Battery-Free Wireless Pushbutton
Battery-Free Wireless
Pushbutton
Useful Tips for Reliable Range Planning
DUX Schaltgeräte GmbH, Schönbachstraße 93, D-04299 Leipzig, 2010-11-12
Tel.: +49 (0) 341 / 8 68 72-0, Fax: +49 (0) 341 / 8 68 72 33, info@dux.de, www.dux.de
1. INTRODUCTION
Compared to wireline systems, wireless solutions enable convenient installation and greatest
flexibility. Based on the physics of radio wave propagation, certain basic conditions must be
observed. The straightforward recommendations in this guide apply to our battery-free radio
bus system based on the ENOcean technology and shall ensure correct installation and
reliable operation of the system.
2. PRINCIPLES OF WIRELESS SIGNALS IN BUILDINGS
The radio transmitters send event-triggered telegrams to the radio receiver. The receiver, also
known as actuator, checks the incoming telegrams and thus controls its outputs. Since the radio
signals are electromagnetic waves, the signal is attenuated on its way from the transmitter to
the receiver. That means, the field strength decreases with increasing distance between
transmitter and receiver, so, the transmission range is limited.
The fact that certain materials are affecting the transmission range must also be taken into
consideration.
It is true that radio waves can penetrate walls, but thereby the attenuation increases even more
than by a propagation in the free field. Here are some examples of different wall types :
Material
Attenuation
Wood, plaster, uncoated glass
Brick, pressboard
Ferro concrete
Glass with metal coating
Metal, aluminium coating
0...10%
5...35%
10...90%
60...90%
90...100%
Moreover, the way of installing the transmitter and especially the receiver is of great
importance. It should definitely be avoided to mount them e.g. in electrical distributors made of
steel, behind metal covers or in lights.
In practice that means that the materials used in buildings are of paramount importance for the
evaluation of the transmission range.
Here are some guiding values to facilitate the evaluation of the environment:
Lines of sight: typical: 30 m range in corridors, up to 100 m in halls
Plaster walls /dry wood:
typical: 30 m range through max. 5 walls
Brick walls / aerated concrete:
Ferro-concrete walls /ceilings:
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
typical: 20 m range through max. 3 walls
typical: 10 m range through max. 1 ceiling
Seite 2 von 13
3. Screening
Metallic parts, such as reinforcements in walls, metallic foils of thermal insulations or metalised
heat-absorbing glass, reflect electromagnetic waves. Thus, a so-called radio shadow is built up
behind these parts, an area that cannot be reached by the radio transmitters.
Some major conditions that can restrict the transmission range:
•
Installation of switch on a metal wall (typical loss of range 30%)
•
Use of metallic switch frames (typical loss of range 30%))
•
Hollow lightweight walls filled with insulating wool on metal foil
•
Inserted ceilings with panels of metal or carbon fibre
•
Lead glass or glass with metal coating, steel furniture
•
Installation of actuators in lights
•
Installation of actuators in blind boxes
•
•
Installation of actuators in concrete floor junction boxes
Tip 1 Fire-safety walls, lift shafts, staircases and service areas should be considered as
screening areas.
Tip 2
Avoid screening by repositioning the transmitting and/or receiving antenna away
from the radio shadow, or by using a repeater.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 3 von 13
4. PENETRATION ANGLE
The angle at which the transmitted signal hits the wall is very important. Depending on this
angle, the effective wall thickness and thus the signal attenuation varies. If possible, the signals
should run vertically through the walling. Walling recesses should be avoided.
Tip 3
Remedy an unfavourable penetration angle by repositioning the transmitting
and/or receiving antenna, or by using a repeater.
5. ANTENNA INSTALLATION
Radio receivers with internal receiving antenna should not be installed on the same side of the
wall as the transmitter. In the wall area, radio waves are rather subject to an interfering
scattering or reflection. Hence, the antenna should be mounted on the opposite side or
adjacent.
Tip 4
Avoid radio propagation along a wall area.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 4 von 13
When using devices with external antenna, the ideal place to install it is in the center of the
room. As far as possible, the antenna should be at least 10 cm away from the wall or concrete
ceiling.
A magnetic base antenna must be attached onto a large metal surface in order to create an
adequate antipole. Due to the polarisation of the radio waves, the magnetic base antenna
should be aligned vertically. When installing the antenna cable make sure not to bend it as
this may cause an irreparable damage (performance reduction through change of
characteristic wave impedence).
