Author Topic: WeatherLink Distorting Indoor Temperature?  (Read 19432 times)

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Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #25 on: May 06, 2013, 11:05:28 AM »
Wow. Just Wow. I just got off the phone with Davis technical support to report that I had spent the last couple of days troubleshooting the issue and to report that I see it on both consoles and both data loggers, and that I had all the details necessary to replicate the issue. The operator became dismissive and told me that I needed to send my console in for repair because their consoles don't have an issue like that. I told him that while I thought it possible that I got two consoles and data loggers that happened to be broken in the exact same manner, the odds were very slim of that unless it's a widespread issue. At this point he got a little more attitude and dismissively asked, "What would you like me to do about it?" I asked him if someone from Davis could test it at which point he reiterated that their consoles do not have an issue. I asked him if he really thought the two were broken, could I return the one they just sent and have them send another. His answer was that, "we can't just keep sending you parts." I asked him if Davis thought I should just keep the console with this issue and be happy with that. Again he asked me what I wanted him to do about it, and I told him it would be nice if someone would test it. At that point he got even more attitude and told me he's testing it right now (he never bothered to get any information about how to replicate the issue). I don't buy it in the least.

This conversation with Davis comes as a complete surprise to me as I have never encountered anyone that wasn't happy to help.
« Last Edit: May 06, 2013, 11:08:09 AM by LABob »

Offline Weather Display

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #26 on: May 06, 2013, 03:38:57 PM »
and I dont think they have ever come across someone so concerned about a small error in indoor temperature reading, which can be corrected with an offset anway
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Offline dalecoy

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #27 on: May 06, 2013, 04:28:29 PM »

  2. Extended experimentation shows that plugging the data logger into the console by itself does not cause the issue. ..... It
     is only when the data logger is connected to an active (powered) USB port on a computer/router.


Obviously, the USB logger contains active circuitry (more than the serial logger), to convert serial to USB.  That circuitry dissipates power, of course, which means heat.  And the harder the logger (including the USB converter) works, the more heat.  You have rather conclusively demonstrated the possible extent of that effect.  But (at least from my tests), the effect does not occur just from connecting the logger to the computer.

My system here uses a serial logger, and WeatherLink software, normally running at a download interval of 10 minutes.  I have an essentially-duplicate test system, so I made some tests.  I can't detect any heating effect (difference) between:

1.  Logger disconnected from the computer.
2.  Logger connected to the computer, but WeatherLink not running.
3.  Logger connected to the computer, with WeatherLink running at 10-minute download interval.

  I would not expect to be able to  see a difference with a USB logger, either.  But perhaps you would run that test. 

However, you are quite correct - I can observe a slight (perhaps 1/2 degree) heating effect when I run the WeatherLink Bulletin for 30 minutes or so.   I would expect that effect to be somewhat greater with a USB logger.

I eliminated Meteobridge as the culprit by reproducing the results with WeatherLink. Here's what I know so far:

  2. Extended experimentation shows that plugging the data logger into the console by itself does not cause the issue. It is only
     once the logger is being read often as Meteobridge-like devices would, or with Weather Bulletin running on WeatherLink.
....It
     is only when the data logger is connected to an active (powered) USB port on a computer/router.


Note strikethrough" replaced by italics above.

Many users will never notice this effect - because they don't read the data that frequently (Meteobridge et al) or run the Bulletin continually.  [Or, I suspect - uploading to WeatherUnderground in "rapid fire" mode].

Having said that, Davis should properly be interested in the information.

When you talked with Davis technical support, did they perhaps think that you were saying "Your USB logger heats up the console all the time", rather than "Your USB logger heats up the console if you're running the WeatherLink Bulletin or using it very rapidly"?

[And it seems clear that in your earlier tests, MeteoBridge did significantly affect the results - in the same way that the Bulletin does when using WeatherLink.]
« Last Edit: May 06, 2013, 04:32:46 PM by dalecoy »

Offline johnd

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #28 on: May 06, 2013, 04:52:04 PM »
However, you are quite correct - I can observe a slight (perhaps 1/2 degree) heating effect when I run the WeatherLink Bulletin for 30 minutes or so.

