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Zero Humidity

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Matt.j5b
Posts: 512
Joined: Mon 28 Nov 2011 2:13 am
Weather Station: Davis VP2/ WLL with DFARS
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Zero Humidity

Post by Matt.j5b »

This is not a problem, just wondering what would be causing it.

Yesterday in the logger download a humidity of 0 was reported but was ignorned which is a good thing. It was recorded by the station but it was only one reading that was bad and the rest of the measurements are fine at that point and it can't be any issue with Cumulus because it downloaded properly and not a problem with the usb adapter because the station recorded only that measurement at only one time.
Just wondering why the station recorded 0 but this didn't affect Cumulus or is it just a rubbish figure recorded. Thanks

16/01/2012 12:14:00.339 : Ignoring outdoor humidity: 0
16/01/2012 12:14:00.339 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
16/01/2012 12:14:17.942 : Ignoring outdoor humidity: 0
16/01/2012 12:14:17.942 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
16/01/2012 12:14:36.768 : Ignoring outdoor humidity: 0
16/01/2012 12:14:36.768 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
16/01/2012 12:14:54.369 : Ignoring outdoor humidity: 0
16/01/2012 12:14:54.369 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
16/01/2012 12:15:00.917 : Writing today.ini, LastUpdateTime = 16/01/2012 12:15:00 PM raindaystart = 13.9860000610352 rain counter = 27.4500007629395
16/01/2012 12:15:11.971 : Ignoring outdoor humidity: 0
16/01/2012 12:15:11.971 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
16/01/2012 12:15:30.797 : Ignoring outdoor humidity: 0
16/01/2012 12:15:30.797 : Old value = 85 New value = 0 EWhumiditydiff = 15.0
Regards, Matt of Brisbane, Australia
Ferny Grove Weather
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Matt.j5b
Posts: 512
Joined: Mon 28 Nov 2011 2:13 am
Weather Station: Davis VP2/ WLL with DFARS
Operating System: RPi Raspbian (Buster)
Location: Ferny Grove, Brisbane, Australia
Contact:

Re: Zero Humidity

Post by Matt.j5b »

I think it is simply interference because below is an example of when I got -30 today but the rest of readings at that logger download were not affected. I do sometimes get connection lost totally and with that I dont't get a logger entry. I think that is a totally different matter. A question about the spike removal setting of EWtempdiff = 15.0. Is it right to say if the difference is more 15 it should be ignored. It seems that it has not been ignorned because I have edit it out of the log files, today file and this year, this month and all time. Or am I seeing this wrong. But it not too hard to edit out.

17/01/2012 10:43:33.675 : Temp difference greater than specified; reading ignored
17/01/2012 10:43:33.675 : Old value = 21.1 New value = -30.0 EWtempdiff = 15.0
17/01/2012 10:43:51.179 : Temp difference greater than specified; reading ignored
17/01/2012 10:43:51.179 : Old value = 21.1 New value = -30.0 EWtempdiff = 15.0
17/01/2012 10:44:10.396 : Temp difference greater than specified; reading ignored
17/01/2012 10:44:10.396 : Old value = 21.1 New value = -30.0 EWtempdiff = 15.0
17/01/2012 10:44:27.860 : Temp difference greater than specified; reading ignored
17/01/2012 10:44:27.860 : Old value = 21.1 New value = -30.0 EWtempdiff = 15.0
Regards, Matt of Brisbane, Australia
Ferny Grove Weather
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serowe
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Joined: Tue 03 Aug 2010 6:23 am
Weather Station: WM918
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Re: Zero Humidity

Post by serowe »

Different sensors will give different default values.

The WM918 which I use causes a reading of -6 if the temp sensor goes open circuit or overheats (direct sunlight on the casing) for any reason. Basically there isn't much you can do about it other than replace the faulty sensor - 1 or 2 of these a year would be acceptable, but if you start to notice them more and more it's an indication the sensor (or even cabling for that matter) may be failing.

