Handbook

IoT communication protocols (blueprint)

**Purpose:** Protocol selection guidance and implementation considerations for IoT device communication. Each protocol entry covers its architecture, message format, QoS, security, power profile, and

IoT communication protocols (blueprint)

Purpose: Protocol selection guidance and implementation considerations for IoT device communication. Each protocol entry covers its architecture, message format, QoS, security, power profile, and best-fit scenarios.

Why protocol selection matters: The application protocol (and its transport) constrains latency, duty cycle, security posture, NAT behavior, and operational cost. Committing late often forces gateways, duplicate stacks, or non-interoperable silos. Treat protocol choice as an architecture decision tied to power budgets, update strategy, and cloud or on-prem integrations — see EMBEDDED-IOT.md for the embedded/IoT map and Embedded / IoT ↔ SDLC ↔ PDLC bridge for lifecycle impact.

Audience: Teams adopting Embedded / IoT Engineering; project-specific protocol configuration stays in docs/development/embedded/protocols/.

Protocol stack (reference layers)

flowchart TB subgraph app [Application] M[MQTT / CoAP / OPC UA / Matter ...] end subgraph trans [Transport] T[TCP / UDP / QUIC ...] end subgraph net [Network] N[IP / 6LoWPAN ...] end subgraph link [Link] L[802.15.4 / BLE / Wi-Fi / Ethernet ...] end subgraph phy [Physical] P[Radio / wire] end M --> T --> N --> L --> P

Protocol	Layer	Focus	Deep dive
MQTT & CoAP	Application	Pub/sub vs REST-like constrained apps — QoS, observe, brokers	`mqtt-coap.md`
BLE & Zigbee	Link + network / app	GATT, mesh, Thread/Matter context, coexistence	`ble-zigbee.md`
LoRaWAN	Network	LPWAN — spreading factors, ADR, class A/B/C, join procedures, fair-use policy	EMBEDDED-IOT.md §3
Modbus	Application (Serial/TCP)	Industrial — RTU vs TCP, function codes, register mapping, polling vs event	EMBEDDED-IOT.md §3
OPC UA	Application (TCP)	Industrial interoperability — information model, security, pub/sub, companion specifications	EMBEDDED-IOT.md §3
CAN bus	Data link	Automotive/industrial — message arbitration, error handling, CANopen, J1939	EMBEDDED-IOT.md §3
Matter	Application	Smart home — Thread/Wi-Fi transport, device types, commissioning, multi-admin	(see `ble-zigbee.md`)

Core knowledge: EMBEDDED-IOT.md — communication protocol overview and selection criteria.

Bridge: Embedded / IoT ↔ SDLC ↔ PDLC bridge — protocol choices across the lifecycle.

Keep project-specific safety documentation in docs/safety/ and hazard analyses in docs/security/, not in this file.

Canonical source

Edit https://github.com/autowww/blueprints/blob/main/disciplines/engineering/embedded-iot/protocols/README.md first; regenerate with docs/build-handbook.py.