Schneider Automation Gmbh

David T Lindner

Andrew G Swales

Merrill W Harriman

James W McGlaughlin, Iii

James V Mc Glaughlin Iii

A method for adapting a computer-to-computer communication protocol, and especially TCP/IP, or any protocol implemented in a general purpose off-the-shelf network like Ethernet, for use in providing communication needed in an industrial control system, and especially an industrial control system using a programmable logic controller (PLC), where there is frequent communication between the PLC and control or monitoring elements, the method aimed at allowing the PLC to perform scanning of its ladder logic at a rate adequate for effective industrial control. The method includes making permanent-type TCP connections between the PLC and a control element or a monitoring element, use of a protocol for communication with a control or monitoring element in which both a read register and a write register instruction is included in a single communication transaction, such as a MODBUS command, and tuning communication between the PLC and a control element or a monitoring element.

Method for adapting a computer-to-computer communication protocol for use in an industrial control system

A programmable logic controller for use as part of an industrial control system or as part of an automated system and a corresponding method, the controller including an interface to the Internet, and including a web server allowing a remote computer to access web pages maintained by the controller providing information relevant to the control function of the controller such as control sensor readings and, optionally, information about the status of the control system. The web server is implemented as part of the controller in such a way that the controller scan rate (the rate at which the ladder logic for all associated control system devices is repeated) is unaffected by execution of the web server.

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Nashua, NH, United States of America

David T Lindner