Real-time Environmental Monitoring

This topic has 12 replies, 4 voices, and was last updated 6 years, 11 months ago by CaleKee.

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July 12, 2017 at 1:58 pm #4604

SaltoUYStation
Moderator

That straight-line drop reminds of when power is cut or systems are reset (rebooted). Was there a power interruption? That might explain the drop event – for the data change… re-analyzing after power cut? I don’t have a solid answer on that.

July 12, 2017 at 2:08 pm #4605

ON1GL
Participant

thanks for replying SaltoUYStation
there was no power loss, the unit is on a ups.
It happens about 24 hours after powerup, just read this pdf file
http://www.winsen-sensor.com/d/files/infrared-gas-sensor/mh-z19b-co2-ver1_0.pdf it could be autocallibration that kicked in (see page 9) ? but what are the correct values ?

July 12, 2017 at 7:01 pm #4606
Radu
Keymaster
It is possible this was the auto-calibration, which is enabled on these sensors by default. The power cycle, although possible as well is discarded because of the continuous data stream. After a power cycle, there should be no data for at least 3 minutes, which is the sensors warmup time on the A3.
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1. Screen-Shot-2017-07-12-at-21.56.50.png
July 13, 2017 at 11:39 am #4608
ON1GL
Participant
24 hours later he did it again (auto-calibration), is this going to be a daily event or is this going to stop after some time ?
Attachments:
1. co2-b.jpg
July 14, 2017 at 1:30 pm #4610

Radu
Keymaster

I am discussing this with the manufacturer, will get back with a reply.

August 16, 2017 at 8:09 pm #4777

ON1GL
Participant

any news on this auto-calibrate problem ?
This sensor is useless with every 24 hours auto-calibrate jumping up or down as much as 100 ppm a day 🙁

August 26, 2017 at 2:21 pm #4809
Radu
Keymaster
I wasn’t able to obtain details on the auto-calibration algorithm from the manufacturer, but what they said is the sensor will eventually settle to the correct values after a few cycles.

I believe this already happened on yours too, since the data seems continuous:
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1. Screen-Shot-2017-08-26-at-17.20.44.png
August 31, 2017 at 9:52 pm #4822
ON1GL
Participant
The unit is now online for almost a month and still the co2 sensor jumps up or down every few days…
It does not seems to settle after a few cycles.
The sensor was at its bottom level (around 340-350 ppm) whole day (not very likely that this is correct) and jumped up this evening.
Attachments:
1. co2-c.jpg
January 9, 2018 at 2:09 pm #5471
Radu
Keymaster
The readings across December. I was able to identify a single “jump”. Please confirm. We can have the auto-calibration disabled, but I don’t think it’s a good idea. All tests on these sensors have shown good correspondence to the reference unit. I’m concerned that disabling auto-calibration will induce a building offset over time.
Attachments:
1. Screen-Shot-2018-01-08-at-19.56.17.png
January 9, 2018 at 3:04 pm #5474

ON1GL
Participant

Following the manual of the sensor “the autocalibration should be on for “indoor” units and off for others, with calibrations from time to time…”
The way it works looking at the data is that if the ppm is to low the sensitivity is increased, if its high the sensitivity is decreased, this happens every 24 hours.
With a outdoor sensor (like here in a city street) the variations are (very) big and causing a almost daily jump of the readings (70-120ppm in both directions).
Switching the autocalibration off and automatic calibration every month at a quit moment ?
Calibration always a tricky business….

January 9, 2018 at 6:02 pm #5477

Radu
Keymaster

Switching the autocalibration off and automatic calibration every month at a quit moment ?

That’s a very good idea!

May 14, 2018 at 5:18 pm #5787

CaleKee
Participant

Hi…i am a new user here. As per my knowledge the power cycle is possible as well is discarded because of the continuous data stream. After a power cycle, there should be no data for at least 3 minutes, which is the sensors warmup time on the A3.
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