need help with my VI

[sai321]

Hi guys, 

I am trying to read some data from Omega LD 701-1/2 non contact displacement sensor. I am facing a weird problem with this sensor. i have a feeling that it's mostly a software issue but i could be wrong. After certain time like 8-10 min the labview is reading a constant voltage of 10.7v when it should read a maximum of 9v and not beyond it. I am attaching my program here so that some one can take a peek into it and help me with the solution 

Thank you in advance

[RTSLVU]

Have you measured the voltage with a voltmeter to see if it is actually 10.7 volts?

[AnalogKid2DigitalMan]

Are both the AI - and + terminals connected properly to the sensor? Sounds like a dis or mis connected ground.

-AK2DM

[sai321]

yes i connected it to multimeter and i got 9.97v as maximum. when i tried moving the target nearer and farther to the sensor the voltage was changing minimum to maximum. once i connect it to NI9205 it appears to go to 10.7 v and stay there and the graph on my vi shows a flat line. My connections are the brown wire of the sensor is connected to positive terminal of the power source which is at 20V dc and the negative terminal is connected to blue wire of the sensor. The blue wire should be connected to  COM according to Omega so i connected a wire from the blue terminal to the com point on NI9205. Black wire is connected to AI20 on the NI9205. (assumed only one sensor connected to explain my connection )

Am i doing something wrong with the connection ?

[sai321]

yes i measured the voltage using multi meter and it read 9.97V. and when the target is moved nearer and farther the voltage changed from 1 to 9V. According to omega the black wire is output and blue wire is output and brown wire is for excitation. so i connected brown wire to positive terminal of the power source which is at 20v DC and the negative terminal is connected to blue wire of the sensor. This blue wire is connected to com point on NI9205 and the black wire is connected to AI20 of NI9205 module. I am assuming only one sensor connected to describe my connections.

[sai321]

which terminal configuration should i choose for voltage in NiDAQ module ?

[AnalogKid2DigitalMan]

That should work as long as your program is setting the input mode of the DAQ to RSE mode. Also make sure the input ranges is set to +/-10V. 

See page 19 for RSE wiring of the manual:

http://www.ni.com/pdf/manuals/374188f.pdf

-AK2DM

[sai321]

---

@AnalogKid2DigitalMan wrote:

That should work as long as your program is setting the input mode of the DAQ to RSE mode. Also make sure the input ranges is set to +/-10V. 

See page 19 for RSE wiring of the manual:

http://www.ni.com/pdf/manuals/374188f.pdf

-AK2DM

---

ok i used 1v as min and 9V as max as per omega non contact displacement sensor specifications