Modbus Viewer: TCP, RTU, BT

Modbus Viewer is a toolkit for engineers and technicians working with Modbus devices. Connect to equipment, inspect and change register values, build dashboards, analyze traffic, or simulate a server to test a Modbus Master.

Modbus connections:

Work as a Modbus Client over TCP, RTU, or RTU over TCP. Connect through Wi-Fi/Ethernet, USB and RS-485 adapters, or Bluetooth SPP. Configure polling intervals, timeouts and communication alerts for your setup. The built-in scanner helps discover devices and their addresses.

Registers and data:

Read and write Coils, Discrete Inputs, Input Registers and Holding Registers. Browse a continuous address range or maintain a list of selected registers. Configure names, data formats and multipliers to make values easier to interpret.

Work with signed values, Float32 and Float64, 32-bit and 64-bit data, DEC/HEX/BIN views, and byte and word order options. Use the bit editor to inspect or change individual register bits.

Modbus TCP and RTU Server:

Create a Modbus TCP or RTU Server with your own register tables, values and attributes. Use it to test a Master, demonstrate a configuration, or make register data available to another Modbus device.

Server simulation:

Create rules that change values in the actual TCP or RTU Server register tables. Select one address or a range of Coils, Discrete Inputs, Input Registers or Holding Registers.

For IR/HR, choose sine, triangle, saw, square, random, linear or custom expressions; for Coil/DI, use toggle, pulse or random signals.

Preview generated values before starting the server. Once the server runs, a connected Master reads them as ordinary register data. Enable rules individually and use Start/Stop to control the simulation.

HMI dashboards:

Build dashboards for monitoring and control with customizable widgets. Configure names, measurement units, numeric precision, text size and the number of tiles per row. Edit variable values directly from an HMI dashboard.

Trends and logs:

Follow changing values on interactive charts. Navigate recordings with the Trend Calendar, synchronize charts and adjust chart density. Export trend data and logs to CSV for further analysis.

MQTT and Home Assistant:

Use the MQTT Terminal to interact with a broker, Explorer to inspect topics, and customizable MQTT dashboards to monitor data. Home Assistant MQTT Discovery helps integrate supported entities into a Home Assistant setup.

RTU Sniffer and diagnostics:

Capture and inspect communication between a Modbus Master and Slave, or analyze previously saved Sniffer and Client logs. Automatic baud rate detection helps identify RTU connection settings.

The HEX Log Inspector decodes raw packets into a readable structure with register addresses and values. A configuration wizard can turn analyzed traffic into Client or Server settings.

Excel files and projects:

Import and export register tables for Client, Server, HMI and MQTT using Excel files. Save your configuration as a project and restore it later.

Recent changes:
7.1.1:
• Simulation rule cards now show a live waveform preview.
• Removed the duplicate Linear function from simulation rules.
7.1.0:
• Debut release of register simulation for TCP/RTU Server.
• Custom fast-scroll bars.
• Extended Unit ID range (up to 255), fixed variable name displays.
• Added Polish, Turkish, Indonesian, and Vietnamese localizations.
• UI improvements.