F.A.Q

Frequently Asked Questions about Serial Port and SerialTool

Last updated on by Oliver Reed

SerialTool includes a powerful COM Sniffer that lets you monitor, capture, and analyze serial communication in real time. It is designed for professional debugging of RS232, RS485, TTL, and virtual COM ports, with advanced features for logging, traffic inspection, and detailed communication analysis.

COM Sniffer is a professional serial port monitoring tool with a kernel driver that captures all COM port traffic, including transmitted and received data, DTR/RTS changes, baud rate updates, and IOCTL activity. It is ideal for debugging serial communication used by third-party software or your own applications.

COM Sniffer includes a powerful kernel driver that allows you to monitor all serial port traffic on a COM port, even when it is being used by third-party software.

It captures and displays all transmitted and received serial data in real time, giving you full visibility into the communication flow of the port.

COM Sniffer can also detect and distinguish important serial events and control operations such as DTR, RTS, baud rate changes, and all IOCTL activities, making it an advanced tool for serial port monitoring and debugging.

It is an essential utility for serial communication debugging, whether you need to inspect software developed by third parties or you are a developer building and testing your own serial port application.

By showing exactly what your application sends and receives at every step, COM Sniffer helps you save hours of debugging time and quickly identify communication errors, configuration problems, and protocol issues.

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SerialTool includes a powerful Modbus Client (Master) for Serial RTU/ASCII and TCP over IPv4 and IPv6, with support for register reading and writing, automatic polling, Modbus device mapping, remote slave scanning, traffic monitoring, live charts, and raw command execution.
It is designed for professional testing and debugging of industrial Modbus devices, and it also supports exporting device mappings in CSV, Text, and PDF format.
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SerialTool Tips


The Portable version of SerialTool allows you to run SerialTool without installing it on your system or performing a setup. For the Portable version, we use the AppImage packager, which requires only that the FUSE library is installed on your system.
The FUSE userspace library (libfuse) is typically available via your distribution’s package manager. It is recommended to refer to the distribution's package manager of your specific Linux distribution.



Example on Ubuntu (>= 22.04):
Here are the steps to launch SerialTool:
  • 1. Extract the zip file you downloaded.
  • 2. Install FUSE library.
  • 3. Make the file executable using the terminal command:
  • 4. Try launching it directly from the terminal:

The ZIP archive containing SerialTool includes detailed instructions for installation.

If Serial Port is not opening it may be because the device file of the serial port does not have permissions to allow to currently logged in user to “read” or “write” to the serial device.

1. Open Terminal and replace <username> with your username.

If the group wasn’t found, or if you still get an error, the dialout group may have a different name.

1. Open Terminal and enter this command:

2. Take note of the group name in the response:

3. To add your user to the group, enter the following command in the terminal, replacing <group> with the group name from the previous step, and <username> with your username:

4. Sign in and out for the changes to take effect.

SerialTool is not deployed by an Apple identified developer at the moment. SerialTool is not containing any malware or harmful code like many other applications available on the internet and you need to override the security settings.

Due to enhanced security measures introduced in macOS 15.x Sequoia, applications downloaded from the internet may be flagged by Gatekeeper and prevented from running. If you encounter a message stating that “SerialTool is damaged and can’t be opened” or similar, it is not an error in the application, it is a result of the system quarantine flag.

You can enable SerialTool directly from MacOS Terminal (adjusting the path if needed):

Press Return, then enter your administrator password when prompted.
Once the quarantine is removed, simply double-click the SerialTool.dmg file in the ZIP archive.

The ZIP archive containing SerialTool includes detailed instructions for installation.


SerialTool License


Here is the answer to some frequently asked questions about using the free version of SerialTool.

Free version

  • The free version of SerialTool can be used without any limitations and may also be installed on multiple machines at the same time within the same companies, organization, school, or university, without any issues related to royalties or specific usage restrictions.
  • The free version of SerialTool can also be installed at clients’ premises, without any usage restrictions or obligation to pay royalties.

PRO version

  • If you purchase the time-limited PRO version, once the license expires, SerialTool will operate only in Free mode, regardless of the version currently installed on your PC.
  • If you purchase a PRO license with unlimited installations, the PRO version can be extended to all installations regardless of their use. A daily limit of 5 installations is set for security reasons only. If this limit is not suitable for your needs, you may contact us to temporarily extend it to a larger number of simultaneous installations. A typical example is multiple PRO version installations in universities or schools, where all users or students need to install the PRO version at the same time.
  • If you purchase the PRO version with no time or installation limits, you will have lifetime access to SerialTool’s PRO features, regardless of the version or the number of machines on which it is used. You may perform multiple installations at any time without any limit.
  • In the case of multiple installations, the PRO version always refers to installations within the same company, organization, school, or university, and cannot be extended to install or use the PRO version for clients or third parties outside the entities mentioned above. This limitation may be changed only by prior written agreement.
  • If you purchase the PRO version with no time or installation limits, you will have lifetime access to SerialTool’s PRO features, regardless of the version or the number of machines on which it is used. You may perform multiple installations at any time without any limit.
  • The PRO license and its associated account may not be transferred, under any circumstances, to third parties.
  • The license is non-refundable under any circumstances and for any reason.
  • If a single license is purchased, it cannot be transferred or replaced for any device other than the one it was originally generated for.
    For example: if you purchase a single license and then dispose of your computer, it cannot be transferred to a new one. However, if you reinstall or format your computer but keep the same hard drive, the license can be installed again.

If you have any questions, you may contact us at any time.