Communication interface between various drives and programmable logic controllers

Nowadays, the market pushes companies to make their production flexible and to develop their productivity in order to be competitive. These conditions have led companies in the automation, initially aiming at Industry 3.0 and now at Industry 4.0. The programmable logic controllers (PLCs) are playing a key role in this industrial evolution. The PLC allows a complete control of industrial plants because it is able to interface with all the devices of the factory. Specifically, the control of the electric motors is carried out by means of drive. There are two types of drive: inverter drive and servo drive. Inverter drive controls the speed of an electric motor, while a servo drive adjusts the position of an electric motor. These devices interface with programmable logic controllers through data structures. Therefore, communication is a fundamental aspect for the execution of an electric motor control. Data communication structures depend on the type of drive and the manufacturer of the drive. Particularly, Siemens communication structures are called telegrams, while the Rockwell Automation ones are called data type. In addition, Siemens company provides pre-set blocks to programmers. These blocks facilitate the implementation of the control but they restrict the programmer and user manipulation. The thesis objective is to construct an interface that eliminates these constraints. The interface block aims to allow the communication between CPU and drive regardless of the type of drive and the manufacturer of drive. To implement the interface block, the Siemens and Rockwell Automation communication structures have been chosen, because they are very different from each other. Generally, other producers base their communication structures on Siemens telegrams and Rockwell Automation data types. Initially, a thorough analysis of the communication modes between CPU and drive has been performed both in the case of Siemens systems and in the case of Rockwell Automation systems. Next, the interface block has been implemented, and finally a series of tests have been executed to verify the block operation. The interface block has been tested by using firstly a Siemens CPU and a Siemens drive inverter, secondly a Siemens CPU and a Siemens servo drive and finally a Rockwell CPU and a Rockwell inverter. The test results have been positive: all the features that were required for the block have been executed and the communication between CPU and drive has been successful. A further development of this thesis could be the construction of a converter that allows a direct conversion from a software environment to another. In this way, it would be possible not only a communication between PLC and drive regardless of the drive type and the drive manufacturer, but also a free implementation of the program regardless of the programming software chosen.