Tip 5 A so-called „active antenna“ is a radio receiver with attached antenna, which
communicates with the actuator e.g. via a shielded cable. The cable should not be bent
during installation and preferably not be extended, because the signal degrades with
increasing length. All receivers of the type S_789-601, S_789-602 and S_8003-001 can use
the external receiving antenna S_758-910. Hence, the receivers can also be installed in steel
cabinets and the like.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 5 von 13
6. DISTANCE BETWEEN RECEIVERS AND OTHER SOURCES OF INTERFERENCE
Radio transmitters can be mounted to any other transmitters without problems. However, the
distance between the radio receivers and other transmitters (e.g. GSM / DECT / Wireless
LAN) and high-frequency sources of interference (lights, transformers, computers, audio and
video equipments) should be at least 50 cm.
Tip 6
The distance between the radio receiver and other high-frequency transmitters
should be at least 50 cm, the transmitter position is not critical.
7. USE OF REPEATERS
In case of poor reception quality it may be helpful to use a repeater. Repeaters mostly do not
require any configuration (e.g. programming) and are simply put into operation by connecting
them to the supply voltage. Possible applications are shown in the illustrations of the chapters
„Screening“ und „Penetration“.
Tip 7
In the preliminary planning stage, it may be worth to consider a retrofitting of the
system with radio repeaters.
Some radio repeaters cannot be cascaded in their basic function; already repeated telegrams
are not repeated again („1-level“ repeater). Repeaters which can be switched to 2-level
function permit cascading of two repeaters but which are rarely required in the building
technology.
Tip 8
The use of too many repeaters is counterproductive (higher costs, telegram
collisions).
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 6 von 13
8. FIELD INTENSITY METER
The EPM100 is a mobile field intensity meter enabling the installer to easily determine the
optimal mounting positions for sensors and receivers. Furthermore, it can be used for checking
faulty connections of already installed devices. The meter indicates the field intensities of
received radio telegrams and any interfering radio signals in the 868MHz range:
The lighting-up of the GREEN LED signalises that the received field strength has sufficient
power reserve for a reliable installation. So, any later changes of the ambient conditions
(additional attenuation due to the installation of lightweight walls, shadowing by people in the
room, etc.) will not affect this reserve. To distinguish a possible interfering transmitter the
YELLOW LED simultaneously signalises a valid radio telegram.
How to use the field intensity meter and determine the mounting positions of sensors and
receivers: Person 1 operates the radio sensor and generates radio telegrams by pressing the
button. Person 2 checks on the meter the received field intensity and thus determines the ideal
mounting position.
Field intensity meter EPM100 and field intensity testing set EPM200
Tip 9 The field intensity meter EPM100 permits on-site determination of the ideal mounting
position as well as identification of an interfering transmitter.
Tip 10
Even after careful planning, the EPM100 should be used during installation to verify
proper reception at the receiver position.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 7 von 13
9. PLANNING GUIDE FOR COMMERCIAL BUILDINGS
Wireless coverage in commercial buildings is usually restricted by fire-safety walls that must be
considered as screening. Inside the fire-protection zones lightweight or glass partition walls are
generally used as featuring good radio propagation properties (except for metal
reinforcements or metalised walls!). The two common installation architectures are:
•
Automation Systems (e.g. TCP/IP, LON, EIB)
To ensure complete coverage 1 to 2 wireless gateways placed centrally to the automation
bus are sufficient per fire-protection zone (see illustr. under Tip 12)
•
Direct Control of the Actuators
Typically, the wireless paths to be covered are not very long (“cubicle installation”)
Unfavourable conditions can be improved by an appropriate repositioning of the devices (or
antennas), or by using a repeater. In the latter case, please observe the application and
installation instructions in chapter 7 „Use of Repeaters“.
Tip 11
For a highly robust wireless transmission system it is advisable to implement a
redundant radio receiver path. For this purpose, programme two gateways for
parallel reception of one radio transmitter or install one repeater per radio cell.
placing of the
gateway antennas
dead spots
fire barriers
lift shaft, staircases, service
shafts, toilets
Tip 12
Position the wireless gateways in a way to ensure that no screening blocks the
connection to any corner inside the fire-protection zone (potential sensor positions).
10. PLANNING GUIDE FOR RESIDENTIAL BUILDINGS
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 8 von 13
For applications restricted to one or two rooms (e.g. when retrofitting a switch or an awning),
the direct transmission range is usually adequate. For applications „throughout“ the building,
one needs to differentiate as follows:
Flats, terraced or single-family detached houses up to 400 sqm
•
•
•
Larger residential units up to 3 rooms (living and bedroom) should be equipped with a
radio repeater. The local position of the repeater is not critical, but should be placed
centrally in the residential unit (e.g. in the center of the middle floor).
The radio repeaters are designed in a way that a second repeater can be added in case
of heavy ceiling reinforcement or other screening.
Note: The use of too many repeaters is contraproductive (higher costs, telegram collisions).
Multi-family Residences and Multi-storey Buildings
•
•
Use separate radio systems for each flat.
