Customize the data ranges and set values for slow, medium, and fast data rates to configure your DAQ device's data acquisition rate.

For devices that support downsampling, you can use an anti-aliased filter to downsample at 100 Hz.

You can configure any analog input device to use the Slow, Medium, or Fast data rate level.

Configure onboard counters, 62xx/63xx multifunction I/O device counters, and digital modules to use these data rate levels. However, you must first configure an analog input channel or digital channel in the same chassis to access these data rates.

CompactDAQ counter modules require a data rate resource at the Medium data rate level. When adding a CompactDAQ counter module, change modules using the Medium data rate to Slow or Fast.

Complete the following steps to configure the available data rates for your DAQ device:

  1. Click Configure Data Rates on the toolbar or click Configure from the Data Rate Level pull-down selector.
  2. Specify each frequency in hertz or seconds (for intervals) for the desired slow, medium, fast, counter, or digital rates. Available data rate types vary by device.
  3. Click Done to apply the rates.

Why is my module not sampling at the rate I specified?

The data rate for your module may be different than the rate you configure for one of the following reasons:
  • Modules support specific rates. Configure your module to sample at various rates; however, hardware limitations may adjust it to the nearest supported rate using FlexLogger.
    Note The coerced rate is faster than the rate you specify. For example, if you configure 11 Hz for a module that supports 10 Hz and 20 Hz, FlexLogger uses 20 Hz.
  • Modules sample at the lowest common rate. If you configure multiple modules in the same chassis to the same rate and the modules support different data rates, FlexLogger sets a common, supported rate. Use a common rate to prevent data loss and ensure effective synchronization. For example, if you set the NI-9219 and the NI-9236 to Medium (200 Hz), the NI-9236 can't sample slow enough to meet the 200 Hz configuration. As a result, both modules use the actual rate of ~793 Hz because it's the common rate closest to the rate you configured.

Configure modules in the same chassis with different timing rates or place the modules in separate chassis to use supported rates.

Why does my module say the rate is downsampled?

Many modules support downsampling in software to meet a lower data rate than the modules support. Downsampling occurs when all the modules set to the same rate support downsampling. The available downsampling rate is 100 Hz.

Why is my module rate not downsampled?

If your module meets the requirements, but isn't downsampling, check the following items:

  • An existing downsampling preview feature interferes with the default, anti-aliased downsampling filter. Navigate to File » Preferences » Preview features and disable the Enable downsampling from a coerced hardware sample rate to slower sample rate feature.
    Note The existing preview feature supports arbitrary data rates, but doesn't offer antialiasing.
  • C Series Slow Sample Devices don't support downsampling. Refer to C Series Device Groupings in the NI-DAQmx User Manual for a list of slow sample devices. If you have one slow sample device set to the same rate as modules that support downsampling, it prevents downsampling for all the modules.