Windows
x64 installer
The simulator serves TCP on Windows; RTU needs a virtual COM pair.
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The Modbus client for macOS, Windows and Linux.
Read and write devices over RTU serial, Modbus TCP and RTU over TCP, keep register maps as files, see the RS-485 bus as it runs and test against a built-in simulator. Native Rust, with no browser engine inside.
From the value that looks wrong to the frame that explains it.
A dense, keyboard-first workspace where registers, bus timing and frames get the room and the chrome steps back. Every screen here is the app itself, running on fictional sample devices.
Every serial port has a scheduler, and the bus view shows it: a timeline of transmit, wait and receive per unit, bus occupancy, the t3.5 gap, timeouts, the backoff of a unit that stopped answering and what its silence costs the others, and the adapter's latency timer.
Raw hex and decimal next to the decoded value, with type, scale and unit from the map. The inspector gives the address in three notations (protocol 0-based, 1-based and 4xxxx), because manuals use all three, and applies the map's validity rules: a sentinel value or a status bit marks a reading invalid instead of passing it off as a number.
The same 32-bit reading in ABCD, CDAB, BADC and DCBA side by side, with the map's order marked. When a manual says “little endian” and means the word order, the one row that reads a plausible value settles it.
Every frame on the connection, newest first, filtered by unit, function code or errors only. Select one and it is decoded field by field, the CRC checked against the one computed, with the frame's timing. The log exports as CSV or text.
On a live-plant connection a write asks you to type the register's name, previews the raw value (in two's complement for a negative number) and the frame it will send, and reads the register back after writing. Read-only connections hide every write.
Registers that must change together go out in one FC16 frame per block. Every block is validated before any byte reaches the bus, a block aimed at unit 0, the broadcast address, is refused, and one bad block stops the whole request.
Serve any map over TCP and, on Linux and macOS, over RTU on a virtual serial pair, with value generators and fault injection: exceptions, delayed replies, silence and bad CRCs. Point a connection at it and work through the whole app with no hardware.
Paste a hex blob from a gateway or an MQTT message, or a raw RTU or TCP frame, and read it against a map: register by register, or field by field.
A register map is a JSON file you can keep in git. Edit it as a table or as JSON with a validation strip, import and export CSV, and diff the working copy against git HEAD or the saved file.
Ctrl K (Cmd K on macOS) reaches every connection, device, register and view without hunting through the tree.
Every device, on every line.
A USB adapter on the bench, a serial-to-Ethernet converter at a plant and a PLC on the network sit in one explorer, grouped by site, with the devices on each connection under it by unit ID.
- Three transports
- RTU over a serial port, Modbus TCP, and RTU over TCP for the serial-to-Ethernet converters in front of an RS-485 line. Each connection holds its devices by unit ID.
- Function codes 01, 02, 03, 04, 05, 06, 15 and 16
- Read coils, discrete inputs, holding and input registers; write a single coil or register, or many at once. Modbus terms are used as the spec writes them: unit ID, coil, exception code, broadcast, t3.5.
- Grouped by site, colored by connection
- Mark a connection as a live plant and its color tints the toolbar, the tab and the status bar, so it never looks like the bench, and every write asks first. A read-only connection hides writes entirely.
- Serial ports that keep their names
- On Linux, connections save the stable /dev/serial/by-id path, so a port keeps its name when the adapter is re-plugged; your user needs the dialout group (uucp on Arch). On macOS only /dev/cu.* ports are listed. On Windows, a port another program holds is reported as busy.
- Nothing added to the protocol
- Modbus has no authentication or encryption, and Mb Studio adds none. It stores no passwords.
Connections
- BRBench RS-485/dev/serial/by-id/usb-FTDI_FT232R_USB_UARTRTU · 57600 8N1
- SISimulator127.0.0.1:5020 and a virtual serial pairRTU + TCP
- CACold rooms, line A10.20.4.15:4001Live plant
- IPIrrigation PLC192.168.50.10:502Read-only
- PHPump houseConnection refusedRefused
Serial RTU, Modbus TCP, RTU over TCP Live plants ask before any write
Serial ports on Linux
Join the dialout group once (log out and back in after). FTDI adapters hold every short reply for 16 ms by default; lowering the latency timer to 1 ms speeds up every transaction, until the adapter is re-plugged.
sudo usermod -aG dialout $USERecho 1 | sudo tee /sys/bus/usb-serial/devices/ttyUSB0/latency_timerLight or dark, it is the same tool.
