I have a setup where only AIN0 is receiving an accelerometer input. It also has a 10.5 MOhm from AIN0 to GND.
The AIN1..AIN3 inputs have a 10.5MOhm to ground also.
However when I tap the accelerometer, the AIN0 shows a response, but the other AINputs are also mirroring the AIN0 input to some degree.
The attached images show the LJStreamM diagram, and also my T7 setup.
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.png%3Fitok=Ybt-OlgU "LabJack + JEDI One Can Create a Powerful Distributed DAQ Ecosystem")
Also as can be seen in the diagram, the AIN1 to AIN3 inputs have a voltage offset, even though they have a resistor to ground.
Floating channels will often be affected by whatever channel was sampled previously:
https://labjack.com/support/app-notes/floatingunconnected-inputs
In your case you might think that AIN1-AIN3 are not floating because you have a 10M holding them to GND, but 10M is a very high source impedance and not guaranteed to hold AIN1 to 0.0V to within the accuracy specs of the T7. 1k works under all conditions, but the max value guaranteed to work for various conditions can be determined from Table 2 here:
https://labjack.com/support/app-notes/SettlingTime
For example, if using Gain=1 (+/-10V range), ResolutionIndex=1 and a 1M resistor, you would need to manually specify a settling time of 5000us to meet accuracy specs.
Thanks. The hardware guy told me that the output impedance of the accelerometer is 100 Ohm, but it is AC Coupled output. So he said that an extra resistor isn't needed here!
The specific parts we're using is the ACC-103:
http://www.omega.com/Manuals/manualpdf/M1607.pdf
And we're powering the signal with the ACC-PS2:
http://www.omega.com/pressure/pdf/ACC-PS1_ACC-PS2.pdf
The problem is the 10.5 MΩ resistors on AIN1, 2, and 3. The resistance is so large that the line is effectively floating. Try switching those resistors to 1 kΩ.