Multiplex control system with programmable logic for controlling signal transfer between controllers and one or more controlled systems

• US 4,998,194 A
• Filed: 03/28/1989
• Issued: 03/05/1991
• Est. Priority Date: 03/28/1988
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Okamoto, Tadashi, Azusawa, Noboru
• Primary Examiner(s): RUGGIERO, JOSEPH F
• Application Number:
  US07/329,514
• Time in Patent Office: 707 Days
• Field of Search: 364/131-136, 364/184-187, 364/138, 364/139, 364/200 MS File, 364/900 MS File, 364/140, 364/141, 371/9.1, 371/11.1, 371/11.3, 371/36
• US Class Current: 700/4
• CPC Class Codes: G05B 19/052 Linking several PLC's
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems

Abstract

A multiplex control system has controllers for delivering control data to at least one common controlled system, and a multiplex mode switching device which is constructed to permit the logic for selecting the control data to be changeably set therein. The mode selection logic of the multiplex mode switching device can be set and changed freely by the user so that a desired logic is obtainable for the selection of the control data from the controllers, whereby the adaptability and utility of the multiplex control system are increased.

Claims

1. A multiplex control system for controlling at least one controlled system with a plurality of controllers, comprising:

a plurality of controllers, each generating a respective control signal for controlling at least one controlled system, and

a multiplex mode switching device connected to said controllers and including a plurality of buffer memories each storing a respective one of said control signals delivered from said controllers, a central processing unit operating under control of a readable and writable program memory for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with a programmed multiplex mode logic which is stored in said program memory and which is changeable by re-writing said program memory, and means for delivering said actual control signal from said central processing unit to said controlled system.

2. A multiplex control system according to claim 1, wherein said programmed multiplex mode logic includes one of a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals.

3. A multiplex control system for controlling at least one controlled system with a plurality of controllers, comprising:

a plurality of controllers, each generating a respective control signal for controlling at least one controlled system; and

a multiplex mode switching device connected to said controllers and including a plurality of buffer memories each storing a respective one of said control signals delivered from said controllers, a central processing unit operating under control of a readable and writable program memory for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with a programmed multiplex mode logic selected from a plurality of programmed multiplex mode logic stored in said program memory, and means for delivering said actual control signal from said central processing unit to said controlled system.

4. A multiplex control system according to claim 3, wherein said plurality of programmed multiplex mode logic include a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals;

and

said central processing unit including means reading out a selected one of said programmed multiplex mode logic from said program memory to generate said actual control signal in accordance with inputted information.

5. A multiplex control system for controlling at least one controlled system with a plurality of controllers, comprising:

a plurality of programmable controllers each having a central processing unit and operating to perform control computations, in accordance with a preset program and on the basis of input data which represents the state of said controlled system, to generate a control signal for controlling said at least one controlled system; and

a multiplex mode switching device including a plurality of buffer memories each storing a respective one of said control signals delivered from said controllers, a central processing unit operating under control of a readable and writable program memory for generating an actual control signal for actually controlling said controlled system on the basis of stored control signals in said buffer memories and in accordance with a programmed multiplex mode logic which is stored in said program memory and which is changeable by re-writing said program memory, and means for delivering said actual control signal to said controlled system.

6. A multiplex control system according to claim 5, wherein said programmed multiplex mode logic includes one of a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals.

7. A multiplex control system for controlling at least one controlled system with a pluralilty of controllers, comprising:

a plurality of programmable controllers each having a central processing unit and operating to perform control computations, in accordance with a preset program and on the basis of input data which represents the state of said controlled system, to generate a control signal for controlling said at least one controlled system; and

a multiplex mode switching device including a plurality of buffer memories each storing a respective one of said control signals delivered from said controllers, a central processing unit operating under control of a readable and writable program memory for generating an actual control signal for actually controlling said controlled system on the basis of stored control signals in said buffer memories and in accordance with a programmed multiplex mode logic selected from a plurality of programmed multiplex mode logic stored in said program memory, and means for delivering said actual control signal to said controlled system.

8. A multiplex control system according to claim 7, wherein said pluralilty of programmed multiplex mode logic include a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals;

and

said central processing unit including means for reading out a selected one of said programmed multiplex mode logic from said program memory to generate said actual control signal in accordance with inputted information.

