How to use B control energy manager with openHAB

How to read the wattage and electric energy from B-control energy managers EM100, EM210 and EM300

Introduction

The B-control energy manager is mostly used in combination with an solar powered system to measure the energy and wattage. B-control released the specification of the JSON and the Modbus interface. With this information, it is possible to get the data and use it with openHAB.

Getting data over JSON

The following instruction use the Exec Binding in combination with a Linux bash script. Additionally the software tools cURL and jq are required. CURL and JQ are included in most Linux distributions. If jq is not available on a particular Linux distribution, you can download it from the project homepage.

The Bash script bcontrol reads the data over the B-Control Energy Manager JSON interface and writes the output to the file bcontrol.out in the path /opt/bcontrol.

Before continuing with this example, create the folder bcontrol in /opt.

Create the file bcontrol and copy the folowing content in to it. Make the file executable.

#!/bin/bash
# Script to get data from B-Control Manager over the JSON interface

# path to write JSON output
JsonPath="/opt/bcontrol"

# file name for JSON output
JsonFile="bcontrol.out"

# file Name cookie-file (output of curl)
CookieFile="cookie.txt"

# IP addresse of B-Control manager
BcontrolIP="192.168.1.12"

# build needed path and links
JsonOutput="${JsonPath}/${JsonFile}"
CookiePath="${JsonPath}/${CookieFile}"
JSONLink="http://${BcontrolIP}/mum-webservice/data.php"
LoginLink="${BcontrolIP}/start.php"

# get data (JSON) from B-Control Manager
curl -s -b $CookiePath -X GET $JSONLink > $JsonOutput

# check if login is pass
AuthError=$(/usr/local/bin/jq 'has("authentication")' $JsonOutput)

if [ $AuthError  = "true" ]
then
  echo "Login Error: Login will be repeat!"
  curl -s --cookie-jar $CookiePath $LoginLink > /dev/null
  curl -s -b $CookiePath --cookie-jar $CookiePath -d "login=<serial-no>&password=<password>&save_login=1" $LoginLink > /dev/null
  curl -s -b $CookiePath -X GET $JSONLink > $JsonOutput
fi

# Rueckgabe des gewuenschten Wertes
case "$1" in
	CurrentConsumption)	echo $(/usr/local/bin/jq '.["1-0:1.4.0*255"]' $JsonOutput);;
	CurrentFeeding)		echo $(/usr/local/bin/jq '.["1-0:2.4.0*255"]' $JsonOutput);;
	TotalConsumption)	echo $(/usr/local/bin/jq '.["1-0:1.8.0*255"]' $JsonOutput);;
	TotalFeeding)		echo $(/usr/local/bin/jq '.["1-0:2.8.0*255"]' $JsonOutput);;
	*)			echo "unknown parameter!"
				exit 1;;
esac

exit 0

Replace / with the USER name (default is this the serial number of the B-control manager), / with the password of the B-control manager (if no password has been set, leave it blank) and change the IP Address of the B-control manager.

Now you can test the script without openHAB with the command:

/opt/TQManager/bcontrol TotalConsumption

If everything is okay, you will get a valid value. You are now able to use the scrit in openHAB.

To use the script in openHAB, copy the Exec Binding to the folder called addons. In your items file you can define the following Number items.

Number BCM_consumption_wattage		"current wattage consumption [%.1f W]"	{exec="<[/opt/bcontrol/bcontrol@@CurrentConsumption:5000:REGEX((.*?))]"}
Number BCM_feeding_wattage		    "current feeding wattage [%.1f W]"	    {exec="<[/opt/bcontrol/bcontrol@@CurrentFeeding:5000:REGEX((.*?))]"}
Number BCM_energy_value_consumption	"energy value consumption [%.1f Wh]"	{exec="<[/opt/bcontrol/bcontrol@@TotalConsumption:10000:REGEX((.*?))]"}
Number BCM_energy_value_feeding		"energy value feeding [%.1f Wh]"	    {exec="<[/opt/bcontrol/bcontrol@@TotalFeeding:10000:REGEX((.*?))]"}