datasheet for KDEC by Radiometrix

datasheet for KDEC by Radiometrix
Hartcran House, 231 Kenton Lane, Harrow, Middlesex, HA3 8RP, England
Tel: +44 (0) 20 8909 9595, Fax: +44 (0) 20 8909 2233,
Issue 2, 27 July 2012
KDEC is designed to provide the user
with a complete receiver interface for
Radiometrix transmitters such as KTX2
and KFX2. No additional parts needed to
implement a complete system suitable for
applications requiring high security RF
remote control.
Figure 1: KDEC board
Up to 5 relays to control mains powered devices rated up to 8A, 250VAC/30VDC
Volt-free changeover contacts
Learn button - remembers up to 16 different transmitters
Remembers transmitters when switched off
Visual indication of Learn function
Visual indication of low supply voltage at the Transmitter
Visual indication of activated relays
Momentary or Latched outputs
Basic antenna included - setup is simple as Plug-and-Play
Receiver module on-board
Terminal block to connect external power supply
SMA RF connection
9 – 16VDC supply
Quiescent current consumption: 20 to 25mA @ 12V
Current consumption (with all LEDs and relays active): 180- 185mA @ 12V
RF interface for Security and Alarm systems
Status reporting and monitoring secure systems
Industrial controls
HVAC controls
Wireless door entry systems
Simple On/Off switching
General Description
KDEC is optimised for use with the KFX2 (Key-fob transmitter) or KTX2 modules by means of a jumper link on
the PCB, according to the preference of the user.
When optimised for KFX2 it is not possible to activate more than one output per transmission and up to 5 relay
outputs are available, matching the number of button inputs on the KFX2.
Alternatively, when optimised for use with the KTX2 module, the KDEC has simple output functionality. New
function-codes are fed to the relays as they are received, e.g. reception of a function-code (S0, S2) will
activate relays 1 and 3 simultaneously. For both versions, momentary/latched relay action is also selected by
means of a jumper link on the board.
Visual Indications
The following status LEDs will light, depending on the status of KDEC.
Relay active (Red)
TX Low Battery (Red)
Learn/Learnt (Orange)
POWER (Green)
Relay energised; S0-S3 Function-code output
Transmitter supply voltage <3.8V (approx.)
Multi-function indicator – see below
Power supply present
Using KDEC
Learning a transmitter
The Learn button is pressed momentarily (<1s) and a 6-second (approx.) window follows, during which the
Learn LED is lit and a message received from a Radiometrix code-hopped transmitter during this period is
used to Learn that transmitter into the KDEC memory. The function code used to activate the transmitter
during learning is also stored in memory and when the same function code is used again from that transmitter
during normal operation the Learn LED lights to indicate this. Note: if a transmitter has already been stored it
is simply re-learned (with the function code updated if this is different). Upon learning a transmitter the Learn
LED flashes several times to indicate success.
Activating output relays
Once a transmitter has been learned its transmissions will be acted upon, i.e. the function code contained
within the transmission is fed to the output relays. When optimised for use with KFX2, extra processing
ensures that only one relay at a time is energised.
Either momentary or toggled/latching outputs can be used. Note that this distinction applies to all the outputs,
not individual relays. When Momentary Output mode is selected the output is activated for a short period (470
– 570ms) for reception of a single message. If the same message is received repeatedly the output status is
refreshed during this period: in effect, the output is “held-on” whilst a user keeps the relevant function line
enabled at the transmitter. When Latched Output mode is selected the decoding of a single message causes
the function-code within the message to toggle the output(s).
Care should be exercised when using Latched (or more accurately ‘toggled’) mode with KDEC optimised for
use with KTX2; consider the following example: one function-line (S0) is taken high and held high at the
transmitter. On reception of the message, Relay 1 will change state. Whilst the same message is being
decoded the relay will not change state again. However, if another function-line (e.g. S1) is taken high whilst
S0 is still held high, it will cause a new transmission with new hop-code and new function code (S0, S1). On
reception of this message Relay 2 will change state but so will Relay 1, since the new message contains S0
and S1, which toggles Relays 1 and 2 of the KDEC.
KDEC optimised for KFX2 (being a key-fob transmitter with up to 5 buttons) deals with this issue by not
responding to additional button-presses whilst one button is already pressed. However, this is at the expense
of removing transparency to the function-code being received. The user may require more than one relay to
be activated at once: in this case, KFX2 optimised mode should be used.
