pH SubSystem failure

[mcarleton]

I keep running into problems with the pH probe:

ph subsystem: Failed read probe:pHError:write /dev/i2c-1: remote I/O error

I can't get any reading with or without a probe connected, it's happened on two different boards now both after about 3 days of operation.  Are there any troubleshooting steps I can go through or anything I need to verify?  I also tried a different probe but I don't think the probe is even visible to the controller.  I thought maybe I damaged the connector on the last one but this time that really doesn't seem to be the case.

[Rob F]

Sorry to hear about the issues, can you try running the following command in Raspberry Pi terminal window.

i2cdetect -y 1

You should get 40, 70 and 63 show up in a list, 63 is the pH circuit.

[mcarleton]

Sorry to hear about the issues, can you try running the following command in Raspberry Pi terminal window.

i2cdetect -y 1

You should get 40, 70 and 63 show up in a list, 63 is the pH circuit.

I get 20, 40 & 70

   0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --

[Rob F]

Interesting, it looks like it's address is 20, 32 in reef-pi. If you go to the pH driver and change address to 32 it should start working. Remember to go to "admin" tab and press the "reload" button after changing the address.

I'm not sure why the address changed, just to be sure nothing else did run the following commands in the Pi terminal.

This downloads a python script
sudo wget -c https://robo-tank.ca/Robo-Tank_pH_Script.zip

This unzips the file
sudo unzip Robo-Tank_pH_Script.zip

This runs the script
python Robo-Tank_pH_Script.py

After the last command it’ll say Enter Command: Then type in the following, must be capital letters.

ADDRESS,32

It should then print out "I2C address set to 32".

Now type in the following, it must be a capital letter.

R

It should now print out a pH value, if it does you’re connected to the circuit.

Now type in the following command, must be a capital letter. This restores the defaults on the pH circuit and disables the calibration.

D

It’ll say query failed but it will have worked.

Now you can power down the controller and power back up.

Go back to reef-pi pH driver and change address back to 99 if you changed to 32.

[mcarleton]

Perfect, that worked on both boards and restored readings from the pH sensor.  Rob you're a gentleman and a scholar!

[Rob F]

Great, good job.

[boinzemwende]

Hallo Guys,

ich have also the same problem with my ph-Sensor.I follow the issue to solve that ,but it is still beeing the same problem.
Maybe,can somebody Help me?Thank you all.

Elisee

[Rob F]

Hi Elisee, I got your email, based on the picture you sent it looks like it was a typo for ADDRESS,17. Let me know how it goes.

[MarzioM]

Ciao Rob, I am facing the same problem, no reading from the PH probe.
Following your instructions I downloaded and unpacked the script, but running the command "i2cdetect -y 1" does not detect any peripheral corresponding to the PH card.
I checked that i2C is enabled on the Rasp, and it is active.
Do you have any other tests to suggest me?

Thanks

Marzio

   

[Rob F]

Hi Marzio, sorry for the trouble, this was definitely a problem. Looking at dates I think you're board will have a pad to reset the circuit, could you try that and see if it starts working again?

While the controller is powered short out the pad in picture and the LED that will blink 3 times after it resets. Once the LED flashes unplug power from controller and power back up.



If you don't have that pad here's an image showing two points to short out so this does same thing.

[MarzioM]

Thanks Rob, tomorrow after dinner I’ll apply your suggestion and report back the results. BR

[Rob F]

Thanks Rob, tomorrow after dinner I’ll apply your suggestion and report back the results. BR

Sounds good. I should have been a little clearer, when you short out those pads it'll take 3-6 seconds for that LED to flash, it can feel like a long time but it will happen.

[MarzioM]

Thanks Rob, tomorrow after dinner I’ll apply your suggestion and report back the results. BR

Sounds good. I should have been a little clearer, when you short out those pads it'll take 3-6 seconds for that LED to flash, it can feel like a long time but it will happen.

Rob, I was too eager to try it, I did it before starting my workday.
Problem solved, the address was resetted to 63, now PH sensor is working perfectly.
You are a Guru, thanks a lot for your suggestion.
Ciao

[Rob F]

Rob, I was too eager to try it, I did it before starting my workday.
Problem solved, the address was resetted to 63, now PH sensor is working perfectly.
You are a Guru, thanks a lot for your suggestion.
Ciao

That's great, I'm glad it worked.