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Analog Signal Noise

Hello all,


I'm trying to output an analog signal in the form of a voltage from my DAQ card to a temperature controller as shown in the attached figure. However there's an error in my signal as I'm not reading the correct temperatures on my temperature controller. There is a lot of noise in the signal. Another possible reason seems to be the presence of a ground loop. I'm using output in a Differential mode. Is my wiring incorrect as shown in the Figure? Only one end is grounded into the temperature controller. 


Any possible suggestions?


I'm new to Data acquisition, so you'll have to guide me through it. 

All help greatly appreciated,



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Hi Ronak,

       I've taken a look at the document you posted and I'm curious- what DAQ card are you using (the SCB-68 is a connector block that should connect to a DAQ card in your computer)? This article has a section on eliminating thermocouple noise.  Additionally, there is this field wiring guide:  Table one gives recommendation for how to connect different types of measurements properly. It doesn't look like your wiring is wrong, but that could vary depending on which DAQ card you have.  Finally, I think you would have better luck on the Multifunction DAQ forum (this specific forum is for our switch hardware and software products).  Thanks!


Applications Engineer
National Instruments

Digital Multimeters
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