When a charger connects to an OCPP server, the first thing it says is "I'm here, this is my brand and model." This introduction message is called BootNotification. It looks simple, but it determines whether the charger is accepted, sets its clock and fixes the pace of all communication that follows.
When is BootNotification sent?
A charger sends a BootNotification:
- On first power-up or when it restarts after a power cut,
- After a Reset command,
- When a firmware update completes and the charger restarts,
- In some implementations, when the WebSocket connection is re-established after a long outage.
In OCPP 1.6J, the charger should not send other messages until it receives an Accepted reply to its BootNotification, except where the CSMS explicitly allows it.
What does the message contain?
In OCPP 1.6J the required fields are chargePointVendor (manufacturer) and chargePointModel (model). Optional fields include the serial number, firmware version, ICCID and IMSI (SIM card details), meter type and meter serial number. In OCPP 2.0.1 and 2.1 the information is grouped under a chargingStation object, and a reason field is added (PowerUp, FirmwareUpdate, RemoteReset, Watchdog and so on). That field is very valuable for understanding why the charger restarted.
An example 1.6J request:
[2, "1001", "BootNotification", {"chargePointVendor": "ExampleBrand", "chargePointModel": "DC60", "firmwareVersion": "3.2.1"}]
The CSMS's three possible replies
Accepted
The charger is recognised and can start operating. The reply carries two important values:
currentTime: the current time for the charger to set its clock.interval: the time between Heartbeat messages (seconds).
Pending
The CSMS has seen the charger but has not accepted it yet. This reply is used, for example, when the charger is waiting for approval in the dashboard or when the CSMS wants to send some settings first. In this state the CSMS can send configuration and query messages to the charger. The charger repeats the BootNotification after the interval.
Rejected
The charger was not accepted. This usually happens because of an unrecognised charger ID or an unauthorised connection. The charger waits for the specified time and tries again.
Common problems in the field
The charger keeps sending BootNotification
If the reply is Pending or Rejected, the charger enters a loop. Check whether the charger is waiting for approval in the dashboard. In Üreticy, unrecognised chargers appear in the pending chargers list and are added to the account with one click.
The time looks wrong
If the charger does not apply the currentTime value, session times can drift. This causes serious confusion in reporting. See our article on time synchronisation in OCPP for details.
Frequent restarts
If the reason field in 2.0.1 shows Watchdog or Unknown, the charger may be restarting on its own. Investigate hardware causes such as the power supply, a firmware bug or overheating. In 1.6J you can reach a similar conclusion by monitoring how often BootNotifications arrive.
Model or serial number is empty
Some chargers do not send the optional fields. The serial number is important for inventory management; ask the manufacturer to populate this field through a firmware setting.
Why is BootNotification data valuable?
Every BootNotification records who the charger is, which firmware it runs and when it restarted. This information makes it possible to:
- Build a fleet inventory by firmware version,
- Detect unexpected restarts,
- Manage mobile lines using SIM card details.
To go step by step when connecting your charger for the first time, see our guide to connecting a charger to an OCPP server.
Commissioning checklist
When connecting a new charger, following this order at the BootNotification stage makes your work easier:
- Enter the charger's OCPP URL and charger ID (Charge Point ID) exactly as they appear in the dashboard.
- Restart the charger and check in the logs that the BootNotification request arrives.
- Confirm that the reply is Accepted and that the interval value is what you expect.
- Then check that StatusNotification messages arrive for each connector.
- Finally, start and stop a short charging session with a test card.
Once these five steps are complete, the charger is ready for operation.
Conclusion
BootNotification is the gateway to OCPP communication. An Accepted reply lets the charger operate, sets its clock and fixes the Heartbeat pace; Pending and Rejected make the charger wait. Monitoring this message and its reply properly speeds up commissioning and helps you notice silent faults early. Üreticy's OCPP software records every BootNotification together with the firmware version and restart reason.