Invoking Web services from programmable logic controllers

The adoption of service-oriented architectures based on web services in industrial application domains enables the seamless integration of business software with manufacturing tasks and promises increased interoperability. To be able to invoke a manufacturing task running on a programmable logic controller (PLC) as a web service from a business application, the SOAP4PLC engine has been proposed. In this paper, an extension of the SOAP4PLC engine is presented to invoke a web service based business application from a PLC application. A use case is shown in which the extended SOAP4PLC engine is used to interface a PLC application concerned with realizing the functionality of a charging station for electrical vehicles with a web service based accounting system.