COMMUNICATION BETWEEN AUTOMATION EQUIPMENT AND EXTERNAL DEVICES OR CLIENTS
Publication Date: 2010-Nov-29
The IP.com Prior Art Database
AbstractREST based application architecture for automation equipments using HTTP or other protocols for distributed communication.
Suresh Kumar, Srijit Kumar, Kjell I Svensson
REST based application architecture for automation equipments using HTTP or other protocols for distributed communication.
Communication between automation equipment and external devices or clients has been based on RPC based protocols like COM, DCOM or Web services based on SOAP (Simple Object Access Protocol) and WSDL (Web Service Definition Language).
This invention solves the following problem
· Platform independence and interoperability.
· This invention does not force the vendor to provide client software.
· Independent evolution of server without affecting the client through server driven work flow.
· Provides access to web based clients.
· Provides backward and forward compatibility between automation equipment and client applications.
· Uniform interface to the client.
An automation equipment has at least one processing unit and is configured to execute stored program (instructions) and applications which generally perform various functions such as human machine interface (HMI), data logging, I/O interfacing, advanced control (including motion control), and enterprise connectivity. Automation equipment is typically part of assembly lines, machine tools and processing equipment. The primary categories of automation equipments are Distributed Control System (DCS), Programmable Logic Controller (PLC), Robot Controller and Programmable Automation Controller (PAC).
This invention involves exposing the services of automation equipment to an external device or client through a uniform interface using HTTP  as an application protocol and resource oriented architecture based on RESTful framework  . A resource is a distributed component that is identifiable by a unique name (URI). A resource may have one or more representations. A representation is the data (state) about the resource in a particular format and language (media type). The uniform interface corresponds to a set of generic operations that can be applied to a resource. In the context of HTTP, the uniform interface corresponds to URI , HTTP methods and media type description  6].
HTTP is a synchronous request/response application protocol. In HTTP, a client always initiates a request and the server responds to the request; the server never initiates a request to the client. This communication pattern limits HTTP applications to synchronous “pull” only interaction pattern. Emulation of asynchronous communication over a synchronous communication channel is achieved through polling, long poll, streaming (e.g. BOSH ), HTML5 WebSockets  or user-defined callbacks over HTTP (e.g. WebHooks  ).
Figure 1 HTTP and REST based Application Architecture for an Automation Equipment
Figure 1 provides an overview of a generic HTTP based solution architectur...