Serial Port Monitor.
How to analyze COM port.

Monitoring and analyzing COM port activity are essential tasks when working with serial devices and applications. You need the ability to observe the flow of data through RS232/422/485 ports to verify the status of a device, receive event notifications, and identify problems with your infrastructure. Monitoring serial port traffic can also be very helpful when you are installing new equipment.

Table of contents:

1. The Issue
2. Solution
3. Monitor COM port activity: a how-to guide
   • ★ First case: how to monitor serial port activity
   • ★ Second case: Compare monitoring sessions
   • ★ Third case: Resending data to a serial port
4. FAQ
5. Conclusions

The Issue

There is no built-in facility in the Windows operating system to monitor serial ports, but there is specialized RS232 monitor software which allows you to conduct Windows serial port monitoring.

Solution

Eltima Software’s Serial Port Monitor fills this gap in Windows functionality. It is a serial port analyzer that offers a convenient method of observing your system’s serial traffic. Developers can easily monitor a serial port during the development, testing, and optimization of serial devices and applications. We will show you how to monitor COM port transmission in the article.

Monitor COM port activity: a how-to guide.

To monitor and analyze serial data, COM port monitor offers three ways to solve this problem:

First case: Monitoring serial port activity.

The first step is to download, install, and launch Serial Port Monitor. Next, you need to start a new session in the RS232 monitoring software. Here’s how it is done:

1. Navigate to the main menu in the RS232 monitor application. Select “Session >>>New session”. You can also use the “Ctrl + N” keyboard shortcut or click the toolbar’s “New” icon.
2. The “New monitoring session” screen will be displayed.
3. Choose how you want your RS232/422/485 data displayed by selecting one or more of these view modes:
   
   
   • • Table view – A table is used to display recorded IRPs.
   • • Line view – displays all details concerning requests passed through a particular serial line.
   • • Dump view – shows data passed through the serial line.
   • • Terminal view – Data is shown as ASCII characters in a text console.
   • • Modbus view – displays two-way transmission of Modbus data (RTU and ASCII).
4. You control how a new serial protocol analyzer session behaves by using the “Start monitoring now” and “Start in new window” checkboxes.
   Capture options allow you to select the events you wish to capture. Choose from Create/Close, Read/Write, and Device Control.
   After selecting the options, click “Start monitoring” to start the new serial analyzer monitoring session.


5. The new monitoring window opens and displays all selected data visualizers.


6. You can save the RS232 monitoring session by selecting “Session >>> Save session/Save session As” from Serial Port Monitor’s main menu.

Second case: Comparing monitoring sessions

Comparing the results from two different monitoring sessions enables you to gain valuable insight into the functionality of your serial communication.

After you have monitored a serial bus and saved the session, you can compare it to another session to identify the differences by using Serial Port Monitor.

To compare monitoring sessions, follow these steps:

1. Start or open a monitoring session.
2. Select “Session >>>Compare Sessions” from the main menu.
3. Choose the monitoring file which will be used for the comparison.
4. The two sessions are displayed side-by-side. This makes it easy to compare the sessions and quickly identify their differences.

Third case: reproduce monitoring session.

The ability to reproduce data transmitted between serial applications or devices and serial interfaces can provide critical information when troubleshooting communication problems. Using this serial data analyzer, you can send the same data stream repeatedly to monitor how an app or device reacts to the transmission.

Follow these steps to analyze data from a serial port:

1. Open a current monitoring session or begin a new session.
2. Select “Session >>>Reproduce session” which is where you will configure the parameters that the transmission will use.
   
   
   • Use port - This parameter is used to specify which serial port will be the recipient of the data streams.
   • Send requests to this port - Enable this option if you are replicating data that would be sent from a serial application to the port.
   • Respond as a device - This option is employed when the data is sent to a COM port as if it were transmitted by a serial device.
   • Preserve time intervals - Specify the time interval between the transmission of data packets with this option.
   • Custom IO timeout - Define specific Read/Write timeout parameters you want to enforce for this session.
3. Click “Start”.