Terminology and Conventions
Based on Open Charge Point Protocol 1.6, Edition 2 FINAL (2017-09-28). This guide covers the key terminology, conventions, definitions, and abbreviations used throughout the OCPP 1.6 specification.
1. Conventions
Section 2.1The conventions used throughout the OCPP 1.6 specification follow established standards for requirement levels and normative content.
RFC 2119 Keywords
The key words in this document are to be interpreted as described in RFC 2119, subject to
an additional clarification clause.
Absolute Requirements
MUST MUST NOT REQUIRED SHALL SHALL NOTRecommendations
SHOULD SHOULD NOT RECOMMENDED NOT RECOMMENDEDOptional
MAY OPTIONALAdditional Clarification: The phrase "valid reasons in particular circumstances" relating to the usage of SHOULD, SHOULD NOT, RECOMMENDED, and NOT RECOMMENDED is to be taken to mean technically valid reasons, such as the absence of necessary hardware to support a function from a charge point design. It specifically excludes decisions made on commercial, or other non-technical grounds, such as cost of implementation or likelihood of use.
Normative Sections
All sections and appendixes, except "Scope" and "Terminology and Conventions", are normative, unless they are explicitly indicated to be informative.
2. Definitions
Section 2.2This section contains the terminology that is used throughout the OCPP 1.6 document. These definitions are essential for understanding the specification.
Key Terms
Central System
Charge Point Management System: the central system that manages Charge Points and has the information for authorizing users for using its Charge Points.
Charge Point
The physical system where an electric vehicle can be charged. A Charge Point has one or more connectors.
Charging Profile
Generic Charging Profile, used for different types of Profiles. Contains information about the Profile and holds the Charging Schedule.
Connector
An independently operated and managed electrical outlet on a Charge Point. Usually corresponds to a single physical connector.
Transaction
The part of the charging process that starts when all relevant preconditions (e.g. authorization, plug inserted) are met, and ends at the moment when the Charge Point irrevocably leaves this state.
Complete Definitions Table
| Term | Definition |
|---|---|
Central System | Charge Point Management System: the central system that manages Charge Points and has the information for authorizing users for using its Charge Points. |
CiString | Case Insensitive String. Only printable ASCII allowed. |
Charge Point | The Charge Point is the physical system where an electric vehicle can be charged. A Charge Point has one or more connectors. |
Charging Profile | Generic Charging Profile, used for different types of Profiles. Contains information about the Profile and holds the Charging Schedule. In future versions of OCPP it might hold more than 1 Charging Schedule. |
Charging Schedule | Part of a Charging Profile. Defines a block of charging Power or Current limits. Can contain a start time and length. |
Charging Session | A Charging Session is started when first interaction with user or EV occurs. This can be a card swipe, remote start of transaction, connection of cable and/or EV, parking bay occupancy detector, etc. |
Composite Charging Schedule | The charging schedule as calculated by the Charge Point. It is the result of the calculation of all active schedules and possible local limits present in the Charge Point. Local Limits might be taken into account. |
Connector | The term "Connector", as used in this specification, refers to an independently operated and managed electrical outlet on a Charge Point. This usually corresponds to a single physical connector, but in some cases a single outlet may have multiple physical socket types and/or tethered cable/connector arrangements to facilitate different vehicle types (e.g. four-wheeled EVs and electric scooters). |
Control Pilot signal | Signal used by a Charge Point to inform EV of maximum Charging power or current limit, as defined by IEC 61851-1. |
Energy Offer Period | Energy Offer Period starts when the EVSE is ready and willing to supply energy. |
Energy Offer Suspend Period | During a transaction, there may be periods the Energy Offer to EV is suspended by the EVSE, for instance due to Smart Charging or local balancing. |
Energy Transfer Period | Time during which an EV chooses to take offered energy, or return it. Multiple Energy Transfer Periods are possible during a Transaction. |
Local Controller | Optional device in a smart charging infrastructure. Located on the premises with a number of Charge Points connected to it. Sits between the Charge Points and Central System. Understands and speaks OCPP messages. Controls the Power or Current in other Charge Point by using OCPP smart charging messages. Can be a Charge Point itself. |
OCPP-J | OCPP via JSON over WebSocket. |
OCPP-S | OCPP via SOAP. |
Phase Rotation | Defines the wiring order of the phases between the electrical meter (or if absent, the grid connection), and the Charge Point connector. |
Transaction | The part of the charging process that starts when all relevant preconditions (e.g. authorization, plug inserted) are met, and ends at the moment when the Charge Point irrevocably leaves this state. |
String | Case Sensitive String. Only printable ASCII allowed. All strings in messages and enumerations are case sensitive, unless explicitly stated otherwise. |
3. Abbreviations
Section 2.3Common abbreviations used throughout the OCPP 1.6 specification, grouped by category.
Protocol & Network
| Abbreviation | Meaning |
|---|---|
CSL | Comma Separated List |
DNS | Domain Name System |
DST | Daylight Saving Time |
FTP(S) | File Transport Protocol (Secure) |
HTTP(S) | HyperText Transport Protocol (Secure) |
JSON | JavaScript Object Notation |
NAT | Native Address Translation |
PDU | Protocol Data Unit |
SOAP | Simple Object Access Protocol |
URL | Uniform Resource Locator |
UTC | Coordinated Universal Time |
EV & Charging
| Abbreviation | Meaning |
|---|---|
CPO | Charge Point Operator |
EV | Electrical Vehicle, this can be BEV (battery EV) or PHEV (plug-in hybrid EV) |
EVSE | Electric Vehicle Supply Equipment (IEC 61851-1) |
ICCID | Integrated Circuit Card Identifier |
IMSI | International Mobile Subscription Identity |
SC | Smart Charging |
Phase Rotation Codes
| Abbreviation | Meaning |
|---|---|
RST | 3 phase power connection, Standard Reference Phasing |
RTS | 3 phase power connection, Reversed Reference Phasing |
SRT | 3 phase power connection, Reversed 240 degree rotation |
STR | 3 phase power connection, Standard 120 degree rotation |
TRS | 3 phase power connection, Standard 240 degree rotation |
TSR | 3 phase power connection, Reversed 120 degree rotation |
4. References
Section 2.4Normative and informative references cited in the OCPP 1.6 specification.
Standards
IEC 61851-1 Electric vehicle conductive charging system - Part 1: General requirements
IEC 61851-1 2010
RFC 2119 Key words for use in RFCs to Indicate Requirement Levels
S. Bradner. March 1997.
OCPP Specifications
OCPP 1.5 Open Charge Point Protocol 1.5
Previous version of the protocol
OCPP 1.6 CT OCPP 1.6 Compliance Testing
Compliance testing specification for OCPP 1.6 implementations
OCPP-J OCPP JSON Specification
Implementation guide for OCPP over JSON/WebSocket
OCPP-S OCPP SOAP Specification
Implementation guide for OCPP over SOAP