Hitachi, Ltd.

Nissan Motor Company Limited

Hitachi Control Systems, Inc.

Masaoki Takaki

Keiji Hideshima

Kazuyoshi Asada

Haruo Koyanagi

Kunio Yamanaka

Isao Yasuda

Hirokazu Sawano

Hiroharu Suda

Shoichi Masui

Naoki Sasaki

Yoshiyuki Nihashi

Norio Murayama

Shuichi Senda

Atsutaro Kamei

Mikihiko Oonari

A sequence program for a system to be sequence-controlled is divided into a plurality of divisional programs, which are stored in a program memory of a sequence processor. A main program including a plurality of instruction blocks is read out from the system under control and the execution or non-execution status of the divisional program for the corresponding instruction block is determined and stored in the program memory of the sequence processor. An address table indicating correspondence between the divisional programs and their top addresses is stored in a data memory of a sequence control processor. The sequence processor cyclically executes the main program, and when it determines the need for execution of the divisional program in a certain instruction block, it issues an interrupt signal including identification information for identifying the corresponding divisional program to the control processor. The control processor responds by interrupting the execution of the main program by the sequence processor, looks up the address table to obtain the top address of the corresponding divisional program and causes the sequence processor to execute it, and after the execution thereof, resumes the execution of the main program. By excluding the step execution programs from the main program, the main program sequence cycle time can be shortened. Since no jump destination address information is included in the main program, insertion and deletion of the instruction block to and from the main program are facilitated.

Sequence control method and apparatus

A programming equipment is used for automatically constructing programs by selecting and interconnecting a plurality of previously prepared unit programs in accordance with instructions by an operator. A screen of a display unit is divided into a plurality of partial display areas. A memory has a plurality of unit storage areas, one for each partial display area, for storing unit program names and data flow specifications. The information of the respective area is displayed in block form on the display unit so that the operator can readily construct a process data flow by operating the input device while watching the display unit. The programming equipment reads out the area information from the areas in a predetermined sequence, and selects and interconnects the unit programs to construct the program corresponding to the process data flow.

Interactive equipment for computer programming by linkage of labeled

Novel method and system for controlling input/output in a process control wherein state signals of object processes to be controlled are applied to a CPU via a process input/output unit and operated in the CPU in accordance with a logic programmed and stored in advance, and results of the operation are delivered out to the object processes to control the same. A buffer memory is interposed between the CPU and the process input/output unit. While reception and delivery of data are performed between the CPU or processor unit and the buffer memory, fetching of the state signals of the object processes or delivery of the process controlling signals is performed between the buffer memory and the object processes, thereby attaining a high rate processing as viewed from the overall processing of the system.

Method and system for controlling input/output in process control

A sequence control system includes a main memory unit for storing therein a sequence program, an operation and control unit for decoding the sequence instruction and executing the designated operations, an input unit for fetching states of a process to be controlled as inputs, and an output unit for producing an output signal to control the process.

Programmable sequence controller

A programmable sequence controller is provided with a display signal processor for preparing and correcting a sequence program in combination with a CRT (or cathode ray tube) display device. The signal processor simply effects signal processing of branch points and composition points in case where a so-called 'ladder diagram' constituting the sequence diagram with relay symbols is prepared and displayed. Branch information is stored in an FIFO (or first in first out) register. The branch information is sequentially received and stored, and the information thus stored is read out in the order of storage, thus preparing the ladder diagram. There are provided a register for instructing the FI operation and a register for instructing the FO operation. The sequence display controller is applicable to the cases where a new ladder diagram is to be prepared, the diagram once prepared is corrected, and the operation is checked.

Sequence display controlling method and controller

A sequence control system suitable for checking the operation of an information processor includes a process I/O unit for receiving input data from process inputs and providing output data to process outputs; a sequence processing unit for calculating data at the process outputs by performing sequence operations according to the sequence programs stored in a sequence program memory on the basis of the data at the process inputs; a buffer memory provided between the process I/O unit and the sequence processing unit for storing both the process input data from the process I/O unit and the output data from the sequence processing unit; a control arrangement for setting the input data to the buffer memory and for allowing access to a selected sequence program according to manually set input information; a display for displaying the selected sequence program accessed through the control arrangement; and a switch for interrupting the transfer of I/O data between the process I/O unit and the buffer memory. The sequence processing unit determines the output data on the basis of the input data stored in the buffer memory and applies the output data to the buffer memory. The control arrangement, in response to the manually set input information, causes the associated sequence program to be read from the sequence program memory and then the data of the inputs and outputs associated with the sequence program to be read from the buffer memory thereby to indicate them on the display.

Sequence control system

A method and an apparatus for diagnosing a fault in a sequence control system performing control in accordance with a predetermined sequence, wherein memory means having bits corresponding to respective ones of a plurality of predetermined sequence steps is provided. The sequence of steps actually applied to an object to be controlled are sequentially stored in corresponding bits. Each time a sequence step is applied to the object to be controlled, the contents of the memory means are checked to see whether or not any of the sequence steps applied thus far have been skipped. If any sequence step has been skipped, a fault is determined. Preferably, a fault is also determined when any of the intervals of sequence steps successively applied exceeds a predetermined length of time. Upon determination of a fault, the sequence step associated with the fault is identified, and the control circuit associated with the sequence step in fault is preferably displayed.

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Hitachi, Japan

Masaoki Takaki