Clearing the memory
When the memory is full, no new transmitters can be learned. To clear the memory of all stored transmitters,
the Learn button is pressed and held for more than 6s approx. The Learn LED will go out and upon releasing
the button it will flash once to indicate that the memory has been cleared. It is not possible to remove
individual transmitters from the memory.
Jumper settings
Relay Mode
Position A
(or not fitted at all)
KFX Keyfob optimised
Position B
KTX Module optimised
Latching / Toggled
Jumper T position is only read at power-up and should be set before power is applied.
Jumper M position is read repeatedly during operation and can be changed at any time.
SAFETY WARNING: Extra care should be taken when handling the electrical connection from relay to 250AC
device. Mains power should be disconnected before connecting the wires to 3-way terminal blocks to prevent
electric shock. Exposed wires or terminal block should not be touched during evaluation.
Code-hopped messages – technical brief
Transmission format is 1250bps (nominal rate) Manchester encoding. Although the function-code is only 4
bits, total message length is 67 bits. This includes a 28-bit serial number and a 32-bit encrypted hop-code.
Note that the serial number and function code data is not encrypted. The correct status of the transmission is
used to validate the data. This is achieved through use of the ever changing hop-code (changes for every
new message) and by synchronising the KDEC to the transmitter(s) in use. Put another way: KDEC “Learns”
individual unique transmitters, as required by the user.
The hop-code is encrypted using the serial number of the transmitter plus the manufacturer code (64- bit),
which is kept secret and is not transmitted. The function-code (S0-S3) appears twice in the message and
forms a part of the hop-code encryption process.
If KDEC loses synchronisation with the transmitter (e.g. repeated transmitter activation whilst out of range)
then the transmitter must be activated twice with valid and sequential hop-codes before KDEC will allow the
control to be processed. The hop-code is only valid if it is within a forward window of +32768 activations. This
mechanism prevents “code-grabbers” from breaking the security of the system by recording and rebroadcasting old codes. Additionally, KDEC allows up to 14 transmissions to occur whilst the transmitter is out
of range before two valid sequential transmissions are required to use the system. In practice a user may not
notice the latter, since human reaction to the unsuccessful attempt is simply to “press the button again”.
The level of redundancy and encryption in a message mean that, in simple terms, KDEC will only output a
function-code that has been received from a properly recognised and synchronised transmitter.
9A825258E !8C
Figure 3: Timing diagram – showing action upon receiving a message with S0 = 1
The typical time delay between a “button-press” at the transmitter and relay activation by the KDEC board is
Ordering Information
Where “xxx” is frequency band in MHz – 433 is standard.
Please contact sales for other requirements.
Whilst the KDEC will operate with both KFX and KTX transmitters regardless of Jumper settings, it is
recommended that Jumper T be placed in position A (or not fitted at all) when KDEC is used with 4
and 5 button Key-fobs. For these key-fobs, a combined function-code (S0, S2) is used as the code
for one of the buttons.
Radiometrix Ltd
Hartcran House
231 Kenton Lane
Harrow, Middlesex
Tel: +44 (0) 20 8909 9595
Fax: +44 (0) 20 8909 2233
Copyright notice
This product data sheet is the original work and copyrighted property of Radiometrix Ltd. Reproduction in
whole or in part must give clear acknowledgement to the copyright owner.
Limitation of liability
The information furnished by Radiometrix Ltd is believed to be accurate and reliable. Radiometrix Ltd
reserves the right to make changes or improvements in the design, specification or manufacture of its
subassembly products without notice. Radiometrix Ltd does not assume any liability arising from the
application or use of any product or circuit described herein, nor for any infringements of patents or other
rights of third parties which may result from the use of its products. This data sheet neither states nor
implies warranty of any kind, including fitness for any particular application. These radio devices may be
subject to radio interference and may not function as intended if interference is present. We do NOT
recommend their use for life critical applications.
The Intrastat commodity code for all our modules is: 8542 6000
R&TTE Directive
After 7 April 2001 the manufacturer can only place finished product on the market under the provisions of
the R&TTE Directive. Equipment within the scope of the R&TTE Directive may demonstrate compliance
to the essential requirements specified in Article 3 of the Directive, as appropriate to the particular
Further details are available on The Office of Communications (Ofcom) web site:
Information Requests
Riverside House
2a Southwark Bridge Road
London SE1 9HA
Tel: +44 (0)300 123 3333 or 020 7981 3040
Fax: +44 (0)20 7981 3333
European Communications Office (ECO)
Nansensgade 19
DK 1366 Copenhagen
Tel. +45 33896300
Fax +45 33896330
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF