We created already a universal communication class in the last two episodes (Part 7 here and Part 8 here). It allows us with a little less than 60 lines of code in a separate .h file to handle one or even multiple Nextion HMIs connected to our MCU (Arduino or whatsoever), optionally using a second serial port for debugging each. And we can use this classes' cmdWrite() method to send commands to each of our connected Nextion HMIs without caring about the terminator which is automatically added. With this "Multiple Nextion HMIs on one Arduino", we went already beyond most existing libraries.Since, depending on our MCU and its number of serial ports, our class has alternatively to deal with HardwareSerial, SoftwareSerial, AltSoftSerial, USBSerial, we learned that the GNU C++11 compiler which is used by the Arduino IDE is a bit (in fact, very very) finicky about the type of passed object references (Serial, Serial1, Serial2, etc.) when it comes to construct depending objects like our NexComm class, we had the occasion to learn about template classes. We will need this knowledge later.