How to start monitoring without any sensor....

You have downloaded the themis image, but don’t have any wired or wireless temperature sensor.

No problem ! We’ll use openweathermap and nodeRED, which is preinstalled on the themis image.

openweathermap provides current weather all over the world through a network of weather stations. Thanks to its API, it is very easy to integrate and historise datas from OWM into Themis. And everything is free !

1) create an OWM account

sign up to OWM

You will need to choose a username and to provide a valid email address. Signup process as usual : the system will send you a confirmation email to activate your account…..

once logged in OWM, go to the API keys tab and copy the default key (generated during account activation

2) open nodeRED and construct a flow

if your themis IP is 192.168.1.37, just browse to https://192.168.1.37:1880

NodeRED is composed of nodes which you can find in the left column of the dashboard

We will use the following ones :

node name action
inject triggers the actions according to a regular time step
openweathermap interrogates the OWM API - requires the OWM API key
function javaScript function to produce a json object with the datas from the payload transmitted by openweathermap
emoncms posts the json object to Emoncms - requires the emonCMS write API key
debug displays selected message in the debug sidebar tab.

nodeRED most basic nodes

At its final stage, the flow should look like that :

the flow

inject and OWM nodes configuration

Just define a polling interval (here 30 minutes) and enter your city name….

nodes configuration part 1

An alternative is to provide geographic coordinates (latitude and longitude)

emoncms node configuration

If your local emonCMS/themis server has not been configured, you have to do it providing its write API key.

To publish, the node needs a node number or string : just give emonpi

nodes configuration part 2

you can find the emonCMS API key within the account details

emoncms API key

function node configuration

Use the following javascript code :

tempc = msg.payload.tempc;
hum = msg.payload.humidity;
msg = {temp_ext:parseInt(tempc),HR_ext:parseInt(hum)};
mytime = new Date().toISOString();
return {payload:msg, time: mytime};

3) check if your values are coming in

Once the flow has been successfully deployed, you just have to browse themis inputs:

emoncms inputs