How to capture serial port data

Tracking down a problem that might appear during the development stage of the custom application or a driver for a COM device and dealing with it in the shortest time would not be possible without the ability to capture serial data and store it for later use and analysis.

Unfortunately, Windows does not offer any built into the OS utilities that would help achieve this. So, one would need to resort to the help of a specialized Serial port Monitor that would assist with capturing and examining the data exchange between RS232 devices and Windows applications.

This article will show you how to capture serial port data and identify key serial communication settings such as baud rate, COM port number, stop bits, data bits, and parity. This information is especially important for testing COM ports.

Table of contents:

1. Capture COM port data using Serial Port Monitor
2. Step-by-step instructions to capture serial port activity

Key features of Serial Port Monitor

• RS232 data capture. Capture and view the data exchange between the connected serial appliance and the application which opens the corresponding COM port. The information is collected in real time once the data packets are being transferred.
  
  
• Monitor lots of serial ports at once. An activity from multiple COM ports can be captured using Serial Port Monitor. Data will be displayed in logs on a first-in-first-out basis, which will be especially convenient for later analysis.
  
  
• View and export data. Select one from the 5 available view modes: Table, Line, Dump, Terminal or Modbus to display data in the required form. Capture serial data to file to examine it when the most convenient for you.
  
  
• Send data to a serial device. A built-in terminal will allow you to open/close RS232 ports and send specific types of data to a serial device, which will be an excellent method to check its response to a certain command.

Step-by-step instructions to capture serial port activity

In the following section, you'll be guided through a clear, step-by-step process to capture serial (COM port) activity using the Serial Port Monitor tool. From launching a new monitoring session to selecting the proper COM port and capture settings, these instructions are designed to help you log every detail of your serial communication, ideal for diagnosing issues or analyzing data flows. Let’s dive in:

1. To start capturing serial data, one will need to download Serial Port Monitor, install and start the application. After that, a new session should be started.
   
   
2. Select the “New session” option from the “Session” menu. Other ways are to choose “New” on the toolbar or press “Ctrl+N”.
   
3. Select the COM port to monitor and the visualizers that will be displayed.
   
   
4. Choose whether you would like to “Start monitoring now” or “Start in new window” for the immediate behavior of a new session.
   
5. In “Capture options” specify the events you’d like to capture – Create/Close, Read/Write, Device Control.
   
   
6. Select “Start monitoring” to begin the session.
   
   
7. To save the session, select “Session → Save session/ Save session As” in the main menu. Also, you can click the “Save” icon on the main toolbar or press “Ctrl + S”.

Every view can be exported into the separate logs of various formats (HTML, ANSI/UNICODE TXT). Besides, serial data captured from the Table view can be saved to a CSV file and used in MS Excel. To export a view, select the “Export to” option in the view menu on the toolbar.