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What Is the Maximum Throughput On My USB cDAQ Device?

Updated Feb 27, 2019

Reported In

Hardware

  • CompactDAQ Chassis

Issue Details

How can I calculate the maximum throughput, or data transfer rate, of my cDAQ device?

Solution

The maximum amount of throughput, or data transfer, for a particular cDAQ device is system and device dependent. Below is a summary of the different types of USB cDAQ form factors and how to calculate the maximum throughput for your device.

USB cDAQ Devices

The NI X Series DAQ devices and cDAQ devices with a USB 2.0 bus can sustain a throughput of 32 MB/s, while the cDAQ devices with a USB 3.0 bus can sustain data transfer rates of 250 MB/s.

In order to determine whether or not a device can handle the throughput of a given application, you will need to calculate the amount of data that will be streamed across the bus during that application. An example for calculating the data transfer rate of a device is shown below.

Example: suppose you have a 14-slot cDAQ-9179 (USB 3.0) and want to determine whether or not it can sustain the throughput of running 14 NI-9234 modules, acquiring at the maximum sampling rate (51.2 KS/s), across all 4 channels of every device. You could calculate the total data that will be streamed across the 9179's USB bus using the equation below:
Because the total rate of data transfer during this application (8.6 MB/s) does not exceed the maximum throughput of the 9179's USB 3.0 bus (250 MB/s), there should not be bandwidth issues acquiring data at these rates on this device.