User's Manual
User Manual VC-EVCC
© 2021 Vector Informatik GmbH Version 1.3.0 25
stop sending certain CAN messages. Please refer to the chapter “UDS communication” for
more information about configurable message cycle times.
5.1.2 End-to-End Protection of CAN Messages
The VC-EVCC uses the MICROSAR Safe End-to-End (E2E) for protection of the CAN
messages VCVCCU_ChargeFromVehicle and VCVCCU_ChargeToVehicle. The E2E Profile
1 is used to encode and decode the exchanged data. This method comprises a sequence
counter and a Cyclic Redundancy Checksum (CRC) to protect for data consistency,
reliability and validity.
The E2E Profile 1 uses the following polynomial of CRC-8-SAE J1850 which protects
against corruption of data ensuring its validity for use.
0x1D (x
8
+ x
4
+ x
3
+ x
2
+ 1)
5.1.2.1 VCVCCU_ChargeFromVehicle
The CAN message VCVCCU_ChargeFromVehicle contains the following signals which are
used for E2E protection.
E2E_Cnt_ChargeFromVehicle (Counter): This signal is used to ensure the data is
received periodically.
Caution
The vehicle must ensure that the value of E2E_Cnt_ChargeFromVehicle is
incremented for every message cycle. The incrementation shall start from value 0x0.
Once the value 0x0E is reached the vehicle shall reset the value to 0x0 and start to
increment the value again.
The VC-EVCC will raise a DTC if the current counter value deviates from the
previously received counter value by a value of 3 or more or if the counter value is
unchanged for more than three correctly received messages.
E2E_CRC_ChargeFromVehicle: This signal is used to ensure the data validity.
The VC-EVCC performs the following calculation to determine the correctness of the CRC
received from the signal E2E_CRC_ChargeFromVehicle.
Calculated CRC = CRC8 over Data ID (0xFF21) and the seven bytes of the CAN
message (Byte 0 to Byte 6) including the empty area (set to 0xFF) but excluding the
CRC byte (Byte 7) itself.
E2E Profile 1 requires a XOR-operation of the calculated CRC with value 0xFF. The
result is the final CRC value which is added to the CAN message.
Note
For detailed information about E2E Profile 1 and the respective CRC calculation please
refer to the specifications “AUTOSAR_SWS_E2ELibrary” and
“AUTOSAR_SWS_CRCLibrary” of AUTOSAR release 4.