The offline behavior of Charge Stations, particularly regarding authorization handling, is influenced by a combination of configuration keys and internal logic on the charger itself. For OCPP (Open Charge Point Protocol), offline handling is particularly important because it ensures chargers remain functional when the connection to the central system is temporarily lost. This article focuses on the offline authorization handling behavior as per OCPP 1.6 protocol version.
Legend:
LocalAuthorizeOffline, LocalAuthListEnabled, AuthorizationCacheEnabled and AllowOfflineTxForUnknownId are all Boolean configuration keys (TRUE/FALSE). Some may be optional as per OCPP 1.6.
Key Configuration Variables Influencing Offline Authorization
LocalAuthorizeOffline(Boolean):- If
True, the charger allows transactions to proceed using its Authorization Cache and/or the Local Authorization List. - If
False, transactions are rejected when offline, unless AuthorizeTrxForUnknownId is set to True.
AllowOfflineTxForUnknownId(Boolean):- If
True, the charger allows transactions to proceed even if the presented token (RFID or other) is not in its local cache and/or its local authorization list. - If
False, the charger may rely on its token cache and/or local authorization list.
- Authorization Cache:
- The charger maintains a local token cache (often configured with parameters like size and expiry). When offline, the cache may be critical (
AuthorizationCacheEnabled) for determining if a token is valid.
- Local Authorization List:
- The Local Authorization List is a list of identifiers that can be synchronized with the Central System. The list contains the authorization status of all (or a selection of) identifiers and the authorization status/expiration date. Identifiers in the Local Authorization list can be marked as valid, expired, (temporarily) blocked, or blacklisted, corresponding to IdTagInfo status values Accepted/ConcurrentTx, Expired, Blocked, and Invalid, respectively.
- The Charge Point indicates whether the Local Authorization List is supported by the presence or absence of the
LocalAuthListManagementelement in the value of theSupportedFeatureProfilesconfiguration key. Whether the Local Authorization List is enabled is reported and controlled by theLocalAuthListEnabledconfiguration key.
For full details on OCPP behavior and configuration keys, CPO operators can check the OCPP 1.6 specification: ocpp/docs/v16/ocpp-1.6.pdf at master · mobilityhouse/ocpp · GitHub