pH calibration

Questions about the Waspmote board and its modules
scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

pH calibration

Post by scdwhite » Mon Feb 05, 2018 4:04 am

Hello. I calibrated my pH smart water ions probe this evening and was satisfied with the outcome. I transferred to a tub to run over night as a test. However, pH is reporting 15+ and volts is 0.002. I have the reference probe also plugged in along with temperature. Temperature reading is fine. I have rerun both my PCS firmware and my calibration file through the waspmote IDE. Outcome is the same. I am wondering if the pH or reference probe is damaged although there is no reason for that to have happened.

libelium-dev
Posts: 27967
Joined: Mon Sep 28, 2009 1:06 pm

Re: pH calibration

Post by libelium-dev » Mon Feb 05, 2018 8:51 am

Hi,

Could you copy the output through the serial monitor for the example code? Connect the pH sensor to socket A.
http://www.libelium.com/development/was ... r-reading/

Could you share with us some images of your devices? You can use some free service like google drive, dropbox...

Regards

scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

Re: pH calibration

Post by scdwhite » Mon Feb 05, 2018 10:28 am


scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

Re: pH calibration

Post by scdwhite » Mon Feb 05, 2018 11:42 am

I have swapped out sensor housings and appear to have eliminated any kind of cable problem. I have chloride, ammonium and nitrate sensors that I have not calibrated yet. I understand that ph and chloride need the reference probe?

libelium-dev
Posts: 27967
Joined: Mon Sep 28, 2009 1:06 pm

Re: pH calibration

Post by libelium-dev » Tue Feb 06, 2018 8:36 am

Hi,

pH sensor and ion sensors need the reference probe to work. Please try to use the pH sensor and change the holder of the reference probe in order to check if any holder is damaged. Or maybe the above problem was caused because the reference didn't make good contact with the holder.

Regards

scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

Re: pH calibration

Post by scdwhite » Tue Feb 06, 2018 8:49 pm

Yes. I will rerun this, but I have already swapped out the holder for pH and reference with same issue occurring. I have fiddled with the BNC connector several times. I will try a different script as noted in the original response. But as I noted in my original post, I had good numbers and it was only after I prepared the unit for overnight testing did this issue develop.

libelium-dev
Posts: 27967
Joined: Mon Sep 28, 2009 1:06 pm

Re: pH calibration

Post by libelium-dev » Wed Feb 07, 2018 2:58 pm

Lets us know if the problem occurs again.
Regards

scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

Re: pH calibration

Post by scdwhite » Wed Feb 07, 2018 3:35 pm

Here is what I did.

1. Connected USB cable to my computer noticed only a single led flash on the plug&sense.
2. Ran the hello world script. outcome: success
3. Ran the script posted by libelium dev: http://www.libelium.com/development/was ... r-reading/ outcome: all temp, ph and ph volts were -1 or 0 using port A

Restarted the process:
1. Turned off plug&sense. Reboot computer as I noticed that waspmote IDE was running really slow on compile and upload steps (windows 10)
2. Turned on plug&sense and plugged in USB. Several LED flashes this time.
3. Ran the script posted by libelium dev: http://www.libelium.com/development/was ... r-reading/ outcome: all temp, ph and ph volts were -1 or 0 using port A
4. Ran the script that I had modified listed here: https://clemson.box.com/s/xzn61yn80dumi ... vwo0vh994x using port D. outcome: success good ph readings.

Conclusion: No idea why one script worked and the other did not. Both scripts call the same library. They are slightly different in assigning the port from what I can tell.

libelium-dev
Posts: 27967
Joined: Mon Sep 28, 2009 1:06 pm

Re: pH calibration

Post by libelium-dev » Thu Feb 08, 2018 12:53 pm

Hi,

It is a weird issue. As our code use socket A and your code uses socket D, please try to upload your code but modifying it to connect the pH sensor to socket A in order to discard a problem in that socket.

Regards

scdwhite
Posts: 20
Joined: Thu Jan 11, 2018 9:08 pm
Company: ESS

Re: pH calibration

Post by scdwhite » Sun Feb 11, 2018 5:14 pm

I was not able to confirm that it was a socket issue. And I lost my good pH readings altogether and I am back to the orignal problem that I reported on. I am beginning to think that it is a bad reference probe or possibly a bad reference socket E.

I tried to calibrate chloride and ended back to where I began. Low voltage readings and non-sensical readings of -1 mg/l for chloride. I went back to pH and could not get any of the ports to properly report pH from my sample. Typical results are seen below.


Temp: 21.7413024902 Celsius Degrees | pH: 13.2912712097 | volts: 0.6557162284
Temp: 21.6894836425 Celsius Degrees | pH: 13.2649765014 | volts: 0.6626534461
Temp: 21.7244262695 Celsius Degrees | pH: 13.2380237579 | volts: 0.6696543693
Temp: 21.7244262695 Celsius Degrees | pH: 13.2115936279 | volts: 0.6765625000
Temp: 21.7240295410 Celsius Degrees | pH: 13.1854209899 | volts: 0.6834037303
Temp: 21.7585449218 Celsius Degrees | pH: 13.1582355499 | volts: 0.6904668807
Temp: 21.7248840332 Celsius Degrees | pH: 13.1303062438 | volts: 0.6978081703

Removing the reference probe does not have any affect on these readings. Removing pH does alter the readings.

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