Problem with analog inputs on sbrio 9627

[Giuliano06]

Hey guys!!

I have a problem in my Single Board RIO 9627.
I am using 4 differential analog inputs (AI0, AI1, AI2 and AI3).
What happens is that when I place a sensor or even a button on one of the inputs and nothing on the other inputs, it affects all other inputs, raising each input voltage levels.
Can anyone tell me how to solve this in the hardware or software?


Thank you!

[Henrik_Volkers · Accepted solution]

Multiplexed inputs need to have a low impedance! Otherwise you have ghosting.

Tie the open inputs to GND (or don't read them 😉 )

If you want to read switches or buttons use a pull up or down resistor.

[rghosh86]

Hi,

I am using sbRIO 9627 for voltage measurement using the on-board 16 bit ADC which have 8 differential channels as input. I am using a total of 8 sensor array for processing the real-time data. We have observed that the readings of the (A0,A1,A2,A3) varies drastically with (A4,A5,A6,A7). Generally in most of the cases the background noise level of one pair of channel is higher than the other. All sensors are subjected to same input conditions. Regards,