I'm french student and I worked on this project during an internship. This project allows to create a modbus communication between Arduino Uno and Raspberry Pi 2, using a switch and ethernet cables ...

To store one byte of memory, three bytes of memory must be reserved. The maximum amount of reserved memory depends on the programmer’s implementation and the hardware specifications. 0 ...

That said, this probably isn't the most useful place ask such questions--this forum focuses on other Computer hardware, so while what you're asking isn't against the rules here (and my welcome is ...