Connect String Pots and Linear Pots to NI 9216

[askhassan]

I meant by the power supply an external power other than the power for the DAQ and the modules connected to it. Do I understand correctly?

[GerdW]

Yes.

[askhassan]

So If I am not using a power supply, the potentiometers will be floating, so to have it in differential mode the 1 terminal on the potentiometer will go to AI- and the 2 (outpout signal) will go to AI+  what about the 3 terminal for each potentiometer ? also considering that there will be 10 potentiometers connected to the NI 9205, is that going to be enough power for all of them 

[cbutcher]

---

@askhassan wrote:

So If I am not using a power supply, the potentiometers will be floating, so to have it in differential mode the 1 terminal on the potentiometer will go to AI- and the 2 (outpout signal) will go to AI+  what about the 3 terminal for each potentiometer ? also considering that there will be 10 potentiometers connected to the NI 9205, is that going to be enough power for all of them 

---

If you are not using a power supply (of any kind, e.g. power supply unit, battery pack, hamster wheel with dynamo) then you won't have anything to measure.

[askhassan]

I mean just the power supply from the grounded Module NI 9205

[cbutcher]

The NI 9205 doesn't have a power supply. It has a single digital output (that won't supply anything like the power you presumably want) and then a large number of analog inputs.

You haven't mentioned anything that will provide a current to your potentiometers.

[askhassan]

Ok I see, I thought since the module is connected to the cDAQ that will supply voltage excitation. So if I have an external power supply, how would be the connections for a differential mode for the 10 pot?

Sorry its my first time to deal with all of this.

Thanks for your help 

[cbutcher]

---

@cbutcher wrote:

Well, for a potentiometer you have 3 pins - two end pins and a middle pin (on a schematic, physical layout could be whatever).

The end pins (1 and 3 on the 9600, 1 and 2 on the SP1) should be connected to your ground and a suitable voltage source (e.g. 5V). The middle pin (2 for 9600, 3 (blue) for SP1) is the one that will vary according to position/extension. You connect this to your AI+ pin on the 9205.

You can connect your grounds to AI Sense (NRSE), AI GND (RSE) or AI- ((pseudo-)Differential) depending on the wiring configuration you choose for the 9205.

Note that unless you externally are grounding your potentiometers, they are "floating" sources for the purpose of the diagram on the link I previously gave. The power supply can be a way for these to become grounded - take care to ensure that the source voltage (e.g. 5V above) is sharing a ground with your 9205.

---

Hopefully this helps more now.

[askhassan]

Thank you it really helps. I have one more question, so all the string pots will share the + and - terminals of the power supply and each one will have separate AI+ for their input wire in the pinout. For the ground each wire will go to AI- for the differential mode ? I just need to figure out how they would all work together (10 of them)

Thanks again !

[RavensFan]

Exacty!  (negative of the power supply and the pots will also go to common of the DAQ card)