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21January2021/Version 0
LEM International SA
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1228 PLAN-LES-OUATES Switzerland
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7.2. Transactions
7.2.1. Concept
To log the energy used during a charging cycle, the DCBM handles two specific requests: “start
transaction” and “stop transaction”.
When the “start transaction” command is received by the DCBM, the latter starts accumulating
energy into a specific transaction. A transaction is made unique by its chosen transaction identifier,
which can link it to the end user.
When the “stop transaction” command is received by the DCBM, the latter stops accumulating
energy to the current transaction and sends a complete report in response. The data structure
contains all the transaction information, e.g. energy registers, status information, timestamps. The
whole data structure is authenticated by a signature mechanism.
The signature can be verified using product’s public key and a verification software, refer to section
Following figure illustrates the process of transaction.
Figure 40: Transaction concept
Time
Po
w
er
DCBM
Charger controller
St
ar
t
St
op
Re
ad
Re
ad
En
er
gy
Transac�on
: Request
: Response
Stop command
Acknowledgement of the
stop command and full
data structure from DCBM
Start command
Iden
�fi
ers from Charger
controller
Acknowledgement of the
start command from DCBM
-
Intermediate readings
[op�onal]
Data structure
from DCBM
-
