This parameter is necessary for OCPP based communication with the backend system. Its exact use differs depending on the specific version and variant of OCPP in use. The parameter length is limited to 128 characters.
In SOAP based OCPP messages the standard defines a SOAP header element called chargeBoxIdentity. This element must be set in every message from a charger to a backend system to identify the charging station from which the message was received. This parameter is used to fill this SOAP header element in SOAP based OCPP.
In JSon based OCPP communication there is no header like in SOAP messages. Instead the ChargePointID is added to the URL when the web socket connection to the backend is established. This parameter is used for that. It is added to the configured backend URL automatically to identify the connecting charger towards the backend.
If no ChargePointSerialNumber (the manufacturer serial number of the charging station) is in the manufacturer parameters, this parameter is also used to fill this field of a OCPP BootNotification message.
If two or more slave devices are connected, each Slave must identify itself to the master with its respective Connector ID added as a suffix. E.g. #2 or #005 should be appended to the ChargePointID. Please note that suffixes #, #0 or #1 are reserved and cannot be used.