Nowadays companies aim to become more and more competitive. More production with less wastes of time, energy, matter is the aim of these new tools which are composing the industry 4.0. This new era of digitalization has already started.This paper will present the technologies and concepts necessary to understand the setting up of a digital solution, and its implementation in a factory which would have evolved step by step, by enlarging and creating new sections, with different PLCs.

 It will be explained how the different communication protocols, due to the different brands of PLCs, are creating problems in the communication when it is about implementing a digital solution. It will also propose several potential solutions, and several solutions will be proposed and compared. Also, the reasons of the chosen final solution will be explained. These results have been obtained by consulting several studies concerning the new technologies about industry 4.0, but also by going directly on the field, to notice the problems and applicable solution beyond the theoretical aspect. Interviews on several occasions with the actual leader of the market for the implementation of digital solution is composing a solid and precious testimony about what could be done to implement such solutions for now. Indeed, papers are presenting technologies which could be developed, or already existing, as the one which will revolutionize the interconnectivity, but it seems that this is for a near future, while the actual reality seems to be different. The final decision which has been taken will be explained regarding the methodology followed to solve the problem. It will be presented that a solution which is more appealing is not always the optimal solution, depending of the company configuration, needs and long term goal. This document will present the explaining why and how to determine the corresponding solution for a specific company.