pH sensor measurement

[henry ho]

Hi, Im doing a pH signal conditioning circuit and now Im done with the hardware part. So now im having a problem in Labview. Can anyone help me in this?

In my program I need a section that allow user to calibrate the pH measured and a display of the pH reading in graph and record it down.

and by the way, how am i gonna connect my hardware to the DAQ card on my computer? As my hardware only got 2 pins - output and ground, and my DAQ card using a DB 37 pins.

any suggestions will be greatly appreciated! 

Thanks!

Henry 

[KateB]

1. What is DAQ card model you use?
2. Probably write a program that allow user to write down a pH value at that reading voltage, and log calibrated value to a file. Then, at the beginning pf program, read this calibrated value and keep it in array. Then, use interpolate 1D.vi to change voltage reading into pH.
3. There's example shown how to read analog voltage, and record reading shown in Help>>Find Examples>>Hardware Input and Output>>DAQmx>>Analog Measurements>>Voltage>>TDMS Streaming - Cont Log and Read.vi.
If you lag of LabVIEW skill, I'd recommend run through these tutorials before continuing your project: http://zone.ni.com/devzone/cda/tut/p/id/5247

[henry ho]

1. Im using ADLINK PCI-9221 DAQ card.

2. Im not sure about the explanation you gave because Im still new to labview. Can you show me any examples on the program of calibration?

[KateB]

1. Since I don't have any Adlink experience, I'd recommend you to call Adlink for support, but for the recording part, you can refer to Help>>Find Examples>>Fundamentals>>File Input and Output>>Write to Text File.vi.
2. You must write a calibration program to acquire a pH data, and have a control to let user manually fill in pH value. Then, have a button to write a pH value and voltage to a file. This is to record a relation between pH and voltage. In actual program, you must first read calibrate data from a file, and put it to Interpolate 1D.vi in order to translate voltage into pH.

[henry ho]

1. I have attached the pin assignment for PCI-9221 does they function as the same like NI DAQ? 2. Lets say if i measured a pH buffer of 4, but the reading is 4.3. How i gonna write a program to tell the labview that i want a pH of 4 and show 4? 3. What is Interpolate 1D.vi?

[henry ho]

http://www.adlinktech.com/PD/marketing/Datasheet/PCI-9221/PCI-9221_Datasheet_9.pdf