How to take Diffential measurement using labjack u6? i am using Labview 2011. any one got examples for NRSE, RSE AND DIFFERENTIAL Measurements? or any detail information to understand how take these measurements?
I read two voltages, i need to take one signal to see the response of my system.
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Differential channels from AIN0 to AIN13 are arranged in even/odd pairs, so if your positive channel is AIN0 the negative channel is AIN1. Do a reading from AIN0 where you set the negative channel to AIN1, rather than 199 which means single-ended:
https://labjack.com/support/datasheets/u6/hardware-description/ain/chann...
In software you want to use the iotype LJ_ioGET_AIN_DIFF not LJ_ioGET_AIN, or use the easy function eAIN which has an input to specify the negative channel:
https://labjack.com/support/datasheets/u6/high-level-driver/example-pseu...
https://labjack.com/support/datasheets/u6/high-level-driver/example-pseu...
Make sure your differential connections are valid. A common mistake it to connect totally floating signals that are not referred to the U6
https://labjack.com/support/app-notes/differential-analog-inputs
Thanks for the response.
I got three wires coming out of my device, one positive voltage (black color), second differential (brown color) and green ground.
i connected black one to AIN0 and brown one to AIN1 and green one to ground. so can you confirm me
which wave form give me NRSE , RSE AND DIFFERENTIAL MEASUREMENTS.
I AM USING EAIN function to read the signal
So the 3 wires coming from your devices are signal+, signal-, and ground? Where does your device get power?
To initially figure out if your signal is connected properly and measuring properly, I suggest you start with the Test panel in LJControlPanel. Confirm the analog input channel is reading as expected.
As for your program, eAIN is the easiest way to read a sample from a channel so that is a good way to go.
yes it is analog output from a dectector rs 232 +signal, -signal and a ground.power sources for labjack and detector are isolated.
Referenced Single ended measurement
ain0 +signal channel in 0
ain1 -signal channelin 199
grnd to ground in lj
take reading from ain0
differential measurement
ai0 +signal channel in 0
ain1 -signal channel in 1
grnd to grnd in lj
take response from ain 1
Is it right if am.
I'm not following exactly what you are saying. Without seeing a datasheet for the sensor we are guessing, but I would say the safest way to connect it without knowing details is:
Signal+ to U6-AIN0
Signal- to U6-AIN1
100k resistor from U6-AIN1 to U6-GND
You would then take a differential reading of AIN0 (Ch+=0, Ch-=1).
If the device is isolated from the LabJack, as you mentioned, then you should be able to just connect as follows:
Signal+ to U6-AIN0
Signal- to U6-GND
Then take a single ended reading of AIN0 (Ch+=0, Ch-=199).
yeah i got it now !! thank you
i connected
+ve to 2 and
-ve to 3
gnd wire to gnd on board
to take single ended reading
using eain() function in labview
Channel IP is set 2
Channel IN Is 199
for differential reading
Channel IP is set to 2
channel IN is set to 3
let me know if am wrong!!
Yes, that all sounds reasonable based on the information at hand.