That sounds plausible, ie continuous LOOP calls at eg 2sec intervals are causing extra current flows and resulting heating. But I'd be more inclined to think that it's not the logger at all causing this, but simply extra workload on the main console CPU and associated circuitry. An archive interval of 1 minute might conceivably contribute also, if it were used.
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Offline Weather Display

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #29 on: May 06, 2013, 05:20:55 PM »
maybe put a fan next to the console, to keep it cool, if indoor temperature accuracy is that important
(i.e like a FARS system)
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Offline dalecoy

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #30 on: May 06, 2013, 05:22:52 PM »
That sounds plausible, ie continuous LOOP calls at eg 2sec intervals are causing extra current flows and resulting heating. But I'd be more inclined to think that it's not the logger at all causing this, but simply extra workload on the main console CPU and associated circuitry. An archive interval of 1 minute might conceivably contribute also, if it were used.

Oh - of course!  I should have thought of that.  I feel extremely  :oops:

Someone could actually test that - someone who has a logger that is not placed inside the console.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #31 on: May 06, 2013, 10:56:55 PM »
and I dont think they have ever come across someone so concerned about a small error in indoor temperature reading, which can be corrected with an offset anway

Except it can't be corrected with an offset because the error is variable. One hour it's 0.8°F high, two hours later it's 2°F high, and two hours after that it's right on the money. It's all over the map.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #32 on: May 06, 2013, 11:01:32 PM »

  2. Extended experimentation shows that plugging the data logger into the console by itself does not cause the issue. ..... It
     is only when the data logger is connected to an active (powered) USB port on a computer/router.


Obviously, the USB logger contains active circuitry (more than the serial logger), to convert serial to USB.  That circuitry dissipates power, of course, which means heat.  And the harder the logger (including the USB converter) works, the more heat.  You have rather conclusively demonstrated the possible extent of that effect.  But (at least from my tests), the effect does not occur just from connecting the logger to the computer.

Are you waiting at least thirty minutes after plugging in? The effect is slow. The first 0.1°F takes 5 - 10 minutes. Then every five or six minutes it will raise another 0.1°F until it reaches somewhere between 0.8°F and 2.0°F higher.

When you talked with Davis technical support, did they perhaps think that you were saying "Your USB logger heats up the console all the time", rather than "Your USB logger heats up the console if you're running the WeatherLink Bulletin or using it very rapidly"?

I hope so, because that's exactly what I meant to tell them. As long as the USB logger is connected to a USB port that has power it will raise the console's temperature. I'm thinking about making a time lapse demonstration for the forum.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #33 on: May 06, 2013, 11:11:13 PM »
Someone could actually test that - someone who has a logger that is not placed inside the console.

That was my plan: just get a ribbon cable and put the logger away from the console. I'd be curious if the heat is emanating from the logger itself, or something on the board inside the console. I think mounting a thermometer on a circuit board that is performing other tasks was a bad design choice, and doubly so for neglecting to mount it at the bottom of the board where natural convection would help mitigate potential convective heat issues.

Does anyone know where to get a ribbon cable that will fit that slot and at least a foot long (it has to pass through the wall the console is mounted on)? If that doesn't work I may open the console to study the layout and see whether a small fan can be added inside. Running on 5V it should be silent, but offer enough flow to dissipate that small amount of heat.
« Last Edit: May 06, 2013, 11:21:39 PM by LABob »

Offline Bushman

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #34 on: May 06, 2013, 11:37:03 PM »
Someone on the forum already modded a console to include a fan.  They were a low cost improvement.
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Offline dalecoy

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #35 on: May 07, 2013, 10:07:56 AM »
 But (at least from my tests), the effect does not occur just from connecting the logger to the computer.

Are you waiting at least thirty minutes after plugging in? The effect is slow. The first 0.1°F takes 5 - 10 minutes. Then every five or six minutes it will raise another 0.1°F until it reaches somewhere between 0.8°F and 2.0°F higher.


How about "overnight"?  I don't observe any heating effect from just connecting to the computer, without WeatherLink running.

However - note that I'm using a serial logger, not a USB logger.  So, the difference could be because of that.

Did you preform your "connect to the computer" test first without any weather software running? 

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #36 on: May 07, 2013, 10:14:13 AM »
How about "overnight"?  I don't observe any heating effect from just connecting to the computer, without WeatherLink running.

