Top 5 Most Frequently Made Mistakes When Using a Serial Monitor
Having a serial monitor can be a huge assist when you’re dealing with devices that talk over COM ports. It allows you to see the data flowing between your computer and the device in real time. This can speed up troubleshooting, make development simpler, and make testing more consistent. But, like with any tool, there are some common pitfalls people fall into—particularly if they’re new to it.
Let’s go through the top five things you must not do when using a serial monitor. Having these fixed early will save you many hours of frustration and wasted time.
Selecting the Incorrect COM Port
This is a very easy one. If your computer has more than one COM port (and many do), it’s simple to get the wrong one. You may think the monitor isn’t working when actually, you’re simply viewing the wrong channel. Always double-check which port your device is using. Most operating systems will show active ports, and you can usually match them based on which one appears or disappears when you plug in your device.
Tip: Connect your device, launch your device manager, and observe which new COM port appears. That’s most likely the one you need.
Using Wrong Baud Rate or Settings
Serial communication relies on both parties agreeing on how quickly to speak and how data is formatted. If your serial monitor is configured to the incorrect baud rate, data bits, or parity, the output will appear as random characters or garbage. It may appear as though the device is faulty when it’s simply a matter of mismatched settings.
Tip: Always check your device’s documentation and match those settings in your serial monitor.
Forgetting to Close Other Programs Using the Port
A COM port may be utilized by only one program at a time. When a different application (such as a development tool, log application, or even another serial monitor) has already occupied the port, your serial monitor will not be able to connect to it. This could cause connectivity errors or result in appearing as if the device is not responding.
Tip: Make sure no other programs are connected to the same port before launching your monitor.
Not Logging Data for Later Use
It’s useful to watch the data live, but occasionally the issue occurs too quickly or haphazardly to observe at the time. If you’re not keeping the data in a log, you might miss crucial information. A log will allow you to go back and see what occurred, report the data to a colleague, or show that a device emitted a particular message.
Tip: Always turn on logging when testing or troubleshooting. Store the data in a format such as CSV or TXT so you can analyze it later.
Omitting Error Codes or Unexpected Data
Sometimes we’re so concerned with “whether the device speaks” that we don’t pay attention to what it’s saying. If your device returns an error code or bizarre response, it’s worth taking a closer look. These can be indications of configuration problems or even hardware failure.
Tip: Don’t simply look for a response—read it carefully. It may be telling you precisely what’s amiss.
Thus, using a serial monitor is a powerful way to understand how your devices are talking. But even the best tools won’t help if used incorrectly. By avoiding these common mistakes, you’ll get better results, catch problems earlier, and save yourself a lot of time in the long run.