9. A multiplex control system for controlling at least one control system with a plurality of controller, comprising;

a plurality of programmable controllers each having a central processing unit and operating to perform control computations, in accordance with a preset program and on the basis of input data which represents the state of said controlled system, to generate a control signal for controlling said at least one controlled system; and

a multiplex mode switching device including;

(a) a plurality of linkage devices each corresponding to a respective one of said programmable controllers and having a communication portion for communicating with the corresponding controller through a communication line, a buffer memory for temporarily storing said control signal and a buffer memory for temporarily storing said input data;

(b) a central processing unit, having a program memory, for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with programmed multiplex mode logic which is stored in said program memory and which is changeable by re-writing said program memory; and

(c) a process-input/output section for delivering said actual control signal from said central processing unit to said controlled system, and enabling said input data to be stored in a buffer memory of said linkage devices.

10. A multiplex control system according to claim 9, wherein said programmed multiplex mode logic includes one of a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals.

11. A multiplex control system for controlling at least one controlled system with a plurality of controllers, comprising:

a plurality of programmable controllers each having a central processing unit and operating to perform control computations, in accordance with a preset program and on the basis of input data which represents the state of said controlled system, to generate a control signal for controlling said at least one controlled system; and

a multiplex mode switching device including;

(a) a plurality of linkage devices each corresponding to a respective one of said programmable controllers and each having a communication portion for communicating with the corresponding controller through a communication line, a buffer memory for temporarily storing said control signal, and a buffer memory for temporarily storing said input data;

(b) a central processing unit, having a program memory, for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories in accordance with a programmed multiplex mode logic selected from a plurality of programmed multiplex logic stored in said program memory; and

(c) a process-input/output section for delivering said actual control signal from said central processing unit to said controlled system, and enabling said input data to be stored in a buffer memory of said linkage devices.

12. A multiplex control system according to claim 11, wherein said plurality of programmed multiplex mode logic include a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals;

and

said central processing unit includes means for reading out a selected one of programmed multiplex mode logic from said program memory to generate said actual control signal in accordance with inputted information.

13. A multiplex control system for controlling at least one controlled system with a plurality of controllers, comprising:

a multiplex mode switching device including a plurality of buffer memories each of storing a respective control signal for controlling said at least one controlled system, a central processing unit operating under control of a readable and writable program memory for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with a programmed multiplex mode logic which is stored in said program memory and which is changeable by re-writing said program memory, and means for delivering said actual control signal to said controlled system; and

a plurality of controllers capable of controlling said controlled system through said multiplex mode switchding device.

14. A multiplex mode switching device comprising:

a plurality of buffer memories each storing a control signal for controlling at least one controlled system;

a central processing unit, having a program memory, for generating an actual control signal for actually controlling said controlled system on the basis of the control signals for controlling said controlled system stored in said buffer memories in accordance with a programmed multiplex mode logic which is stored in said program memory and which is changeable by rewriting said program memory; and

a process-output means for delivering said actual control signal to said controlled system.

15. A multiplex mode switching device comprising:

a plurality of data communication means connectable respectively to a plurality of programmable controllers for controlling at least one controlled system;

a plurality of buffer memories each temporarily storing a respective control signal delivered from said programmable controllers through said data communication;

a central processing unit, having a program memory, for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with a programmed multiplex mode logic which is stored in said program memory and which is changeable by re-writing said program memory; and

a process-output means for delivering said actual control signal to said controlled system.

16. A multiplex mode switching device according to claim 15, wherein said programmed multiplex mode logic includes ones of a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals.

17. A multiplex mode switching device comprising:

a plurality of data communication means connectable respectively to a plurality of programmable controllers for controlling at least one controlled system;

a plurality of buffer memories each temporarily storing a respective control signal delivered from said programmable controllers through said data communication means;

a central processing unit, having a program memory, for generating an actual control signal for actually controlling said controlled system on the basis of control signals stored in said buffer memories and in accordance with a programmed multiplex mode logic selected from a plurality of programmed multiplex mode logic stored in said program memory; and

a process-output means for delivering said actual control signal to said controlled system.

18. A multiplex mode switching device according to claim 17, wherein said plurality of programmed multiplex mode logic include a logical product of said stored control signals, a logical sum of said stored control signals and a majority decision with respect to said stored control signals;

and

said central processing unit includes means for reading out a selected one of said programmed multiplex mode logic from said program memory to generate said actual control signal in accordance with inputted information.