Method and apparatus for program navigation and editing for ladder logic programs by determining which instructions reference a selected data element address

• US 5,267,145 A
• Filed: 02/14/1992
• Issued: 11/30/1993
• Est. Priority Date: 06/30/1989
• Status: Expired due to Term

• Current Assignee: ICOM Incorporated
• Original Assignee: ICOM Incorporated
• Inventors: Zifferer, Scott C., Menter, Joseph J. Jr.
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Loomis, John C.
• Application Number:
  US07/837,674
• Time in Patent Office: 655 Days
• Field of Search: 364/DIG. 1, 364/DIG. 2, 364/138, 364/191, 364/192, 364/193, 364/198, 371/19, 395/700, 395/155, 395/919, 395/922
• US Class Current: 700/86
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 2219/13142 Debugging, tracing
• CPC Class Codes: Y10S 706/919 Designing, planning, programming, CAD, CASE
• CPC Class Codes: Y10S 715/967 Visual or iconic programming

Abstract

The present invention is a method that provides productivity aids for developing, debugging, and troubleshooting ladder logic programs used in Programmable Logic Controllers (PLCs). The present invention discloses methods for searching ladder logic programs of programmable logic controllers for instructions, addresses, and symbols. The user can select an address or symbol in the ladder logic program and display on a computer a cross-reference list for the selected address or symbol. The cross-reference list shows all ladder logic instructions, and their locations in the ladder logic program, that use the selected address or symbol. An instruction location can be selected from the cross-reference list and the corresponding point in the ladder logic program will be displayed on the computer.

Claims

1. A method of navigating through a program using a computer, the program being stored in memory on a computer and comprising a plurality of instructions and a plurality of data elements each located at a particular address, each instruction referencing at least one data element using the address for the element, the method comprising:

(a) displaying the program on a monitor attached to the computer, accepting commands from an operator into the computer, and modifying the program in the computer in response to the accepted commands;

(b) selecting a data element address from the displayed program by accepting commands from the operator into the computer by highlighting an the address on the monitor using a cursor-controlled movable highlighting element;

(c) displaying a cross-reference list for the selected address on a monitor attached to the computer, wherein the displaying step (c) comprises overlaying at least a portion of the displayed program on the monitor with the displayed cross-reference list, wherein the cross-reference list comprises program identifiers for programs containing instructions which reference the selected address, instruction types for the instructions which reference the selected address, and instruction locations in the programs for instructions which reference the selected address;

(d) selecting a location from the cross-reference list displayed on the monitor by accepting commands from the operator into the computer by highlighting the location no the monitor using a cursor-controlled movable highlighting element; and

(e) displaying the program containing the instruction on the monitor at the selected location in the program, wherein the displaying step (e) comprises overlaying at least a portion of the displayed cross-reference list on the monitor with the displayed program, so that the program can be studied and edited.

2. The method of claim 1, wherein the addresses are represented by symbols, and wherein the selecting step (a) comprises choosing a symbol representing the data element address.

3. The method of claim 2, wherein the choosing step comprises displaying a symbol list on the monitor and identifying the symbol representing the data element address therefrom.

4. The method of claim 3, wherein the identifying step further comprises selecting the symbol from the list of symbols displayed on the monitor by highlighting the symbol using a cursor-controlled movable highlighting element.

5. The method of claim 1, wherein the selecting step (a) comprises choosing a data element address by highlighting an instruction using the address using a cursor-controlled movable highlighting element.

6. The method of claim 1, wherein the cross-reference list further comprises a description of the selected address.

7. The method of claim 1, wherein the cross-reference list further comprises an indication of alternative uses of the selected address.

8. The method of claim 1, wherein the selecting step (c) comprises choosing a location from the cross-reference list displayed on the monitor by highlighting the location using a cursor-controlled movable highlighting element.

9. A method of navigating through a program for studying, debugging, modifying or developing the program, the program being stored in memory on a computer and comprising a plurality of instructions and a plurality of data elements each located at a particular address, each instruction being positioned at a location in the program and referencing at least one data element using the address for the element, the computer including means for displaying, editing and developing the program, the method comprising:

(a) creating a cross-reference record for the instructions including the instruction'"'"'s locations in the program and the data element addresses referenced by each of the instructions;

(b) selecting a data element address rom the displayed program;

(c) displaying a cross-reference list for the selected address on a monitor attached to the computer, the cross-reference list being generated from the cross-reference record and including locations in the program where instructions reference the selected address;

(d) selecting a location from the cross-reference list displayed on the monitor; and

(e) displaying a representation of the program on the monitor at the selected location in the program, so that the program can be studied or edited.

