# KNX bus interface

<abstract>
This article explains how to install the knxd daemon on a CM3-Home and use it with the KNX bus interface. 
</abstract>

Tested with Raspberry Pi OS Release date: January 11th 2021

@include='knx_warning'

In this article we will control a KNX relay PLANA 1453 made by Vimar wired as shown below. The relay 
address was already configured. 

<img src="./cm3home_knx.jpg">

## Install knxd-tools

	sudo apt update
	sudo apt install knxd-tools

## Setup

Comment this line in __/etc/knxd.conf__:

	# KNXD_OPTS="-e 0.0.1 -E 0.0.2:8 -u /tmp/eib -b ip:"

and add this line in order to use the KNX port available on the CM3-Home board:

	KNXD_OPTS="-e 1.1.128 -E 1.1.129:1 -u /tmp/eib -b tpuarts:/dev/ttyAMA0"

Change the User and Group from __knxd__ to __root__ on __/lib/systemd/system/knxd.service__:

	[Unit]
	Description=KNX Daemon
	After=network.target knxd.socket
	Requires=knxd.socket
	
	[Service]
	EnvironmentFile=/etc/knxd.conf
	ExecStart=/usr/bin/knxd $KNXD_OPTS
	#User=knxd
	#Group=knxd
	User=root
	Group=root
	Type=notify
	
	Restart=on-failure
	RestartSec=10
	
	[Install]
	WantedBy=multi-user.target network-online.target
	Also=knxd.socket


then reload the systemd definitions: 

	sudo systemctl daemon-reload

and restart the __knxd__ daemom:

	sudo systemctl restart knxd.service

In case of errors check the log messages by typing:

	journalctl -f -u knxd

## Let's try to control the KNX relay

Relay ON:

	knxtool on ip:localhost 1/6/105
	
Relay OFF:

	knxtool off ip:localhost 1/6/105
	
## Links

* [Knxd repository on GitHub](https://github.com/knxd/knxd)
* [Command line parameters](https://github.com/knxd/knxd/wiki/Command-line-parameters)

@include='bio_guiott'
@include='bio_tanzilli'