Accessing NI MAX Tasks from NI-DAQmx Python Library

Updated Mar 13, 2018

Reported In

Software

  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

I am using the Python Library for NI-DAQmx and I want to access an already created task from the NI MAX Database, but i cannot find this in the Python Documentation for NI-DAQmx. Is this possible?

Solution

Yes, the NI-DAQmx Python Library is capable of accessing an already created task from the NI MAX Database. In order to do so you will need to follow the bellow presented steps:
  • Access the Python Console
  • Import the NI-DAQmx library by entering the following command: "import nidaqmx"

  • In order to access the NI MAX Database, you will have to instantiate a System object that contains the information regarding the connected devise, tasks and so on. This is achieved by the following command: "<object name>  = nidaqmx.system.system.System()"

  • Now, you can access the collection of tasks stored in your system, and visualize the names of those tasks by entering: "<system object name>.tasks.task_names".

  • In order to access one of the tasks, you will need to instantiate a PersistedTask object. PersistedTask is a class that stores the task information in the Database. You can do this in two ways:
  1. Statically: <persisted task object name> = nidaqmx.system.storage.persisted_task.PersistedTask('<task name from the collection obtained at previous step>')
  2. Programmatically: <persisted task object name> = nidaqmx.system.storage.persisted_task.PersistedTask(<system object name>.tasks.task_names[<index of the task you want to access>]). Bare in mind that the indexing starts at 0.

  • Now that you accessed the task in the database you will need to load it, so the System will know that you are currently using and reserve it and create a Task object. The command for this is: "<task object name> = <persisted task object name>.load().

  • Now that you have a task object created, you can execute all the task methods implemented in the Python Library for NI-DAQmx.

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