Patent Number: 052531864
Section: description

DESCRIPTION OF THE PREFERRED EMBODIMENTS The basic blocks in a process facility monitoring system to which the present invention could be applied are illustrated in FIG. 1. As illustrated in FIG. 1, a processor 10 which may be included in a workstation, such as a SPARCstation 2 from SUN Microsystems, Inc. of Mountain View, Calif., receives data from sensors (not shown) in the process facility via a data acquisition system 12 while operating under the control of a program stored in a storage unit 14. The data acquisition system 12 may be any conventional system adequate for the number of sensors required and connectable to the processor 10, while the storage unit 14 may be any of a variety of mass storage devices, used individually or in combination. Since the purpose of the system illustrated in FIG. 1 is to provide information to an operator of the process facility, an operator display 16, such as a cathode ray tube display is provided. An operator input unit 18, such as a mouse, touch screen, light-pen, keyboard, etc., permits the operator to control what is displayed. As illustrated in FIG. 2, like the conventional process facility monitoring system disclosed in U.S. Pat. Nos. 4,803,039 and 4,815,014, it is necessary to store 20 initial, sequential and constraining conditions for a procedure to be monitored. In addition, the text of the procedure and other related information also may be stored in the storage unit 14. The conditions and related information may be stored in many different forms. As noted above, the two referenced patents disclose a system which has been implemented by encoding all of the conditions in a FORTRAN program, while other systems which monitor process facilities in a different manner utilize expert systems. It is also possible to use external files, accessed by a program, to store much of the information. In the preferred embodiment, an external file may be used for ease of updating. One of the files may contain transform flags which may be set 22 to designate transformable sequential conditions prior to beginning 24 execution of the procedure. The purpose of monitoring systems of the type to which the present invention is applied is to aid an operator in executing the steps of a procedure. For a complex process facility, such as a nuclear power plant, the procedures are not the simple execution of one step after another, but may contain branches, steps which may be skipped or performed in any order or simultaneously, etc. Since the present invention is not directed to the order of execution of steps per se, FIG. 2 indicates the execution of multiple steps by loop block 26. However this should not be taken as a literal description of how the steps must be executed, but rather as a recognition that a procedure includes many steps and involves progressing from one step to another with a defined relationship between the steps, even though the relationship may not be so simple that steps change by incrementing an iteration value. Regardless of how the order of execution of the steps is defined, at least one step is executed at a time. Each step may have several sequential conditions corresponding to the step. According to the defined procedure, all of these sequential conditions should be met to complete a step. In a computer task for checking sequential conditions, a sequential condition loop block 28 may be used to control repeated checks of the sequential conditions associated with a corresponding step I. An iterative value J is initialized and incremented by the loop block 28 so that each sequential condition can be compared with sensor readings in the process facility to determine 30 whether the condition is met. When a condition has been met, the transform flag is checked 32 and if the transform flag is set, an enable flag for sequential condition J is set 34. In addition to predefined transformable sequential conditions, in the preferred embodiment the operator is given the ability to select sequential conditions to be tracked as transformed conditions in the same manner as constraining conditions are tracked. This may be accomplished in several ways. The operator display 16 could be used to display the sequential conditions and the process facility status corresponding to these conditions. Associated with the display of this information could be a box which the operator may check using the operator input device 18. In this case, all or a selected set of the sequential conditions for the current executing step may have such a box. In most applications, it is expected that an operator will rarely select a sequential condition to be transformed into a constraining condition. Therefore, in the preferred embodiment, a display screen like that illustrated in FIG. 3 is displayed on the operator display 16. At the bottom of the screen is a command menu 36 which may include command buttons 37-40 for selecting auxiliary screens. These screens permit selection of items, such as user reports, print log, access to other procedures, etc. As indicated by command button 40, one of the options which may be provided in the command menu 36 is to modify settings. When a request to modify settings is detected 42 (FIG. 2) by an operator selecting the area of command button 40 using a touch