usb 6009 measurements resistence

[cassio]

Using the DAQ 6009 to measure various resistances of resistors?

[jyang72211 · Accepted solution]

Sure.  You just need to know what you are doing.  Also, it depends on what accuracy you are looking for.

[cassio]

The accuracy may be around 10%. What do I know if is possible and if you have a VI to measure resistance using the 4-wire and using the DAQ 6009.
Thank you very much

[jyang72211]

Hi, 

You can do the following:

Circuit connection:

Analog out -> precision shunt resistor (1ohm) -> resistor of interest -> analog out's gnd

You will then put a analog in accross the shunt resistor and another analog in across your resistor of interest. 

From the voltage across the shunt and the known resistance (1ohm), you can calculate the current across the resistor of interest (circuit in series).  With the calculated current and the voltage measured across the resistor of interest, you can calculate resistance with ohm's law.

Watch out for the following:

1. Since there is a max current rating on your analog out, you can't measure resistance with low value.  If low resistance measurement is desired, you can subsitute the analog out with a power supply.

2. Make sure the shunt resistor is rated high enough in power for your application, or it will be fried. 

See link below for more info. 

http://www.allaboutcircuits.com/vol_1/chpt_8/9.html

[cassio]

Hello, I wonder if using an external power supply (model MPS - Minipa of 3003) in parallel with one of the inputs of the DAQ 6009 and also a resistor whose resistance is known. Do you measure other resistances? And the other channels?. What I want to do is measure voltage and current of several resistors placed in all analog inputs, save the values of voltage and current and save a file. Then take each set of values to apply Ohm's Law (V / I) and save the file again and plot graphs. Thanks

[jyang72211]

Not really clear about what you want.  Can you draw a picture?

Yik

[cassio]

I have to develop a tool to get these following functions:

- Use the device as voltímeter;

- Use the device as ammeter;

- (VI) read the current and a file note;

- (VI) read voltage and write a file;

- Divide the values of voltage by the current to find the resistance;

- Build graph of resistance versus time and current;

- I wonder if you can do this with device USB 6009.

Tanks 

[cassio]

Want to use the USB device 6009 as well as a voltmeter and ammeter. This device has 8 analog inputs. So will I use some input as voltimetro and others as ammeter? Thanks

[Dennis_Knutson]

The 6009 is not capable of measuring current. You calculate the current by taking a voltage reading across the known resistor. The 6009 can make a differential voltage reading so use this mode across the known resistor.

Message Edited by Dennis Knutson on 03-01-2010 08:11 PM

[cassio]

Now I understand. Thank you for the information