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
  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. New session
  2. The “New monitoring session” screen will be displayed. New monitoring session
  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. The process of monitoring

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

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. Compare Sessions
  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. The table of compare

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. Reproduce 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. The table of reproduce session
  3. Click “Start”.
The frequently asked questions
Yes. The internal analyzer can act as a distinct application inside Serial Port Monitor.
Ensure that you started monitoring by specifying “Monitoring” >>>“Start” option from the main menu, or by clicking the “Start” toolbar icon.
The COM port may be in use by another application. Make sure that no other software is monitoring the port at this time.
Yes. As many serial ports as you wish can be monitored simultaneously. Simply open a new instance of the RS232 protocol analyzer for each port to be monitored.
Yes. Use this syntax on the command line:

SerialMonitor.exe /New COM1 11111

where:

1rst “1” stands for the Table view

2nd “1” – Line view

3rd “1” – Data view

4th “1” – Terminal view

5th “1” – Auto start

There are some considerations regarding the danger of electrical voltages when using Serial Port Monitoring software. The ports use voltages that can cause substantial damage to unsuitable devices. Other, non-serial interfaces also make use of a 9 or 25 pin connector. You should not try connecting the interface if you are not certain it is, in fact, a serial port.
You can use a device known as a breakout box to identify serial interfaces in a safe manner. A meter can also be used to ascertain if the device is using ± 12 volts on the port’s DTR and RTS lines. You can also consult the device’s documentation to determine the purpose of the interface.

This software does not serve as a breakout box despite the presence of its line status indicators (LEDs). The output voltage is negative (-) 12 volts when the signals are inactive or low. This is a dangerous voltage with which to be testing.

Conclusions


It is a complicated undertaking to monitor the flow of data between a computer and its serial interfaces. Without using RS232 monitoring software it is extremely difficult. Individuals working with serial devices and applications can use the software to make their jobs easier in numerous ways. Professional tools such as Serial Port Monitor allow you to easily track serial traffic. The application makes it easy to log, display, monitor, and analyze all of your system’s serial data activity.

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