System and method for implementing logic control in programmable controllers in distributed control systems

• US 7,225,037 B2
• Filed: 09/02/2004
• Issued: 05/29/2007
• Est. Priority Date: 09/03/2003
• Status: Active Grant

• Current Assignee: Unitronics Limited (Unitronics 1989 R G Limited)
• Original Assignee: Unitronics Limited (Unitronics 1989 R G Limited)
• Inventors: Shani, Haim
• Primary Examiner(s): Pham; Thomas K.
• Application Number:
  US10/932,889
• Publication Number:
  US 20050085928A1
• Time in Patent Office: 999 Days
• Field of Search: 700/18, 700/86, 700/87, 700/65, 717136-140, 709/217, 709/218, 709/225, 709/205
• US Class Current: 700/18
• CPC Class Codes: G05B 19/056 Programming the PLC

Abstract

The present invention provides a system and method for implementing logic control in programmable controllers in distributed control systems using a wired or wireless network. A software application is used to define the configuration of the network. Based on the network configuration, a compiler engine automatically assigns each statement of the control program to at least one programmable logic controller in the network. Each statement is then transmitted over a data transmission medium to the programmable logic controller assigned to the statement.

Claims

1. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

e. for each constant and variable set by the statements of the machine code, determining the number of statements which reference the previously set constant or variable; and

f. storing the number of referencing statements and a pointer to each referencing statement.

2. A method as defined in claim 1, further comprising the step of:

a. reassigning at least one of the statements to a different programmable logic controller based on the number of referencing statements.

3. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

e. identifying at least one external input/output connection referenced by the statements assigned to a first programmable logic controller;

f. identifying a second programmable logic controller having the at least one referenced external input/output connection;

g. adding at least one gluing statement to the control program for notifying the first programmable logic controller of a change at the referenced external input/output connection; and

h. assigning the at least one gluing statement to the second programmable logic controller.

4. A method as defined in claim 3, further comprising the step of:

a. transmitting a message over the data transmission medium from the second programmable logic controller to the first programmable logic controller notifying the first programmable logic controller of a change at the referenced external input/output connection.

5. A method as defined in claim 4, wherein the message is transmitted only if the first programmable logic controller needs to be notified of the change at the referenced external input/output connection.

6. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

e. identifying at least one external input/output connection referenced by the statements assigned to a first programmable logic controller;

f. identifying a second programmable logic controller having the at least one referenced external input/output connection;

g. adding at least one gluing statement to the control program for instructing the second programmable logic controller to make a change at the referenced external input/output connection; and

h. assigning the at least one gluing statement to the first programmable logic controller.

7. A method as defined in claim 6, further comprising the step of:

a. transmitting a message over the data transmission medium from the first programmable logic controller to the second programmable logic controller instructing the second programmable logic controller to make a change at the referenced external input/output connection.

8. A method as defined in claim 7, wherein the message is transmitted only if the second programmable logic controller needs to be instructed to make the change at the referenced external input/output connection.

9. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein automatically assigning each statement of the machine code to a specific programmable logic controller based on the defined network configuration includes;

a. for each statement, determining the value of more than one binding criteria for each programmable logic controller;

b. for each statement, computing a score for each programmable logic controller, wherein the score is a function of the value of each of the more than one binding criteria and a weight of each of the more than one binding criteria; and

c. assigning each statement to at least one programmable logic controller based on the computed scores.

10. A method as defined in claim 9, wherein the more than one binding criteria is selected from the group consisting of input timing constraints, output timing constraints, CPU usage, memory usage, and communication.

11. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

e. storing the statements in a mirror memory area of each of the programmable logic controllers;

f. instructing each of the programmable logic controllers to stop processing a plurality of old statements stored in a memory area;

g. instructing each of the programmable logic controllers to swap the plurality of old statements stored in the memory area for the statements stored in the mirror memory area; and

h. instructing each of the programmable logic controllers to process the statements.

12. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement, wherein the data transmission medium includes electromagnetic waves, the network has a mesh topology, and a radio frequency module and an antenna are embedded in each of the programmable logic controllers;

e. relaying a message from an originating programmable logic controller to a destination programmable logic controller using at least one intermediate programmable logic controller; and

f. tracking in a cost table, in each of the originating programmable logic controllers, the number of intermediate programmable logic controllers between the originating programmable logic controller and the destination programmable logic controller.

13. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement, wherein the data transmission medium includes electromagnetic waves, the network has a mesh topology, and a radio frequency module and an antenna are embedded in each of the programmable logic controllers;

e. relaying a message from an originating programmable logic controller to a destination programmable logic controller using at least one intermediate programmable logic controller;

f. tracking in a cost table, in each of the originating programmable logic controllers, the number of intermediate programmable logic controllers between the originating progran-imable logic controller and the destination programmable logic controller;

g. relaying a flood message from the originating programmable logic controller to the destination programmable logic controller using at least one intermediate programmable logic controller;

h. determining the least number of intermediate programmable logic controllers required to relay the flood message;

i. relaying a message comprising the least number of intermediate programmable logic controllers required to relay the flood message, from the destination programmable logic controller to the originating programmable logic controller; and

j. updating the cost table of the originating programmable logic controller.

14. A method for implementing a control program in a network of programmable logic controllers having input/output connections, comprising the steps of:

a. translating the control program from a source code into a machine code having a plurality of statements;

b. defining the configuration of the programmable logic controllers and the input/output connections in the network;

c. automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

d. transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

e. establishing a connection between a first web access control client in a first control element and a wide area network;

f. requesting a handle for a second web access control client in a second control element from a web access control server in the wide area network;

g. transmitting the handle from the web access control server to the first web access control client; and

h. transmitting a message from the first control element to the second control element over the data transmission medium wherein the message is not relayed through the web access control server.