10. The method of claim 9, wherein the addresses are represented by symbols, and wherein the selecting step (b) comprises choosing a symbol representing the data element address.

11. The method of claim 10, wherein the choosing step comprises displaying a symbol list on the monitor and identifying the symbol representing the data element address therefrom.

13. The method of claim 9, wherein the selecting step (b) comprises choosing a data element address by highlighting an instruction using the address using a cursor-controlled movable highlighting element.

14. The method of claim 9, wherein the cross-reference list further comprises a description of the selected address.

15. The method of claim 9, wherein the cross-reference list further comprises an indication of alternative uses of the selected address.

16. The method of claim 9, wherein the selecting step (d) comprises choosing a location from the cross-reference list displayed on the monitor by highlighting the location using a cursor-controlled movable highlighting element.

12. The method of calm 11, wherein the identifying step further comprises selecting the symbol from the list of symbols displayed on the monitor by highlighting the symbol using a cursor-controlled movable highlighting element.

17. An apparatus for navigating through a program, the program being stored in memory on a computer and comprising a plurality of instructions and a plurality of data elements located at a particular address, each instruction referencing at least one data element using the address for the element, the apparatus comprising:

(a) means for displaying the program;

(b) means for selecting a data element address from the displayed program;

(c) means for displaying a cross-reference list for the selected address on a monitor attached to the computer, wherein the cross-reference list comprises instruction types and instruction locations in the program which reference the selected address;

(d) means for selecting a location from the cross-reference list displayed on the monitor; and

(e) means for displaying the program on the monitor at the selected location in the program.

18. The apparatus of claim 17, wherein the addresses are represented by symbols, and wherein the means for selecting (a) comprises means for choosing a symbol representing the data element address.

19. The apparatus of claim 18, wherein the means for choosing comprises means for displaying a symbol list on the monitor and means for identifying the symbol representing the data element address therefrom.

20. The apparatus of claim 19, wherein the means for identifying further comprises means for selecting the symbol from the list of symbols displayed on the monitor by highlighting the symbol using a cursor-controlled movable highlighting element.

21. The apparatus of claim 17, wherein the means for selecting (a) comprises means for choosing a data element address by highlighting an instruction using the address using a cursor-controlled movable highlighting element.

22. The apparatus o claim 17, wherein the cross-reference list further comprises a description of the selected address.

23. The apparatus of claim 17, wherein the cross-reference list further comprises an indication of alternative uses of the selected address.

24. The apparatus of claim 17, wherein the means for selecting (c) comprises means for choosing a location from the cross-reference list displayed on the monitor by highlighting the location using a cursor-controlled movable highlighting element.

25. An apparatus for navigating through a program for studying, debugging, modifying or developing the program, the program being stored in memory on a computer and comprising a plurality of instructions and a plurality of data elements each located at a particular address, each instruction being positioned at a location and referencing at least one data element using the address for the element, the computer including means for displaying, editing and developing the program, the apparatus comprising:

(a) means for creating a cross-reference record for the instructions, the cross reference record comprising the instruction locations in the program and the addresses being referenced by the instructions;

(b) means for selecting a data element address from the displayed program;

(c) means for displaying a cross-reference list for the selected address on a monitor attached to the computer, the cross-reference list being generated from the cross-reference record and including one or more locations in the program where instructions reference the selected address;

(d) means for selecting a location from the cross-reference list displayed on the monitor; and

(e) means for displaying a representation of the program o the monitor at the selected location in the program, so that the program can be studied or edited.

26. The apparatus of claim 25, wherein addresses are represented by symbols, and wherein the means for selecting (b) comprises means for choosing a symbol representing the data element address.

27. The apparatus of claim 26, wherein the means for choosing comprises means for displaying a symbol list on the monitor and means for identifying the symbol representing the data element address therefrom.

28. The apparatus of claim 27, wherein the means for identifying further comprises means for selecting the symbol from the list of symbols displayed on the monitor by highlighting the symbol using a cursor-controlled movable highlighting element.

29. The apparatus of claim 25, wherein the means for selecting (b) comprises means for choosing a data element address by highlighting an instruction using the address using a cursor-controlled movable highlighting element.

30. The apparatus of claim 25, wherein the cross-reference list further comprises a description of the selected address.

31. The apparatus of claim 25, wherein the cross-reference list further comprises an indication of alternative uses of the selected address.

32. The apparatus of claim 25, wherein the means for selecting (d) comprises means for choosing a location from the cross-reference list displayed on the monitor by highlighting the location using a cursor-controlled movable highlighting element.