OCPP explained: 1.6J vs 2.0.1 vs 2.1
OCPP (Open Charge Point Protocol) is the open standard that lets a charging station talk to the software that runs the network. The two versions in use are 1.6J (JSON over WebSocket, 2015) and 2.0.1 (2020, approved as IEC 63584 in 2024); they are not compatible. OCPP 2.1 arrived in January 2025 and builds on 2.0.1. OCPI is a different protocol, for roaming between networks.
What OCPP does
Every charger needs a back end to authorise drivers, record energy and send commands. Without a standard, each manufacturer would need its own software. OCPP is that standard, maintained by the Open Charge Alliance. The back end is called a CSMS (charging station management system); in version 1.6 the same thing was called the Central System. For the role of a CSMS in a business, see what is a CSMS.
OCPP 1.6J, 2.0.1 and 2.1 side by side
| OCPP 1.6J | OCPP 2.0.1 | OCPP 2.1 | |
|---|---|---|---|
| Released | 2015 (SOAP and JSON; “J” is JSON over WebSocket) | 2020 (2.0 first appeared in 2018) | Announced 23 January 2025 |
| Standing | The most widespread version in the field | Approved as IEC 63584 in 2024 | Builds on 2.0.1; existing 2.0.1 logic should keep working |
| Notable features | Smart charging (charging profiles, load balancing), local list management | Device management, improved transactions, security, ISO 15118 support, display messages | ISO 15118-20 with bidirectional transfer, V2X, DER control, improved smart charging, battery swapping, local cost calculation, prepaid cards, ad hoc card payment and dynamic QR codes |
| Compatible with 1.6? | - | No | No |
The table summarises the Open Charge Alliance’s descriptions. Check the specification for exact message definitions.
Scroll sideways to see the whole table
Which version should you choose?
- Existing chargers: use what they support. Most chargers on the market speak 1.6J, and many newer ones also speak 2.0.1.
- New purchase: prefer chargers that support 2.0.1 or newer, because that is where security, device management and ISO 15118 development is going.
- Your back end: it must speak every version your chargers use. Mixed fleets are normal.
- 2.1: check what your charger actually implements. A claim of 2.1 support can mean the 2.0.1 base only.
OCPI and ISO 15118 are different things
OCPP
Between a charging station and its own back end (CSMS).
OCPI
Between companies: charge point operators (CPO) and e-mobility service providers (eMSP). It handles authentication, authorisation, billing and session exchange, either peer to peer or through a hub. Used for roaming.
ISO 15118
Between the car and the charger. It enables Plug and Charge, where the car authenticates itself automatically with certificates over TLS. First published in 2014; Edition 2 in 2019.
A single session can touch all three: the car and the charger use ISO 15118, the charger and its CSMS use OCPP, and the CSMS of the operator talks to a roaming partner over OCPI.
What this means in Armenia
Armenia’s public network has both AC and DC chargers. Connector types differ more than in Europe, because cars arrive from the United States, China and Europe; see connector types in Armenia. The protocol is the same whatever the plug. Our CSMS accepts 1.6J, 2.0.1 and 2.1 for the core flows. Features exclusive to 2.1 and certificate-based Plug and Charge are not implemented yet.
Questions to ask a charger supplier
- Which OCPP versions and which message sets does the charger support, and can I see a conformance report?
- Does it support Basic authentication over TLS, and client certificates?
- Does it buffer transactions offline and replay them on reconnect?
- Which smart-charging profile features work?
- Who updates the firmware, and how is it delivered?
Questions and answers
What does OCPP stand for?
Open Charge Point Protocol, an open standard maintained by the Open Charge Alliance.
Is OCPP 2.0.1 backward compatible with 1.6?
No. They are different protocols, so a back end has to implement each separately.
What does the “J” in 1.6J mean?
It marks the JSON-over-WebSocket flavour of OCPP 1.6; the other flavour used SOAP.
Is OCPP the same as OCPI?
No. OCPP connects a charger to its back end; OCPI connects companies for roaming.
Do I need ISO 15118?
Only for Plug and Charge and vehicle-to-grid features. It is not required to run a basic public network.
Sources
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