ORP question or a problem..

[Armetas]

Hi,

I have some problems with my ORP module. I calibrated it as it was mentioned in instructions, and seems that everything went well, but after few hours orp started showing 550 mv constantly (previously it was in range of 320-350 mv). Tried to re-calibrate, but nothing helped. Noticed that after disconnecting probe it keeps showing 550 mv. When I put BNC terminator on it show 29 mv. Need help with this issue...

[rimai]

What are the numbers you got when doing the calibration?

[Armetas]

What are the numbers you got when doing the calibration?

What i've done is:

Started calibration (0 mv) - attached BNC connector, press OK
Then connected ORP probe with given fluid (470 mv) and pressed OK
Then added probe into aquarium, into probe holder near PH probe.

After that ORP showed ~320-350 in tank.

Yesterday somehow I managed to keep it working, it showed ~360 mv, but from that moment it keep rising, and now it is 450 mv and it is going up...

[rimai]

The module does not come with the calibration fluid.
The probe comes in a storage solution that is only good for storage during transportation.
You should find the solution online or in your local store.

[Armetas]

The module does not come with the calibration fluid.
The probe comes in a storage solution that is only good for storage during transportation.
You should find the solution online or in your local store.

Well allright... But even if the probe is not calibrated - it should show some values, not 550 mv...

[rimai]

550mV is the max range.
If you calibrated with that fluid, which has about 200mV and you place it in your tank which has about 350mV, you would go above scale.

[Armetas]

550mV is the max range.
If you calibrated with that fluid, which has about 200mV and you place it in your tank which has about 350mV, you would go above scale.

Oh, heres the point...ok, i'll try to find solution for 470 mv to calibrate the probe

[Armetas]

It would be nice to get calibrating solutions with expansions or RA, because now I need to wait till I get such calibrating solutions. Its not so easy to get them...

[Armetas]

Ok, about 550 mv is it clear that it is because of calibration. Another question is why ORP probe shows only 0 mv...

[rimai]

If you don't get it calibrated properly, you will go out of bounds and get unpredictable results.
Try adding this to the setup() section of your code:

Code: Select all

    InternalMemory.ORPMax_write(285);
    InternalMemory.ORPMin_write(1400);    

This will force default calibration numbers, instead of using whatever numbers you got, which most likely are wrong numbers.

[Armetas]

Ok, now I've tried everything, and I can say that there is a problem...

1) i've tried adding code that you suggested. It worked only for couple of hours. After that ORP keeps showing 0 mv
2) I've bought expensive Hanna 470 mv solution. Calibrated: as 0 mv it showed numbers 1866, and for 470 mv it showed 188. So for 3-4 hours it was ok, but in the morning I've checked ORP and it is 0 mv again...

I don't know what to do now... Maybe the probe is faulty?

[rimai]

The numbers you got look correct.
When it shows 0mV, what happens when you reboot RA?

[Armetas]

The numbers you got look correct.
When it shows 0mV, what happens when you reboot RA?

After reboot it shows the same 0 mv. On controller it sometimes looks that it shows 0.9 or 0.5 (but the last number is cut off)

[rimai]

Use the joystick and go into calibration mode.
What number do you see?
Make sure to choose cancel when you are done. Don't click ok.

[Armetas]

I see 0 mv and number - 0

[rimai]

Can you check you cables and power supply to the module?

[Armetas]

ORP Extension is connected to expansion hub (all lights are green in ORP extension) tried to change cable from ORP extension to expansion hub - didn't helped.

[rimai]

What if you connect the ORP module directly into the relay box?

[Armetas]

Ok, tried it. Same result. 0 mv. Connected directly to relay box (main). Also tried to other expansion hub slots. Nothing...

[rimai]

Can you please go into calibration, connect the terminator and check which values you get?
I want to work with raw values instead of calibrated values, just because there may be a problem with the calibration numbers.

[Armetas]

Getting: 0 mv and 1875 numbers

[rimai]

Ok, 1875 is good...
So, we know for sure that the module is working and responding with correct numbers.
Can you connect the ORP probe and do the same thing and read what numbers you get one more time just to ease my mind?

[Armetas]

Getting: 0 mv and 0 number

[rimai]

Ok, so can you do the same thing, but using the pH probe now?

[Armetas]

It started to show:
0mv and numbers 100
and keep on going till 1950

[rimai]

Awesome, that's good because the pH probes give negative mV readings for alkaline water.
Connect the ORP probe back.
Now, what numbers do you get if you place the probe in a cup with tank water?
And what number do you get if you place the probe in a cup with tap water from the faucet?

[Armetas]

In cup with tank water: 0 mv and 0 number
In cup with tap water from the faucet: 0 mv and 0 number

[Armetas]

I don't know what happened. Didn't do anything but suddenly it started to show some ORP values... When calibrating getting:

0 mv and 619 numbers

Same was and other days...After the night it showed again 0

[rimai]

Could it be any bad connection somewhere??

[Armetas]

Could it be any bad connection somewhere??

I don't think so, as everything is connected without tension. And nothing was done or even touched and it started showing something