01 Joost Demarest - KNX Association

www.knx.org

KNX RF – Then, Now, Future

Inn Style – Maarssen – 8 maart 2012

Joost Demarest – System and Admin Director

KNX Association Diegem/Brussels Belgium

KNX Radio Frequency

Mr. Joost Demarest

Page No. 2

March 12 KNX: The worldwide STANDARD for Home & Building Control

Contents

1. Original system requirements for KNX RF

2. Relevant standards

3. KNX RF Physical Layer

4. KNX RF telegram structure

5. KNX RF retransmitter functionality

6. KNX (RF) Easy Mode

7. KNX Bibat procedure

8. Recent KNX RF extensions

9. Future of KNX RF

KNX Radio Frequency

Mr. Joost Demarest

Page No. 3


Original system requirements for KNX RF

retrofit market mainly

home & residential market

Decentralised (no master) but

centralised functions possible

usable as stand alone solution and together with other KNX media

(media couplers)

Implementation on off-the-shelf components, small footprint

Re-transmitter use only for bigger installations

Bi- and unidirectional implementations possible

Low power consumption

for all application domains of home automation

lighting, shutters & blinds, security, HVAC, ..

KNX RF metering protocol as subsystem to KNX RF

Non-PC based programming (« Easy installation »), future tool

support

KNX Radio Frequency

Mr. Joost Demarest

Page No. 4


Layers 3-7 = EN 50090-series

Layers 1-2, approved by CLC/TC 205 as EN 50090-5-3

common solution with/according to CEN/TC 294

EN 13757-3/-4 (Metering!)

RF according to CEPT/ERC 70-03 (868 MHz - Band)

Data Link Layer according to IEC 870-5-2 (FT3 - Protocol)

Relevant Standards

KNX Radio Frequency

Mr. Joost Demarest

Page No. 5


KNX RF Physical Layer (1) acc. to CEPT/ERC 70-03

PO

WE

R [

ER

P ]

868.0 868.6 870 [MHz]

FREQUENCY

Application: SRD SRD MAC, SRD SRD

Alarms Alarms Alarms

Duty Cycle: < 1% < 1% < 0.1 % <0.1% t.b.d. <10 % < 10% 100%

[mW]

500

25

10

5

25 mW

10mW

25 mW

5 mW

10mW

25 mW

600 kHz 500 kHz 300 kHz 100 250 kHz

500mW

25 mW

100kHz

KNX Radio Frequency

Mr. Joost Demarest

Page No. 6


KNX RF Physical Layer (2)

Characteristic Value Remark

Frequency band 868 .... 868.6 MHZ 1% duty cycle

Center frequency fc = 868.300 MHz

Frequency tolerance +/-35 ppm +/-30.4 kHz

Modulation FSK

FSK deviation fDEV = ± 40 kHz to ± 80 kHz typically 50kHz

Rx Bandwidth 300 kHz

Rx sensitivity typical -95 dBm (BER 10-4) -80 dBm minimum

Tx minimum ERP 0 dBm

Bit coding Manchester

bit "0" is coded as fHI to

fLO transition, chip

sequence "10" bit "1" is

coded as fLO to fHI

transition, chip sequence

"01”

Bitrate 16.384 kBit/sec

Chiprate (transmit) 32.768 kChips/secenables usage of clock

crystal

Jitter per transition Tx +- 5 µsec

Blocking performance Class 2 EN 300 220 1, 9.3.3 for

class 2 receivers

Chip rate tolerance Tx +/- 1.5%

Chip rate tolerance Rx +/- 2%

KNX Radio Frequency

Mr. Joost Demarest

Page No. 7


KNX RF Physical Layer (3)

Characteristic Value Remark

Duty cycle 1 %

Preamble 30 Chips

Manchester violation chip sequence "000111"necessary for capture

effectSync word chip seq "011010010110"

Postamble 2 to 8 chips

Hamming distance 6

Protection CRC 16 bit

Data link layer IEC 870-5-1/2 FT3

Typical air time per frame ~16ms typical 4 byte datapoint

Retransmitters up to 3 cascading possible

KNX Radio Frequency

Mr. Joost Demarest

Page No. 8


KNX RF general frame structure

Preamble max. 15 x 01 chip preamble for synchronisation

Manch. Violation

Sync Word

Block 1 10 bytes fixed length, more info on next slide

CRC 2 bytes CRC after each data block

Further blocks 16 bytes details of block 2 on next slides

Last block 1 to 16 bytes

Postamble 2 to 8 chips provides defined end of frame

Block 1 CRC Preamble Block 2 Postamble CRC CRC ...

