ModbusBB is a Windows Modbus master/client, slave/server simulator and command-line tool for SCADA and automation engineers testing PLCs, meters, inverters, drives and gateways.

Connect to multiple devices over TCP, RTU, ASCII, RTU-over-TCP or UDP. Read/write coils and registers, inspect raw TX/RX frames, decode 16/32/64-bit values and strings with selectable byte order, scaling and units, and use FC08/17/22/23/43 device tools.

Simulate devices with value generators, exceptions and delays. Scan devices/registers, plot trends, log CSV data, configure watchdog alerts and automate tests with CLI JSON/CSV output.

Free 30-day trial: all features, 15-minute sessions. $10 USD lifetime license: unlimited session time, one user on up to 3 computers, free updates. License activation and verification at least every 30 days require internet access.

Published by Max Energic Apps. Docs: https://modbus.maxenergic.com/docs.html

Features

  • Modbus TCP, RTU, ASCII, RTU-over-TCP and UDP
  • Multiple simultaneous connections, each with multiple poll tabs
  • Raw TX/RX traffic monitor (hex + ASCII) with filter, pause and export
  • Auto-reconnect with backoff, configurable retries and timeouts
  • Float32/64, Int16/32/64, UInt16/32/64, String, Hex, Binary - 4 byte orders
  • Scaling, offset, units and engineering values; Modicon address notation
  • Device Tools: FC43/14 device ID, FC17, FC08, FC22 mask write, FC23, raw requests
  • Register-map library for common energy meters, inverters and drives
  • Slave simulator: TCP/UDP/RTU/ASCII, multiple unit IDs, generators, exception injection
  • Live trend chart with zoom/pan and CSV/PNG export
  • Watchdog alerts with actions: CSV log, sound, write register
  • Scriptable CLI: JSON/CSV output, --trace, exit codes, workspace run, simulate
  • Workspaces, slave & register scanners, CSV data logging, dark/light theme

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Additional Project Details

Operating Systems

Windows

Intended Audience

Engineering

User Interface

.NET/Mono

Programming Language

C#

Related Categories

C# Communications Software, C# Networking Software, C# SCADA Software

Registered

2026-03-28