Connecting Emoncms with openHAB

In this post I’ll explain how energy data from Emoncms can be made visible in openHAB. My scenario is as follows: I have Emoncms running on a dedicated Raspberry Pi and openHAB running on another server. This will also work if you have both systems running on the same machine. My goal was to make the energy data visualized in Emoncms available in openHAB and display it there, too.

Find the MQTT Configuration

First, we need to find the MQTT configuration for EmonHub. This can be found on the Emoncms web interface by navigating to Setup | EmonHub | Edit Config | Section [[MQTT]]

We will need this data later to connect the MQTT broker.

Install the MQTT Binding in openHAB

On your openHAB web interface, open the Paper UI and install the MQTT binding:

Add an MQTT Broker

In the openHAB Paper UI, add a new thing of type MQTT Broker. As broker hostname/IP, enter localhost or 127.0.0.1 if your Emoncms installation is on the same device. Otherwise, enter the local IP address of the machine running Emoncms.

Also, the username and password you configured in the MQTT configuration of your EmonHub (see above) must be entered:

Add a MQTT Thing

Now we can create a thing representing your Emoncms / EmonPi. Select the broker you just created as bridge.

Create channels for each value you want to transfer between Emoncms and openHAB. For example, for my first power value I created a new Number Value Channel and entered the following MQTT State Topic:

emon/node1/power1

The exact name depends on your Emoncms configuration. In the example, a node named node1 is configured which receives power values in a channel named power1.

We now have a number value channel in openHAB which looks like this:

Add openHAB Items

For each channel we can now create items an openHAB items file. For the channel above, my item looks like this:

Number:Power Energy_Power1 "Power 1 [%d W]" <energy> (gEnergy) { channel="mqtt:topic:fc2fe9b1:power1" }

Note that I have defined a group named gEnergy in my openHAB configuration. You can read more about group configurations here. Now we can use the item Energy_Power1 in openHAB (for example in sitemaps). Create other channels and items accordingly. Now you can monitor your energy data in Emoncms and openHAB at the same time 🙂

Controlling 433 MHz Power Outlets with openHAB2

I’m currently building a home automation system based on the incredibly powerful openHAB 2 platform. We already have a few remotely switchable 433 MHz power outlets by the manufacturer Brennenstuhl in our home which we currently switch using the provided remote controls. I was wondering whether we could control them from the OpenHAB platform as well, and indeed found a way to achieve this.

My openHAB 2 instance does not run on a Rasberry Pi, but on a dedicated Ubuntu Server. If your platform is Raspberry, your hardware setup and configuration might be different, but still I think this article will be useful for the OpenHAB binding configuration.

Hardware

First, I looked for a suitable device capable of sending and receiving 433 MHz signals. I ended up with a nanoCUL device connected via USB. There are many DIY nanoCUL kits available on the internet that you can assemble yourself, but there are also pre-built nanoCULs available. I chose the latter and ordered an assembeled nanoCUL USB device including an antenna and a USB adapter. It looks like this:

nanoCUL with antenna and USB adapter

OpenHAB Binding

After some research I found a suitable binding to integrate nanoCUL with openHAB: it is called Intertechno Binding. It is an older v1 binding, and is not displayed in my Bindings list after the installation (even when activating the Include Legacy 1.x Bindings option). But it works nonetheless.

To configure the nanoCUL, edit the file services/culintertechno.cfg and add the following configuration:

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device=serial:/dev/ttyUSB1 
baudrate=38400
parity=NONE

You have to adjust the device (in my case /dev/ttyUSB1) to the device matching the nanoCUL on your system. To find out which device it is, I used a script I found in this stackexchange answer.

Binding the Device using a Unique Identifier

After a few reboots I discovered an issue: sometimes, the nanoCUL was bound to /dev/ttyUSB1, other times to /dev/ttyUSB0. This lead to errors and conflicts in openHAB. To solve this problem, I used a device path like the following in services/culintertechno.cfg:

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device=serial:/dev/serial/by-id/<id of your nanoCUL>
You can find the device ID of your nanoCUL using
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ls -la /dev/serial/by-id/
But when I started openHAB2, the following error occurred:
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org.openhab.io.transport.cul.CULDeviceException: gnu.io.NoSuchPortException
I found out that this can be solved by adding the device path to the java startup options of openhab2. In my case, these can be configured in /etc/default/openhab2:
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EXTRA_JAVA_OPTS="-Dgnu.io.rxtx.SerialPorts=/dev/serial/by-id/<id of your nanoCUL>"
After adding the option and restarting openhab2 with sudo service openhab2 restart, the error disappeared and now the system has the correct device association after every reboot.

Item Configuration

The tricky part was to find out which codes to send to switch the power outlets on or off. After long research, I found this FHEM Wiki page which finally helped me to figure out the codes. The power outlets are configured with DIP switches like the following:

The first 5 switches identify the logical group of power outlets. The remote control that comes with the power outlets has the DIP switches 1-5 only (excluding A-E). A-E identifies one of 5 power outlets in the group.

To derive the code to be sent from openHAB, you just have to translate the switch states into a sequence of 0 and F, where 0 corresponds to “switch up” and F corresponds to “switch down” (I did not get why “switch up” is encoded with a lower value than “switch up”, but anyway this is how it works for me). So for the switch states shown above, the code is

0F00FF0FFF

This is the basic code to address a specific power outlet in a specific group, where the first five digits encode the group and the last five hex digits the outlet in the group. To control whether the outlet should be turned on or off, one the following two codes has to be appended: FF = ON or F0 = OFF. So in conclusion, to switch on the above outlet, the complete code is

0F00FF0FFFFF

and to switch it off, the code is

0F00FF0FFFF0

In the item configuration, this is added as follows:

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Switch MyOutlet_B "My Outlet B" {culintertechno="type=raw;commandOn=0F00FF0FFFFF;commandOff=0F00FF0FFFF0"}

And that’s it folks, it works like a charm for me 🙂 I hope this post will be useful to others who want to integrate their 433 MHz power outlets in openHAB 2.