ModbusSniffer

ModbusSniffer is a tool designed for capturing and analyzing network traffic using the Modbus protocol. It makes it easier to debug and diagnose communications between industrial devices.

★★★★★

5.0(1 ratings)

• Real-time traffic capture. The tool continuously monitors the selected port, recording all Modbus TCP or RTU packets that travel across the network. Data is displayed in a structured interface with timestamps.
• Advanced address filtering. Lets you configure filters based on IP addresses, device IDs, or Modbus function types. This helps focus the analysis on specific frames without noise in the results.
• Detailed frame decoding. Each captured packet is broken down field by field: function code, affected registers, written/read values, and error codes when present.
• Log export. Captured data can be saved in CSV or TXT formats for later external analysis. Metadata such as connection settings and session parameters is included.
• Offline test mode. Supports loading previous capture files to simulate and study scenarios without needing a physical connection to real equipment.
• Modbus RTU over TCP support. Correctly interprets encapsulated frames that use serial-to-Ethernet converters, preserving the original structure of the protocol.
• Communication statistics. Generates performance metrics such as response time, error rate, and distribution of command types per device.
• Automatic error detection. Identifies and highlights Modbus exceptions, invalid checksums, and timeouts in the monitored transactions.
• Alert threshold configuration. Lets you define limit values for parameters such as response delay or query frequency, generating notifications when they are exceeded.
• Multi-window interface. Makes it possible to open several simultaneous monitoring sessions with different filters or devices in separate tabs.
• Configuration backup. Stores connection profiles with all technical parameters so you can quickly reconnect to frequently audited devices.

Development of ModbusSniffer began in 2018 as a personal project of an engineer specializing in industrial control systems. Stable version 1.0 was released in 2020. The code is written in Python using libraries such as PyQt for the graphical interface and Scapy for packet handling. Active maintenance continues with regular updates that add support for new protocol variants.

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