NI USB-6008 negative voltage

[Ajtimstoj]

Hi, i newbie in LV and NI, i have some problem to read voltage from my NI 6008. 

I connect to AI GND and AI0 the KT1501 sensor (image) in my test.VI the voltage is -1.416 if i push the sensor the number go to -1.26 .

The sensor and wire are good because one of test program work greet (the test program from other company -Executable program)

Is there something wrong I am doing in terms of reading in the values?

Thanks!
 

[Larry.C]

Hi Ajtimstoj,

What you should try and do is work with one of LabVIEW's excellent examples in-built into LV. A particularly good one for your application would be found by going to Help >> Find Examples:

In the browse tab look for:

Hardware Input and Output >> Daqmx >> Analog Measurements >> Voltage >> Cont Acq&Graph Voltage-Int Clk.vi

Hope this helps with your project.

Kind Regards,

[Rod42]

Or download NI's example front panel for USB 600x at http://zone.ni.com/devzone/cda/tut/p/id/9541

Rod.

[Ajtimstoj]

I test it but the voltage start at -1.4.. I do not know where the problem was. 

[shjukheter]

Hello,

          You need understand something here about 6008 pin configuration. The Ai0+ and Ai0- is meant for differential input signal. Now, you told that you connected one wire to GND and Another to Ai0+ which means that 6008 will take it as single ended input. So, what voltage you are expecting from sensor? Is sensor output is differential or single ended?

If it is single ended means, now your setup is correct!

[Ajtimstoj]

Sensor output is single ended, and what is RSE? Because in THIS Vi program i see diferrent menu AI-RSE and AI-Diferencial. 

[shjukheter]

First you try to play with "DAQ Assistance" and then once you got what exactly you are looking for. Than convert the program with using DAQmx VI.

 So, When you use the DAQ assistance, it will provide an option "Let the NI-DAQ choose". Select that and try a bit. By the way what sensor your are using and any manuval for that sensor.

See this video for more information about DAQ with DAQ Assistant.

http://www.youtube.com/watch?v=72157fx31vw

[shjukheter]

Differential means you need to connect the coming sensor output two wires to two of the channels Aio+ and Ai0-. If you want to ground the 6008 means you can use system ground. My guess is, try without GND terminal. Connect your two coming sensor leads to two inputs of the channel.

[Ajtimstoj]

This is my sensor 

[shjukheter]

AS I said before, the sensor output coming from sensor is seemed to be differential(signal+ and signal- in your datasheet). So, connect those two pins to + and - channels of 6008 and try again. I can only guide you to the right path. I can't solve your task for you. So, you need try a bit.