Signal Noise When Using the USB-6001 with Differential Wiring

Updated May 3, 2018

Reported In

Hardware

  • USB-6001

Software

  • Measurement & Automation Explorer (MAX)

Driver

  • NI-DAQmx

Issue Details

I have a two sensors connected to my USB-6001. I am connecting my sensors in a differential configuration to the corresponding positive and negative terminals. I am getting a high amount of noise on my signal around the expected values as seen in NI MAX.

Solution

When getting noise on your signal, there are many issues that can come into play.
  • Make sure that the sensors are wired correctly to the device.
  • When wiring in the differential configuration, it is important to have a bias resistor connecting your sensor to the AI-GND. This will allow your sensor to know what is the reference to the ground. 
  • Additionally, you can wire one of the sensors in RSE configuration to remove the noise. This will allow the other sensor in differential configuration to reference the ground.

Additional Information

In the USB-6001 all the Analog Inputs shared a common source ground. Therefore grounding one sensor will allow the other sensors to reference that ground. 

Please see the Field Wiring and Noise Considerations for Analog Signals document to better understand the different configuration methods and how to best minimize noise with your system.

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