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OCPP

OCPP 1.6J

Salia charging stations connect to a backend (Central System) with OCPP 1.6J, that is OCPP 1.6 over WebSocket with JSON. This page describes which parts of the protocol the station implements and where it deviates from what a backend may expect. The fault codes the station sends are listed on OCPP Error Codes.

Applies to firmware 2.5.0 and later on all charging stations with the Salia controller. Each station has one connector (connector 1); connector 0 stands for the station as a whole.

Connection

Topic	Behaviour
Protocol	OCPP 1.6J, WebSocket subprotocol ocpp1.6. SOAP and OCPP 2.0.1 are not supported.
Backend URL	ws:// or wss://. The URL is used exactly as entered, so it has to contain the charge point ID, for example wss://backend.example.com/ocpp/CP-0001. A changed CentralSystemURI takes effect after a restart.
TLS	wss:// uses TLS 1.2. The server certificate, including the host name, is only checked when Verify CERT is enabled in the OCPP settings of the web UI. The option is off in the factory setting; without it any server certificate is accepted.
Authentication	HTTP Basic Auth with user name and password. The credentials are set in the station's web UI; they cannot be changed over OCPP (AuthorizationKey is not supported). Client certificates are not supported.
Response time	The backend has to answer every request within 60 seconds. Otherwise the station closes the connection and connects again.
Time	The station takes its time from BootNotification and Heartbeat (and NTP, if configured). Calibration-law (Eichrecht) stations refuse transactions until the clock is set. Other stations also start transactions with an unset clock (allowTxWithInvalidTime); their timestamps are then wrong.
BootNotification	chargePointVendor and chargePointModel (up to 20 characters each), chargePointSerialNumber and chargeBoxSerialNumber (if set; up to 25 characters each), firmwareVersion, meterType, meterSerialNumber; iccid and imsi on stations with a mobile modem.
Registration	The station starts transactions, online or offline, only after the backend in CentralSystemURI has accepted a BootNotification at least once. Changing CentralSystemURI discards transactions that were not yet sent to the previous backend.

Feature profiles

The configuration key SupportedFeatureProfiles reports Core,FirmwareManagement,LocalAuthListManagement.

Profile	Support
Core	Supported, limits below.
Firmware Management	Supported.
Local Auth List Management	Supported, full updates only.
Reservation	Not supported. ReserveNow is answered with Rejected.
Smart Charging	Not reported. SetChargingProfile is accepted in a limited form, see below.
Remote Trigger	Not reported. TriggerMessage works for some messages, see below.

The extensions of the OCPP 1.6 Security Whitepaper (signed firmware update, certificate management, security events, GetLog) are not implemented.

While a restart is pending (after Reset or a firmware installation) the station answers most requests with a CALLERROR GenericError.

Messages

Core

Message	Direction	Notes
Authorize	Station → backend	Sent for cards that are not authorized locally, while online.
BootNotification	Station → backend	After Pending or Rejected the station retries after the interval from the answer.
ChangeAvailability	Backend → station	Connector 0 and 1. Inoperative while the connector is Preparing, Charging or Finishing is answered with Scheduled and applied when the vehicle is unplugged. Kept across a restart.
ChangeConfiguration	Backend → station	Keys see Configuration keys. Unknown keys: NotSupported; read-only keys: Rejected.
ClearCache	Backend → station	Accepted if the authorization cache is enabled, otherwise Rejected (factory setting).
DataTransfer	Both	Vendor-specific. A DataTransfer from the backend with an unknown vendorId is answered with UnknownMessageId. On calibration-law stations the station sends the meter's public key after BootNotification (vendorId generalConfiguration, messageId setMeterConfiguration); this can be switched off with sendMeterPublicKeyOnBootNotification.
GetConfiguration	Backend → station	All keys or the requested ones; unknown keys in unknownKey.
Heartbeat	Station → backend	When no other message was sent for HeartbeatInterval seconds.
MeterValues	Station → backend	Only during a transaction, always with transactionId. Not stored while offline.
RemoteStartTransaction	Backend → station	Connector 1. A chargingProfile in the request is ignored. The vehicle has to be plugged in within ConnectionTimeOut. Rejected if the station is not registered, the connector is not Available, Preparing or Finishing (for example Faulted), the meter is not ready, a storage fault is active, 336 transactions are waiting to be sent, another authorization is pending, or the clock is unset on a calibration-law station.
RemoteStopTransaction	Backend → station	Stops with reason = Remote. Rejected if the transactionId is unknown or the station or connector is Unavailable.
Reset	Backend → station	Soft and Hard both stop a running transaction and restart the whole station after about 10 seconds. Rejected during a firmware update.
StartTransaction	Station → backend	Stored on the station before it is sent and sent again after a connection loss.
StatusNotification	Station → backend	Available, Preparing, Charging, Finishing, Unavailable, Faulted. SuspendedEV and SuspendedEVSE are not used: a paused session stays Charging. Notifications for connector 0 and 1 are sent at most once every 10 seconds together and carry the status at that moment, so a status that lasts shorter can be skipped. Identical notifications are not repeated, except after a reconnect.
StopTransaction	Station → backend	Reasons EmergencyStop, EVDisconnected, HardReset, SoftReset, Local, PowerLoss, Remote, UnlockCommand, DeAuthorized, Other. idTag is not sent.
UnlockConnector	Backend → station	Socket variants only; on stations with a fixed cable the answer is NotSupported. A running transaction is stopped (reason = UnlockCommand). The answer is sent once the lock has opened (Unlocked) or after 20 seconds (UnlockFailed); the backend's response timeout must be longer than 20 seconds.

