The telematics control unit in each vehicle publishes position, CAN signals, battery and diagnostic data to ConnectMQ and receives remote commands on its own topics. Your vehicle backend, mobile app and service tools subscribe — over cellular links that come and go.
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PUBLISH vehicles/veh-20417/telemetry
{"ts":"2026-10-22T07:42:10Z","lat":52.5201,"lon":13.4049,"speed_kmh":48,"soc":71,"odo_km":38412,"dtc":[]}QoS 1 · TLS 8883 · PUBACK
Vehicles drive through tunnels, underground car parks and roaming zones. HTTP polling from the TCU wastes data and misses commands, and every new service — remote unlock, pre-conditioning, diagnostics, software campaigns — tends to bring its own connection to the car. Engineering teams end up maintaining several pipelines to the same vehicle.
The TCU or an in-vehicle gateway reads CAN and OBD signals and publishes position, speed, state of charge, DTCs and status to the vehicle’s topics in compact JSON or binary payloads.
The vehicle backend, data platform and driver or fleet apps subscribe to what they need — one vehicle, a model line or the whole fleet through wildcards.
The app or backend publishes a command — lock, unlock, climate, locate — with QoS 1. The vehicle acknowledges on a response topic, and a persistent session holds the command while the vehicle is offline.
Your OTA service publishes a campaign notice with the package URL to a vehicle group. Vehicles download the package from your servers and report download, install and version status over MQTT.
Small MQTT headers, a configurable keep-alive and persistent sessions keep data use low and let a vehicle catch up on queued messages after a dead zone.
QoS 1 for commands and campaign messages; MQTT 5 message expiry and response topics help make sure a stale unlock is never executed hours later.
Each vehicle gets its own credentials and ACL, so a TCU can only publish to and receive from its own topics.
Last Will and a retained status topic tell the backend at once when a vehicle goes offline and when it is back.
vehicles/veh-20417/telemetry
vehicles/veh-20417/commands
vehicles/veh-20417/commands/response
vehicles/veh-20417/status (retained)
ota/campaigns/tcu-fw-4-2/announce (retained)Yes. MQTT is widely used between telematics units and vehicle clouds because it is lightweight, keeps one long-lived connection open and copes well with cellular coverage that comes and goes. Most cloud IoT platforms and many telematics stacks support it.
MQTT is well suited to coordinating a campaign: notifying a vehicle group, collecting download and install progress and confirming the new version. The update package itself is normally downloaded over HTTPS from your OTA service or CDN — ConnectMQ does not host or sign packages.
Use TLS, unique credentials per vehicle and ACLs, so only your backend may publish to a vehicle’s command topic and each vehicle reads only its own. Add a command ID, an expiry and an acknowledgement on a response topic, and validate every command in the vehicle before acting on it.
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