Fahrenheit to Celsius (Weathershield mote)

[DrSproc]

For my Canadian compadres, here's a quick way I got my dashboard talking Celsius for the weathershield mote... this assumes the mote's in the field transmitting values in Fahrenheit. 

Login to your raspberry pi and make a backup copy of the metrics.js file

cp /home/pi/gateway/metrics.js /home/pi/gateway/metrics.js_bak

Next nano into metrics.js

nano /home/pi/gateway/metrics.js

and modify the following line in the //WeatherShield metrics section

Code Select Expand

FH : { name:'F', regexp:/F\:(-?\d+)/i, value:'', valuation:function(value) {return (((value/100)-32)*(5/9)).toFixed(2);}, unit:'°', pin:1, graph:1, graphValSuffix$:'C', graphOptions:{ legendLbl:'Temperature', lines: { lineWidth:1 }}},

ctl-O to save and ctrl-x to exit...

reboot your pi and you ready to see Celsius...
I also altered the Value description on the web page, with a "C"...

The formula is a well know conversion of F to C
 

[Kilo95]

Could you tell me how to add 0.7229 to the value on the pressure reading? That's my correction factor for my elevation. I tried in the sketch and failed. I assume if you can manipulate the temp reading from F to C you could add 0.7229 to the P reading. I've tried a couple things but failed. Thanks

[DrSproc]

Kilo... I would change it this way...

Code Select Expand

from...
P : { name:'P', regexp:/P\:([\d\.]+)/i, value:'', unit:'"', pin:1, },

to...
P : { name:'P', regexp:/P\:([\d\.]+)/i, value:'', valuation:function(value) {return (value+0.7229).toFixed(2);}, unit:'"', pin:1, },

hope this helps... 

[Kilo95]

Much thanks

[Kilo95]

tried that then sudo reboot. my gateway gui hangs up at "waiting for socket connection". if i revert to my metrics.js_bak it works fine...

[Felix]

Check the logs for errors.
But don't just copy paste from a non code text, note that the forum will place smiley faces where the character combination matches one.
It should be in a code block (I updated the above). Try it again.

[DrSproc]

Thanks Felix...

[Kilo95]

I'll check the log and try again. I didn't copy and paste. I manually entered it. I'll go back through and try it again. I really appreciate it

[Kilo95]

ok. i changed it to the suggested and the gateway gui wouldn't update. i checked the log and it said it "has no method 'toFixed'". i deleted ".toFixed(2)" and tried it again. i'm attaching a screenshot

http://imgur.com/gallery/B9JvX

[DrSproc]

Please post the full line as you have it in the metrics.js file.  I have a hunch something is missing. Like a semicolon or a bracket.

[Kilo95]

i cut an pasted this one from the above to metrics.js:

P : { name:'P', regexp:/P\[\d\.]+)/i, value:'', valuation:function(value) {return (value+0.7229).toFixed(2);}, unit:'"', pin:1, },

new screen shot of gateway.sys.log:

http://imgur.com/gallery/kPBEx

[DrSproc]

Kilo...

Looks like the script treats the pressure value as a string data type...

What can be done in this case is to parse the value into a float and then apply the correction factor for your area...

...lastly trimming to two decimal places, so the values look consistently formatted for display...  try replacing with this code...

Code Select Expand

P : { name:'P', regexp:/P\:([\d\.]+)/i, value:'', valuation:function(value) {return (parseFloat(value)+0.7229).toFixed(2);}, unit:'"', pin:1, },

[Kilo95]

Perfect! Works like a charm. Much appreciated

[DrSproc]

Good stuff!