CONFIG_INPUT_STREAM

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Configure the properties of an input stream. This block is used to set the properties of an input stream for a given task before reading samples from the stream. **Compatibility:** 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 configure. timeout : float The amount of time, in seconds, to wait for the function to read the samples (default is 10.0 seconds). offset : int Specifies an offset in samples per channel at which to begin a read operation. This offset is relative to the location you specify with `relative_to` (default is 0). relative_to : Literal Specifies the point in the buffer at which to begin a read operation. Valid options are: - "First Pretrigger Sample" - "First Sample" - "Reference Trigger" - "Most Recent Sample" - "Current Read Position" (default) overwrite : bool Specifies whether to overwrite samples in the buffer that you have not yet read. If True, overwrite unread samples; if False, do not overwrite unread samples (default is False). Returns: out : Optional[DataContainer] This block does not return any meaningful data; it is designed for configuring the input stream properties.

Python Code

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


@flojoy(deps={"nidaqmx": "0.9.0"})
def CONFIG_INPUT_STREAM(
    task_name: str,
    timeout: float = 10.0,
    offset: int = 0,
    relative_to: Literal[
        "Current Read Position",
        "First Pretrigger Sample",
        "First Sample",
        "Reference Trigger",
        "Most Recent Sample",
    ] = "Current Read Position",
    overwrite: bool = False,
    default: Optional[DataContainer] = None,
) -> Optional[DataContainer]:
    """Configure the properties of an input stream.

    This block is used to set the properties of an input stream for a given task before reading samples from the stream.

    **Compatibility:**
    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 configure.
    timeout : float, optional
        The amount of time, in seconds, to wait for the function to read the samples (default is 10.0 seconds).
    offset : int, optional
        Specifies an offset in samples per channel at which to begin a read operation. This offset is relative to the location you specify with `relative_to` (default is 0).
    relative_to : Literal
        Specifies the point in the buffer at which to begin a read operation. Valid options are:
        - "First Pretrigger Sample"
        - "First Sample"
        - "Reference Trigger"
        - "Most Recent Sample"
        - "Current Read Position" (default)
    overwrite : bool, optional
        Specifies whether to overwrite samples in the buffer that you have not yet read. If True, overwrite unread samples; if False, do not overwrite unread samples (default is False).

    Returns
    -------
    Optional[DataContainer]
        This block does not return any meaningful data; it is designed for configuring the input stream properties.
    """

    task = DeviceConnectionManager.get_connection(task_name).get_handle()

    task.in_stream.timeout = timeout

    task.in_stream.offset = offset

    relative_to = {
        "First Pretrigger Sample": nidaqmx.constants.ReadRelativeTo.FIRST_PRETRIGGER_SAMPLE,
        "First Sample": nidaqmx.constants.ReadRelativeTo.FIRST_SAMPLE,
        "Reference Trigger": nidaqmx.constants.ReadRelativeTo.REFERENCE_TRIGGER,
        "Most Recent Sample": nidaqmx.constants.ReadRelativeTo.MOST_RECENT_SAMPLE,
        "Current Read Position": nidaqmx.constants.ReadRelativeTo.CURRENT_READ_POSITION,
    }[relative_to]
    task.in_stream.relative_to = relative_to

    overwrite = (
        nidaqmx.constants.OverwriteMode.OVERWRITE_UNREAD_SAMPLES
        if overwrite
        else nidaqmx.constants.OverwriteMode.DO_NOT_OVERWRITE_UNREAD_SAMPLES
    )
    task.in_stream.overwrite = overwrite

    return None

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Example App

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Download this Flojoy App

This app shows how to use input stream blocks for with National Instruments Compact DAQ module.

Blocks used:

• CREATE_TASK_ANALOG_INPUT_CURRENT
• CONFIG_INPUT_STREAM
• READ_INPUT_STREAM
• READ_INPUT_STREAM_INTO_BUFFER
• 2x LINE
• PRINT_DATACONTAINER
• TEXT_VIEW
• TIMER
• LOOP

The blocks were connected as shown, and the app was run. The result displayed the first 100 samples from an analog module in the first plot and constantly updated the second plot with the latest data from the device buffer.