U6 to strain gauge connection

10 posts / 0 new

Thu, 03/17/2022 - 03:27

Suriya

Hello everyone, I am planning to use a strain gauge(no particular module chosen) and labjack u6 for my project. But I have no clue to connect these two? Can anyone guide mt through the proesses to be carried out? (Please bear with me as I am very new to this) Thanks in advance!

Thu, 03/17/2022 - 10:46

LabJack Support

We would recommend looking

We would recommend looking for sensors that are in full-bridge configurations (4-wire output). Individual strains would require manual wheatstone bridge circuit completion to measure, such as by using 3 inactive strains to complete a wheatstone bridge circuit, and that would be more difficult to setup. We have some related information in the following app note:

https://labjack.com/support/app-notes/bridge-circuits

The following old forum topic has information about setting up a full-bridge circuit measurement on the U6:

https://forums.labjack.com/index.php?showtopic=4376

Fri, 03/18/2022 - 04:04

Suriya

Now how do I integrate it

Now how do I integrate it with the labjack u6?

Sat, 03/19/2022 - 00:56

Suriya

How do I use a voltage

How do I use a voltage divider circuit with a thermistor and a 100 ohm resistor with the labjack u6? Also I need help regarding the usage of LJ LogUD? Thanks in advance

Mon, 03/21/2022 - 10:45

LabJack Support

Now how do I integrate it

Now how do I integrate it with the labjack u6?

In terms of software, the easiest way to log and graph measurements from the AIN would be to use our LJLogUD software. You would be able to set up the gain/range and differential reading in LJLogUD. The following page has more info on all of the U6 software options:

https://labjack.com/support/u6-software-options

For more info about LJLogUD, I would recommend seeing the following documentation:

https://labjack.com/support/software/applications/ud-series/ljlogud

For the thermistor setup you propose, you would want a circuit similar to Figure 1 on the following page where R2 is the 100Ω resistor and Vin is your excitation:

https://labjack.com/support/app-notes/measuring-resistance

We would recommend using one of our LJTick-Resistance modules instead of a measurement resistor as it integrates a measurement resistor and has a good excitation voltage built in. I would also suggest seeing our temperature sensor application note to explore alternatives to the thermistor:

https://labjack.com/support/app-notes/temperature-sensors

Mon, 03/21/2022 - 22:37

Suriya

How do I access the voltage

How do I access the voltage from the voltage column of the LJ Log UD?

File Attachment:

LjlogUd_Voltage.PNG

Tue, 03/22/2022 - 15:19

soloman

There is a small "Write To

There is a small "Write To File" button under the exit button. This will start saving your data to the current working directory. Also note that your scaling equations section is not set up correctly. Unfortunately, the scaling equations cannot take any arbitrary input. Each scaling equation should be formatted as y=.... The default for row0 is y=a, which is just saying the scaled value (y) should be equal to the raw value (a). The raw value variable is b for row1, c for row2, etc. The following docs have additional information:

https://labjack.com/support/software/applications/ud-series/ljlogud/ljlo...

Wed, 03/23/2022 - 01:01

Suriya

Thanks for the help on how to

Thanks for the help on how to use the LJ LogUD. Now the labjack U6 has am inbuilt InAmp. How do I apply the gains and output the voltage with the gains in the LogUD

Wed, 03/23/2022 - 01:15

Suriya

I am also working on a

I am also working on a project where I need to calculate the voltage drop across the strain gauge. I have attached the circuit in the below image. The resistance of the strain gauge at initial conditions is 115 ohms and along with that, a 1k ohm resistor is used. The input voltage is 5V. The voltage drop I expect is 4.4V but my LJ Log UD shows me the output as attached in the second picture. Can anyone suggest a solution for this?

File Attachment:

Circuit.jpeg

LJLogUD_Output.PNG

Wed, 03/23/2022 - 09:45

#10

LabJack Support

The gain/range settings in

The gain/range settings in LJLogUD are as follows:

LJ_rgBIP10V     // +/- 10V, i.e. Gain=x1
LJ_rgBIP1V      // +/- 1V, i.e. Gain=x10
LJ_rgBIPP1V     // +/- 0.1V, i.e. Gain=x100
LJ_rgBIPP01V    // +/- 0.01V, i.e. Gain=x1000

The issue with your logger reading is that you are using the ±0.01V range setting, and the reading cannot exceed the maximum of ~0.01V. You should use the ±10V range setting for your test.