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Configuration and programming of the S7-1200 PLC in PROFIBUS communication with the UNIDRIVE SP for industrial use

Abstract:

This article shows the implementation of a PROFIBUS-DP data link between a SIEMENS's S7-1200 PLC, working as a network master using a CM 1243-5 communications module, and the UNIDRIVE SP from Control Techniques with its SM-PROFIBUS expansion module to work as a slave on the same network with the purpose of controlling electric AC motors, whether these are induction or AC servo motors. Additionally, a basic explanation on data transfers is made, both cyclic and non-cyclic (PPO4 Word and CT only Word) and some of their typical characteristics, which are found when we deal with the industrial communications protocol PROFIBUS DP. Similarly, concepts as VSD, VSD's parameters list and data words on the VSD's internal memory are reviewed, and also the VSD's basic configuration using the CTSoft software for setting up, run and operate and electric motor, having control over its variables or to establish the information exchange between the PLC and the Drive and therefore, to automate a process. Simultaneously, we address the steps to create a PLC program using the TIA PORTAL software for receiving information from the VSD, store it in internal variables (PLC's internal memory). The end result, is the development of an environment which allows to interpret and manipulate said information, give instructions through the same PROFIBUS DP network to the VSD so it commands the AC motor or servo motor used on the process, hence the possibility to automate a whole system even if the devices (PLC and VSD) are from different manufacturers, thanks of the use of the VSD's GSD file given by the manufacturer.