Skip to content
Flojoy Docs

ATTACH_ANALOG_INPUT_THERMOCOUPLE

Attach channel(s) to a task to measure temperature using a thermocouple. **Compatibility:** Compatible with National Instruments devices that utilize NI-DAQmx. Tested with a simulated NI-9219 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 attach the channel(s) to. 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 0.0). max_val : float Specifies in **units** the maximum value you expect to measure (default is 100.0). units : Literal The units to use to return thermocouple measurements (default is "Celsius"). thermocouple_type : Literal The type of thermocouple being used (default is "J"). cold_junction_source : Literal Specifies the source of cold junction compensation (default is "Constant"). cold_junction_value : Optional[float] Specifies the cold junction temperature in **units** if `cold_junction_source` is set to "Constant" (default is 25.0). cold_junction_channel : str Specifies the source of cold junction compensation if `cold_junction_source` is set to "Channel" (default is ""). Returns: out : Optional[DataContainer] This block does not return any meaningful data; it is designed for creating a task to measure temperature using a thermocouple.
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_THERMOCOUPLE(
    task_name: str,
    cDAQ_start_channel: NIDAQmxDevice,
    cDAQ_end_channel: NIDAQmxDevice,
    min_val: float = 0.0,
    max_val: float = 100.0,
    units: Literal["Celsius", "Fahrenheit", "Rankine", "Kelvin"] = "Celsius",
    thermocouple_type: Literal["K", "R", "N", "E", "J", "S", "T", "B"] = "J",
    cold_junction_source: Literal["Constant", "Channel", "Built In"] = "Constant",
    cold_junction_value: float = 25.0,
    cold_junction_channel: str = "",
    default: Optional[DataContainer] = None,
) -> Optional[DataContainer]:
    """Attach channel(s) to a task to measure temperature using a thermocouple.

    **Compatibility:**
    Compatible with National Instruments devices that utilize NI-DAQmx. Tested with a simulated NI-9219 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 attach the channel(s) to.
    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 0.0).
    max_val : float, optional
        Specifies in **units** the maximum value you expect to measure (default is 100.0).
    units : Literal, optional
        The units to use to return thermocouple measurements (default is "Celsius").
    thermocouple_type : Literal, optional
        The type of thermocouple being used (default is "J").
    cold_junction_source : Literal, optional
        Specifies the source of cold junction compensation (default is "Constant").
    cold_junction_value : Optional[float], optional
        Specifies the cold junction temperature in **units** if `cold_junction_source` is set to "Constant" (default is 25.0).
    cold_junction_channel : str, optional
        Specifies the source of cold junction compensation if `cold_junction_source` is set to "Channel" (default is "").

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

    # Attach the requested channel(s) to the task
    units = {
        "Celsius": nidaqmx.constants.TemperatureUnits.DEG_C,
        "Fahrenheit": nidaqmx.constants.TemperatureUnits.DEG_F,
        "Rankine": nidaqmx.constants.TemperatureUnits.DEG_R,
        "Kelvin": nidaqmx.constants.TemperatureUnits.K,
    }[units]

    thermocouple_type = {
        "K": nidaqmx.constants.ThermocoupleType.K,
        "R": nidaqmx.constants.ThermocoupleType.R,
        "N": nidaqmx.constants.ThermocoupleType.N,
        "E": nidaqmx.constants.ThermocoupleType.E,
        "J": nidaqmx.constants.ThermocoupleType.J,
        "S": nidaqmx.constants.ThermocoupleType.S,
        "T": nidaqmx.constants.ThermocoupleType.T,
        "B": nidaqmx.constants.ThermocoupleType.B,
    }[thermocouple_type]

    cold_junction_source = {
        "Constant": nidaqmx.constants.CJCSource.CONSTANT_USER_VALUE,
        "Channel": nidaqmx.constants.CJCSource.SCANNABLE_CHANNEL,
        "Built In": nidaqmx.constants.CJCSource.BUILT_IN,
    }[cold_junction_source]

    # Build the physical channels strin
    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}"

    task.ai_channels.add_ai_thrmcpl_chan(
        physical_channels,
        min_val=min_val,
        max_val=max_val,
        units=units,
        thermocouple_type=thermocouple_type,
        cjc_source=cold_junction_source,
        cjc_val=cold_junction_value,
        cjc_channel=cold_junction_channel,
    )

Find this Flojoy Block on GitHub

Example

Having problems with this example app? Join our Discord community and we will help you out!
React Flow mini map

This app shows how to use a thermocouple and voltage input blocks for with National Instruments Compact DAQ modules.

Blocks used:

  • CREATE_TASK_ANALOG_INPUT_THERMOCOUPLE
  • CREATE_TASK_ANALOG_INPUT_VOLTAGE
  • CONFIG_TASK_SAMPLE_CLOCK_TIMINGS
  • TASK_WAIT_UNTIL_DONE
  • 2x READ_TASK
  • 2x LINE

The blocks were connected as shown, and the app was run. The result displayed the first 100 samples taken from the two devices’ buffer for multiple channels. The app ensures that the operation is complete for the thermocouple task before stopping it.