And, mentioning cabling - always good to periodically check any cable runs to make sure they haven't been broken down by UV (outdoor weather stations but usually supplied with indoor grade cable only) or chewed through by mice, rats or possums...
Punctuation is the difference between 'Let's eat, grandma' and 'Let's eat grandma'
Matt.j5b
Posts: 512
Joined: Mon 28 Nov 2011 2:13 am
Weather Station: Davis VP2/ WLL with DFARS
Operating System: RPi Raspbian (Buster)
Location: Ferny Grove, Brisbane, Australia
Contact:

Re: Zero Humidity

Post by Matt.j5b »

It have not happened any more often than before, I often have weeks without it happening. The cable is good condition, my other station which have out in the open for 23 months is also going well. I don't think anything major have caused this or any failing. I don't use a cable from the temp hum sensor so there can not be trouble with the cable because the cable only runs from the temp hum sensor to the wind and rain sensors. I can't do any better because the cable to the sensor is only a couple of metres from the main outdoor unit and doesnt go through the open that far and is quite close to the indoor. I think it may got to do with the location rather than the sensor but it is fine the way it is. This type of station is like this and there is no big problem.
Regards, Matt of Brisbane, Australia
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serowe
Posts: 484
Joined: Tue 03 Aug 2010 6:23 am
Weather Station: WM918
Operating System: Win Server 2008 R2
Location: Ferntree Gully, VIC, Oz
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Re: Zero Humidity

Post by serowe »

I know you say 'it doesn't go far' but it's amazing how cables can break down and they 'seem' OK (been there, done that with a rain sensor that only has 4 feet of exposed cable which failed last year after 10 years of UV hitting :) This cable is now inside exterior conduit for additional protection.)
Punctuation is the difference between 'Let's eat, grandma' and 'Let's eat grandma'
Matt.j5b
Posts: 512
Joined: Mon 28 Nov 2011 2:13 am
Weather Station: Davis VP2/ WLL with DFARS
Operating System: RPi Raspbian (Buster)
Location: Ferny Grove, Brisbane, Australia
Contact:

Re: Zero Humidity

Post by Matt.j5b »

Well I would agree that uv does degrade because the rain gauge of my first La Crosse station have gone from white to cream so because it would to happen to that then of course it could happen to the cable. :)
But for at least now it has been fine but it not an ongoing problem. This is now the station work: There are three outdoor sensors – a rain, a wind and temp hum sensor. The two other sensors connect to the temp hum sensor by cable. Therefore operating power from these sensors is supplied from the temp hum sensor which uses 2 AA Batteries. Then all the outdoor data is transmitted to the indoor unit via wireless 433mhz or cable nomally at 128 second intervals (with wireless). I use wireless.

Now the temp hum sensor or the cable to the other sensors are receiving interference but not very often and is located in a spot where the surrounding material would interference. I have been aware of this the whole time I have owned both stations. It is no real problems, it’s only a minor matter. :D
Regards, Matt of Brisbane, Australia
Ferny Grove Weather
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steve
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Re: Zero Humidity

Post by steve »

Matt.j5b wrote: A question about the spike removal setting of EWtempdiff = 15.0. Is it right to say if the difference is more 15 it should be ignored.
Yes, that's right, and those messages you posted show that's what it's doing. But note that the difference has to be in one jump, and it only has affect on 'live' data rather than logger data.
Steve
Matt.j5b
Posts: 512
Joined: Mon 28 Nov 2011 2:13 am
Weather Station: Davis VP2/ WLL with DFARS
Operating System: RPi Raspbian (Buster)
Location: Ferny Grove, Brisbane, Australia
Contact:

Re: Zero Humidity

Post by Matt.j5b »

That all right Steve, it does not happen that often particularly because using the logger there is not much of a chance getting the strange figure at the logger entry. Strange thing is that goes to the figure and back to normal and is fine for a while. Not much of a problem to fix up and nothing to get worried about. Thanks for your response, I didn't know it didn't apply to the logger but that is not a issue.
Regards, Matt of Brisbane, Australia
Ferny Grove Weather
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