However - note that I'm using a serial logger, not a USB logger.  So, the difference could be because of that.

Did you preform your "connect to the computer" test first without any weather software running? 

Whenever I'm testing something, I always make sure to replicate it twice and corroborate by multiple methods if possible. In this case, after I had seen it rise with the WeatherLink software I closed WeatherLink and waited for it to cool off. When that didn't happen after about 20 minutes (it should have started to fall by then) I unplugged the USB cable from the computer. The cooling began shortly after disconnecting the cable. I waited for the temperature to fall until it stabilized and connected the USB cable again with no software running. The temperature climbed back up again. I can only guess that something in the logger or the console starts doing work as soon as it sees power on that pin. Since you don't see it, I'm guessing it's the logger.

Offline dalecoy

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #37 on: May 07, 2013, 10:17:16 AM »
Re: connecting using a ribbon cable, etc., see  http://www.wxforum.net/index.php?topic=10315.0

The "second page" of that topic is probably what you need, and note that the first information about pin spacing is later corrected.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #38 on: May 07, 2013, 10:40:27 AM »
Thanks for the link. Looks like the only option is to build a cable out of a female and male connector and some wire. I don't know if I'm that motivated. I'll probably decide not to do it for awhile until I get more frustrated and end up doing it anyway. :grin:

Offline Weather Display

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #39 on: May 07, 2013, 03:19:51 PM »
Quote
I don't know if I'm that motivated. I'll probably decide not to do it for awhile until I get more frustrated and end up doing it anyway.
bit perplexed by that
you made davis run around in circles sending you replacement parts, and got them all frustrated on the phone, which you then named and shamed them on here on this forum, and now you cant be motivated re a possible solution(s)?
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Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #40 on: May 07, 2013, 03:26:57 PM »
Quote
I don't know if I'm that motivated. I'll probably decide not to do it for awhile until I get more frustrated and end up doing it anyway.
bit perplexed by that
you made davis run around in circles sending you replacement parts, and got them all frustrated on the phone, which you then named and shamed them on here on this forum, and now you cant be motivated re a possible solution(s)?

I'm not selling a product that doesn't work within its specifications. I was sold a product that doesn't work according to Davis' own specifications. Why shouldn't they try to fix it? Are you saying I should only expect a business to stand behind their products if I'm willing to spend my own money and free time jury-rigging their equipment to perform as they advertised it would?

And what do you mean "got them all frustrated on the phone"? I called them back to tell them that the replacement part has the same issue. Do you consider that inappropriate?

Offline johnd

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #41 on: May 07, 2013, 04:02:11 PM »
I'm not selling a product that doesn't work within its specifications. I was sold a product that doesn't work according to Davis' own specifications.

Isn't that a grey area? I'm not motivated to read back through all of this thread, but isn't it the case that it is in spec as long as you don't hammer the logger with continuous loop requests? The specs don't - AFAICR - stipulate the precise conditions under which they are valid. For no logger installed then they certainly all ought to be correct. But when you push the envelope as with the repetitive loops on the serial interface then who is to say whether that should or shouldn't be covered by the specs.

Davis really ought to do what they've done with wireless Envoy console and provide a jack on the VP2 console for an external temp sensor to be attached so as to eliminate this sort of issue. But I think that in reality you're looking at the limitations in specifications of what is still a relatively inexpensive weather station (bearing in mind that a high-end station would cost in a price band of say $10-50K).
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Offline SLOweather

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #42 on: May 07, 2013, 04:41:05 PM »
Rename it Console Temp and be done with it. That's what it is.

Every measuring device ever made has one or more design compromises, and Davis has their share. If you are trying to accurately and repeatably measure indoor environmental temperatures to 0.1F then a weather station console is probably the wrong tool.

And, whatever you do, if the temp is that important to you, don't turn on the backlight.

Offline George Richardson

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #43 on: May 07, 2013, 05:48:56 PM »
Just had a thought. The console specification of +/- 1°F is for the console, not the console with the WeatherLink Data Logger added.

Offline dalecoy

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #44 on: May 07, 2013, 10:28:05 PM »
Folks, I personally think it's interesting to find out what's actually going on - and do that by carefully-controlled experimentation if necessary - and have that critiqued by others in this forum. 

