How Many DAQmx Tasks Can I Run Simultaneously?

Updated Jun 15, 2018

Reported In

Software

  • LabVIEW
  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

I have a PCI/PCIe DAQ card or an USB DAQ device (X/M/E/S Series devices). How many DAQmx tasks of each kind can I run simultaneously on the same device?

Solution

Because hardware-timed tasks typically use more onboard resources than software-timed tasks, the total number of possible concurrent tasks typically depends on whether you are running tasks that use hardware timing or software (on demand) timing.
 

Hardware-Timed Tasks

Hardware-timed tasks require timing information from the System Timing Controller to use for sample clocks, reference clocks, triggers, etc. The following table illustrates the number of hardware-timed tasks available to the user.

 

Hardware-Timed Tasks
# of Tasks per Module
Analog Input1
Analog Output1
Counter InputN
Counter OutputN
Digital Input1
Digital Output1
 

Software-Timed Tasks

Most software-timed tasks do not require a signal from a System Timing Controller in order to run. Software-timed means the host computer is controlling how often a sample is read from or written to the module.

 
Software-Timed (On Demand) Tasks# of Tasks per Module
Analog Input1
Analog Output1 Task for each AO channel
Counter InputN
Counter OutputN
Digital Input1 Task for each digital line capable of Digital Input
Digital Output1 Task for each digital line capable of Digital Output


The number of counter tasks is always limited by the number of counters you have. Depending on whether you are using a counter task that uses multiple counters (like measuring frequency using the two counter method), you may be restricted to less counter tasks. To determine if you need one or two counters for your counter task, refer to How Many Counters Does Each Type of Counter Task Require?

Additional Information

There are different timing engines in the NI CompactDAQ (cDAQ) chassis. If you are using this platform to develop your application, review the amount of tasks that can run simultaneously in the following document: Number of Concurrent Tasks on a CompactDAQ Chassis Gen II

What is a Task in NI-DAQmx?: Channels and Tasks in NI-DAQmx

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