IEC870-5-2 (FT3)

KNX Radio Frequency

Mr. Joost Demarest

Page No. 9


KNX RF Block 1

Length 1 byte total number of user bytes counting

from C-field

C-field 1 byte fixed to value 44h

Esc 1 byte escape code to separate KNX from

metering (fixed to value FFh)

Ctrl 1 byte uni or bidirectional sender

signal strength

battery state

SN 6 bytes Serial number/domain address of

sender

C-field ESC Length Ctrl SN

KNX Radio Frequency

Mr. Joost Demarest

Page No. 10


KNX RF Block 2

Ctrl 1 byte standard or extended?

Standard frame variable difference with frame on other

media lies in

- LFN: duplication avoidance

- Domain address bit: indicates

significance of SN field in Block 1

Data variable actual payload, remaining in next

block

Standard frame Data Ctrl

KNX Radio Frequency

Mr. Joost Demarest

Page No. 11


Re-transmitter Technology

RT

T = Transmitter

= Receiver

= Retransmitter

R

M-1-2(LFN)

M-1(LFN)

M(LFN)

T

RT1

RT2

RM-1(LFN)

M(LFN)

M-2(LFN)

up to 3 Retransmitters are supported

No need for meshed networking

Link Layer Frame Number (LFN) + history list

solution to multipath communication

and avoiding message duplication:

routing counter

Limitation of number of retransmissions

short interframe time + random delay: 0...10 ms

avoiding collisions of retransmitted messages

Dedicated retransmitters avoid complexity and overhead in

normal end devices!

KNX Radio Frequency

Mr. Joost Demarest

Page No. 12


Concept of KNX Easy Installation

Device Functionality is made known to the partner device or configurator

via “E-Mode channels”

Instead of via ETS product database entries

Functionality of product is already contained in E-Mode device –

S-Mode device is in theory “empty”

E-Mode channels are a collection of data points and parameters

Each Group Object has one or more different connection codes, depending

on its functionality (e.g. switch, time, temperature, …)

During configuration, group objects with the same

connection code can be linked.

Push button: same approach but partner device decides

whether linking is possible

Easy installations are limited to one single line

KNX Radio Frequency

Mr. Joost Demarest

Page No. 13


Example Easy channel Heating actuator

KNX Radio Frequency

Mr. Joost Demarest

Page No. 14


KNX Easy Controller Mode

One single, central controller takes over role of ETS

Procedure

Assignment of unique individual address to each found E-Mode device

Read out of the E-Mode channels and parameters

Show capabilities of devices on controller’s display

Installer indicates which channels shall be linked

Controller decides on group addresses and parameters and

downloads the devices

I only have Channel

CH_motion_detector_basic here

Group

Addresses

Associations

Parameters

Group

Addresses

Associations

Parameters

According the links requested by the user, this is

your address table, association table and

parameters block:

Channel

CH_LIGHT_ACTUATOR_COMPLEX

selected here

According the links requested by the user, this is

your address table, association table and

parameters block:

KNX Radio Frequency

Mr. Joost Demarest

Page No. 15


KNX Push button Mode

No central intelligence

Procedure

Each device searches for itself a free Individual Address

Installers first selects actuator channel (e.g. by pressing a button)

Installer then selects sensor channel

Devices negotiate whether or not a link can be established

Linking must always be done two by two

I am 05FFh,

0100017A34AAh

I am 05FFh,

0908013FA14Dhh

Enter_Config_Mode

Start_Link

I am CH_light-actuator-complex

COOL.

I am ch_motion_detector_BASIC

I have an input

CC_TIMED_STARTSTOP

GrEAT! MY output cc_TIMED_STARTSTOP

HAS Group address 8300h. USE that!

