Modbus/docs/superpowers/specs/2026-08-02-modbus-runtime-cleanup-design.md

Modbus Runtime Cleanup Design

Goal

Reduce the XDM-60T4-E Modbus RTU slave build surface and remove IAR-only
communication snapshots without changing Modbus behavior, TouchWin mapping,
RTC-backed register retention, or the two live-watch data arrays requested by
the user.

Confirmed Decisions

• Retain holdingRegisters, coilStorage, and extendedHoldingRegister as
  global data objects for IAR Live Watch.
• Remove request/response frame snapshots, register/coil mirror arrays,
  diagnostic status values, UART error snapshots, and snapshot sequence state.
• Remove only unused HAL source entries from EWARM/Modbus.ewp; retain all
  vendor files under Drivers/STM32F4xx_HAL_Driver.
• Preserve test sources, reference documents, the uC-OS2_temp reference
  directory, IAR settings, and the downloadable EWARM/Modbus/Exe/Modbus.hex.
• Remove generated host test binaries, crash dumps, and IAR intermediate build
  artifacts. Add ignore rules so they do not return to version control.

Safety Constraints

• The ordinary Modbus data range, coils, 0x41/0x42/0x43 private functions,
  USART1 receive recovery, T1.5/T3.5 timing, and RTC backup behavior must not
  change.
• Modbus.hex is retained as the deployable firmware image. Modbus.out,
  Modbus.sim, IAR object files, and map files are reproducible outputs.
• Existing host tests and the IAR target build are the regression gate. No
  pre-existing user modifications are reverted, staged, or committed.

Deliverables

• Leaner IAR source list and runtime source code with focused Doxygen comments.
• docs/项目设计.md describing the final architecture and exact file:line
  source locations after cleanup.