Free Serial Analyzer

Monitor and Analyze Serial Port Data Flows
Zero price software
by HHD Software

Free Serial Analyzer Overview

Free Serial Analyzer is a non-intrusive Serial Port sniffer and software RS-232/RS-422/RS-485 protocol analyzer for Windows.

It supports monitoring of serial port data on both 32-bit / 64-bit Windows desktop/server platforms including Windows 10, Windows 11 and Windows Server 2022. Windows 11 ARM64 is also supported.

Our software-based free serial port monitor is an ideal alternative to expensive hardware RS232/RS485/RS422 logic analyzers. This COM port analyzer utility requires no additional cabling and allows you to effectively capture/display any data and commands transmitted through your computer's serial ports.

The captured raw data is automatically decoded, analyzed and each serial communication packet is then presented in an easily readable format, allowing you to quickly and efficiently analyze data exchanged over RS 232, RS 422, or RS 485 serial interfaces.

For the best user experience, our product supports advanced data filtering. All intercepted serial data can be filtered by Requests, I/O Codes and even by custom filtering rules.

You can consider this serial port packet sniffer an effective tool to simplify development, testing and debugging of serial applications and devices.

Using our free serial protocol analyzer you don’t have to worry about any additional hardware, null-modem cables, DB-25 or DE-9 connectors and so on. It’s a pure software-based serial port sniffing solution. Just download, install and start using it in seconds!

How Free Serial Analyzer Works

Program installs filter driver on top of a serial device driver. Filter driver then intercepts I/O requests issued by an application communicating with a serial device. All control requests (requests that configure port parameters) and data transfer requests (requests that pass data between app and RS-232/RS-422/RS-485 hardware device) are monitored. Each serial data request is then parsed and displayed in an easy-to-understand form using several different views.

This freeware serial snooper even allows you to trace serial data transferred between applications and devices connected to the remote PC (Device Monitoring Studio Server, network or Internet connection to the remote computer is required then).

Download this free com port monitoring software now!

Free Serial Analyzer OS support:

Our Free Serial Port Snooper supports all modern Windows server and desktop platforms starting from Windows Vista, including Windows 11 and Windows 10 operating systems. Both x86 and x64 versions are supported.


Free Serial Analyzer Features

Our Freeware Serial Port Monitor allows you to capture and decode monitored packets in real time even at high and non-standard data transfer rates. It supports all standard Bit rates of 75, 110, 300, 1200, 2400, 4800, 9600, 19200, 38400, 57600 and 115200 bit/s and non-standard rates as well.

  • It intercepts and traces all Input/Output Control Code Requests (IOCTLs) and I/O Request Packets (IRPs) from DTE (data terminal equipment) and DCE (data circuit-terminating equipment) devices
  • It displays the status of Serial (Modem) control lines: Transmitted Data TxD, Received Data RxD, Data Terminal Ready DTR, Carrier Detect DCD, Data Set Ready DSR, Ring Indicator RI, Request To Send RTS, Clear To Send CTS
  • It monitors data from plug and play (PnP) serial ports and I/O ports (COM Ports) interfaced by 16550 UART: COM1, COM2, COM3, COM4 … COMn; custom and virtual serial ports registered and visible in Windows device manager under standard Ports (COM & LPT) device class.
  • It may capture serial port traffic which flows via Com ports created by our Free Virtual Serial Ports.
  • It supports monitoring of exchanged serial data from external devices connected to the PC via USB to Serial converters.

This Free COM Port Analyzer supports all standard Data bits, Parity (odd, even, mark, space), Stop bits, XON/XOFF Software and Hardware Flow control.

Paid editions of this product may also be used as affordable rs485/rs232 MODBUS sniffer, ACSII/RTU protocol analyzer and serial data logger.

If you are looking for non-intrusive software-based serial port monitoring solution to view serial protocol packets, this Free Serial Port Analyser is exactly what you need. This COM port monitoring tool requires no additional hardware and allows you to facilitate serial application development, debug protocol errors, view and test device failures.

Usage Scenarios

Our Free Serial Port Monitor Usage Scenarios

You can use this communication viewer and debugger to analyze serial protocols. This will come in handy for:

  • Serial protocol development, system integration and diagnostics
  • Detecting errors in asynchronous data transmission
  • Analyzing of data transferred between any RS232/422/485 device and Windows application
  • Development of RS232, RS485 and RS422 peripheral devices and device drivers
  • Debugging any serial port software or hardware, snooping serial data and control requests
  • Researching functionality of any third-party hardware devices and software applications
  • Debugging and testing different MODBUS devices
  • Testing and troubleshooting serial protocols between device and device driver
  • Analyzing and reverse-engineering RS-232/RS-422/RS-485 serial protocols

Target Groups

Free Software Serial Port Logic Analyzer Target Groups

Our free serial data parser, decoder and analyser is an extremely useful tool for the following target groups:

  • Serial port device drivers and software application developers
  • RS232/422/485 hardware developers, manufacturers and vendors
  • System integrators and consultants
  • Field and lab engineers
  • Programmers, testers and other IT specialists
  • SCADA software system engineers
  • Industrial control equipment support specialists
  • Science technicians and university students

Supported Serial Devices

Free Serial Protocol Analyzer allows you to capture communication data flowing between computer and the following serial devices:

  • Dial-up Modems, Fax-Modems, mini-ATS, Computer terminals, teletypes
  • POS terminals, shop till systems, Bar code scanners and other point of sale devices
  • Industrial automation systems, RS232/485/422 industrial equipment
  • Network equipment, Wireless LAN equipment, Serial device servers, NPort servers
  • Console ports, Routers, Multiplexers, Hubs, Switches, firewalls, load balancers
  • RS-232 to RS-422/485 converters, Multiport Serial Boards, Serial to fiber converters
  • Printers, test instruments, scientific instruments, relays, lamps, Telescopes
  • Test and measuring equipment, multimeters, oscilloscopes, manometers, sensors
  • Network-enable serial devices, Serial device controllers, uninterruptible power supply
  • Low-speed satellite modems, satellite phones, GPS receivers, other satellite based transceiver devices
  • PLCs, VFDs, servo drives, CNC controllers, other CNC equipment programmable via RS232/422/485
  • Entertaining equipment, simulators, MIDI-serial devices
  • HVAC, door entry systems, other security systems
  • Bar-code readers, Cash registers, Card readers
  • Diagnostic equipment, software debuggers that run on a second computer

Our free com port snooper supports monitoring of legacy and PnP serial ports, serial to usb converters, serial adapters and software-based Virtual Serial Ports.

Supported Serial Requests

Our serial snooper supports spying serial port for the I/O and Control Requests.

Supported Serial I/O Requests:


Supported Serial Device Control Requests:


Download this Free COM Port Monitor and start analyzing Serial Port communications in seconds!

Free Serial Analyzer Advantages

  1. Fast. It runs smoothly at high data rates without compromising PC performance.
  2. Flexible. It supports advanced data filtering and layout customization.
  3. Remote. It monitors devices connected to the remote computer.
  4. Social. It allows you to ask questions and get answers from experts.
  5. FREE. It costs nothing!
Carl Murphy
For my colleagues in the development office it was necessary to use a free version to get to know this software program. The needed settings were open and it was not complicated to get in closer touch with the different opportunities.
Carl Murphy PrehKeyTec GmbH
Rating: 5.0
Based on:4 reviews
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Monitor and Analyze Your Serial Port Connections
Free Serial Analyzer Advantages
Monitor and Analyze Your Serial Port Connections