Whether or not Davis acknowledges (and/or advertises in specifications) the information is a bit secondary, as far as I'm concerned. 

Whether some rather-small effect is significant, is a matter for decision by the user - but to decide means to have access to information.

We have big "arguments" around here as to what height to mount an anemometer, whether lightning protection is necessary, whether to report "temperature in my back yard" if it's not measured at a particular height over particular vegitation, whether dew counts as precipitation, etc. 

If LABob wants to find out exactly why a combination of hardware and software is causing a particular effect, let's try to help if we can.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #45 on: May 07, 2013, 11:34:27 PM »
Whether some rather-small effect is significant, is a matter for decision by the user - but to decide means to have access to information.

We have big "arguments" around here as to what height to mount an anemometer, whether lightning protection is necessary, whether to report "temperature in my back yard" if it's not measured at a particular height over particular vegitation, whether dew counts as precipitation, etc.  

If LABob wants to find out exactly why a combination of hardware and software is causing a particular effect, let's try to help if we can.

Thanks dalecoy. I suppose my frustration stems from the fact that I know I am a nut for precision and accuracy, and I know a lot of people aren't that particular so I have to pay a premium for it. That's why I studied the specifications of a lot of different weather systems before deciding the Davis offered the best compromise of price vs/ accuracy. We're not talking about 0.1°F here like some suggest (even scientific instruments aren't that accurate), but 2.0°F is too far off the mark. I can grab an Oregon Scientific thermometer from Walmart for about $10 with that kind of accuracy, but I didn't want that kind of accuracy so I paid a lot more money for something advertised as being better. I had a list of things I wanted in a weather station, primarily the ability to log data, upload to CWOP, and better accuracy than your run of the mill instruments found in places like Walmart and Target. The Davis was advertised as meeting those requirements and I based my purchasing decision on those specifications. I really don't think it's appropriate or fair even to come down on me for being frustrated that what I was led to believe I was purchasing isn't what I was sold.

Everything in life is a tradeoff ... even the decision to sit down and write a post here instead of cleaning the kitchen like I should :grin: It's OK that Davis has to make design compromises, but they should make those clear to the buyer. If I had seen something telling me that a data logger would affect the indoor temperature and humidity readings, I honestly would have probably passed on the Davis. I almost did because of the backlight warning in the manual, but decided I could mount it in a location that wouldn't need a backlight. I'm not even really that bothered that it is an issue. It was only one particular representative, whom I am not publicly naming, who was very dismissive and even a little confrontational that had me frustrated. The other two people at Davis were wonderful. They sent the other data logger and console without me even asking them to do that. They just showed up.

Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #46 on: May 07, 2013, 11:41:05 PM »
Isn't that a grey area? I'm not motivated to read back through all of this thread, but isn't it the case that it is in spec as long as you don't hammer the logger with continuous loop requests? The specs don't - AFAICR - stipulate the precise conditions under which they are valid. For no logger installed then they certainly all ought to be correct. But when you push the envelope as with the repetitive loops on the serial interface then who is to say whether that should or shouldn't be covered by the specs.

The serial logger only warms up on repeated polling. The USB logger warms up with no polling at all - even if it's just plugged into a powered USB hub that isn't connected to anything. Either way, a logging thermometer that cannot measure temperature accurately while logging isn't very useful.

Offline Weather Display

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #47 on: May 08, 2013, 12:43:40 AM »
but for the vast majority of customers, its accurate enough, for indoor temperature (which is really just a guide)

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Offline Bushman

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #48 on: May 08, 2013, 12:51:50 AM »
but for the vast majority of customers, its accurate enough, for indoor temperature (which is really just a guide)


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Offline LABob

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Re: WeatherLink Distorting Indoor Temperature?
« Reply #49 on: May 08, 2013, 08:38:19 AM »
but for the vast majority of customers, its accurate enough, for indoor temperature (which is really just a guide)

"Accurate enough" isn't an empirical measurement. Davis specifications are ±1.0°F and their product isn't performing according to their specifications. If the "vast majority of customers" are happy with products that fail to perform according to specification that's not really relevant to the question. One has to wonder why someone would spend almost ten times as much money for a weather station if they're going to be happy with the lower accuracy of less expensive units.

 

anything