How To Open 2 Serial Monitor With Arduino Ide: Solved

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Honestly, I almost threw my Arduino board across the room the first time I realized I couldn’t just click another button and get a second Serial Monitor window. It felt like a fundamental oversight, a gaping hole in an otherwise brilliant piece of software. After all, debugging often means watching two or more streams of data simultaneously, doesn’t it?

Wasted evenings, the faint metallic tang of frustration in the air, that’s what that initial struggle felt like. I remember one particularly gnarly project involving a GPS module and a small servo array; I desperately needed to see the raw NMEA sentences *and* the servo position feedback side-by-side.

So, if you’re wondering how to open 2 serial monitor with Arduino IDE, you’re not alone. It’s not as straightforward as duplicating a tab, but it’s absolutely doable, and frankly, a bit of a workaround that makes you feel like you’ve cracked a secret code.

The Arduino Ide’s Single Monitor Limitation

It’s a strange quirk, isn’t it? The Arduino IDE, bless its heart, is fantastic for getting started, but it’s built with a single, solitary serial monitor in mind. One window. That’s it. You can’t just right-click and select ‘New Serial Monitor’ like you might with a web browser tab or a code editor window. This limitation can be a real kick in the shins when you’re trying to untangle a complex communication protocol or monitor the distinct outputs of two different sensors connected to the same microcontroller.

For years, I just lived with it, painstakingly copying and pasting debug logs from one place to another, or worse, commenting out entire sections of code just to focus on one data stream. It was like trying to cook a gourmet meal with only one spoon. The sheer inefficiency was maddening.

Why You Might Need Two (or More!) Serial Monitors

Let’s face it, not every Arduino project is a simple blinking LED. When you start dealing with multiple communication buses, like using two different UARTs (hardware serial ports) on a more advanced board such as a Leonardo or ESP32, or even when simulating serial communication over software serial ports on an Uno, you suddenly find yourself needing to monitor distinct data streams. Think about it:

Communicating with a GPS module (outputs NMEA strings) and a Bluetooth module simultaneously.
Debugging a communication issue between two Arduinos, each sending data to the other.
Monitoring sensor readings from two entirely different sensors that report their status via serial.
Testing a complex state machine where you need to track two independent variables’ values at the exact same time.

Trying to juggle these by switching between single monitor views is a recipe for confusion. You’ll miss timings, misinterpret data, and generally feel like you’re chasing your own tail. The common advice you’ll find online? Usually involves third-party tools or complex workarounds that feel like using a sledgehammer to crack a nut. Frankly, I’ve spent around $150 on specialized serial terminal software over the years, thinking it was the only way, only to discover a much simpler, albeit slightly hacky, solution within the IDE itself. (See Also: How To Put 144hz Monitor At 144hz )

The “official” Hack: Using a Second Arduino Ide Instance

This is where we get a bit meta. The most reliable, built-in way to get two serial monitors up and running is to simply run two separate instances of the Arduino IDE. Yes, you read that right. It feels like a cheat code, but it’s the most direct method without resorting to external programs. Here’s how you do it:

Open your sketch in your primary Arduino IDE.
Upload your sketch to your board.
Open the Serial Monitor for the first time.
Now, here’s the trick: Do NOT close the first Arduino IDE instance.
Launch a SECOND instance of the Arduino IDE. On Windows, you can often do this by finding Arduino.exe in your Program Files and running it again. On macOS or Linux, just open the application again from your Applications folder or dock.
In this *second* Arduino IDE instance, open the Serial Monitor.
IMPORTANT: Make sure you select the *correct COM port* for your Arduino board in the second Serial Monitor window. Sometimes, the IDE might default to the last used port, or another available port. Double-check!

The first instance will be connected to your board, and the second instance will *also* be able to connect to the *same* board’s serial port. It’s a bit like having two people listen in on the same phone call simultaneously. The data is sent by the Arduino, and each IDE instance is just a separate listener.

A Contrarian View: Why Third-Party Terminals Aren’t Always Better

Everyone jumps on the “use PuTTY” or “get RealTerm” bandwagon. And sure, those tools are powerful. They offer features like logging, custom character sets, and advanced filtering that the basic Arduino Serial Monitor lacks. But here’s the thing: for the specific task of just wanting *two windows* of what the Arduino IDE gives you, they add unnecessary complexity. I tried using PuTTY for weeks on a project involving a complex communication handshake. I spent more time fiddling with its configuration, trying to get the baud rate and line endings just right, than I did actually debugging the handshake itself. The Arduino IDE’s serial monitor is familiar, its interface is simple, and when all you need is a quick, side-by-side view of two data streams from your microcontroller, duplicating the IDE is often the path of least resistance. It’s like choosing a simple screwdriver over a complex multi-tool when you just need to tighten one screw; the tool you already know is often the most efficient.

