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projnikdroid edited this page Jul 30, 2026 · 1 revision

ModbusViewer

A cross-platform (Windows + macOS) Modbus TCP/RTU master tool — a free, open-source Qt6/QML alternative to Modbus Poll, for testing, polling, and debugging Modbus devices, PLCs, and SCADA systems.

Quick links

What it does

  • Modbus TCP and RTU (serial) master — one connection screen for both transport types.
  • Full register-type support: Coils, Discrete Inputs, Input Registers, and Holding Registers, in both a dense table (Normal view) and a curated list/card view (Favorites).
  • Live polling of a contiguous range or a hand-picked list of registers, with read coalescing so nearby registers merge into the fewest possible requests.
  • Register writes — Holding Registers and Coils — with immediate re-read to confirm.
  • Per-register value formatting: Signed/Unsigned Decimal, Hex, Binary, Float32, Int32, with configurable byte order, scale, offset, and unit.
  • Tag database import from CSV or JSON, so registers get real labels instead of bare addresses.
  • Auto-reconnect with a "connection lost" state that keeps last-known values on screen instead of clearing them.

Wiki pages

  • Getting Started — install, build, and connect to your first device
  • Modbus Register Types — what Coils/Discrete Inputs/Input Registers/Holding Registers mean and how this app exposes them

This wiki is a lighter companion to the docs in the repo — for the authoritative, always-current technical detail, see PROGRESS.md and docs/.

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