ocpp2mqtt

A lightweight OCPP 1.6 Central System (CSMS) that bridges EV chargers to MQTT. Every message a charger sends (status, meter values, transactions…) is published as MQTT topics, and every charger command (start/stop charging, set current limit, reset…) can be triggered by publishing to an MQTT topic.

Built for home / self-hosted setups (e.g. integrating a wallbox into openHAB, Home Assistant, Node-RED, …) where you want a single, hackable MQTT interface to your charger.

How it works

   EV charger  ──WebSocket (ocpp1.6)──►  ocpp2mqtt   ──MQTT──►  broker  ──►  your automation
                ◄───── commands ───────              ◄──MQTT───            (openHAB / HA / …)

• The charger connects to ws://<host>:9000/<charger_id> using subprotocol ocpp1.6.
• Incoming OCPP messages are published under ocpp2mqtt/<charger_id>/....
• Commands are sent by publishing to ocpp2mqtt/<charger_id>/cmd/<command>.

Requirements

• Docker + Docker Compose
• An MQTT broker (e.g. Eclipse Mosquitto)
• An OCPP 1.6 capable charger reachable on the network

Quick start

git clone <this-repo>
cd ocpp2mqtt
cp .env.example .env      # then edit .env with your broker host / credentials
docker compose up -d
docker compose logs -f

Point your charger's OCPP backend URL to:

ws://<server-ip>:9000/<charger_id>

<charger_id> is free-form; it becomes the MQTT topic namespace for that charger.

Configuration

All configuration is via environment variables (see .env.example):

Variable	Default	Description
MQTT_HOST	mosquitto	MQTT broker hostname / IP
MQTT_PORT	1883	MQTT broker port
MQTT_USER	(empty)	MQTT username (omit for anonymous)
MQTT_PASS	(empty)	MQTT password
MQTT_PREFIX	ocpp2mqtt	Root topic prefix
OCPP_PORT	9000	WebSocket listen port for chargers
EXPECTED_CHARGERS	(empty)	Comma-separated charger IDs; their status is pre-published as Disconnected (retained) on startup
LOG_LEVEL	INFO	DEBUG / INFO / WARNING / ERROR / CRITICAL

OCPP_IPV4 / OCPP_IPV6 in .env are only used by the example docker-compose.yml to assign static addresses on a macvlan network — adapt or remove the networks: section to match your own setup.

MQTT topics

Published by the bridge (charger → MQTT)

Topic	Retained	Payload
ocpp2mqtt/bridge/status	yes	online / offline (LWT)
ocpp2mqtt/<id>/status	yes	Connected / Disconnected
ocpp2mqtt/<id>/last_connected	yes	ISO-8601 timestamp of last connect
ocpp2mqtt/<id>/last_disconnected	yes	ISO-8601 timestamp of last disconnect
ocpp2mqtt/<id>/disconnect_reason	yes	normal_closure / connection_error_<code> / unexpected_error
ocpp2mqtt/<id>/boot	no	{"vendor":..., "model":..., "firmware":...}
ocpp2mqtt/<id>/firmware	yes	charger firmware version
ocpp2mqtt/<id>/heartbeat	no	ISO-8601 timestamp
ocpp2mqtt/<id>/connector/<n>/status	yes	OCPP status (e.g. Charging)
ocpp2mqtt/<id>/connector/<n>/error	yes	OCPP error code
ocpp2mqtt/<id>/connector/<n>/meter/<measurand>	no	{"value":..., "unit":...}
ocpp2mqtt/<id>/connector/<n>/session/start	no	{"meter_start_wh":..., "id_tag":...}
ocpp2mqtt/<id>/session/stop	no	{"meter_stop_wh":..., ...}
ocpp2mqtt/<id>/cmd/<command>/response	no	command result

On disconnect, the instantaneous meters (power_active_import, current_import*) are republished as 0 so dashboards don't show stale "still charging" values. Cumulative energy and voltages keep their last value.

Commands (MQTT → charger)

Publish to ocpp2mqtt/<id>/cmd/<command>:

Command	Payload example
start	{"connector_id": 1, "tag": "FREE"}
stop	{}
set_limit	{"amps": 16} (clamped to 6–32 A; 0 pauses the charge), optional {"purpose": "tx"}
unlock	{"connector_id": 1}
reset	{"type": "Soft"} or {"type": "Hard"}
change_availability	{"available": false, "connector_id": 0} (false = block charging)
trigger	{"message": "StatusNotification", "connector_id": 1}
get_configuration	{} or {"keys": ["MeterValueSampleInterval"]}
change_configuration	{"key": "MeterValueSampleInterval", "value": "15"}

Example — set the charging current to 16 A:

mosquitto_pub -h <broker> -u <user> -P <pass> \
  -t 'ocpp2mqtt/my_wallbox/cmd/set_limit' -m '{"amps": 16}'

Worked example — first-time charger setup

The following sequence configures meter-value sampling and disables authentication on a real charger (here my_wallbox). Adjust the topic namespace to your own <charger_id>.

# Read which configuration keys the charger supports
#   → response on ocpp2mqtt/my_wallbox/cmd/get_configuration/response
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/get_configuration' -m '{}'

# Choose which measurands are reported on each sample / aligned interval
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"MeterValuesSampledData","value":"Energy.Active.Import.Register,Power.Active.Import,Current.Import,Voltage"}'
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"MeterValuesAlignedData","value":"Energy.Active.Import.Register,Power.Active.Import,Current.Import,Voltage"}'

# Sampling cadence (seconds)
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"MeterValueSampleInterval","value":"15"}'
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"ClockAlignedDataInterval","value":"15"}'

# Keep buffering meter values while the charger is offline
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"MeterValuesSkipWhenOffline","value":"true"}'

# Disable RFID authentication (free charging on a trusted network)
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/change_configuration' \
  -m '{"key":"AuthEnabled","value":"false"}'

# Charging control
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/start'     -m '{"connector_id": 1}'
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/unlock'    -m '{"connector_id": 1}'
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/stop'      -m '{}'
mosquitto_pub -t 'ocpp2mqtt/my_wallbox/cmd/set_limit' -m '{"amps": 16}'

⚠️ Security notes

This bridge is designed to run on a trusted local network. By default:

• The WebSocket endpoint is not authenticated — any host that can reach :9000 can register as a charger.
• Authorize and StartTransaction accept any RFID tag — there is no access control on who may charge.

Do not expose port 9000 to the internet. Put it behind a VPN / firewall, and rely on your MQTT broker's authentication for the control side.

Tech stack

• ocpp (The Mobility House, MIT) — OCPP 1.6 protocol
• websockets — WebSocket server
• paho-mqtt — MQTT client

License

MIT © Edoardo Barbano