One radio gateway per flat can be used for cross-property connection via an established
automation system (e.g. EIB, LON, TCP/IP, usw.) eingesetzt werden.
Small Residential Unit (up to 3 walls and 1 ceiling)
transmitter or receiver
Tip 13:
For a studio apartment or 2 floors of a town house, the direct transmission range is
usually adequate.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 9 von 13
Multi-room flat and single-family detached house
(more than 3 walls, more than 1 ceiling)
Tip 14
In a larger residential unit, it is generally advisable to install a central repeater to
ensure wireless coverage.
Extreme example in a single-family detached house
Tip 15
In rare cases of heavily reinforced concrete ceilings or thick basement walls, a
second repeater may be necessary to ensure full coverage (both repeaters must be
switched to 2-level function, see information in chapter 7).
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 10 von 13
11. WIRELESS SYSTEM DEBUGGING
Check-up with the EPM 100
The EPM 100 has 4 LED's in the upper part 4.
no radio signal
Ο
red
border area good reception
Ο
Ο
yellow
green
telegram
Ο
yellow
When observing the above information on selecting the ideal mounting place for
transmitters and receivers, a smooth operation of the devices should be ensured.
Nevertheless, should you encounter any wireless transmission problems, the following
debugging table may be a useful tool:
Fault
Possible Cause
Transmitter
received not
at all
Transmitter fails to send
Checking and Remedy
Place the EPM100 near to the sender (distance abt.
20-50cm).
Activate a transmission telegram – both, the green
LED and the yellow one for telegram fail to light
up. If only the green LED lights up no telegram will
be transmitted.
→
Check the transmitter. When operating in both
directions, a distinct click should be heard; when you hear
the clicking but the transmitter fails to send properly , it must
be replaced.
Transmitter is installed
Near the receiver (distance abt. 20-50 cm) the
outside the receiver range EPM100 does not reiceive a transmission telegram:
Activate a transmission telegram - only the red LED of the EPM
lights up.
→
Reposition the transmitter or receiver by observing the
hints for range planning and mounting.
Transmitter was removed Program new transmitter into the receiver
(or possibly exchanged)
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 11 von 13
Receiver does not receive Near the receiver (distance abt. 20-50cm) the EPM
100 has good reception of the transmission
telegram. Both, the green LED and the yellow one
for telegram are lighting up.
→
Check the receiver and the receiving antenna.
If only the yellow LED for the border area and the yellow one
for the telegram light up, it may happen that the receiver
does not respond because it has been installed e.g. in the
wall.
Transmitter not
programmed
Reprogram the transmitter into the receiver
Antenna not correctly
installed
Check antenna connection
Interfering transmitter
existent
At least one of the GREEN LED's of the EPM100
lights up occasionally but none of the YELLOW
ones: Invalid telegrams are occasionally received
→
Fault
Remove source of interference
Possible Cause
Checking and Remedy
Interfering transmitter
permanently existent
Near the receiver either the yellow LED (for border
area) of the EPM100 or the green LED lights up.
→
Remove source of interference
High-frequency source of Remove the source of interference (telephone, PC, etc.),
interference near the
distance at least 50 cm to the ENOcean receiver
receiver
Near the receiver (distance abt. 20-50 cm) the
Transmitter is Transmitter is placed in the
EPM100 receives transmission telegrams only in
intermittently border area of receiver's
the border area: Activate a transmission telegram – only
not received range
the two yellow LED’s are lighting up.
→
Reposition the transmitter or receiving antenna or install
a repeater.
Temporary change of
ambient conditions
(cabinet, door, plants,
people, interfering
transmitter)
Check distance to high-frequency sources of interference, at
least 50cm. Otherwise refer to “Transmitter is placed in the
border area of receiver's range“
The mounting place of the
Reposition the transmitter within the reception range
transmitter changes
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 12 von 13
occasionally (e.g.
transmitter mounted on a
mobile object)
Interfering transmitter
existent
Near the receiver either the yellow LED (for border
area) of the EPM100 lights up temporarily, or the
green LED.
→ Invalid telegrams are occasionally received.
If the frequency of 868.3MHz is used by several systems, it
may of course happen that two or more signals meet . In this
case one has to accept the facts.
DISCLAIMER
The information provided in this document serves to describe typical features of the radio bus
system and are not to be understood as specified operating characteristics. No liability is
assumed for any errors or omissions. We reserve the right to make changes without prior
notice.
DUX Schaltgeräte GmbH
Schönbachstraße 93, D-04299 Leipzig
Tel.: +49 (0) 341 / 8 68 72-0
Fax: +49 (0) 341 / 8 68 72 33
info@dux.de, www.dux.de
Seite 13 von 13
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