ATTACH_ANALOG_INPUT_STRAIN_GAGE

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Attach channel(s) to a task measure strain. **Compatibility:** Compatible with National Instruments devices that utilize NI-DAQmx. Tested on a simulated NI-9236 module. This block is designed for use with Windows and Linux systems due to NI driver availability. Ensure you have installed the NI-DAQmx runtime from https://www.ni.com/en/support/downloads/drivers/download.ni-daq-mx.html. Params: task_name : str The name of the task to create. cDAQ_start_channel : NIDAQmxDevice The device and channel to read from. cDAQ_end_channel : NIDAQmxDevice To read from only one channel, set this to the same as `cDAQ_start_channel`. To read from multiple channels, set this to the last channel you want to read from. min_val : float Specifies in **units** the minimum value you expect to measure (default is -0.001). max_val : float Specifies in **units** the maximum value you expect to measure (default is 0.001). units : Literal The units to use to return strain measurements (default is "STRAIN"). strain_config : Literal Specifies information about the bridge configuration and measurement (default is "Full Bridge 1"). voltage_excitation_source : Literal Specifies the source of excitation (default is "Internal"). voltage_excitation_value : float Specifies in volts the amount of excitation to supply to the bridge (default is 2.5). gage_factor : float Contains information about the strain gage and measurement (default is 2.0). initial_bridge_voltage : float Specifies the initial voltage across the bridge before any strain is applied (default is 0.0). nominal_gage_resistance : float Contains information about the strain gage and measurement (default is 350.0). poisson_ratio : float Contains information about the strain gage and measurement (default is 0.3). lead_wire_resistance : float Specifies the resistance of the lead wires connected to the strain gage (default is 0.0). Returns: out : Optional[DataContainer] This block does not return any meaningful data; it is designed for creating a task to measure strain.

Python Code

from flojoy import flojoy, DataContainer, NIDAQmxDevice, DeviceConnectionManager
from typing import Optional, Literal
import nidaqmx


@flojoy(deps={"nidaqmx": "0.9.0"})
def ATTACH_ANALOG_INPUT_STRAIN_GAGE(
    task_name: str,
    cDAQ_start_channel: NIDAQmxDevice,
    cDAQ_end_channel: NIDAQmxDevice,
    min_val: float = -0.001,
    max_val: float = 0.001,
    units: Literal["STRAIN"] = "STRAIN",
    strain_config: Literal[
        "Full brige 1",
        "Full brige 2",
        "Full brige 3",
        "Half brige 1",
        "Half brige 2",
        "Quarter brige 1",
        "Quarter brige 2",
    ] = "Full brige 1",
    voltage_excitation_source: Literal["None", "External", "Internal"] = "Internal",
    voltage_excitation_value: float = 2.5,
    default: Optional[DataContainer] = None,
    gage_factor: float = 2.0,
    initial_bridge_voltage: float = 0.0,
    nominal_gage_resistance: float = 350.0,
    poisson_ratio: float = 0.3,
    lead_wire_resistance: float = 0.0,
) -> Optional[DataContainer]:
    """Attach channel(s) to a task measure strain.

    **Compatibility:**
    Compatible with National Instruments devices that utilize NI-DAQmx. Tested on a simulated NI-9236 module.

    This block is designed for use with Windows and Linux systems due to NI driver availability. Ensure you have installed the NI-DAQmx runtime from https://www.ni.com/en/support/downloads/drivers/download.ni-daq-mx.html.

    Parameters
    ----------
    task_name : str
        The name of the task to create.
    cDAQ_start_channel : NIDAQmxDevice
        The device and channel to read from.
    cDAQ_end_channel : NIDAQmxDevice
        To read from only one channel, set this to the same as `cDAQ_start_channel`. To read from multiple channels, set this to the last channel you want to read from.
    min_val : float, optional
        Specifies in **units** the minimum value you expect to measure (default is -0.001).
    max_val : float, optional
        Specifies in **units** the maximum value you expect to measure (default is 0.001).
    units : Literal, optional
        The units to use to return strain measurements (default is "STRAIN").
    strain_config : Literal, optional
        Specifies information about the bridge configuration and measurement (default is "Full Bridge 1").
    voltage_excitation_source : Literal, optional
        Specifies the source of excitation (default is "Internal").
    voltage_excitation_value : float, optional
        Specifies in volts the amount of excitation to supply to the bridge (default is 2.5).
    gage_factor : float, optional
        Contains information about the strain gage and measurement (default is 2.0).
    initial_bridge_voltage : float, optional
        Specifies the initial voltage across the bridge before any strain is applied (default is 0.0).
    nominal_gage_resistance : float, optional
        Contains information about the strain gage and measurement (default is 350.0).
    poisson_ratio : float, optional
        Contains information about the strain gage and measurement (default is 0.3).
    lead_wire_resistance : float, optional
        Specifies the resistance of the lead wires connected to the strain gage (default is 0.0).

    Returns
    -------
    Optional[DataContainer]
        This block does not return any meaningful data; it is designed for creating a task to measure strain.
    """
    # Check if task already exists
    task = DeviceConnectionManager.get_connection(task_name).get_handle()

    # Attach the requested channel(s) to the task
    name, address = cDAQ_start_channel.get_id().split("/")
    if cDAQ_end_channel:
        _, address_end = cDAQ_end_channel.get_id().split("/")
        address = f"{address}:{address_end[2:]}"
    physical_channels = f"{name}/{address}"

    units = nidaqmx.constants.StrainUnits.STRAIN  # TODO: Support custom scale
    strain_config = {
        "Full brige 1": nidaqmx.constants.StrainGageBridgeType.FULL_BRIDGE_I,
        "Full brige 2": nidaqmx.constants.StrainGageBridgeType.FULL_BRIDGE_II,
        "Full brige 3": nidaqmx.constants.StrainGageBridgeType.FULL_BRIDGE_III,
        "Half brige 1": nidaqmx.constants.StrainGageBridgeType.HALF_BRIDGE_I,
        "Half brige 2": nidaqmx.constants.StrainGageBridgeType.HALF_BRIDGE_II,
        "Quarter brige 1": nidaqmx.constants.StrainGageBridgeType.QUARTER_BRIDGE_I,
        "Quarter brige 2": nidaqmx.constants.StrainGageBridgeType.QUARTER_BRIDGE_II,
    }[strain_config]

    voltage_excitation_source = {
        "None": nidaqmx.constants.ExcitationSource.NONE,
        "External": nidaqmx.constants.ExcitationSource.EXTERNAL,
        "Internal": nidaqmx.constants.ExcitationSource.INTERNAL,
    }[voltage_excitation_source]

    task.ai_channels.add_ai_strain_gage_chan(
        physical_channels,
        min_val=min_val,
        max_val=max_val,
        units=units,
        strain_config=strain_config,
        voltage_excit_source=voltage_excitation_source,
        voltage_excit_val=voltage_excitation_value,
        gage_factor=gage_factor,
        initial_bridge_voltage=initial_bridge_voltage,
        nominal_gage_resistance=nominal_gage_resistance,
        poisson_ratio=poisson_ratio,
        lead_wire_resistance=lead_wire_resistance,
    )

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Download this Flojoy App

This app shows how to use a strain gage input block for with a National Instruments Compact DAQ module.

Blocks used:

• CREATE_TASK_ANALOG_INPUT_GAUGE
• CONFIG_TASK_SAMPLE_CLOCK_TIMINGS
• READ_TASK
• LINE

The blocks were connected as shown, and the app was run. The result displayed the first 100 samples taken from the device buffer for 3 channels.