ISO/TS 20684-5:2022

Overview

ISO/TS 20684-5:2022 - Intelligent transport systems (ITS) - Roadside modules SNMP data interface - Part 5: Logs defines user needs, requirements and design elements for recording timestamped information on ITS field devices (traffic signals, message signs, weather stations, traffic sensors, and C-ITS roadside equipment). Built on SNMP conventions, this technical specification standardizes how roadside modules create, store and expose log entries so a manager can determine the state of an object instance immediately when a trigger occurs - without frequent polling.

Key topics and technical requirements

• Logging model: Defines four core components - Log, Log Event Factory, Log Manager, and use of a UTC clock for timestamps (ISO/TS 20684-7 dependency).
• User needs: Configure device to capture user‑defined exceptions and transient events (e.g., vehicle counts every 15 minutes, diagnostic or operational events).
• Data exchange and capabilities:
  • Managers must be able to determine log capabilities (maximum entry size and maximum logging latency).
  • Configure and verify global logging limits: maximum stored data size, maximum number of events, and maximum event age.
  • Retrieve individual logged events and log statistics.
• Log entry size: Each log entry shall support data values of at least 400 octets.
• Management operations: Create/verify/configure log event factories and log managers; toggle, delete, clear old/all events; retrieve summary and detailed statistics.
• Protocol artifacts: Includes normative Management Information Base (MIB) definitions (Annex A) and a Requirements Traceability Matrix (Annex B).
• Security and dialogues: Covers security vulnerabilities and custom dialogues (e.g., clearing old events - Clause 7, security considerations - Clause 8).

Applications and users

Who benefits:

• ITS agencies and transportation authorities
• Field device and roadside equipment vendors
• System integrators and network managers
• C-ITS platform operators and traffic management centres

Practical uses:

• Capture transient events that fall between polling cycles (reducing network load).
• Maintain accurate time‑stamped diagnostics and operational histories (door open events, message changes).
• Support multiple managers or systems by segregating logs (operational vs diagnostic).
• Enable open, non‑proprietary procurement and interoperable roadside module deployments.

Related standards

• ISO/TS 20684-1:2021 (overview and relation to ITS architecture)
• ISO/TS 20684-3 (triggers and actions used to call Log Event Factory)
• ISO/TS 20684-7 (UTC clock, object group features)
• SNMP/SMIv2 and related IETF RFCs (management framework and MIB structure)
• Note: There are similarities with portions of NTCIP 1103.

Keywords: ISO/TS 20684-5, ITS logs, roadside modules, SNMP data interface, log manager, log event factory, MIB, ITS field devices.