[ale] [OT] how do I monitor the "weather" in my computer room

[Alex Carver]

On 5/29/2013 14:47, Ron Frazier (ALE) wrote:
> Hi all,
>
> I have a computer in a downstairs room that runs all the time.  The processes I have it doing generate lots of heat; and there is no hvac thermostat there.  There is a heating / air vent and return though, so it gets some air circulation.  I need to monitor the temperature in the room from upstairs.
>
> I bought an Acurite backyard weather thermometer from home depot with remote sensor.  I put batteries in the sensor and display and verified that the sensor is transmitting.  I sat both units a foot apart in the living room maybe 12 feed from the honeywell thermostat on the wall.  I trust the temperature reading of the honeywell more than any other sensor I have.
>
> The honeywell says it's 73 in this room.  It doesn't show decimals.
> My fairly nice Oregon Scientific weather station shows 73.6 in this room.
> A cheap Lacross Technology weather monitor that I use to monitor humidity in the basement says 73.9 in this room.
> And a cheap Lacross Technology (I think) wall clock shows 73.0 in this room.
>
> It's actually annoying that all these sensors within 12 feet of each other are so different.  I guess I'll assume that the actual temperature is between 73 and 74; and I think it's more toward 73.
>
> My NEW weather monitor is showing 74 or 75 on both indoor and outdoor temp with both sensors in the same place, which probably about 1-2 degrees high.  This one doesn't display decimals.
>
> In any case, while that's not ultra critical, I'm considering returning it.
>
> So, I'm looking into other alternatives.
>
> 1) Buy another more expensive weather station, like another Oregon Scientific.  That would cost $ 50 - $ 75.
>
> 2) Buy a wifi or lan attached temperature sensor.  That way, I could just display the weather sensor's web page from a local 192.168.x.x address and see the temperature in the basement room.
>
> 3) Use a rpi plus a sensor to do the same thing as number 2.  Would probably cost more.
>
> 4) Attach a USB temp sensor to the pc downstairs and run a web server on it to display the temperature.
>
> Other than having a more accurate stand alone unit like the one I bought, I like option 2 best.  That way, I could set a web page up in a small window on my monitor upstairs to show the downstairs temperature and set it to auto reload every few minutes.  Also, I could run a script on the downstairs computer to poll the sensor periodically and send me an email if the temperature exceeds a preset limit.
>
> Anyone know what I might use to get this done?
>
> By the way, when I was researching how to monitor my basement humidity, I found out that any humidity sensor less than about $ 300 is probably rubbish for precision.  The tolerance is usually + / - 5%.  I think that's ridiculous, but I guess it's hard to do much better for cheap.

If you're worried about expensive (defined as > $50) then you're out of 
luck for what you want to do.  But, if you're wanting the data more than 
the worry over price you have a couple options assuming live data (not 
data logging devices that require periodic downloads of its memory):

USB device (FTDI serial chip embedded):
http://www.omega.com/ppt/pptsc.asp?ref=TJ-USB&Nav=dasc01
and protocol description
ftp://ftp.omega.com/public/DASGroup/products/TJ-USB/TJ_USB%20Command%20Reference.pdf

The serial protocol can be found on Omega's website (link above).  A 
simple ASCII polled protocol.  You ask for a temperature, it gives you a 
reading.  $95 and you use the computer down stairs (write your own web 
daemon to see it from somewhere else).  There's a related version for 
humidity (the RH-USB) for $149 that is +/- 3%

There's this device for $185 which is wifi enabled and does both RH (3% 
error) and Temp.
http://www.omega.com/pptst/OM-EL-WIFI_Series.html

It uses its own software to configure and record the data but you could 
easily sniff the packet and figure out how the thing works so you could 
write your own software.  My suspicion is that it uses simple HTTP or 
another simple protocol to post data to the logging host via HTTP 
PUT/POST and the initial configuration is where that host's IP is 
established.  The device sleeps for some programmable interval, wakes, 
transmits a reading, then sleeps again.

I own a couple ITHX-D3 devices from Omega and have a couple programs 
running on one of my Linux boxes to record that data to a MySQL database 
and also push data to an internal web server and a serial port LCD 
display.  The DB dumper is actually a quickie CLI PHP script.  The 
serial port display runs from a C program I wrote to poll and push out 
to the display.