Setting Different Analog Input Voltage Levels for Each DAQmx Channel

Updated Jun 26, 2019

Reported In

Software

  • LabVIEW

Driver

  • NI-DAQmx

Issue Details

  • Can I set different voltage ranges for each channel in my task?
  • How do I change the voltage range for each channel in my DAQmx task?
  • I want to set a different analog input range per channel in my DAQmx task. Can I do this?

Solution

You can do this two ways: creating your DAQmx task in NI Measurement and Automation Explorer (NI MAX), or programmatically in LabVIEW.
 

Using NI MAX

  1. Open NI MAX and select your device from the Devices and Interfaces drop-down menu.
  2. Click on Create Task... from the toolbar at the top of the window then Acquire Signals>>Analog Input>>Voltage. Select the device channels you want to include in your analog input task by clicking the first channel, holding the shift key and then clicking the last channel in your list. You can also select them individually by holding the control key and then selecting the channels one by one. Click Next> after selecting the analog input channels you would like to include for your task
  1. Name the voltage task and click Finish
  2. Configure the individual voltage ranges in the configuration panel by clicking each channel and setting the signal input range.
  1. In LabVIEW, wire your task directly in the DAQmx Timing VI, as shown below. The DAQmx Create Task and DAQmx Create Virtual Channel VIs are not necessary because you already created the task and channels in MAX.

If you need to edit the channels in the future, you can do so in NI MAX by adding or removing them as required.
 

    Using Create Channel VIs

    You can also assign different input voltage ranges to your analog input channels exclusively in LabVIEW by using multiple DAQmx Create Virtual Channels VIs to create different channels and set different analog input voltages for each channel.
    1. Place a DAQmx Create Virtual Channel VI for each channel grouping that you would like to have set at the same analog input range. To select multiple channels for one VI, you can use channel expansion
    2. Connect relevant terminals for the physical channels and other settings. To set the lower boundary of the analog input range, wire a double value to the minimum value input terminal. To set the upper boundary of the analog input range, wire a double value to the maximum value input terminal. 
    An example of this is shown below.

    Additional Information

    • If you configure your DAQmx tasks using MAX, National Instruments recommends you create a backup of this configuration for later use: Export/Import the System Configuration in Measurement & Automation Explorer (MAX)
    • Some C Series cards have defined input voltage ranges, such as ±10V, ± 5V, ±2V and ±1V. If a value for minimum and maximum are something different than these, the DAQmx driver will coerce the value up to the nearest voltage range that can fully capture the input. 

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