How to check COM port in Windows 10?

When working with serial devices it is important to have the ability to monitor and inspect the activity of your system’s RS232/422/485 ports. Examining the data flow traveling through the interfaces can be very helpful when installing new devices or troubleshooting a problem. It can be difficult to pinpoint where the problem is actually occurring.

This is how to check RS232 port in Windows 10. Simply follow these steps to check serial ports:

"Control Panel > Device Manager > Ports"
Your system’s COM ports will be displayed.

Device manager

In cases where the displayed information is insufficient for your needs, we offer a professional software application that provides an effective method of testing and analyzing your serial ports.

RS-232 Testing Software

Serial Port Tester is a professional-grade utility to implement serial communication. It can capture and display all data traveling through a system’s COM ports.
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Serial Port Monitor

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Issue: How to check RS-232 port?

If you need to know how to check serial ports in the Windows operating system, you will find there are no native tools to perform this task. There is, however, a software solution that can be used for checking serial port activity and monitoring data transfer through the interfaces.

When problems arise between a serial device and an application, you need to know how to check RS232 communication. The typical method is to follow these general troubleshooting guidelines. We recommend that by developing an understanding of how serial devices work, you can save a substantial amount of time when taking down issues. A program like Serial Port Tester can be instrumental in increasing your knowledge of serial communication.

Solution: Serial Port Tester

There is an effective and efficient method of investigating issues that you may encounter during the development and testing of a serial device driver or application. COM Port Tester from Eltima software answers the question of how to check RS232 communication with a full-featured application which makes it easy to monitor, analyze, display, and log data from your RS232/422/485 serial ports.

Why choose this serial port checking tool?

  • Ease of use. Serial Port Tester features a user-friendly interface. The program makes it easier to check your COM ports with an intuitive display of your serial interfaces.

  • Versatility. There are many scenarios in which COM Port Tester can be extremely useful. You can emulate the sending of data to a designated port in a variety of formats including string, octal, decimal, and binary. All data transmitted through the serial ports can be monitored and recorded in files for analysis at a later time.

  • Reliability. Serial Port Tester fully supports all versions of the Windows OS. This includes the newest iteration of Windows 10 (x32/x64). All of the application’s internal drivers are digitally signed to ensure security.

Checking serial port: step-by-step instructions

In our demonstration, we will use Eltima Software’s Serial Port Tester as the program with which to test serial ports. We will show how to check an RS232 port is working in three different ways.

First case: monitoring the activity of serial ports

To monitor your serial port activity, use these simple steps:

1. Download and install Serial Port Tester. Launch the app and open a new monitoring session by following the next step.

2. From the main menu select “Session > New session”. Alternate methods to start a new session are using the ‘Ctrl + N’ keyboard shortcut or clicking “New” on the toolbar.

New session

3. The “New monitoring session” window should now be displayed.

Table of views

Select the viewing mode which will be used to display the monitored serial data:

  • Line: displays lines of plain text containing IRP details;
  • Terminal: presents the transmitted data as ASCII characters;
  • Table: recorded IRPs are displayed in the form of a table.
  • Dump: two-way serial communication is shown in hexadecimal and string formats;
  • Modbus view displays all transmitted Modbus data (RTU and ASCII).

“Select all” or “Select none” can also be chosen as viewing options.

4. Select “Start monitoring now” if you want to immediately start monitoring the ports. You can choose the “New window” option to start the session in a clean window.

5. Use the “Capture options” menu to select the events to be monitored. Your choices are device control, create/close or read/write.

6. Click the “Start monitoring” button to begin the session.

Process of monitoring session

7. Save the session for late analysis by selecting “Session > Save session/Save session As” from the main menu.

Save session

Second case: Compare monitoring sessions

Many valuable insights about your serial communication can be gained by a comparison of two saved sessions. Saving a monitoring session prior to making any changes and then saving a subsequent session provides the data with which to make your comparison. Differences in the sessions can easily be identified.

Here’s how to compare sessions:

  1. Start or open a monitoring session.
  2. On the main menu, click on “Session>Compare Sessions”. Compare sessions
  3. Select the monitoring file you will use for the comparison.
  4. Serial Port Tester displays the sessions in a side-by-side format. This improves the readability of the data and makes it easy to locate differences in the sessions. Table of comparing

Third case: Reproducing data to a COM port

A feature of Serial Port Tester is its ability to reproduce a data transmission to a COM port. To send data to a serial port follow these steps:

  1. Open a current monitoring session or begin a new session. Reproduce session
  2. “Select Session > Reproduce” and make any changes you wish to the parameters used in the data transmission. Configure the parameters
    • Use port - Specify the serial port that will be the recipient of the transmitted data.
    • Send requests to this port - Enable this option if you want to emulate a data stream being sent from a serial application.
    • Respond as a device - This option is used to emulate data being sent to a COM port from a serial device.
    • Preserve time intervals - Use this option to select predetermined time intervals between data transmissions.
    • Custom IO timeout - Define whatever Read/Write timeout parameters you want to enforce during the session.
  3. Click ”Start”.


Serial Port Tester is a versatile utility that can be extremely useful in many scenarios involving serial communication and devices. We have demonstrated some popular uses of the tool. You will find it a valuable addition to your software toolbox for identifying issues with serial devices and applications.

Serial Port Monitor

Requirements: Windows (32-bit and 64-bit): XP/2003/2008/Vista/7/8/10, Windows Server 2012, Windows Server 2012/2016/2019 , 8.15MB size
Version 8.0.388 (7 Jul, 2020) Release notes
Category: Serial Port Software