I purchased a La Crosse weather station (WS2812) and installed the Heavy Weather software on my CCTV server, since this is the only Windows machine I have running 24x7. The weather station feeds data to the software, and stores current weather data in the currdat.lst file. I periodically copy the file to my Linux server and parse through the currdat.lst file to get various readings from the station.

I am a big fan of graphing the output of various readings, and use MRTG for capturing Server Temps and other data points. I thought I could use MRTG for this but found MRTG only uses integers, and I needed to capture values that were not always integers.

I searched around for an alternative and ended up using RRDTool to capture the data, and graphing out via RRDTool Graph. I am by no means an expert at RRDTool, but these steps gave me the information I need to get values graphing fairly quickly.

Obtain Outdoor Temperature

The weather data file (currlst.dat) has the various weather readings. In this case, I want the outside temperature: [outdoor_temperature] deg_C="7.2" deg_F="45.0" I then have a script to look at the file, and just get me the outside temperature in Farenheit and store that in a file: #!/bin/bash grep -A 2 'outdoor_temperature' currdat.lst >outdoor_temp.dat cat outdoor_temp.dat | egrep "deg_F" | awk 'match($0,"="){print substr($0,RSTART+2,4)}' >outdoor_temp_data.dat The grep -A 2 looks for the outdoor_tempearture, then reads the next two lines
Then the next line in the script looks for "deg_F" and then starts reading 4 characters after the first quotes '"'. I need to find a better way of reading this, if it ever gets to 100+ degrees, or below zero, this will not work.

Next, I'm on the to creating the RRD database for outdoor temperature.

RRDTool to create the RRD

This is script I use to create the RRD for the outside temperature: #!/bin/sh rrdtool create outdoor_temp.rrd \ --start N \ -s 300 \ DS:temp:GAUGE:600:U:U \ RRA:AVERAGE:0:1:5000 There are much better tutorials to explain what each of the variable do, but this created a database I could use, so I went with it. Now, I need to feed it values...the next step.

Update RRD with values

This is script I use to update the RRD for the outside temperature. It uses the outdoor_temp.dat file that is used when I obtain the outdoor temperature: #!/bin/sh var=`cat outdoor_temp.dat` for i in $var; do /usr/bin/rrdtool update outdoor_temp.rrd N:$i done Now that the database is receiving values, I need to then update the graph...the next step.

Graph the values using RRDTool Graph

This is script I use to graph the values for the outside temperature:: #!/bin/sh rrdtool graph /www/outdoor_temp.png -a PNG --title="Outdoor Temperature" --vertical-label "Deg F" \ DEF:temp=outdoor_temp.rrd:temp:AVERAGE \ LINE1:temp#3D59AB \ AREA:temp#3D59AB:Temperature \ HRULE:32#800000 \ 'GPRINT:temp:LAST:Current Outdoor Temperature\: %2.1lf F' I use the HRULE:32#80000 to draw a line at 32 degrees, just for kicks. The AREA: fills the graph, as opposed to a single line. I initially had just the single line (LINE1:) but found I like the graph showing the area better.

Now I have the outdoor temperature graphing.
weather

Graph the values using RRDTool Graph for Week, Month, Year

I then can use another script to graph the values for longer than 24 hours: #!/bin/sh rrdtool graph /www/outdoor_temp_year.png -a PNG --title="Outdoor Temperature Year" --vertical-label "Deg F" \ --height 150 \ --start "-1year" \ DEF:temp=outdoor_temp.rrd:temp:AVERAGE \ LINE1:temp#3D59AB \ AREA:temp#3D59AB:Temperature \ HRULE:32#800000 \ 'GPRINT:temp:LAST:Current Outdoor Temperature\: %2.1lf F' Now I have the outdoor temperature graphing.
You can change the --start "-1year" to "-1week" and/or "-1month" to get weekly and monthly graphs as well.

RRDTool Cron