RS232 Monitor - RS232 Monitor Software

Watch it!

For Windows 2000 - Windows 11 (2019) (incl. Server, x86 and x64). Latest version: 4.4.21 build 527. May 27, 2022.

You have a serial device. You need to know what is going on.

The existing software is not good enough, and it consumes a lot of resources, or you need to swap several free and simple utilities every minute to do one simple action.

RS232 Monitor is a unique monitoring tool for communications via the RS-232 interface. It has a rich set of features and allows you to view all received data in a human-friendly form. The program is designed to use as few resources as possible.

It is not a display connected to an RS232 port :).

RS232 Monitor - Traffic monitor

How can I monitor and control an RS232/RS485 line?

  1. Start Advanced Serial Port Monitor.
  2. Select the necessary mode (look at the "Mode" menu and answers about methods below).
  3. Select the COM port from a drop-down box on the toolbar.
  4. Start RS232 monitoring by clicking the "Open" button in the main window before starting another application.
  5. Select an ASCII and HEX data view mode.
  6. Monitor RS232 communication in real-time, or enable writing to a file using the "Write to file" button on the bottom toolbar.
  7. Click the "Close" button to close the monitoring session.
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Easy RS232 Port Monitoring

FAQ about RS232 monitoring using Serial Port Monitor by AGG Software

Can I monitor data traffic between two peripheral devices?

Yes, you can use a special RS232 monitoring cable, and the cable will both send and receive data at the same time.

Does the program support full-duplex in RS232 protocols?

If you want to monitor traffic sent from your computer to an external device: it works by default without the need for tweaking by you, and it does not require additional hardware.

In the case of controlling traffic between two external serial devices: use the "Dual Port" mode in Serial Port Monitor with a self-made RS232 monitoring cable (see above).

Can the program work in the terminal mode?

The terminal mode is named "Manual" in Port Monitor, and you can easily switch between modes (serialmon, terminal, dual ports) at any time.

Can implement an RS232/RS485 analyzer and watch serial protocols without a breakout cable?

You can watch real-time communications between your serial application and a peripheral device using the "Spy" mode. In this mode, our utility monitors data transfer and all COM port activity of another program, as if "dropping in" between the serial interface and the studied program. It can work on any baud rates (it does not matter because the program intercepts data exchange in the driver).

RS232 Monitoring Mode Selection

Can RS232 Port Monitor work in virtual environments?

Yes, the program and its drivers can work in a virtual machine VMWare, VirtualBox, Parallels, etc., on any host OS and with the Windows guest. Additionally, you can use our software through Remote Desktop. Sorry, but the program does not work with compatibility layers like Wine or CrossOver on MacOS.

Can this serial port software protocols without a breakout cable?

To view the traffic between your serial application and a peripheral device, use "Spy" mode. In this mode, our tool monitors data transfer and all serial port activity, just like if it were "dropping in" to observe the communication between your computer's serial interface and any other program. It can work on any baud rates (as the program intercepts the data exchange in the driver).

Advanced Features

Supported COM types

Virtual ports (VCP)
RS232-USB (USB cables),
Software-based virtual COM port

RS422/R485 converters Yes
Supported equipment Various independent (lab equipment, industrial equipment, DIY)
Windows 10 (64-bit) compatible device driver Yes
Manually send requests with HEX or ASCII data Yes
Serial port sniffer mode Yes
Logging to a file Yes (Binary or Text)
Advanced Serial Protocol Analyzer MODBUS RTU & ASCII
Advanced Features (dual ports mode, plugins, ports autodetection) Yes
Remote monitoring No
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Try Advanced Features and Plugins

Portmon is the free alternative for RS232 port monitoring.

Portmon monitors Windows kernel-level I/O packets sent/received between serial port device drivers and Win32.


Target Groups

Our rs232 software solution is handy for the following target groups:

  • Serial port software application developers.
  • Firmware developers for devices with RS232/422/485 interface.
  • System integrators and consultants.
  • DIY hobbyist (Arduino, Raspberry Pi, and other SMB computers).
  • Programmers, testers, and other IT specialists.
  • SCADA designers.
  • Industrial control equipment support specialists.

RS232 monitor usage scenarios

You can use this product to analyze serial protocols. Serial Port Monitor will come in handy for:

  • Testing and troubleshooting serial protocols between a device and a host computer
  • Monitoring of serial port traffic between any RS232/422/485 device and Windows serial application
  • Development of RS232, RS485, and RS422 peripheral devices and device firmware
  • Debugging any serial port software or hardware, snooping serial data and control requests
  • Researching functionality of any third-party hardware devices and software applications
  • Reverse engineering of communication protocols
  • Simple RS232 device simulation with ASCII or binary data packets

    ASCII device emulator plugin

  • Send a request to a device to execute internal commands
  • Replay log files

How can RS232 Monitoring Tool help you to improve your work?

This tool will help you develop serial interfaces, analyze serial errors, troubleshoot RS232/RS422/RS485 communications. It can autodetect all your COM ports, and it has a simple and user-friendly interface optimized for RS232 interface usage.

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Eliminate RS232 cables