resistance measurement

[ache]

Hi,

sorry i forgot to write that the unknown value is about an external shunt resistance.

Only one last Question until i understood it completely:

Is it true that there is no current "through" the AI channel, but only over the shunt resistance?

That is namely what i measured.

Thank you very much!

yours sincerely,

Michael

[JGoebel]

Hi Michael,

exactly, for this device the AI only measures Voltage, so a current measurement is basically a Voltage measurement over a resistor (shunt).

Some devices also offer internal Shunts, here the current would flow into the device, but internally the process would be the same.

Wish you all the best with the measurement!!

Cheers,
Jan Göbel

[ache]

Hello,

thank you very much for all your fast answers!

yours sincerely,

Michael

[ache]

Hi,

i have another question.

I want to map to this resistance value some temperature values.

The resistance is namely a Thermistor with a nonlinear characteristic.(I only have a table with resistance values and the belonging temperatures) 

How can i realize this in Veristand?

Best wishes,

Michael

[JGoebel]

Hi Michael,

first of all, if you think we will share more messages on this topic, please create a new thread and post a link here so that people looking for topics can find it more easily.

Basically a scaling with a table can be done in several ways:
1. Use a Scale for a channel:
Rightclick "Scales" in the System Configuration and select Add Scale -> LookupTable

Then click your Hardwarechannel (e.g. "AI0") in the Hardware-Section and in the top toolbar there is a Scale-Button to apply the Scale to the channel.
2. Use a Hardware Calibration
In the Project Window select Tools->Workspace Tools->Channel Calibration

You can add a Calibration/Scaling directly to hardwarechannels here
3. If you have more complex scaling requirements you can also use a custom model to scale your signal. You can use LabVIEW to create simple Models or build it in Simulink

Propably Approach#1 is the most suitable for you.

Cheers,
Jan Göbel

[ache]

https://forums.ni.com/t5/PXI/Lookup-table-using-VeriStand/td-p/3934938