15. A method as defined in claim 14, wherein the data transmission medium is selected from the group consisting of direct connection, flat cable, plug-in type rack-connection, plug-in type motherboard-connection, fiber-optic cable, twisted-wire pair, and coaxial cable.

16. A method as defined in claim 14, wherein the data transmission medium includes electromagnetic waves.

17. A method as defined in claim 14, wherein the web access control server is a public server.

18. A method as defined in claim 14, wherein the web access control server is a private server.

19. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein the compiler engine;

a. for each constant and variable set by the statements of the machine code, determines the number of statements which reference the previously set constant or variable; and

b. stores the number of referencing statements and a pointer to each referencing statement.

20. A system as defined in claim 19, wherein the compiler engine:

a. reassigns at least one of the statements to a different programmable logic controller based on the number of referencing statements.

21. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein the compiler engine;

a. identifies at least one external input/output connection referenced by the statements assigned to a first programmable logic controller;

b. identifies a second programmable logic controller having the at least one referenced external input/output connection;

c. adds at least one gluing statement to the control program for notifying the first programmable logic controller of a change at the referenced external input/output connection; and

d. assigns the at least one gluing statement to the second programmable logic controller.

22. A system as defined in claim 21, wherein the second programmable logic controller is configured to transmit a message over the data transmission medium to the first programmable logic controller notifying the first programmable logic controller of a change at the referenced external input/output connection.

23. A system as defined in claim 22, wherein the second programmable logic controller is configured to transmit the message only if the first programmable logic controller needs to be notified of the change at the referenced external input/output connection.

24. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein the compiler engine;

a. identifies at least one external input/output connection referenced by the statements assigned to a first programmable logic controller;

b. identifies a second programmable logic controller having the at least one referenced external input/output connection;

c. adds at least one gluing statement to the control program for instructing the second programmable logic controller to make a change at the referenced external input/output connection; and

d. assigns the at least one gluing statement to the first programmable logic controller.

25. A system as defined in claim 24, wherein the first programmable logic controller is configured to transmit a message over the data transmission medium to the second programmable logic controller instructing the second programmable logic controller to make a change at the referenced external input/output connection.

26. A system as defined in claim 25, wherein the first programmable logic controller is configured to transmit the message only if the second programmable logic controller needs to be instructed to make the change at the referenced external input/output connection.

27. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein the compiler engine;

a. for each statement, determines the value of more than one binding criteria for each programmable logic controller;

b. for each statement, computes a score for each programmable logic controller, wherein the score is a function of the value of each of the more than one binding criteria and a weight of each of the more than one binding criteria; and

c. assigns each statement to at least one programmable logic controller based on the computed scores.

28. A system as defined in claim 27, wherein the more than one binding criteria is selected from the group consisting of input timing constraints, output timing constraints, CPU usage, memory usage, and communication.

29. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein;

a. each of the programmable logic controllers stores the statements in a mirror memory area; and

b. the host computer is configured to instruct each of the programmable logic controllers to stop processing a plurality of old statements stored in a memory area, to swap the plurality of old statements stored in the memory area for the statements stored in the mirror memory area, and to process the statements.

30. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration;

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement; and

d. at least one intermediate programmable logic controller for relaying a message from an originating programmable logic controller to a destination programmable logic controller;

wherein the data transmission medium includes electromagnetic waves;

wherein a radio frequency module and an antenna are embedded in each of the programmable logic controllers;

wherein the network has a mesh topology; and

wherein each of the originating programmable logic controllers is configured to track in a cost table the number of intermediate programmable logic controllers between the originating programmable logic controller and the destination programmable logic controller.

31. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement;

wherein;

a. the data transmission medium includes electromagnetic waves;

b. a radio frequency module and an antenna are embedded in each of the programmable logic controllers;

c. the network has a mesh topology;

d. each of the originating programmable logic controllers is configured to track in a cost table the number of intermediate programmable logic controllers between the originating programmable logic controller and the destination programmable logic controller;

e. the at least one intermediate programmable logic controller is configured to relay a flood message from the originating programmable logic controller to the destination programmable logic controller;

f. the destination programmable logic controller is configured to determine the least number of intermediate programmable logic controllers required to relay the flood message and is configured to transmit a message to the originating programmable logic controller comprising the least number of intermediate programmable logic controllers required to relay the flood message; and

g. the originating programmable logic controller is configured to update the cost table.

32. A system for implementing a control program in a network of programmable logic controllers having input/output connections comprising:

a. a software application for defining the configuration of the programmable logic controllers and the input/output connections in the network;

b. a compiler engine for translating the control program from a source code into a machine code having a plurality of statements and for automatically assigning each statement of the machine code to at least one programmable logic controller based on the defined network configuration; and

c. a host computer for transmitting each statement over a data transmission medium to the programmable logic controller assigned to the statement; and

d. a first web access control client in a first control element for;

i. establishing a connection with a wide area network;

ii. requesting a handle for a second web access control client in a second control element from a web access control server in the wide area network;

iii. receiving the handle from the web access control server; and

iv. transmitting a message to the second control element over the transmission medium wherein the message is not relayed through the web access control server.

33. A system as defined in claim 32, wherein the data transmission medium is selected from the group consisting of direct connection, flat cable, plug-in type rack-connection, plug-in type motherboard-connection, fiber-optic cable, twisted-wire pair, and coaxial cable.

34. A system as defined in claim 32, wherein the data transmission medium includes electromagnetic waves.

35. A system as defined in claim 32, wherein the web access control server is a public server.

36. A system as defined in claim 32, wherein the web access control server is a private server.