# ModbusBB

> ModbusBB is Windows software (Windows 10/11, 64-bit) by Max Energic Apps for testing, troubleshooting and simulating Modbus devices. Version 2.0.2 is a Modbus master/client for Modbus TCP, UDP, RTU-over-TCP, RTU and ASCII. It supports multiple simultaneous connections, each with multiple poll tabs, and saves them in workspaces (.mbws). It has a raw TX/RX hex traffic monitor, 11 data types (16/32/64-bit integers, Float32/Float64, String) in four byte orders with scaling and units, Device Tools (FC08, FC17, FC22, FC23, FC43/14, raw requests), a 9-map device register library, and a slave simulator (TCP/UDP/RTU/ASCII, generators, exception injection). There is also a trend chart, watchdog alerts with actions, CSV logging, and a scriptable CLI with JSON/CSV output and exit codes. Pricing: $10 one-time lifetime license (up to 3 devices, free updates; 1.x keys keep working in 2.0); free 30-day trial with 15-minute sessions. Current version: 2.0.0.

The site also hosts vendor-neutral Modbus guides (addressing, function codes, TCP vs RTU, RS-485 wiring, timeouts, exception codes, byte order, simulation) and free in-browser Modbus tools. For a condensed plain-text fact sheet, see [llms-full.txt](https://modbus.maxenergic.com/llms-full.txt).

## Product

- [ModbusBB home](https://modbus.maxenergic.com/): Overview, what's new in 2.0, use cases, pricing summary and product FAQ
- [Features](https://modbus.maxenergic.com/features.html): Connections and transports, data types, traffic monitor, device tools, device library, simulator, trend, watchdog, CLI and licensing
- [Download](https://modbus.maxenergic.com/download.html): 2.0.2 installer and portable ZIP, SHA-256 checksums, release notes, system requirements and upgrade note
- [Buy a license](https://modbus.maxenergic.com/buy.html): $10 one-time lifetime license via PayPal, what is included, license FAQ
- [Documentation](https://modbus.maxenergic.com/docs.html): Getting started, connections, polls, workspaces, data types and byte order, scaling, address notation, traffic monitor, trend, watchdog, device tools, device library, simulator, licensing, upgrading from 1.x, FAQ and troubleshooting
- [User manual](https://modbus.maxenergic.com/manual.html): Complete step-by-step user manual with annotated screenshots (also as PDF: https://modbus.maxenergic.com/downloads/ModbusBB_User_Manual_2.0.1.pdf): installation, connections, polling, data types, writing, traffic monitor, device tools, register maps, scanners, simulator, trends, watchdog, logging, workspaces, CLI, license, updates, troubleshooting, function and exception code tables, glossary
- [CLI reference](https://modbus.maxenergic.com/cli.html): Modbus command-line tool: every command and option, output formats (table/JSON/CSV/NDJSON), exit codes, PowerShell/cmd/bash examples and CSV logging
- [ModbusPoll alternative](https://modbus.maxenergic.com/modbuspoll-alternative.html): How ModbusBB compares with Witte Software's Modbus Poll

## Modbus guides

- [Learn Modbus](https://modbus.maxenergic.com/learn.html): Protocol basics, master/slave model, frames, function codes, registers, data types and glossary
- [All guides](https://modbus.maxenergic.com/tutorials.html): Index of Modbus tutorials and troubleshooting guides
- [Register addressing: 40001 vs address 0](https://modbus.maxenergic.com/modbus-register-addressing.html): 0-based, 1-based and Modicon addressing and fixing off-by-one errors
- [Modbus function codes](https://modbus.maxenergic.com/modbus-function-codes.html): FC 01-06, 15, 16 plus FC 08, 17, 22, 23 and 43
- [Modbus TCP vs RTU](https://modbus.maxenergic.com/modbus-tcp-vs-rtu.html): Frame format, wiring, speed, port 502, RTU-over-TCP and Modbus UDP
- [RS-485 wiring and termination](https://modbus.maxenergic.com/modbus-rs485-wiring.html): Daisy-chain topology, A/B polarity, 120 ohm termination, biasing and serial settings
- [Modbus timeout troubleshooting](https://modbus.maxenergic.com/modbus-timeout-troubleshooting.html): Step-by-step TCP and RTU checklist using a raw traffic monitor
- [Modbus exception codes](https://modbus.maxenergic.com/modbus-error-codes.html): Codes 01-06, timeouts and CRC errors and how to fix them
- [Float32, 64-bit and byte order](https://modbus.maxenergic.com/modbus-float32-byte-order.html): ABCD/DCBA/BADC/CDAB for 32- and 64-bit values and strings
- [Modbus simulator guide](https://modbus.maxenergic.com/modbus-simulator-guide.html): Testing PLC, SCADA and gateway clients against a simulated slave with generators and exception injection

## Tools

- [Free Modbus tools](https://modbus.maxenergic.com/modbus-tools.html): In-browser Modbus RTU CRC-16 calculator, 4xxxx address converter and Float32 byte-order decoder

## CLI quick examples

- Read: `ModbusBB.CLI read --tcp 192.168.1.10 --unit 1 --holding --address 0 --count 10`
- Float32, word-swapped, JSON: `ModbusBB.CLI read --tcp 192.168.1.10 --input --address 0 --format float32 --byte-order CDAB --output json`
- Log to CSV: `ModbusBB.CLI poll --rtu COM3 --baud 9600 --unit 1 --address 0 --count 4 --interval 1000 --output csv > log.csv`
- Device ID: `ModbusBB.CLI devid --tcp 192.168.1.10 --category regular`
- Exit codes: 0 success, 1 runtime error, 2 usage error, 3 license error, 130 Ctrl+C

## Upgrade note

Existing 1.x license keys keep working in 2.0. Install 2.0 over the old version (don't uninstall first). ModbusBB detects the stored key and re-activates it on that PC (internet needed once). Old connection profiles (.json/.mbprofile) and .mbcfg files open as workspaces.

## Optional

- [Terms of Service](https://modbus.maxenergic.com/terms.html): Trial and lifetime license terms, restrictions and warranty disclaimer
- [Privacy Policy](https://modbus.maxenergic.com/privacy.html): What is and is not collected; Modbus device data is never sent to the vendor
- [Support](mailto:support@maxenergic.com): Email support for trial and licensed users