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There any free Serial port sniffer for monitoring COM port communication?

Kerry Bills 61 Reputation points
2024-10-09T23:25:24.7133333+00:00

Is there any completely free serial port sniffer software available? I'm specifically looking for a tool similar to Electronic Team "COM Port Monitoring" or "Free Serial Analyzer."

To clarify, I’m not asking about basic serial monitors like TeraTerm or Docklight that allow you to open a COM port and send/receive data from a device.

I'm looking for software that can passively monitor and log the data exchanged between a program like TeraTerm and a serial port, providing real-time insights into the communication without directly interacting with the devices involved.

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  1. Anonymous
    2024-10-11T01:40:05.0533333+00:00

    Hi Kerry,

    Thanks for your post. Based on my research, Microsoft didn’t provide any full free Serial port sniffer for monitoring COM port communication. You can see if some 3-third party software can meet your requirements.

    For example,

    Serial Port Monitor | FREE Serial Port Monitor [for Windows] (com-port-monitoring.com)

    Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it. Hope this helps.

    Best Regards,

    Ian Xue

    If the Answer is helpful, please click "Accept Answer" and upvote it.

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  1. Dominique Schluep 410 Reputation points
    2024-10-10T14:54:46.03+00:00

    Hello Kerry Bills

    You could use PuTTY (https://www.chiark.greenend.org.uk/~sgtatham/putty/ ) to monitor serial port communication or try SerialMon (https://www.serialmon.com/).

    Kind regards
    Dominique

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  2. Riccardo Alessi 0 Reputation points
    2025-07-06T20:27:15.8233333+00:00

    Hi,

    Undoubtedly, the best freemium software for working with serial ports on Windows, macOS, and Linux is SerialTool (www.serialtool.com).

    SerialTool is a powerful and versatile software designed for serial communication across Windows, macOS, and Linux. It functions as a Serial Port Utility, Serial Port Monitor, and Serial Port Sniffer, making it an essential tool for both hobbyists and professionals.

    SerialTool supports multiple COM ports simultaneously, enabling concurrent monitoring, communication, and control. It features hexadecimal and ASCII viewers, read/write consoles, and traffic logging with timestamp precision. With built-in support for Modbus RTU and Modbus ASCII, it includes a Modbus client for quick protocol testing.

    Advanced users benefit from a built-in Python scripting engine for automation, serial-to-network bridging, timed packet sending, and automatic response triggers based on incoming data.

    SerialTool also includes Virtual COM Port emulation, allowing you to create, link, and manage virtual port pairs for simulation and loopback testing.

    For deeper insight, SerialTool offers a serial sniffer kernel driver (on Windows) that captures low-level I/O control (IOCTL) signals and raw serial data, even from ports opened by other applications. It features a live session log, byte visualizer, structured packet list, IO controls, and a SerialScope for graphical waveform analysis.

    Data can be exported in binary, hex, ASCII, and directly to .pcap files for Wireshark analysis. A variety of UI themes and dockable windows provide a fully customizable user experience.

    Whether you're developing firmware, debugging hardware interfaces, or reverse-engineering devices, SerialTool delivers the reliability, flexibility, and depth you need in a professional-grade serial communication suite.

    Download the latest versions for Windows, macOS, and Linux at www.serialtool.com.

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