PY Modbus Test Suite

Version updated for https://github.com/php-modbus/py-modbus-test-suite to version v1.0.0.

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Action Type

This is a Composite action.

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What’s Changed

v1.0.0 — 2026-07-07

Initial Release

Docker-based Modbus server simulator suite for testing Modbus clients and SCADA systems, built on pymodbus (pinned 3.13.1).

Server Infrastructure

  • 6 pre-configured endpoints via Docker Compose from a single image: Modbus TCP (host port 502), RTU over TCP (5021), ASCII over TCP (5022), UDP (5023), Modbus/TCP Security TLS (host port 802), RTU on virtual serial via RFC2217 (5024, raw 5025).
  • Non-root container — binds unprivileged in-container ports (5020+); canonical 502/802 come from host port mappings.
  • Health check via python -m mbsim.healthcheck — reads hr[0] of the health device (unit 1, expected 1234), so docker compose up --wait gates on real Modbus readiness.
  • Baked-in config and certs — GitHub Actions service containers cannot mount checkout files; override at runtime with MBSIM_MAP_B64 / MBSIM_SCENARIO_B64 or a volume on /app/config.

Register Map & Generators

  • YAML register map (config/default-map.yaml) defining units 1–3 with holding registers, input registers, coils and discrete inputs; multiple devices entries simulate a multi-drop bus behind one endpoint.
  • 4 deterministic generators — ramp, sine, random_walk, toggle: tick-based, seeded per cell from the map seed — same map, same history, every run.

Fault Injection

  • Scenario YAML (config/scenarios/*.yaml) attaching deterministic faults per rule; matchers device_id, function_code, every_nth, after_n_requests, times — counting is request-order based, never wall clock.
  • 7 fault actions — exception, no_response, truncate, corrupt (CRC/LRC/MBAP), garbage, delay, disconnect.
  • 7 pre-configured fault services behind the faults compose profile (ports 5100–5106): tcp-silent, tcp-slow, tcp-exceptions, tcp-drop, rtu-tcp-badcrc, tcp-truncated, tcp-garbage.
  • Health-safety guard — rules that could hit holding-register reads on the health device are rejected at startup.

CI/CD

  • GitHub Actions composite action (action.yml) for one-step CI integration — inputs services, faults, wait-timeout; output certs-dir for TLS CA pinning.
  • Docker image published to ghcr.io/php-modbus/py-modbus-test-suite (multi-arch amd64/arm64) by .github/workflows/release.yml, gated on the smoke suite.
  • CI-optimized compose file (docker-compose.ci.yml) with no-restart policy.

Documentation

  • Documentation in docs/ covering setup, endpoints, register map, generators, fault injection, environment variables, serial usage, and CI integration.