Home Forum Hardware co2 sensor ?

This topic contains 12 replies, has 4 voices, and was last updated by  CaleKee 1 year ago.

Viewing 13 posts - 1 through 13 (of 13 total)
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  • #4602

    ON1GL
    Participant

    is there something wrong with the co2 sensor,rather suddenly drop in levels ?

    Attachments:
    #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.

    #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 ?

    #4606

    Radu Motisan
    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.

    #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:
    #4610

    Radu Motisan
    Keymaster

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

    #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 🙁

    #4809

    Radu Motisan
    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:

    #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:
    #5471

    Radu Motisan
    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.

    #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….

    #5477

    Radu Motisan
    Keymaster

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

    That’s a very good idea!

    #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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