Twin dark and light themes, dark by default, built to sit next to your IDE. Drag to compare.
And the rest of the toolbox
- Scanner
- Finds the unit IDs that answer on a line and the address ranges each one serves.
- Live charts
- Plot any registers of a device as they are polled, with now, min, average and max for each series.
- Session recording
- Record a session's values to CSV, to read later or hand to someone else.
- Frame log export
- Save the traffic log as CSV or text, to attach to a ticket or compare with another capture.
- Validity rules
- A map can mark sentinel values and status bits that make a reading invalid, so a dead sensor is not read as a temperature.
- Problems first
- Timeouts, exception codes, CRC errors and mute units surface before the normal traffic, counted in the status bar.
- SSH tunnels
- Reach a Modbus TCP device or a serial-to-Ethernet converter that only a bastion host can see. Host keys are pinned on first use; passwords and passphrases go to the system keychain.
- Split editor
- Up to four panes side by side or in a grid: the bus of one line next to a device on another, each keeping its own selection.
- Import and export
- Move connections between machines as one JSON file with every option, passwords only if you ask for them.
- Test before saving
- A new connection can be tested from its dialog before it joins the explorer.
- Copy as mbpoll
- The current read as an mbpoll command line, for a terminal.
- Logs without values
- A local log for when a connection fails or the app crashes. It holds connection names, hosts, errors and timings, never frame contents or register values.
- Fonts and icons inside
- Inter, JetBrains Mono and the Lucide icons are embedded in the app, so it looks the same on every system with nothing else to install.
Native Rust, no browser inside.
The interface is egui drawn with OpenGL. There is no WebKit process, no JavaScript heap and no network process, and the app repaints only when the data changed. Release build, measured on Linux, 2026-10-13.
- First frame
- 70–107 ms
- From launch to the first painted frame, 16 runs.
- CPU, idle
- 0.00 %
- Of one core with nothing connected, over 7 runs; one run read 0.15 %.
- CPU, live
- 0.57 %
- Simulator serving and a client polling 20 registers every second.
- Memory
- 66–87 MB
- PSS of the whole app, idle or live.
- Binary
- 13.5 MiB
- Fonts, icons, the whole interface, SSH and the keychain inside. The .deb is 6.2 MiB.
Next to its siblings, measured the same way
| App | First frame | Idle CPU one core | Memory PSS, all processes | Binary |
|---|---|---|---|---|
| Postgres Studio Tauri | – | 0.17 % | 249 MB | 16.8 MiB |
| Rabbit Studio Tauri | 196–263 ms | 0.03 % | 234–252 MB | 15.8 MiB |
| Mb Studio egui | 70–107 ms | 0.00 % | 66–87 MB | 13.5 MiB |
Release builds with an idle window, CPU over 30 s after launch, memory as the PSS of every process 10 s after the first frame. AMD Ryzen 7 5700G, Linux 7.0, Wayland session. Postgres Studio's first frame was not measured.
Nothing leaves your machine.
Read the privacy policy- No account
- Install it and connect. There is nothing to sign into.
- No telemetry
- No analytics and no update checks. The app talks only to the devices, gateways and serial adapters you set up, and to its own simulator.
- Your files
- Connections stay on your computer; register maps, CSV exports and recordings are saved where you choose.
- MIT licensed
- Native Rust with egui, from one codebase for macOS, Windows and Linux, with no runtime to install.
Download Mb Studio
Version 0.1.0, free and open source.
Mb Studio is not released yet. Installers for Windows, macOS and Linux appear here as soon as the first build is out.
Your system
macOS
Apple silicon
A disk image for Macs with Apple silicon. Only /dev/cu.* serial ports are listed.
Linux
x86_64
Debian, Ubuntu and derivatives.
sudo apt install ./mb-studio_0.1.0_amd64.debAny distribution, nothing to install.
chmod +x mb-studio_0.1.0_x86_64.AppImage./mb-studio_0.1.0_x86_64.AppImageBuilds are not code-signed yet, so the first launch shows a Gatekeeper warning on macOS and a SmartScreen warning on Windows.