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SIEMENS AG, Siemens VDO Automotive SV C BC S454
FCC ID:KR55WK49210 IC:267T-5WK49210
Functional Description /
User Manual
of
SIEMENS VDO
Immobilization system HONDA RxM
Type 5WK49210 / 5WK49215
Functional description_RxM.doc Page 1 of 5
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SIEMENS AG, Siemens VDO Automotive SV C BC S454
FCC ID:KR55WK49210 IC:267T-5WK49210
1. FUNCTIONAL DESCRIPTION
The immobilizer system consists of an engine control module (PGM-FI ECU), a body controller module
(MICU), the Immobilizer (RxM) and a key, see
Figure 1 .
The Immobilizer is mounted on to the ignition lock in which the key can be inserted. The Immobilizer is
located at the steering column of the vehicle.
The RxM is an "active antenna" that contains the following components that are shown in figure 1:
1. Power supply: The voltage regulator is supplied via the SAM with battery voltage (typ. 12V) and
supplies the basestation IC (3) with a stable 5V voltage level.
2. Serial interface: This is used to adapt the micro controllers (7) input and output signals to the signal
levels required by the external components. The level shifting is done by a series of transistors and
RC networks. The circuitry has the typical short-circuit and reverse-battery protection.
3. Basestation IC (PCF7991). The Base station IC drives and modulates the LF antenna (4) to supply
the transponder in the key with energy and to transmit data to it. It demodulates the answer from the
transponder and sends the demodulated signal to the CPU (7).
The Basestation IC does not contain a control logic. Instead, it is controlled by the CPU(7).
4. LF antenna. The LF ("low frequency, typ. 125 kHz") antenna is part of the immobilizer housing and
is mounted to the ignition lock.
5. Antenna circuitry: The antenna circuit is composed of a resonant tank circuitry (resistor, inductor,
and capacitor) which is tuned to 125 kHz. This portion of the circuit is used to transmit and receive
data to and from the transponder. The data is modulated and transmitted at the proper frequency by
the basestation IC (3). The tuning components and voltage limiting resistors are assembled on the
PCB.
6. Resonator: A 15.924MHz MHz resonator is used to provide a clock frequency to the CPU.
7. CPU: The micro controller controls the basestation IC (3). I.e. it turns the voltage regulator for the
basestation IC on and off, controls the communication with the basestation IC and provides the clock
for the basestation IC. Furthermor the micro controller controls all the communication with external
components connected to the S-Net bus. It does the encryption / decryption of the communication with
engine control module (12) and MICU (11). It does the authentication of the transponder (i.e. the
cryptology). The micro controller controls the RF receiver (9) and decrypts incoming RF telegrams. It
controls the communication with external components via CAN and the communication with the
diagnostic computer.
8. Serial interface: This is used to adapt the micro controllers (7) input and output signals to the signal
levels required by the diagnostic computer. The level shifting is done by a series of transistors and RC
networks. The circuitry has the typical short-circuit and reverse-battery protection.
9. RF receiver: The RF receiver receives RF telegrams at a carrier frequency of 313,85MHz
(5WK49210) or 433,92MHz (5WK49215). The RF functionality is not relevant for the immobilizer
function.
10. CAN transceiver: This is the interface between the CPU and the physical bus. The physical layer of the
CAN bus is high speed. The transmission speed is 125kbps.
Functional description_RxM.doc Page 2 of 5
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SIEMENS AG, Siemens VDO Automotive SV C BC S454
ANT COIL (4)
•
•
•
•
•
•
RF
(9)
••••
••••
CONTROL UNIT
Power Supply (1)
FCC ID:KR55WK49210 IC:267T-5WK49210
+B
(14)
transponder IC (13)
PCF7991 (3)
antenna circuit (5)
KEYLESS•IMMOBI.
IG
interface (2)
resonator (6)
CPU (7)
CAN
Transceiver
(10)
interface (8)
Figure 1 System Overview
10400bps 5V
S-NET
•••••+
•••
••••••
DLC
PGM-FI ECU (12)
•••• (11)
METER
IMMOBI indicator
Power
Window
Diagnosis tool
Components outside of the smart immobilizer are:
11. MICU: This Body controller supplies a secret key which is requested by the RxM. The secret key is
exchanged via the S-Net interface line.
12. ECM (Engine control module): This module supplies a secret key which is requested by the RxM.
The secret key is exchanged via the S-Net interface line.
13. Transponder IC in the key. The IC is connected to a parallel resonant circuit formed by the
transponder coil (14) and a capacitor. It derives its power supply from the magnetic field established
by the immobilizer. The IC provides contactless communication with the immobilizer by demodulating the
signals received from the immobilizer and by sending data to the immobilizer via ASK (amplitude shift keying)
modulation.
14. Transponder coil in the key: This coil is magnetically coupled at 125 kHz to the LF antenna (4).
2. Immobilizer parts
The RxM consists of the following parts:
1. Housing including LF antenna, RF antenna and pins for the PCB and connector
2. populated PCB
3. cover
Functional description_RxM.doc Page 3 of 5
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SIEMENS AG, Siemens VDO Automotive SV C BC S454
FCC ID:KR55WK49210 IC:267T-5WK49210
3. Variants
5WK49210 with Receiver 313, 85 MHz US
5WK49215 with Receiver 433, 92 MHz Europe
4. Technical Data
Carrier frequency: 125 kHz ± 1.25 kHz
Carrier field strength: < 40dBµA/m @10m
Modulation: ASK
Supply voltage: 12 V
Battery type: Car battery
Range: < 55mm
Loop coil antenna area: 0.0010 m2
5. Typical usage pattern (for Europe only)
360000 immobilizer operations in 10 years with a typical transmission duration of
0.1 seconds → 36000 seconds (= 10 hours) transmission duration in 87600 hours →
0.41 seconds transmission duration in one hour
Transmitter ON 0.41 seconds / hour
Transmitter OFF 3,599.59 seconds / hour
Duty Cycle: TON / T
(ON+OFF)
x 100% = 0.41 / 3,600 x 100 % =0.011 %
Functional description_RxM.doc Page 4 of 5
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SIEMENS AG, Siemens VDO Automotive SV C BC S454
FCC ID:KR55WK49210 IC:267T-5WK49210
6. Label
US, Canada Mexico:
Siemens VDO
5WK49210
FCC ID:KR55WK49210
IC:267T-5WK49210
Owner Manual:
NOTE
This device complies with part 15 of the FCC Rules and with RSS -210 of Industry
Canada. Operation is subject to the following two conditions: (1) This device may not
cause harmful interference, and (2) this device must accept interference received,
including interference that may cause undesired operation.
CAUTION
Changes or modifications not expressly approved by the manufacturer could void the
user’s authority to operate the equipment.
Europe:
Siemens VDO
5WK49215
Functional description_RxM.doc Page 5 of 5
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