Temperature Monitoring with Raspberry Pi

add grafana

add overview of all important files and services

Write down account names and passwords somewhere

add overview of the general structure of the setup

add “Important: it gets automatically new slaves but doesn't support removing slaves while running.”

add console prompt to code segments

The monitoring setup was developed by Etiénne Wodey. It is explained in this talk by him. The main aspects on how to set it up are documented in this email.

Short version: the raspberry pi reads out temperature sensors connected via one-wire bus, sends the data via LAN to an InfluxDB database located on the Magnesium Server. There the temperatures are stored and can be visualized in the browser using a Grafana, also running on the magnesium server. It can be accessed here

• thingol (server name)
  • debian 9
  • influxdb
    • time series database
    • used for storing temperature values
    • set up as decribed in getting started section
  • Grafana
    • used for visualisation of the values stored in influxdb

rasptemp1.pdf

pictures and schematics

Edit /boot/config.txt:

sudo nano /boot/config.txt

dtoverlay=w1-gpio

Edit /etc/modules:

sudo nano /etc/modules

w1-gpio
w1-therm

Reboot the System:

sudo reboot

There should be folders w1_bus_master<N> in /sys/devices:

ls -l /sys/devices/

Check if there are devices connected:

ls -l /sys/devices/w1_bus_master1/

There should be folders named something like 3b-0000001760f8/. These are the devices connected. Make sure there is a file named w1_slave for every device connected. This file is used to read from and write to the connected devices.

In case the folders or the files don't exist, make sure your devices are connected correctly, the steps above were done and/or reboot the system.

https://collectd.org/index.shtml

collectd is run on the raspberry pi to read out the temperature sensors and send the messages to the influxdb database located on another server.

install collectd:

sudo apt-get update
sudo apt-get install collectd

check the status of the daemon:

sudo systemctl status collectd

if the status is running, stop the daemon:

sudo systemctl stop collectd

to view all systemlog messages by collectd:

journalctl -u collectd -b

The collectd configuration file is located at /etc/collectd/collectd.conf. Edit it:

sudo nano /etc/collectd/collectd.conf

Make sure to adjust the name of the server in the network plugin section to your needs.

The temperature sensors are read out by a python module using the python plugin for collectd. Place the script w1_therm_monitor.py in the folder /home/pi/ or change the ModulePath option for the python plugin in /etc/collectd/collectd.conf if you want to place it in another folder.

The collectd module reads w1_master_slaves, takes all the serial numbers starting with 28 (DS18B20 family) or 3b (MAX31850 family) and reads the corresponding slave files (i.e. the temperatures).

Start the collectd service using:

sudo systemctl start collectd

Check if it runs without errors by reading

sudo systemctl status collectd

journalctl -u collectd -b

https://www.influxdata.com/time-series-platform/influxdb/

set up as decribed in getting started section

Create a database in which you later wish to store the temperatures measured, for now we call it collectd_test.

In influxDB execute:

CREATE DATABASE collectd_test

Check if it was created properly using:

USE collectd_test

Exit using

EXIT

Stop the influxdb server by running:

sudo systemctl stop influxd

The configuration file is /etc/influxdb/influxdb.conf. The documentation can be found here: https://docs.influxdata.com/influxdb/v1.6/administration/config/

The config file we use is this.

The interesting part is:

[[collectd]]
  enabled = true
  bind-address = ":25826"
  database = "collectd_test"
  security-level = "none"

This enables the collectd plugin for influx and writes to the database we specify without any privileges required.

adjust the configuration file to be the same as above.

The collectd plugin for influx requires a types.db document. Copy this from /usr/share/collectd/ on the raspberry pi to /usr/local/share/collectd/ on the server running influxDB.

Start the server by typing

influxd

To check if there are values being written into the database, use another terminal or ssh to log into influx:

influx

USE collectd_test
SHOW SERIES

If something is displayed, try listing those values by using

SELECT * FROM <name of the time series>