Documentation Set Overview

The authoritative specification corresponds to the December 2019 release package. This suite comprises several key components:

• Core Protocol: Defines Open Charge Point Protocol 1.6 standards.
• Errata Sheets: Updates for both JSON and SOAP specifications.
• Specifications: Separate documents for OCPP-J (JSON) and OCPP-S (SOAP).
• Schemas: Describes message structures for both implementations.

While all versions exist, this documentation focuses on the JSON variant due to its prevalence in modern deployments.

Transport Layer Configuration

Connectivity relies on WebSocket channels established over TCP sockets. In this topology, the Charging Station acts as the initiating client, while the Central Management System functions as the listening server.

Endpoint URIs typically follow a unique identifier pattern:

wss://manager.grid-network.io/v1/charger/A042

Handshake Sequence

Client Request

GET /v1/charger/A042 HTTP/1.1
Host: manager.grid-network.io:33033
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Key: MzQxNDUyNTY3OA==
Sec-WebSocket-Version: 13

Server Response

HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: kD8rP4sT6fH2jL9mN0vB5xQ=
Sec-WebSocket-Protocol: ocpp1.6

Keepalive Settings

Connection stability is monitored using WebSocket PING/PONG frames. Configuration parameters allow disabling this feature or setting the interval duration in seconds.

Configuration Key	Valid Range	Behavior
WebSocketPingInterval	0	Disables Client Ping
WebSocketPingInterval	> 0	Sets Interval (Seconds)

Message Flow Logic

Transactions rely on three state identifiers mapped to numeric types:

• CALL (2): Initiated request sent by either party.
• CALLRESULT (3): Successful outcome returned by receiver.
• CALLERROR (4): Failure report sent back to initiator.

Strict sequnecing dictates that responses must complete before new calls are issued on the same session. All payloads utilize UTF-8 encoding.

Message IDs must be unique per connection for outgoing calls. Responses must echo the ID of the corresponding request exactly.

Format Structures

• Call: [2, "<UUID>", "<ActionName>", {Payload}]
• Result: [3, "<UUID>", {Payload}]
• Error: [4, "<UUID>", "<ErrorCode>", "<Description>", {Details}]

Error Classifications

Failures are categorized into distinct error codes managed by the system.

Error Code	Definition
NotImplemented	Action is unrecognized by receiver
NotSupported	Action known but currently unsupported
InternalError	Processing failure within receiver component
ProtocolError	Payload structure is incomplete
SecurityError	Authentication or safety violation occurred
FormationViolation	Syntax mismatch or invalid structure
PropertyConstraintViolation	Field contains invalid data value
OccurenceConstraintViolation	Violation of field occurrence rules
TypeConstraintViolation	Data type does not match schema
GenericError	Exception not covered by specific codes