Control system

Details Control system Control system

2001-06-06

2002-10-08

Black, Thomas (Department: 2121)

Data processing: generic control systems or specific application

Generic control system, apparatus or process

Sequential or selective

C700S019000

Reexamination Certificate

active

06463340

ABSTRACT:

CROSS REFERENCE TO RELATED APPLICATIONS
The present invention claims priority from Japanese Patent Application No. 2000-172452 filed Jun. 8, 2000, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for standardizing computer programs used for control purposes. It relates in particular to a technique for running such programs more simply by standardizing their design, modification and major alteration. The invention also relates to a control system wherein a plurality of control modules are arranged in an hierarchical structure and serve to individually control a plurality of controlled elements contained within a single controlled system. The invention further relates to a control program for this control system.
2. Description of Related Art
A previously proposed structure of a control system provides a plurality of controlled elements in a single control system and a plurality of control modules for individually controlling these controlled elements, and controls these control modules hierarchically.
Regarding this control system, the present applicant has proposed a technique wherein all the control modules have a standardized set of modes and mode transitions, and the components of the overall control system are in an hierarchical structure (see U.S. patent application Ser. No. 09/244,846, hereinafter termed the “prior application”). In the present application, each control module is understood to be such a component.
The prior application will be described with reference to FIG.
12
and FIG.
13
.
FIG. 12
shows the overall configuration of a control system according to the prior application, while
FIG. 13
is a block diagram of a control module according to the prior application. As shown in
FIG. 12
, according to the previously proposed control system there are provided a plurality of controlled elements E(
0
) to E(m) and a plurality of control modules M(
0
) to M(n) for individually controlling these controlled elements E(
0
) to E(m), and these control modules M(
0
) to M(n) are controlled hierarchically. Communication among the control modules is carried out by way of communication lines C(
0
) to C(n) and communication memory COM.
In this control system, even if a certain control module does not use one of the modes belonging to the basic module, that mode is still provided in conformity with the basic module. Moreover, the modes and mode transitions are not extended beyond those provided in the basic module. If there is a need to extend the modes and mode transitions available, another basic module is designed. All the control module modes and mode transitions are standardized in at least one closed control system. All sorts of control states can be designed by setting parameters for these modes and mode transitions in accordance with the conditions imposed by the control specification and the controlled elements.
Thus, by standardizing the modes and mode transitions that the control modules have in common, a control module can be treated in terms of the concept of a component of a control system, which can then be constructed by assembling such components. A further consequence of this approach is that the updating of a control system can be treated in terms of the concept of the replacement of components.
Thus, by standardizing the modes and mode transitions that the control modules have in common, a control module can be treated in terms of the concept of a component of a control system, which can then be constructed by assembling such components. A further consequence of this approach is that the updating of a control system can be treated in terms of the concept of the replacement of components.
In the present application, the applicant has focused on the fact that the control system of the prior application can be made even easier to use by employing a plurality of command types with different characteristics.
This can be achieved by for example providing a convenient command for dealing with circumstances that differ from normal operation, as when the control system is initialized, during maintenance and checking, or when a fault occurs. Alternatively, restrictions on controlled elements or the order in which these elements are controlled can easily be set by providing commands with different scopes. See Takano et al Application No. 09/801,790 filed Mar. 9, 2001.
Using these ideas, a desired sequence of operations can be executed by using job commands to elicit the functions of control modules, and by using state commands to cause these control modules to undergo state transitions. In addition, when a situation occurs that makes it desirable for control modules to undergo state transitions as a matter of urgency during the execution of a sequence, this can be achieved by means of an event command.
The term “pre-emption processing” will be used to denote the process wherein a command issuing source acquires in advance the right to issue a command to a control module that is the target of that command. Job commands and state commands are commands that require pre-emption processing to be carried out in advance in relation to the control module that is the target of the command, and they are commands that become valid for a pre-empted control module. As opposed to this, an event command does not require pre-emption processing to be carried out in advance, and can be issued to any desired control module.
Commands other than job commands spread to control modules hierarchically below the control module that has received the command. A state command spreads to hierarchically lower control modules that are not currently pre-empted by another command issuing source. From the outset, an event command does not require pre-emption processing, and spreads to all hierarchically lower control modules.
It may be noted that although pre-emption processing is not required in order to issue an event command, a control module that is the destination of an event command performs, either simultaneously with or subsequent to receipt of the event command, the same processing as when it is pre-empted. The control module is able to undergo appropriate state transitions in accordance with the state of hierarchically superior control modules after this processing is cancelled.
Furthermore, a control module that is connected hierarchically below a control module that is the destination of an event command should have an existing state of pre-emption cancelled when it receives the event command. The aforementioned “same processing as when it is pre-empted” that is performed by a control module that is the destination of an event command includes, for example, recording information relating to the issuing source of that event command, and deleting this recorded information when the processing is cancelled. This enables the event command issuing source to recognize the validity or invalidity of the processing.
It has been found that if commands are issued and received using the system configuration of the prior application, the time required for a command to be transmitted to the relevant control modules is sometimes not negligible from the point of view of performing control.
For example, with the system configuration of the prior application, when a state command is issued to a particular control module, the control module that receives this state command looks up hierarchically lower control modules that are not currently pre-empted by another command issuing source, and causes the state command to propagate to all these hierarchically lower control modules. Each hierarchically lower control module that receives the propagated state command also looks up hierarchically lower control modules that are not currently pre-empted by other command issuing sources, and likewise causes the command to propagate to these modules. The command is transmitted to the required control modules by repeating this process.
Although the processing time at an individual control module is extreme

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