One day of messages, fully understood
The charger has sent and received several thousand messages today: heartbeats, status reports, meter values, nineteen sessions.
At midnight, the next firmware wave is scheduled.
The questionCan you explain the charger's day, message by message?
The day in eight moments
One charger, another company's software: connects them.
Stop 01opened, boot announced, heartbeat agreed, connectors available.
Stop 021.6 and 2.0.1 side by side in one network, 2.1 in the next tender.
Stop 03Authorize, start, meter values, stop: one session as messages.
Stop 04A meter value each minute, signed start and end readings for the invoice.
Stop 05A remote start for a waiting driver, a setting changed on two hundred chargers.
Stop 06The audit: , TLS, certificates on both sides.
Stop 07Card accepted, no start: the log points to the car side.
Stop 08
Eight moments, one connection. OCPP is how a charger becomes part of a network.
Where to go from here
OCPI and roaming follows the session from the operator to other companies, Plug & Charge the conversation between car and charger, and Load management the in practice. See all learning paths.
Check your understanding
4 questions. Answer all of them to complete this stop. Each answer explains itself.
What did the charger do first after restarting at 6:00 AM?
The charger opens the WebSocket, then sends its boot announcement.
How was the energy of the 9:12 AM session determined?
End reading minus start reading of the charger's meter, signed where measuring law requires it.
Why are some chargers moved from profile 1 to profile 2?
Profile 2 adds TLS and a backend certificate; profile 1 should not be used in the field.
Five chargers did not install the new firmware. Why is that a good sign?
Signed firmware is installed only when its signature verifies; a failed check protects the charger.
- OCPP Open Charge Point Protocol: the open protocol between a charger and its operator's backend. EV charging fundamentals, stop 03 Glossary
- Charging profile An OCPP message that sets a limit in amperes or watts for a station, for new sessions or for one session, valid for a time or as a schedule. Load management, stop 03 Glossary
- WebSocket A connection that the charger opens to the backend and keeps open, so messages can travel in both directions at any time. Stop 02 Glossary
- Security profile One of three OCPP levels of protection, from a password over an unencrypted connection to TLS with certificates on both sides. Stop 07 Glossary