Multitasking industrial controller

  • US 5,636,124 A
  • Filed: 03/08/1995
  • Issued: 06/03/1997
  • Est. Priority Date: 03/08/1995
  • Status: Expired due to Term
First Claim
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1. An industrial controller operating controlled equipment according to a control program divided into at least two tasks each having a starting and completion point, the controller comprising:

  • (a) an I/O module receiving electrical inputs from the controlled equipment;

    (b) a control terminal for entering data from the user providing for each task;

    a task priority, a task characterization as to whether the task is periodic, and thus to be executed to completion regularly according to a time period, or event triggered, and thus to be executed upon occurrence of an event, the event being a change in a predetermined electrical input;

    (c) an electronic memory communicating with the I/O module and the control terminal and storing;

    (i) the at least two tasks of the control program;

    (ii) a task scheduling table receiving the task priority and task characterization from the user;

    (iii) an operating system program;

    (d) an electronic processor communicating with the electronic memory and the I/O module to receive the electrical inputs and operate according to the inputs and the control program, and executing the operating system program to;

    (i) identify a highest priority periodic task requiring current execution based on the task priority and the time period of the task;

    (ii) identify a highest priority event triggered task ready current execution based on the occurrence of its event;

    (iii) if there is no ready event triggered task of higher priority than the highest priority periodic task, execute once to completion the highest priority periodic task;

    (iv) if there is no highest priority periodic tasks of higher priority than the ready event triggered task execute once to completion the ready event triggered task.

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