Remember! you can use several libraries like: Controll.ino ethernet example. Using Arduino Mega and RS485, for example.

Arduino as a suitable solution for Industry. Thanks to the Industrial shield design, you can compare Arduino vs PLC because a PLC is an electronic device using a microcontroller as an Arduino board is. So Industrial Shields offer at the professional users, make plc projects with Arduino. It is also possible to program an Arduino plc ladder software.