PROGRAMMABLE LOGIC CONTROLLER AND PROGRAMMING TOOL FOR PROGRAMMABLE LOGIC CONTROLLER

• US 20150277415A1
• Filed: 03/20/2015
• Published: 10/01/2015
• Est. Priority Date: 03/31/2014
• Status: Active Grant

• Current Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Original Assignee: Jtekt Corporation (Toyota Motor Corporation)
• Inventors: SENDA, Terukazu, YOSHIDA, Kenji, KATO, Satoshi
• Granted Patent: US 10,067,492 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G05B 19/042 using digital processors G05B19/05 takes precedence
• CPC Class Codes: G05B 19/052 Linking several PLC's
• CPC Class Codes: G05B 19/056 Programming the PLC
• CPC Class Codes: G05B 2219/1204 Multiprocessing, several plc's, distributed logic control
• CPC Class Codes: G05B 2219/13153 Modification, change of program in real time

Abstract

A programmable logic controller capable of improving the expandability of a distributed control system and a programming tool for the programmable logic controller are provided. A programmable logic controller (PLC) that constitutes a distributed control system includes: a variable table that includes variable information including identification symbols for identification of a plurality of PLCs and variable names of reference variables, the variable information being set for each of the reference variables; a storage device that has a memory region for storing the reference variables; and an interface circuit that mutually converts communication data for use in communication between the PLC and a different PLC and the reference variables stored in the memory region. The reference variables are variables mutually referenced by the plurality of PLCs.

Claims

1. A programmable logic controller comprising:

a variable table;

a storage device; and

an interface circuit, wherein;

the programmable logic controller performs sequence control in coordination with a different programmable logic controller to constitute a distributed control system;

the programmable logic controller includes reference variables which are variables to be referenced by the different programmable logic controller in the sequence control;

the variable table includes variable information including identification symbols that indicate individual programmable logic controllers that constitute the distributed control system and variable names of the reference variables, the variable information being set for each of the reference variables;

the storage device has a memory region for storing values of the reference variables; and

the interface circuit mutually partially duplicates communication data for use in communication between the programmable logic controller and the different programmable logic controller, and mutually partially duplicates the values of the reference variables stored in the memory region.

2. The programmable logic controller according to claim 1, wherein:

the different programmable logic controller includes an expansion programmable logic controller expected to be additionally installed in the distributed control system; and

the programmable logic controller secures in advance the memory region for storing the reference variable, which is communicated between the programmable logic controller and the expansion programmable logic controller in the case where the expansion programmable logic controller is additionally installed in the distributed control system, in the storage device on the basis of the variable table to permit additional installation of the expansion programmable logic controller.

3. The programmable logic controller according to claim 1, wherein

in the case where the different programmable logic controller is removed from the distributed control system, the programmable logic controller continuously secures the memory region for storing the reference variable, which has been communicated between the programmable logic controller and the removed different programmable logic controller, in the storage device on the basis of the variable table to permit removal of the different programmable logic controller.

4. The programmable logic controller according to claim 3, wherein

in the case where data in the memory region for storage of the reference variable transmitted by the removed different programmable logic controller have an initial value, the programmable logic controller does not execute a step of referencing the reference variable transmitted by the removed different programmable logic controller, among a plurality of steps included in a sequence control program executed by the programmable logic controller, to permit removal of the different programmable logic controller from the distributed control system.

5. The programmable logic controller according to claim 3, wherein

in the case where data in the memory region for storage of the reference variable transmitted by the removed different programmable logic controller have an initial value, the programmable logic controller continues the sequence control without executing an abnormality process to permit removal of the different programmable logic controller from the distributed control system.

6. A programming tool that is used to edit a sequence control program for the programmable logic controller according to claim 1, the programming tool comprising:

a variable table generation unit that receives setting of the variable information to generate the variable table; and

an interface circuit generation unit that specifies the reference variable which belongs to the programmable logic controller on the basis of the set variable information and the sequence control program to generate the interface circuit corresponding to the programmable logic controller.

7. A programming tool that is used to edit a sequence control program for the programmable logic controller according to claim 2, the programming tool comprising:

a variable table generation unit that receives setting of the variable information to generate the variable table; and

an interface circuit generation unit that specifies the reference variable which belongs to the programmable logic controller on the basis of the set variable information and the sequence control program to generate the interface circuit corresponding to the programmable logic controller.

8. A programming tool that is used to edit a sequence control program for the programmable logic controller according to claim 3, the programming tool comprising:

a variable table generation unit that receives setting of the variable information to generate the variable table; and

an interface circuit generation unit that specifies the reference variable which belongs to the programmable logic controller on the basis of the set variable information and the sequence control program to generate the interface circuit corresponding to the programmable logic controller.

9. A programming tool that is used to edit a sequence control program for the programmable logic controller according to claim 4, the programming tool comprising:

a variable table generation unit that receives setting of the variable information to generate the variable table; and

an interface circuit generation unit that specifies the reference variable which belongs to the programmable logic controller on the basis of the set variable information and the sequence control program to generate the interface circuit corresponding to the programmable logic controller.

10. A programming tool that is used to edit a sequence control program for the programmable logic controller according to claim 5, the programming tool comprising:

a variable table generation unit that receives setting of the variable information to generate the variable table; and

an interface circuit generation unit that specifies the reference variable which belongs to the programmable logic controller on the basis of the set variable information and the sequence control program to generate the interface circuit corresponding to the programmable logic controller.