How to communicate with an app via Serial and still use Serial Monitor?

[wrybread]

I have a Python script running on a laptop sending commands to an Arduino Uno via the serial interface. Is there some way to still be able to use Serial Monitor to see debug messages from the Arduino? Maybe using Software Serial?

Or maybe there's some other way to interface the Arduino with the Python script that I'm not thinking of?

[PaulRB]

Yes, get a USB-serial adapter, connect it to 2 unused Uno pins and use software serial with those pins. Connect your python script to the new serial port that appears when the USB-serial adapter is connected to the pc.

[J-M-L]

If the arduino does not send anything back to the python script then you could use that link for debug - just have the python script print out whatever it receives from the Arduino

[jfjlaros]

@wrybread

Is there some way to still be able to use Serial Monitor to see debug messages from the Arduino?

If your laptop runs Linux, you may want to check out this serial multiplexer library and its linux client.

From the quick start:

Create multiple virtual serial devices and use them like the standard Serial object.

#include <serialMux.h>

SerialMux mux(Serial);
VSerial serialA(mux);
VSerial serialB(mux);

void setup() {
  Serial.begin(9600);
}

void loop() {
  serialA.println("Virtual device A.");
  serialB.println("Virtual device B.");
  delay(1000);
}

On the host, two virtual ports are created, e.g., /dev/pts/8 and /dev/pts/9. When we connect to one of these ports, we only see the messages that are sent to that port.

$ picocom -q /dev/pts/8
Virtual device A.
Virtual device A.