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ModbusBB: Modbus TCP RTU Tool

A Modbus master, scanner, slave simulator and logger for Android, over TCP, USB RS-485 and Bluetooth.

ModbusBB is our Modbus toolkit, available for Windows and Android. The Android version is built for site work: you can poll an energy meter or a drive from the panel without carrying a laptop.

Plug in a USB-to-RS-485 adapter with an OTG cable, or pair a Bluetooth serial module, and you're on the bus.

What it does

Every common transport

Modbus TCP, UDP and RTU-over-TCP. RTU over USB OTG RS-485 adapters (FTDI, CH340, CP210x, PL2303) and Bluetooth SPP modules (HC-05/06).

Read and write

Function codes FC01–06, 15 and 16, with 11 data types, all four byte orders, scaling and named registers.

Traffic monitor

Live TX/RX frames, so you can see exactly what goes on the wire.

Scanners

Find the Unit IDs on a bus, sweep register ranges, or send raw frames.

Device tools

FC08 diagnostics, FC17 report server ID, FC43/14 device identification, FC22 and FC23.

Slave simulator

Act as a Modbus slave over TCP, UDP, USB or Bluetooth. Fault injection lets you test how your SCADA side copes.

Logging and alarms

Background recording with trend charts and CSV export. Alarms on high, low, out-of-range or changed values can send a notification or write a value.

Device library

Ready-made register maps for meters and drives such as the Eastron SDM120/630, Carlo Gavazzi EM24, Growatt inverters, ABB ACS580 and Altivar.

Your data

Your Modbus data, device addresses and workspaces stay on the phone. The free version uses Google AdMob, and Firebase collects crash logs and basic app-usage events. ModbusBB does not collect your location or contacts.

Questions people ask

Which USB to RS-485 adapters work?

Adapters built on FTDI, CH340, CP210x or PL2303 chips, connected with a USB OTG cable. Most cheap "USB to RS485" dongles use one of these.

Can ModbusBB act as a slave / server?

Yes. The simulator answers requests over TCP, UDP, USB or Bluetooth. You can inject faults to test how your master handles them.

Is there a Windows version?

Yes. ModbusBB for Windows is at modbus.maxenergic.com, and workspaces (.mbws files) open in both versions.

What does premium add?

Premium removes ads. It comes as a monthly plan, a yearly plan with a 7-day free trial, or a one-time lifetime purchase through Google Play.

Something else? Email support@maxenergic.com and include your phone model and Android version.