Enhancing the performance of industrial controllers by using field programmable gate array based modules

Industrial controllers such as Programmable Logic Controllers (PLC) are industrial derives that are frequently used in process automation. Internally, they use microprocessors to execute programs written using different programmiug language techniques such as Ladder Logic Diagrams, Function Block Diagrams and others. Since the microprocessor e.xevutes instructions sequentially, the time to execute the programs increases as the number of computationally in tensile control algorithms is increased. Industrial controllers are increasingly being used in networked enrironments to reduce cost and for better asset management. The netuorking protocols used for networking in these enrironments often change to introduce new features and enhance existing features. These changes are primarily accomplished by adding communication modules to the PI.C. The problems of increased execution time and increase in the cost of the overall control system caused by the addition of the new modules can be reduced by using programmable logic devices such as Field Programmable Gate Arrays (FPGA). Since FPGAs are highly configurable, multiple communication/control modules can be implemented on a single device. 'The cost of TPGA-based systems is usually low because of the loner non-recurring engineering costs. This paper presents details of a project in which a Xilinx PPG A was used to implement a control algorithm and a serial communication protocol. The paper brings out the advantages of using a FPGA in conjunction with an industrial controller.