KNX Radio Frequency

Mr. Joost Demarest

Page No. 16


Extended group address table because of

Unidirectional devices

T = Transmitter

= Receiver

T

R

Sensor 1 Device SN°

SN°=1

R T

Actuator

Device SN°

SN°=3

Partner SN°

SN°=1 GA=1

T

Sensor 2 Device SN°

SN°=2 GA=1 = Channel

SN°=2

Partner GA

GA°=1

GA°=1

Undirectional senders use fixed and unchangeable Group addresses

Partner device (actuator) has to have extended group address table –

combination with serial number of sensor device makes group address

unique

Big drawback: if sensor needs to be replaced also reprogramming

actuator!

KNX Radio Frequency

Mr. Joost Demarest

Page No. 17


RF extension for bidirectional battery powered

devices (BiBat)

Bidirectional battery-driven RF devices can’t be in receive-mode all

the time because of battery-lifetime

The BiBat extension reduces the active receive windows

of battery operated receivers to a minimum by means of a time slot

procedure

Application:

- heating actuators for radiators

- bidirectional room units

- fire/smoke sensors remote controls with

feedback

Typical battery life times 1-3 years

KNX Radio Frequency

Mr. Joost Demarest

Page No. 18


Recent extensions KNX RF

RF « ready »

Single RF channel version – upgrade of version 1 of KNX RF

RF « multi »

3 fast RF channels and 2 slow RF channels

Bibat

single RF channel version, unchanged compared to version 1 of

HBES RF

Bibat 2

2 RF channels

KNX Radio Frequency

Mr. Joost Demarest

Page No. 19


KNX RF Ready

Single channel, evolution with 4.8ms preamble for Tx

Rx change to ignore some bits in CTRL field

The rest of the stack remains the same

Only a software upgrade of existing products

All new developments shall be RF ready

500mW

868MHz 868.3 868.6 868.9 869.2 869.4 869.7 870MHz

Bibat

KNX RF ready

Duty Cycle 1%

25mW

KNX Radio Frequency

Mr. Joost Demarest

Page No. 20


KNX RF multi

3 RF fast channels for low latency devices

2 RF slow channels for battery powered devices

F3 optional

25mW in F3 is now allowed by regulation

Energy savings Allow very low power consumption for receivers

KNX Radio Frequency

Mr. Joost Demarest

Page No. 22


Compatibility scheme

Existing Add

KNX RF « ready »

products

Tx Ok

Rx Ok

Single channel

Tx Ok

Rx Ok

Tx Ok Rx Ok

Multi channel

Add

KNX RF « multi »

products

Downgrade via

manuf specific

action

KNX RF « ready »

products

Add

KNX RF « multi »

products

Add

KNX RF « multi »

products

Existing

KNX Radio Frequency

Mr. Joost Demarest

Page No. 23


Future of KNX RF (1)

KNX is No. 1 system for home and building control

Especially for the professional market with complex installations

Only system with several supported media

Only system with scalable configuration modes

Usable in different application domains

Supported by many manufacturers

Accepted by many installers

Current Radio Frequency situation

Radio Frequency is a high volume and fast growing business

Many manufacturers however develop and market proprietary

solutions

Many manufacturers wish to change to an open standard

There is no clear number one RF standard, many “standards”

still result in products with proprietary communication

KNX Radio Frequency

Mr. Joost Demarest

Page No. 24


Future of KNX RF (2)

Current KNX RF situation

Insufficient number of involved manufacturers

Insufficient number of available devices

Specification of Encryption and Authentication still work in progress

Use of different configuration modes leads to impossibility to link products of different

manufacturers

No direct tool support - support of current KNX RF solution would lead to difference in look

and feel of ETS for RF

Coupling to TP via manufacturer media coupler specific solutions and ETS plug ins

Not usable for complex installations

What is needed ?

Streamline addressing scheme between TP/PL and RF

If accessed by ETS, devices shall allow the use of a domain address common to the

installation instead of individual serial number

Possibility to develop much simpler media couplers between TP and RF

Finalize the KNX Security concept for encryption and authentication

Support RF in ETS and add RF to KNX Basic course training

www.knx.org

Thank you for your attention!

For more information

Joost Demarest – KNX Association cvba

Tel: +32 2 775 86 44

E-Mail: [email protected]

Web: www.knx.org

mailto:[email protected]

http://www.knx.org/

01 Joost Demarest - KNX Association

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