What Is the Multi-Channel Sampling Rate for PXIe-63X5?

Updated Apr 23, 2020

Reported In

Hardware

  • PXIe-6375
  • PXIe-6365
  • PXIe-6355

Issue Details

NI 63X5 DAQ devices have high AI channel counts (80/144/208 AI channels). According to the specifications sheets, the maximum sampling rates are as follows
 
DeviceSingle Channel Max RateMultichannel Max RateMinimum Rate
NI 6355 (Specifications)1.25 MS/s1 MS/sNo minimum
NI 6365 (Specifications)2 MS/s1 MS/sNo minimum
NI 6375 (Specifications )3.846 MS/s1 MS/sNo minimum

What is the sampling rate when more than one channel are used at the same time? How should I interpret the Multichannel Maximum Sample Rate specification?

Solution

NI 63X5 DAQ devices are not simultaneous sampling. Input channels are multiplexed, and the multichannel sampling rate is aggregate over the number of configured channels.
This means for any 63X5 DAQ devices with more than one channel configured, the highest rate that you could sample any individual channel at would be 1MS/s divided by the number of configured channels.
So if you have configured 10 AI channels, then the highest sampling rate per channel would be 100 kS/s (1MS/s divided by 10).

If using all single-ended AI channels on the device, you should expect to see the following maximum rates per channel.
 
DeviceNumber of Single-Ended
AI Channels
Maximum Sampling Rate
NI 63558012.5 kS/s
NI 63651446.944 kS/s
NI 63752084.807 kS/s

Additional Information

If only one channel is configured for PXIe-63X5, use the Single Channel Maximum Sample Rate from the table above.

For higher sampling rates, consider using a simultaneous sampling DAQ device. These will usually have specified sample rate maximums as S/s/ch.