Firmware Management

Message	Direction	Notes
UpdateFirmware	Backend → station	location (HTTP or HTTPS URL of the firmware file), retrieveDate, retries and retryInterval. The download starts at retrieveDate while the station is connected. The station installs the file and restarts. A second UpdateFirmware during a running update is acknowledged and ignored.
FirmwareStatusNotification	Station → backend	Downloading, Downloaded, DownloadFailed, Installing, InstallationFailed, Installed (after the restart).
GetDiagnostics	Backend → station	Uploads a log archive (.tar.gz) by FTP, FTPS, HTTP or HTTPS. With HTTP(S) the file is sent as POST to <location>/<fileName>. startTime and stopTime are ignored.
DiagnosticsStatusNotification	Station → backend	Uploading, Uploaded, UploadFailed.

Local Auth List Management

Message	Direction	Notes
GetLocalListVersion	Backend → station	-1 while LocalAuthListEnabled is false.
SendLocalList	Backend → station	updateType Full only; Differential is answered with NotSupported, as is any update while LocalAuthListEnabled is false. Up to 10,000 entries.

Smart Charging (limited, not reported)

Message	Direction	Notes
SetChargingProfile	Backend → station	Accepted only with chargingProfilePurpose ChargePointMaxProfile (connector 0) or TxProfile, chargingProfileKind Relative, chargingRateUnit A, stackLevel 0 and exactly one schedule period with startPeriod 0, without duration and minChargingRate. Other profiles are answered with NotSupported. A ChargePointMaxProfile for connector 1 is Rejected, as is a TxProfile for a transactionId other than the running one. ChargePointMaxProfile is kept across a restart; TxProfile ends with the transaction.
ClearChargingProfile	Backend → station	By connector, profile ID or purpose. Unknown if no profile matches.
GetCompositeSchedule	Backend → station	Not supported (Rejected).

Remote Trigger (partial, not reported)

TriggerMessage is accepted for BootNotification, Heartbeat and StatusNotification. MeterValues, DiagnosticsStatusNotification and FirmwareStatusNotification are answered with NotImplemented.

Configuration keys

The Factory setting column shows the values of a station on firmware 2.5.0 as delivered. Keys marked restart are stored at once and answered with RebootRequired; they take effect after the next restart.

Key	Access	Factory setting	Takes effect
AllowOfflineTxForUnknownId	read/write	false	immediately
AuthorizationCacheEnabled	read/write	false	restart
AuthorizeRemoteTxRequests	read/write	false	immediately
ClockAlignedDataInterval	read/write	0	restart
ConnectionTimeOut	read/write	60	immediately
HeartbeatInterval	read/write	from BootNotification (600 before)	immediately, not stored; values up to 2 are rejected
LocalAuthListEnabled	read/write	false	restart
LocalAuthorizeOffline	read/write	false	immediately
LocalPreAuthorize	read/write	false	immediately
MeterValuesAlignedData	read/write	empty	restart
MeterValuesSampledData	read/write	Energy.Active.Import.Register, Power.Active.Import, Power.Active.Import.L1–L3, Current.Import.L1–L3, Voltage.L1-N–L3-N	next transaction
MeterValueSampleInterval	read/write	60	next transaction
StopTransactionOnInvalidId	read/write	true	immediately
StopTxnAlignedData	read/write	empty	next transaction
StopTxnSampledData	read/write	empty	next transaction
TransactionMessageAttempts	read/write	3	restart
TransactionMessageRetryInterval	read/write	30	restart
WebSocketPingInterval	read/write	10	immediately
CentralSystemURI	read/write	as configured	restart; rejected during a transaction
ChargeProfileMaxStackLevel	read only	0
ChargingScheduleAllowedChargingRateUnit	read only	Current
ChargingScheduleMaxPeriods	read only	1
ConnectorPhaseRotation	read only	Unknown
GetConfigurationMaxKeys	read only	10
LocalAuthListMaxLength	read only	10000
MaxChargingProfilesInstalled	read only	2
MeterValuesAlignedDataMaxLength	read only	27
MeterValuesSampledDataMaxLength	read only	27
NumberOfConnectors	read only	1
ResetRetries	read only	0
SendLocalListMaxLength	read only	10000
StopTransactionOnEVSideDisconnect	read only	true
StopTxnAlignedDataMaxLength	read only	27
StopTxnSampledDataMaxLength	read only	27
SupportedFeatureProfiles	read only	see above
SupportedFileTransferProtocols	read only	FTP,FTPS,HTTP,HTTPS
UnlockConnectorOnEVSideDisconnect	read only	true

