Turning an S8 ABC off

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JarredAwesome
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Turning an S8 ABC off

#1 Post by JarredAwesome » 23 Nov 2020, 17:08

Hey everyone,

I just bought my S8, and am eagerly awaiting it’s arrival.

I have found that there are not a lot of good python Libraries for it.

I want to turn off it’s ABC because it’s going in a very high co2 environment.

I found one library that has a command just called ‘s8_abc’. It doesn’t say if it’s to turn it on, off, set a baseline... anything.

The code it sends to the sensor is: \xfe\x03\x00\x1f\x00\x01\xa1\xc3

Anyone know what this is for?

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grovkillen
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Re: Turning an S8 ABC off

#2 Post by grovkillen » 23 Nov 2020, 20:13

We're not officially allowing for turning it off. But it's easy to do in the official application from SenseAir. https://senseair.com/media/2001/uip5_0_0_3_40_setup.exe

The reason is that it have done more harm than good when it's too easy to do. But if you know why you're turning it off then the extra step to do it with their UIP5 shouldn't be too much.
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JarredAwesome
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Re: Turning an S8 ABC off

#3 Post by JarredAwesome » 23 Nov 2020, 20:27

My sensor will be sitting in an environment that is constantly over 5000 ppm. So I feel the abc won’t be a good thing to have on.

I only have a Mac, is there a Linux or max port for that?

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Re: Turning an S8 ABC off

#4 Post by JarredAwesome » 24 Nov 2020, 16:36

Will powering down the sensor once a day prevent it from auto calibrating?

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Re: Turning an S8 ABC off

#5 Post by TD-er » 24 Nov 2020, 16:37

I don't know, but the 1 day interval is not the default interval of the S8.
That's the interval for the MH-Z19 sensors.

JarredAwesome
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Re: Turning an S8 ABC off

#6 Post by JarredAwesome » 24 Nov 2020, 17:17

TD-er wrote: 24 Nov 2020, 16:37 I don't know, but the 1 day interval is not the default interval of the S8.
That's the interval for the MH-Z19 sensors.
The S8 abc period is 15 days. So I guess my real question is:
If I interrupt the power within the time, will it prevent it from doing abc?

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Re: Turning an S8 ABC off

#7 Post by TD-er » 24 Nov 2020, 19:34

I don't know.

JarredAwesome
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Re: Turning an S8 ABC off

#8 Post by JarredAwesome » 25 Nov 2020, 16:09

I wrote to Sensair directly.

They sent me this


Page 16 shows how to disable abc

Thanks everyone

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Re: Turning an S8 ABC off

#9 Post by acidsubway » 06 Feb 2022, 09:06

hello all,

is it now possible to send a command from the ESPEasy interface to turn off the abc calibration?
And if so which one would that be? I have built a sensor that controls my ventilation system,
now it is so that the sensor after several days always shows lower values and then lands at 700ppm but in reality it is 1400ppm.

With kind regards

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Re: Turning an S8 ABC off

#10 Post by TD-er » 06 Feb 2022, 20:47

The reason I disabled that piece of code to set the ABC period on the SenseAir S8 sensors is because there is a bug in the firmware of (older) S8 sensors.
This bug may lead to the undesired behavior that you can only lower the ABC period and not increase it anymore.

If you have such erratic behavior, I am afraid something else is wrong (or you may already have lowered the ABC period from the default 7 week)
The SenseAir S8 does only apply a fraction of the computed correction.
Not exactly like this ,but to give an idea, just imagine the following.
Imagine you have a sensor which was wrongly tuned but reports 1000 ppm too high.
After 1 ABC period, it is clear this offset is +1000 ppm. Only a fraction of the offset will be applied, thus after 1 ABC period the offset is still + 750 ppm (correct with 1/4 of the measured offset)
The next period the offset will be lowered 1/4th of 750 => still 562 ppm too high.

If you're seeing such a shift in values, I think you may have damaged the sensor, or it may have been dirty (or receiving direct sunlight?)
You can damage the sensor by strong vibration (broken mirror, or mechanical offset of the lamp) or by applying a too high voltage (> 5.2 V can damage it, which is not uncommon to see on cheap USB chargers)

But to give an idea of how strong the vibration must be... I have had a SenseAir S8 mounted between radiator and gril of my Volvo V40 for over 2 years (40'000 km) and also on the German autobahn (192 km/h on a 20 year old Diesel with 627'000 km on the clock)

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