3.8 Start Transaction

The StartTransaction message in OCPP 1.6J is sent by a charge point to the central system when a charging session begins. It includes details like the user’s ID tag, connector ID, timestamp, and initial meter reading. This message allows the central system to log the session, track energy usage, and ensure accurate billing or reporting for the user.


API Syntax	Description	Input Params	Return Value
SendStartTransactionRequest	Sends the StartTransaction request to the server. Creates an OCPP frame for the request and sends it using “sendframe”.	void	STARTTRANSACTIONERROR_T

Example:

void UpdateAndSendStartTransaction(char* IdTag, int meterStart, int connectorId, int reservationId)
{
UpdateStartTransactionRequestConnectorId(connectorId);
UpdateStartTransactionRequestIdTag(IdTag);
UpdateStartTransactionRequestMeterStart(meterStart);
UpdateStartTransactionRequestReservationId(reservationId);
(void)SendStartTransactionRequest();
}


API Syntax	Description	Input Params	Return Value
UpdateStartTransactionRequestConnectorId	Updates the connector ID in the StartTransaction request.	int connectorid	void

Example:

	
void UpdateAndSendStartTransaction(char* IdTag, int meterStart, int connectorId, int reservationId)
{
UpdateStartTransactionRequestConnectorId(connectorId);
UpdateStartTransactionRequestIdTag(IdTag);
UpdateStartTransactionRequestMeterStart(meterStart);
UpdateStartTransactionRequestReservationId(reservationId);
SendStartTransactionRequest();
}


API Syntax	Description	Input Params	Return Value
UpdateStartTransactionRequestIdTag	Updates the ID tag in the StartTransaction request.	const char *idTag	void

Example:

	    void UpdateAndSendStartTransaction(char* IdTag, int meterStart, int connectorId, int reservationId)
{
UpdateStartTransactionRequestConnectorId(connectorId);
UpdateStartTransactionRequestIdTag(IdTag);
UpdateStartTransactionRequestMeterStart(meterStart);
UpdateStartTransactionRequestReservationId(reservationId);
SendStartTransactionRequest();
}


API Syntax	Description	Input Params	Return Value
UpdateStartTransactionRequestMeterStart	Updates the meter start value in the StartTransaction request.	int meterstart	void

Example:

void UpdateAndSendStartTransaction(char* IdTag, int meterStart, int connectorId, int reservationId)
{
UpdateStartTransactionRequestConnectorId(connectorId);
UpdateStartTransactionRequestIdTag(IdTag);
UpdateStartTransactionRequestMeterStart(meterStart);
UpdateStartTransactionRequestReservationId(reservationId);
SendStartTransactionRequest();
}


Syntax	Description	Constants/Members
STARTTRANSACTION_REQUEST_T	Structure holds the parameters required to initiate a StartTransaction request.	char uuid[]; int connectorId; idToken idTag[]; int meterStart; char timeStamp[]; int reservationId;
STARTTRANSACTION_RESPONSE_T	Structure holds the information received in response to a StartTransaction request.	AUTHORIZATIONSTATUS_T enumState; IDTAG_INFO_T idTagInfo; int transactionId;
STARTTRANSACTIONERROR_T	Enumeration for StartTransaction error codes	STARTTRANSACTION_SUCCESS STARTTRANSACTION_FAILED STARTTRANSACTION_RESPONSE_SUCCESS, STARTTRANSACTION_RESPONSE_FAILED