Vendor-specific keys:

Key	Access	Factory setting	Meaning
rfidStopTransaction	read/write	false	true: the card that started a session can stop it at the station. Takes effect after a restart.
rfidRequiresEvPresent	read/write	true	true: cards are only read while a vehicle is plugged in. Takes effect after a restart.
useAsTimeSource	read/write	true	Set the clock from BootNotification and Heartbeat.
allowTxWithInvalidTime	read/write	true	Allow transactions before the clock is set (never on calibration-law stations).
allowLocalChargingAlways	read/write	false	true: every card is accepted locally, the answer to StartTransaction is ignored and RemoteStartTransaction is always Rejected.
bootNotificationOnReconnect	read/write	false	Send BootNotification after every reconnect.
webSocketPingTimeout	read/write	120	Seconds without a WebSocket pong before the connection is re-established.
forwardCredentials	read/write	empty	Host for which the Basic Auth credentials are also used for firmware and diagnostics URLs.
ftpTryTLSUpgrade	read/write	false	Try explicit FTPS for diagnostics uploads.
calibrationLawFormat	read/write	empty	Format of the signed meter values: empty, OCMF,plain or OCMF,hex.
sendMeterPublicKeyOnBootNotification	read/write	true	Send the meter's public key by DataTransfer after BootNotification.
StopTransactionSignatureFormat	read only	MR	Signed meter values: start and end in one OCMF data set.
Meter1PublicKey	read only	from the meter	Public key of the calibration-law meter.
vendorId	read only	com.in-tech.smartcharging	vendorId of the station for DataTransfer and StatusNotification.

Authorization

• While online, cards known locally (authorization cache or local list) start charging at once if LocalPreAuthorize is true; all other cards are checked with Authorize.
• Offline, cards from the cache or the local list are accepted only if LocalAuthorizeOffline is true. If it is false, every card counts as unknown, and unknown cards are accepted only if AllowOfflineTxForUnknownId is true.
• A card stops a running session at the station only if rfidStopTransaction is true, and only the card that started it.
• If the backend answers StartTransaction with a status other than Accepted, or with an expiryDate in the past, the station stops the session (reason = DeAuthorized). Keep StopTransactionOnInvalidId at true: with false charging is stopped as well, but no StopTransaction is sent, so the transaction stays open in the backend.

Connection loss and power loss

• Connection loss. Charging continues. StartTransaction and StopTransaction are stored on the station and sent once the connection is back; a transaction started offline receives its transactionId then. Up to 336 transactions are stored; when that many are waiting, no new transaction starts until the connection is back. MeterValues, StatusNotification, Heartbeat and status notifications for firmware and diagnostics are not stored. After reconnecting the station sends the current status of connector 0 and 1.
• Power loss. A transaction that was running when the power failed is ended after the restart with reason = PowerLoss; meterStop and timestamp are taken after the restart. The vehicle has to be authorized again. The same applies to any restart that was not requested by Reset.
• Firmware update. After a successful installation the station restarts at once; a running transaction is then ended with reason = PowerLoss. Schedule updates outside charging sessions.

Signed meter values

On calibration-law (Eichrecht) stations StopTransaction carries the signed meter values in transactionData: a sampled value with context Transaction.End and format SignedData holding the OCMF data set with start and end of the transaction. The meter's public key is available in Meter1PublicKey.

Products

The OCPP implementation is the same on all charging stations with the Salia controller.