AMB8426-M_8626-M_MA_EN_V2_4
Page 34 of 48
Released: Nov.2013
SND_UD:
1. Telegram to be sent to the meter
REQ_UD2:
2. Telegram to be sent to the meter
SND_NKE:
3. Telegram to be sent to the meter
SND_NR:
Telegram from meter
ACK:
Reply to SND_UD
RSP_UD:
Reply to REQ_UD2
CNF:
Reply relating to the sending of the preloaded telegram
10 Encryption with AES-128
To activate the encryption the parameter
accordingly.
Up to 64 AES-keys with their relevant addresses (= devices) can be stored
permanently (in non-volatile memory) in the module.
The module supports the encryption modes 4 and 5 as well as the encryption used in mode C
(Kamstrup).
For the management of the AES-keys the command interface offers the following commands
and
10.1 Incoming RF telegrams
With incoming telegrams the address of the meter is at first searched for in the list of registered
meters. If the meter is registered, it is subsequently tested whether the telegram is encrypted. If
this is the case the telegram is decrypted with the registered AES-key and passed on. The
“ENC-Field” of the module is first reset.
10.2 Outgoing RF telegrams
In order for the module to encrypt a wM-Bus telegram for transmission the mode of encryption
has to be shown in the telegram
Example:
Manufacturer: AMB (0x05A2)
ID: 0x12345678
Version: 0x00
Device type: Water (0x03)
Key: 0x00 0x01 0x02 0x03 0x04 0x05 0x06 0x07 0x08 0x09 0x0A 0x0B 0x0C 0x0D
0x0E 0F
Telegram (non-encrypted):
0x1E 0x44
0xA2 0x05 0x78 0x56 0x34 0x12 0x00 0x03
0x7A 0x35 0x00 0x00 0x00 0x2F
0x2F 0x00 0x7C 0x08 0x54 0x53 0x45 0x54 0x20 0x43 0x4E 0x45 0x2F 0x2F 0x2F
