Author:
Klaudia Kostogłód

12.12.2023

The station's communication with the server via OCPP 1.6 brings many benefits and
streamlines the charging and station operation process. However, if the connection to the
server is lost, the user may lose the ability to charge. The purpose of this document is to
present the configuration of an Enelion station that allows the car to be charged when the
connection to the server is lost.

Setting the configuration key 'AllowOfflineTxForUnknownId' to 'true' will allow the car to be
charged if the connection to the server is lost. The "AllowOfflineTxForUnknownId"
configuration key can be configured in the OCPP configuration settings in the configuration
panel of any charger equipped with the Bridge module and in Lumina.

By default, the "AllowOfflineTxForUnknownId" key is set to "false". If set to "false", the station
will not allow any charging transaction to start after losing connection to the server. This can
be overridden from the configuration panel or OCPP backend by using the
"ChangeConfiguration" message.

Fig.1 View of the "AllowOfflineTxForUnknowId" key in the configuration panel

Station’s operation depends on the selected authorization method:

RFID authorization
The station is configured for RFID authentication and connected to the OCPP server. If the
configuration key "AllowOfflineTxForUnknownId" has the value "true", then even if there is no
connection to the server, the station will accept any unknown or previously accepted ID tag.
An unknown ID tag is described by OCPP as "unknown".

The station connected to the server saves all id tags used on it in a memory called "Cache". If
the charger remembers that a tag is rejected by the server then its id tag memory must be
cleared. To do this, a "ClearCache" message must be sent from the server controlling the
station.

Freecharge
A station configured as "Freecharge" is authorized on the OCPP server with the station serial
number. If such a station has the key "AllowOfflineTxForUnknownId" set to the value "true", it is
possible to connect the car and charge without authorization when the connection to the
server is lost.