), number_of_samples_per_channel), -32768, dtype=numpy.int16)
+        voltage_data = numpy.full((len(sim_ts_power_devices), number_of_samples_per_channel), -32768, dtype=numpy.int16)
+        current_data = numpy.full((len(sim_ts_power_devices), number_of_samples_per_channel), -32768, dtype=numpy.int16)
 
         with nidaqmx.Task() as read_task:
-            for device, output_enable in zip(sim_power_devices, output_enables):
+            for device, output_enable in zip(sim_ts_power_devices, output_enables):
                 read_task.ai_channels.add_ai_power_chan(
                     f"{device.name}/power",
                     voltage_setpoint, current_setpoint, output_enable)