Data processing: generic control systems or specific application – Generic control system – apparatus or process – Sequential or selective
Reexamination Certificate
2000-07-28
2003-01-21
Patel, Ramesh (Department: 2121)
Data processing: generic control systems or specific application
Generic control system, apparatus or process
Sequential or selective
C700S018000, C700S020000, C700S048000, C700S049000, C700S050000, C700S052000, C717S152000, C717S152000, C717S152000, C717S152000, C709S241000, C709S241000
Reexamination Certificate
active
06510352
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention pertains to control and, more particularly, to methods and apparatus for implementing process and other control systems at lower cost, with greater flexibility and robustness.
The terms “control” and “control systems” refer to the control of a device or system by monitoring one or more of its characteristics. This is used to insure that output, processing, quality and/or efficiency remain within desired ranges over the course of time. In many control systems, digital data processing or other automated apparatus monitor a device, process or system and automatically adjust its operational parameters or variables. In other control systems, such apparatus monitor the device, process or system and display alarms or other indicia of its characteristics, leaving responsibility for adjustment to the operator.
Control is used in a number of fields. Process control, for example, is typically employed in the manufacturing sector for process, repetitive and discrete manufactures, though, it also has wide application in utility and other service industries. Environmental control finds application in residential, commercial, institutional and industrial settings, where temperature and other environmental factors must be properly maintained. Control is also used in articles of manufacture, from toasters to aircraft, to monitor and control device operation.
Modern day control systems typically include a combination of field devices, controllers, workstations and other more powerful digital data processing apparatus, the functions of which may overlap or be combined. Field devices include temperature, flow and other sensors that measure characteristics of the subject device, process or system. They also include valves and other actuators that mechanically, electrically, magnetically, or otherwise effect the desired control.
Controllers generate settings for the actuator type field devices based on measurements from sensor type field devices. Controller operation is typically based on a “control algorithm” that maintains a controlled device at a desired level, or drives it to that level, by minimizing differences between the values measured values and, for example, a setpoint defined by the operator. Workstations, control stations and the like are typically used to configure and monitor the process as a whole. They are often also used to execute higher-levels of process control, e.g., coordinating groups of controllers and responding to alarm conditions occurring within them.
In an electric power plant, for example, a workstation coordinates controllers that actuate conveyors, valves, and the like, to move coal or other fuels to a combustion chamber. The workstation also configures and monitors the controllers that maintain the dampers that determine the level of combustion. The latter operate, for example, by comparing the temperature of the combustion chamber with a desired setpoint. If the chamber temperature is too low, the control algorithm may call for incrementally opening the dampers, thereby, increasing combustion activity and driving the temperature upwards. As the temperature approaches the desired setpoint, the algorithm incrementally levels the dampers to maintain the combustion level.
The design of control systems and specification of the control algorithms is typically performed using tools known as configurators. An exemplary such tool is provided with the I/A Series® (hereinafter, “IAS” or “I/A”) systems, marketed by the assignee hereof. A graphical configurator, FoxCAE,® provided with those systems permits an engineer to model a process hierarchically and to define a control algorithm from that hierarchy. Once configuration is complete, the control algorithm is downloaded to the control devices. This may involve “compiling” the algorithm in order to convert it into code understood by the controllers and other control devices.
While prior art products such as the aforementioned ones by the Assignee hereof continue to meet success in the marketplace, there remains a need for advancement.
In view thereof, an object of this invention is to provide improved methods and apparatus for control. A related object is to provide such methods and apparatus as can be achieved with lower cost, greater flexibility and robustness.
Another object of the invention is to provide such methods and apparatus as facilitate the modeling of control processes by engineers and users alike.
A related object is to provide such methods and apparatus as facilitate the generation of higher-quality modeling software at lower cost and more widespread applicability.
A further object is to provide such methods and apparatus as can be used in process and other control systems.
SUMMARY OF THE INVENTION
The foregoing are among the objects attained by invention which provides, in one aspect, an improved control device for a process or other control system. The device provides a virtual machine environment in which Java objects, or other such software constructs, are executed to implement control (e.g., to monitor and/or control a device, process or system). These objects, referred to herein as process control objects (PCOs), define blocks, which are the basic functional unit of the control. They also define the input, output and body parts from which blocks are formed, and the signals that are communicated between blocks. PCOs also define nested and composite groupings of blocks used to control loops and higher-level control functions.
By way of non-limiting example, a control system with devices according to the invention can have a workstation and controllers, each providing a Java virtual machine (JVM) environment. Executing on the devices are Java PCOs embodying their respective control functions and signaling. Thus, PCOs executing in each controller monitor and control sensors and actuators under that controller's purview. PCOs executing in the workstation monitor and control the controllers themselves (as well, perhaps, as monitoring the outputs of some of the field devices). Intelligent field devices in the control system may also execute PCOs, thereby, further distributing the control function and taking up tasks otherwise handled by the controllers and workstation.
Referential Communication Between Process Control Entities
Further aspects of the invention provide control devices as described above in which individual data, such as measurements, setpoints or other values, are communicated block-type PCOs by reference. To this end, only one object of each pair of objects between which a given datum is communicated stores the datum itself, e.g., by non-limiting example, in a data structure referred to as below as a “variable.” The other block maintains only a reference, i.e., a pointer, address, symbolic or other reference, to the datum. In order to access the sole instance of the datum as between at least those two blocks, the latter block interrogates—or, if permitted, sets the value of—the datum by using the pointer, address or other reference.
A given datum, according to further aspects of the invention, can be maintained in the block that is the logical and/or physical source of the measurement, setpoint or other value to which it pertains. For example, a PCO embodying an analog input (AIN) block maintains a data structure containing data measured by it. PCO blocks that use those measurements access that data structure and, thereby, the data, by reference.
The data structures embodying data can themselves be PCOs, e.g., by non-limiting example, instantiated from the “signal” class described in the detailed description, below. According to further aspects of the invention, in addition to storing specific measurements, setpoints or values (e.g., the “variables” described below), these data structures can maintain range, status, time stamps and/or other information pertaining to them.
Thus, for example, a “float” variable data structure in a PCO analog input block maintained in a thermocouple sensor device can have, in addition to a floating point value represen
Badavas Paul C.
Hansen Peter D.
Nutter & McClennen & Fish LLP
Patel Ramesh
Powsner David J.
The Foxboro Company
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