Dual ethernet protocol stack for maximum speed access to a programmable logic controller (PLC)

• US 6,587,884 B1
• Filed: 12/31/1999
• Issued: 07/01/2003
• Est. Priority Date: 09/10/1997
• Status: Expired due to Term

• Current Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Original Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Inventors: Naismith, Ronald H., Tanzman, Allan, Papadopoulos, A. Dean
• Primary Examiner(s): Geckil, Mehmet B.
• Assistant Examiner(s): Prieto, Beatriz
• Application Number:
  US09/477,113
• Time in Patent Office: 1,278 Days
• Field of Search: 709/230, 709/231, 709/238, 709/249, 709/250, 709/253, 709/321, 709/220, 709/218, 370/85.5, 370/431
• US Class Current: 709/230
• CPC Class Codes: G05B 19/05 Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
• CPC Class Codes: G05B 19/054 Input/output
• CPC Class Codes: G05B 2219/1208 Communication, exchange of control, I-O data between different plc,
• CPC Class Codes: G05B 2219/15038 Internet, tcp-ip, web server see under S05B219-40
• CPC Class Codes: G05B 2219/31104 Remote configuration of parameters of controlled devices
• CPC Class Codes: G05B 2219/31124 Interface between communication network and process control, store, exchange data
• CPC Class Codes: G05B 2219/31156 Network structure, internet
• CPC Class Codes: G05B 2219/31186 TCP-IP internet protocol
• CPC Class Codes: G05B 2219/31422 Upload, download programs, parameters from, to station to, from server
• CPC Class Codes: G05B 2219/32126 Hyperlink, access to program modules and to hardware modules in www, web server, browser
• CPC Class Codes: G05B 2219/34038 Web, http, ftp, internet, intranet server
• CPC Class Codes: H04L 41/0803 Configuration setting
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/02 based on web technology, e.g. hypertext transfer protocol [HTTP]
• CPC Class Codes: H04L 67/025 for remote control or remote monitoring of applications
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 67/142 Managing session states for stateless protocols; Signalling session states; State transitions; Keeping-state mechanisms
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: H04L 69/16 Implementation or adaptation of Internet protocol [IP], of transmission control protocol [TCP] or of user datagram protocol [UDP]
• CPC Class Codes: H04L 69/161 Implementation details of TCP/IP or UDP/IP stack architecture; Specification of modified or new header fields
• CPC Class Codes: H04L 69/169 : Special adaptations of TCP, UDP or IP for interworking of IP based networks with other networks protocols for interworking, protocol conversion H04L69/08
• CPC Class Codes: H04L 69/329 : in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 : Network security protocols

Abstract

A control system includes an Internet web interface to a network of at least one programmable logic control system running an application program for controlling output devices in response to status of input devices. The Web interface runs Web pages from an Ethernet board coupled directly to the PLC back plane and includes an HTTP protocol interpreter, a PLC back plane driver, a TCP/IP stack, and an Ethernet board kernel. The Web interface provides access to the PLC back plane by a user at a remote location through the Internet. The interface translates the industry standard Ethernet, TCP/IP and HTTP protocols used on the Internet into data recognizable to the PLC. Using this interface, the user can retrieve all pertinent data regarding the operation of the programmable logic controller system.

Claims

1. An interface module for receiving data requests from a remote location in order to provide access to a programmable logic controller from a communication network, the module comprising:

a central processing unit;

a real time operating system operating the central processing unit;

a network interface for communicating with the communication network at a nominal data transfer rate of not less than 100 Mbs;

a back plane driver for communicating with the programmable logic controller through a back plane of the programmable logic controller;

a dual protocol stack comprising;

a first protocol stack for communicating a broad range of network messages;

a second protocol stack for quickly communicating a specialized set of network messages;

a client task for communicating with the back plane driver and the protocol stack for initiating received requests;

a server task for communicating with the back plane driver and the protocol stack for responding to received requests; and

a protocol task for communicating with the back plane driver and the protocol stack for receiving and responding to protocol task requests.

2. The interface module of claim 1 wherein the communication network is a world-wide network known as the Internet using an Internet Protocol (IP).

3. The interface module of claim 2 wherein the interface module functions as a web site on the Internet, the interface module including a global IP address.

4. The interface module of claim 2 wherein the interface module allows a user at a remote location to view data within the programmable logic controller from a browser connected to the Internet.

5. The interface module of claim 1 wherein the network interface is an Ethernet driver.

6. The interface module of claim 1 wherein the protocol stack is a Transmission Control Protocol stack.

7. The interface module of claim 1 the protocol task includes a server task using a hypertext transport protocol (HTTP) to deliver hypertext documents to the network interface.

8. The interface module of claim 7 wherein the HTTP task accepts a connection, parses an HTTP request, and calls the real time operating system to process the request.

9. The interface module of claim 1 wherein the first and second protocol stacks are TCP/IP stacks.

10. The interface module of claim 9 wherein the second protocol stack is implemented when source protocol is the Internet Assigned Number of 502 and the destination port is above port number 3072.

11. The interface module of claim 9 wherein the dual TCP/IP stack comprises a first stack capable of handling a broad range of TCP/IP messages and a second stack capable of handling a less broad range of TCP/IP messages more quickly than the first stack.