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AssigneeSchneider Automation Inc.
InventorGilbert Brault
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This invention relates to a communication system between a programmable logic controller (PLC) equipped with an HTTP server and a client machine (C) via a network (B), characterized in that it comprises, in the central processing unit (CPU) of this controller, a means (API 1a) for adding “group sheets” (M1, M2. . . ) in XML format, whereon elements or signals for watching or controlling the process automated by the application of the programmable logic controller are grouped, as well as a means (API 1b) for adding/deleting elements or signals on these sheets, by specifying the type thereof, a means (API 1c, API 1d) for reading or writing these elements, and a means (API 2b, API 2c, API 2d) for reading these sheets and for writing on these sheets upon a query from the HTTP server.
A communication system between a programmable logic controller (PLC) equipped with an HTTP server and a client machine (C) via a network (B), characterized in that it comprises, in the central processing unit (CPU) of this controller, a means (API 1a) for adding “group sheets” (M1, M2 . . . ) in XML format, whereon elements or signals for watching or controlling the process automated by the application of the programmable logic controller are grouped, as well as a means (API 1b) for adding/deleting elements or signals on these sheets, by specifying the type thereof, a means (API 1c, API 1d) for reading or writing these elements, and a means (API 2b, API 2c, API 2d) for reading these sheets and for writing on these sheets upon a query from the HTTP server.
The system according to any of the preceding claims, characterized in that it has a reading means (API 2d), called subscribed read, generating a sheet (L2) grouping the element modifications of a “group sheet”, which happen between two successive server pollings.
The system according to any of the preceding claims, characterized in that it has a mechanism based on indicators (HTTP write flags) enabling the controller program to test whether the value of an element has changed since the last controller cycle, after a sheet (E3) has been written via the HTTP server.
The system according to any of the preceding claims, characterized in that has a means (API 2a) for storing and creating write sheets in XML format (E3) through HTTP queries as well as writing sheets (M1, M2) at the beginning of the cycle so as to update the sheets and associated elements.
The system according to any of the preceding claims, characterized in that it has a means (API 2e) for creating a definition sheet (L3) grouping additional descriptive information (comments, . . . ).
Dependencies are inferred from the claim text.