How should I connect my AIGND and DGND connections to an external circuit or an ASIC?
My ASIC has a GND connection which is connected to the GND of my external circuit. My ASIC delivers two outputs at e.g. about 3.54 volts and 3.53 volts which I feed into AI0 and AI8 respectively of the NICARD PCI 6031E and I acquire in differential mode which means AI0 - AI8 or 3.54-3.53 volts.
I need to be sure of how to connect AIGND and DGND and my cicuit (or IF I DO NOT need to connect them to my circuit) since I tried various configurations and even recommended resistors and I have different behaviour (DATA, NOISE) for different combinations.
I send you two sketches. I attach them in this email.
One is, of the physical connections and the other is of the software scheme.
Let me know if you need more details please.
At the moment I have AIGND connected to GND but I can easily disconnect that.
I want to know first if my ASIC is a FLOATING or a GROUNDED source?
I also need to know where I should connect what. Where to connect AIGND and DGND?
I need to know for sure because each configuration gives me a different result on my user interface in the PC. So I need to know which connectoins are the correct ones and if I need resistors. But first and most important let us decide, is my ASIC a FLOATING or a GROUNDED source?
Thanks and regards,
Javier Contreras.
