OpenWebNet

OpenWebNet is a Communication Protocol developed by Bticino since 2000.

OpenWebNet Protocol allow a “high level” interaction between a remote unit and Bus SCS of MyHome domotic system.

Latest protocol evolution has been improved to allow interaction with well known home automation systems like KNX and DMX512-A system, by using appropriate gateways.

The OpenWebNet protocol is disclosed on MyOpen community.

OpenWebNet Protocol

The protocol is thought to being independent from the used technology. For example it’s possible to use a supervisor software connected via Ethernet, via serial RS-232 or via USB to a gateway that is directly connected to a domotic system.

Everyone can require protocol message extension. It's enough to propose your own RFC. It will be examined and disclosed if it respects OpenWebNet syntax.

Syntax

An OpenWebNet message is structured with variable length fields separated by the special character '*' and closed by '##'.

The characters admitted in the fields are numbers and the character “#”.

The structure of a message is therefore:

• field1*field2*… *fieldN##

The following fields are admitted: WHO WHERE WHAT DIMENSION VALUE

WHO

It characterizes the domotic system function to which the OpenWebNet message is referred.

For example: WHO = 1, characterizes the messages for lighting system management.

WHERE

It characterizes the set of objects to which the OpenWebNet message is referred. It can be a single object, a group of objects, a specific environment, the entire system, etc.

For every WHO (and therefore for every function) there is a specified WHERE table.

The tag WHERE can also contain optional parameters: WHERE#PAR1#PAR2… #PARn.

Example of where: all the lights of group 1, sensor 2 of zone 1 of alarm system, etc.

WHAT

It characterizes an action to do or a status to read. For every WHO (and therefore for every function) there is a specific WHAT table.

The field WHAT can also contain optional parameters: WHAT#PAR1#PAR2… #PARn.

Example of actions: switch ON light, dimmer to 75%, switch DOWN shutter, radio ON, etc. Example of status: light ON, active alarm, battery unload, etc.

DIMENSION

Is a range of value that characterizes the dimension of the object to which the message is referred. For every WHO (and therefore for every function) there is a specific DIMENSION table.

It’s possible to require/to read/to write the value of one dimension. Every dimension has a prefixed number of values, described in VALUE field.

Example of dimension: sensor temperature, loudspeaker volume, firmware version of a device, etc.

VALUE

It characterizes the read/written value of a written/required/read dimension.

Message

There are 4 types of OpenWebNet Message:

Command / Status Message

Status Request Message

Request/Read/Write Dimension Message

Acknowledge Message

Command / Status Message

*WHO*WHAT*WHERE##

Status Request Message

*#WHO*WHERE##

Request/Read/Write Dimension Message Request:

*#WHO*WHERE*DIMENSION##

Read:

*#WHO*WHERE*DIMENSION*VALUE1*...*VALUEn##

Write:

*#WHO*WHERE*#DIMENSION*VALUE1*...*VALUEn##

Acknowledge Message ACK:

*#*1##

NACK:

*#*0##

Gateway OpenWebNet

It's possible to interact with the SCS home automation bus by using a specific gateway.

There are two typologies of gateways that allow a connection to the field bus by using different standard protocols:

• Gateway Ethernet (Linux based)
• Gateway USB / RS232

Gateway Ethernet

The current implementation by BTicino is also an embedded web server. It works as a translator between OpenWebNet messages via TCP/IP and the SCS messages transmitted on the SCS bus.

Actually it is possible to control three different kinds of buses:

• BUS SCS
• KNX
• DMX

Gateway USB / RS232

The gateway is an interface that works as a translator between the OpenWebNet messages transmitted on USB or Serial and the SCS messages transmitted on the SCS bus.

Example

OpenWebNet message examples

Command Message

Switch Off of light 77

*1*0*77##

WHO = 1 WHAT = 0 WHERE = 77

Status Message

Scenario 1 of scenario unit 23 activated.

*0*1*23##

WHO = 0 WHAT = 1 WHERE = 23

Request status message

Status request of probe 1

*#4*1##

WHO = 4 WHERE = 1

Request Dimension Message

Request of Temperature Measured, probe 44

*#4*44*0##

WHO = 4 WHERE = 44 DIMENSION = 0

Read Dimension Message

Temperature Measured, probe 44

*#4*44*0*0251*2##

WHO = 4 WHERE = 44 DIMENSION = 0 VALUE1 = 0251 (T=+25,1°C) VALUE2 = 2 (System in "cooling mode")

Write Dimension Message

Volume set at 50%, environment 2

*#16*#2*#1*16*##

WHO = 4 WHERE = #1 DIMENSION = 1 VALUE1 = 16

See also

• Home automation
• KNX
• DMX

References

• Moneta, D. Mauri, G. Bettoni, C. Meda, R. - Cesi ricerca (Italy) http://www.cired.be/CIRED07/pdfs/CIRED2007_0522_paper.pdf Test Facility for the assessment of local energy management systems; 19th Conference on Electricity Distribution, Vienna (21–24 May 2007).

• Moneta, D. Bisone, L. Mauri, G. Meda, R. - Cesi ricerca (Italy) http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?tp=&arnumber=4209527&isnumber=4209049 New interactions between LV customers and the network: further possibilities for home automation functions ; IEEE International Conference on Robotics and Automation, Rome (10–14 April 2007).

• Bonino, D. Castellina, E. Corno, F. - Politecnico di Torino (Italy) http://www.cad.polito.it/pap/db/ictai08.pdf DOG: an Ontology-Powered OSGi Domotic Gateway; Torino (September 2008).

External links

• MyOpen Bticino
• DOG A Domotic OSGi Gateway able to expose different domotic networks as a single, technology neutral, home automation system. It supports OpenWebNet protocol.
• IANA, TCP ports assignment. OpenWebNet is associated to port 20005
• MyHomeVillage.com Description of home automation projects.