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System and method for programming a logic control unit

  • US 6,505,341 B1
  • Filed: 11/10/1998
  • Issued: 01/07/2003
  • Est. Priority Date: 11/10/1998
  • Status: Expired due to Fees
First Claim
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1. A process for generating a control program for execution by a programmable logic control unit having a plurality of input ports for receiving input signals from components of an external system under control, and a plurality of output ports for providing output signals to components of the external system, the program listings being easily read and understood by one not trained in the arts of software engineering, comprising the steps of:

  • (ai) providing a variable editing user interface allowing a user to select and edit existing variables stored in a file and including input variables associated with corresponding ones of the input signals, and output variables associated with corresponding ones of the output signals, and to define new variables;

    (aii) displaying a list of previously defined variables;

    (aiii) selecting a type of variable from a predetermined set of types of variables;

    (aiv) selecting and editing an existing variable of the selected type, or defining a new variable of the selected type by entering a variable name identifying the variable, and specifying particular characteristics of the new variable; and

    (av) storing the edited or defined variable in said file and returning to step (aii) until all desired variables have been edited and/or defined;

    (bi) providing a program level editing user interface allowing the user to edit a program level stored in said file, said program level including a plurality of states defining a sub-process of said control program for asynchronous execution by the programmable control unit, or to define a new program level;

    (bii) selecting and editing an existing program level, or defining a new program level by assigning a level value, level type and level description thereto; and

    (biii) storing the edited or new program level in said file and returning to step (bii) until all desired program levels have been edited and/or defined;

    (ci) providing a state editing user interface allowing a user to select and edit an existing state stored in said file, or to define a new state having at least one variable associated therewith, said variable being assigned a data value upon transition of said control program to the corresponding state during execution of said control program by the programmable control unit;

    (cii) selecting and editing an existing state, or defining a new state and assigning at least one variable thereto; and

    (ciii) storing the edited or new state in said file;

    (di) providing a condition editing user interface allowing a user to select and edit a condition associated with a particular state and stored in said file, or to add a new condition to a selected state said condition specifying a transition from an associated state as a source state to a corresponding selected destination state upon satisfaction of said condition during execution of said control program by the programmable control unit;

    (dii) selecting a stored condition for editing, or defining a new condition for a particular state by assigning thereto a condition address, a condition name, a destination state address, and a destination state name, said destination address specifying, for said condition, a transition from its associated state, as a source state, to a selected destination state when said condition is true during execution of said control program; and

    (diii) storing said edited or new condition in said file; and

    (e) generating said control program as a function of the associative relationships of said stored variables, states, and conditions stored in said file.

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