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Digital/Analog GND in combination with PCB

Hi all,

 

For a project I am using an external power supply for powering 16 sensors, either digital or analog.

This power supply is able to supply a voltage of 5V and 12V, and both have a seperate ground (dont ask me why they have 2 grounds, but here is the external power supply: https://nl.rs-online.com/web/p/embedded-switch-mode-power-supplies-smps/7066195/ ).

 

I am making a connector board PCB to power all sensors (mostly 5V) in a parallel circuit. The sensor signal from this board go to a NI-USB 6211 DAQ card. 

 

Note: the ground lines are on the bottom of the PCB and therefore not visibleNote: the ground lines are on the bottom of the PCB and therefore not visible

 

My questions: 

- How should I connect the ground of the DAQ card to the PCB?

- Do I need to do this for all AIGND/AOGND/DIGND/DOGND, or is one enough?

- Because there is one sensor that needs a 12V supply, do i need to connect the DAQ to a different GND for this one?

 

Thanks in advance!

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Hello Bryan_1995,

 

The connection depends on sensors specifications but try to separate digital sensors "D_GND" and analogue ones "A_GND" so connect them with appropriate terminal of DAQ.

 

I recommend you to check if the output and GNDs of the power supply are isolated or not. I haven't find info on the seller web page you shared but you can connect with the manufacturer to check the info.

 

Additionally, I recommend you to put low pass filters in power lines of sensors as digital ones may produce noise and effect on analogue sensor's readings.

 

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