reference voltage from GRND and DAC0
Posted 02 April 2013 - 11:00 PM
Posted 03 April 2013 - 08:24 AM
I am having trouble clearly understanding your post. To help I suggest you make a wiring diagram of your setup. One great way to share a wiring diagram is using Google Drawings:
Make a drawing and then post the link to the drawing here.
Posted 03 April 2013 - 08:55 PM
Posted 03 April 2013 - 09:40 PM
Are you having problems with this? Or just checking if it is OK?
The only risk in your setup is if the U3 ground is connected to earth ground (through the laptop), and the battery is also connected to earth ground. That would mean have a big ground loop, which could cause problems. In other words, you want the connection from U3 GND to Controller B- to be the only ground connection. If there is another ground connection somehow through the USB then you have a loop.
If you want to be safe and make sure you don't have such a ground loop, add a USB isolator such as the following:
Posted 03 April 2013 - 10:11 PM
Posted 04 April 2013 - 12:22 PM
But I thought you did have a common ground? Your diagram shows U3 GND connected to Controller B-. Is B- the common reference for PIN 2?
scenario explained in test 2 may be because the controller and labjack is not having a common ground line.
The ground loop described happens back through the USB connection. If you have an isolator inline, that breaks that ground connection.
using a USB Isolator (as mentioned earlier) how will it ensure that the ground loop is stopped?
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