FPGA based gateway for interfacing a PLC to an OPC UA client

Abstract

The advancement in technology has led to the use of Programmable Logic Controllers (PLCs) in the industry with the aim of introducing automation. A PLC is equipped with a Human Machine Interface (HMI) which is used by the machine operator to control the machinery. Many PLCs have a very basic HMI which allows the machine operator to perform very simple operations such as starting or stopping the machine. Alternatively, PLCs with a very advanced HMI provides features such as viewing historical data, alarms and events. The only factor that discourages companies from purchasing PLCs with an advanced HMI is the high cost of such advanced PLCs. This thesis attempts to develop a system which enables the user of the PLC to have access to the features of an advanced HMI without the need to buy a PLC with an advanced HMI. The OPC Unified Architecture (UA) Protocol is a communication standard released by the OPC Foundation, which may be used to provide a solution to this problem. The main aim of this thesis is to implement the OPC- UA on a Field Programmable Gate Array (FPGA). The OPC UA FPGA based- server will serve as a gateway between the PLC and the OPC UA Client The OPC UA FPGA Server is connected to the PLC and hence the user of this system may read from the PLC's memory or write to the PLC's memory by using the OPC UA Client Program.