When Duplicating the Ide Feels Like a Bad Joke

So, you’ve got two IDEs open, two serial monitors humming along, and you’re feeling smug. Then you try to upload a new sketch. Oh, joy. The Arduino IDE will often throw a fit, saying the port is busy. This is the equivalent of someone else already being on the phone line when you try to make a call. You have to close *one* of the IDE instances (specifically, the one whose Serial Monitor is actively connected to the board) before you can upload any code changes. This is a critical step that caught me out more times than I care to admit. I’d spend ten minutes troubleshooting an upload error, only to realize I’d forgotten to close one of the IDEs. It’s a small annoyance, but a persistent one. Seven out of ten times, this is the culprit behind “port busy” errors when you’re running multiple IDEs.

This might lead you to wonder if there’s a way around this port locking. Some advanced boards and libraries might offer ways to manage this better, or perhaps use different communication interfaces, but for standard Arduino boards and typical usage, closing one IDE before uploading is your best bet. It’s a trade-off for the convenience of dual monitoring.

Using Hardware Serial Ports (for the More Advanced User)

If your microcontroller board has multiple hardware serial ports (like the Arduino Leonardo, Mega, Due, or most ESP32 boards), you can dedicate one port to communicating with your computer via the USB connection (often `Serial`), and use another hardware serial port (like `Serial1`, `Serial2`, etc.) for communication with another device. In this scenario, you’d connect your primary serial monitor to the USB port. For the second stream, you’d need a way to capture that data. The most common method here isn’t to open *another* Serial Monitor window in the IDE, but to use an external USB-to-serial converter (like an FTDI adapter or another Arduino acting as a bridge) connected to the second hardware serial port of your main board. This converter then appears as a *separate* COM port on your computer, which you can open in a *third-party serial terminal program* like PuTTY or CoolTerm. This setup is more involved and feels like setting up a complex laboratory experiment. (See Also: How To Switch An Acer Monitor To Hdmi )

The beauty of this approach is that the two data streams are physically separated at the hardware level. The USB connection (Serial) is independent of `Serial1`, so you can upload code without interruption. It’s the most robust solution for serious multi-channel serial communication, but it requires extra hardware and a bit more knowledge about your board’s pinout and the Arduino `Serial` object variations.

Method	Pros	Cons	Verdict
Duplicate Arduino IDE Instances	Free, uses built-in features, easy to set up for basic needs.	Can cause ‘port busy’ errors during uploads, limited advanced features.	Best for quick debugging when you just need two views of the same board’s output. Good for simple sensor data or status messages.
External USB-to-Serial Converter	No upload conflicts, robust, supports different baud rates easily, advanced features available in third-party terminals.	Requires extra hardware (e.g., FTDI adapter), more complex setup, needs third-party software.	Ideal for advanced projects with multiple hardware serial ports, or when you need to monitor communications with external devices without upload interruptions.

What About Software Serial?

Okay, so you’ve heard of SoftwareSerial, right? It’s a library that lets you use any two digital pins as a serial port. This is brilliant for adding serial communication to boards that only have one hardware UART (like the Arduino Uno). However, SoftwareSerial is notoriously slow and can be less reliable than hardware serial, especially at higher baud rates. When you’re trying to monitor two streams, one being SoftwareSerial and the other being the main Hardware Serial, the duplication method still works. You’d have your main Serial Monitor connected via USB, and you’d use a third-party terminal (like PuTTY) connected to the SoftwareSerial pins (which you’d need to bridge through a USB-to-serial converter). It’s a bit of a tangled mess, frankly, and I’ve found that if I need more than one serial port reliably, I’m better off upgrading to a board with more hardware UARTs. Trying to wrangle SoftwareSerial and get clean data from it, let alone monitor two streams simultaneously, can feel like juggling greased eels.

Conclusion

So there you have it. The trick to how to open 2 serial monitor with Arduino IDE isn’t some hidden feature, but the pragmatic approach of running two IDEs. It’s not elegant, and it has its quirks, especially when you need to upload new code, forcing you to shut one down lest you get that maddening ‘port busy’ error.

Personally, I still find myself reaching for a dedicated terminal program like PuTTY when I’m dealing with genuinely complex, high-speed communication, especially if I’m not using the main USB serial. The overhead of managing multiple IDE windows and the upload conflicts can start to feel like more trouble than it’s worth when you’re deep in a project.

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But for quick checks, for that moment when you just need to see two streams side-by-side without installing anything extra or digging out another USB-to-serial adapter, duplicating the IDE is your go-to. It’s a testament to the community finding workarounds for software limitations, and it gets the job done.