# 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.