NI 9207 connection problem

[pizzanews]

Hello, guys.

I meet some awful troubles about connection on NI 9207.

First of all, I tried using oxygen sensor for my study. But i even don't know how can i connect which line to which port of NI 9207.

Posted picture No.1 is sensor's specification. It is showing "Output at 0% O₂" telling 0.3±0.2mV and "Sensitivity" telling 12-13mV in 21% O₂.

I understand that sensor will show analog output voltage. So i setted DAQmx like signal read →  Analog read → Voltage → and select channel.

Then made VI (No.3 picture) and connected sensor line to NI 9207 port. 

But problem occured.

Problem 1) Although i tested well ventilated room, sensor's mV value too low like 1.9 mV.

                  It is totally different with sensor's specification.

Problem 2)When i touched sensor's body, mV was up to 5 mV.

So i though i have connecting problem.

No.2 picture is sensor's wire color.

Red wire is high side of differential channel. i connected that line to AI0+ port of NI 9207.

Black wire is low side of differential channel. i connected that line to AI0- port.

Green wire is 12V port and white is ground. So i connected that line with 12v supply machine.

But problem is now... 

I don't know what port to connected with clear wire which is analog ground(shield wire).

I never met this line before. I don't know clearly that line.

So i connected that line to COM port of NI 9207.

And this sensor has thermocouple for reference.

So i connected thermocouple's yellow line to AI2+ and red one is connected AI2-.

I though the reason oxygen sensor not work well is because of line connecting problem.

So i wonder

1) which color line have to connect with which NI 9207's line.

2) What is clear line;analog ground(shield wire).

3) Should i connect this green, clear, and white line?

4) In this sensor, there are two anaolg read line one is sensor read and other is thermocouple. Then, should i made 2 DAQmx in same VI? Actually, i dont need to read temperature. Maybe, if im right, that thermocouple is for reference of Oxygen concentration.

5) What should i do for work well next...?

I know this type of question is really hard to understand and i have to post this question to sensor company's website Q&A. But i have no time to wait there answer and I experienced having really helpful solves. So i posted it.

Please help me out guys.

*Picture

No1: Sensor spec

No2: Sensor wire color spec

No3: My VI

No4: NI 9207 port.

[GerdW]

Hi pizza,

- you might use COM for analog ground wire as is described in the 9207 manual…

- to check your NI9207 module and your VI you can replace the sensor signal by a simple AA battery giving you a ~1.5V signal (or ~1.2V for a NiMH accumulator). This way you can make sure your DAQ setup is working and maybe the sensor has a problem…

[AnalogKid2DigitalMan]

One item I noted on your BD- you have the min/max range set to -/+10V.

For this millivolt signal you need to decrease those to a smaller appropriate range (depends on what the 9207 supports).

Doing so will increase your resolution.

-AK2DM

[pizzanews]

Thank you for reply.

I use COM port for analog ground. But im confused, cause i heard that COM port is used for Digital input ground. Could i use COM line for analog input ground? Although already i have negative line with black colored wire.

[GerdW]

Hi pizza,

---

@pizzanews wrote:

I use COM port for analog ground. But im confused, cause i heard that COM port is used for Digital input ground. Could i use COM line for analog input ground?

---

Where did you hear that?

And why don't you trust the datasheet you got from NI for your module? It explains the usage of the COM pins, even with schematics…