screen, light pen, mouse, etc. in the input unit 18, a menu is displayed 44 permitting the operator to set the transform flag of a sequential condition. The display may be limited to the sequential conditions for the currently executing step I, or the program executing in the processor 10 may permit the operator to scan through the sequential conditions for a number of steps, such as all of the previously executed steps, in addition to the currently executing step and set the transform flag for any sequential condition corresponding to these steps. When all of the sequential conditions for the currently executing step I have been tested, a determination is made as to whether step I has ended 46. This determination may be made in several ways. The process facility monitoring method disclosed in U.S. Pat. Nos. 4,803,039 and 4,815,014 include action buttons 48, 49 which permit the operator to indicate when an action has been completed 48 or if an action is to be overridden 49. When all of the actions within a step have been indicated as completed or overridden, a determination will be made 46 that step I has ended. Alternatively, the process facility monitoring system may be computer paced, whereby the sensor readings must indicate that all of the sequential conditions have been met in order for the determination 46 to be made that step I has ended. Regardless of how the determination 46 is made, according to the present invention the enable flag for all transformable sequential conditions in step I are set 50 when the determination 46 is made that step I has ended. Thus, if a transformable sequential condition is overridden in a step, the enable flag corresponding to that condition will be set 50 so that the sequential condition will continue to be checked as a constraining condition in the subsequent steps. In an alternative embodiment, the check for a transform flag and setting of an enable flag as each condition is met which is indicated in blocks 30, 32, 34, may be eliminated and the setting 50 of enable flags at the end of each step may be relied upon. As described above, in addition to moving sequentially through a procedure, a process facility monitoring system like that disclosed in U.S. Pat. Nos. 4,803,039 and 4,815,014 continually checks constraining conditions. When transformable sequential conditions are included according to the present invention, the program steps illustrated in FIG. 4 will be executed in checking constraining conditions. As in the case of FIG. 2, the flowchart in FIG. 4 is representative of the computer operations which must be performed. These steps can be implemented in many ways. If the processor 10 is capable of multi-tasking operation, the sequential condition iteration loop controlled by block 26 of FIG. 2 may be located in one or more tasks, while the computer program code represented by the flowchart in FIG. 4 is in a separate task. In this manner, the multi-tasking operating system will control the simultaneous execution of the program flow in FIGS. 2 and 4. Alternatively, a single application program may be written encompassing both FIGS. 2 and 4 and the program code corresponding to the blocks illustrated in FIG. 4 may be inserted in place of one of the ellipses 52, 54 in FIG. 2, or some other timing mechanism may be used to determine when the constraints loop illustrated in FIG. 4 is performed. Regardless of exactly how it is determined to execute the constraints loop in FIG. 4, each of the constraining conditions must be checked in some manner at appropriate times during execution of a procedure. In FIG. 4, a constraints loop block 56 is illustrated as one example of how to control checking all of the constraining conditions. However, the present invention may be implemented in an expert system or using other software which does not support iteration loops, but has other known mechanisms for repeatedly checking a large number of conditions. Regardless of how the constraining conditions are checked, a determination is made 58 whether a constraining condition is violated and a warning is displayed 60 for those constraining conditions which are found to be violated. In addition, an iteration loop block 62 or other means for checking transformable sequential conditions is provided. For each sequential condition, determinations must be made regarding whether the sequential condition is transformable 64 and if so whether it has been enabled 66. If these determinations are made in the affirmative, the condition is a transformed condition which will be treated like a constraining condition and checked to determine 68 whether the condition has been violated. A warning will be displayed 70 in a manner similar to that for constraining conditions when a transformed condition is violated. As noted above, the present invention may be implemented in many ways. In the case of complex procedures, it is common to have a computer-based procedure maintaining support system for defining the procedures. The system used for computer-based support may provide means for automatically generating the control codes to create transformable sequential conditions. In a case where a FORTRAN program is used to provide a process facility monitoring system, instead of having transform flags, the procedure maintaining support system may copy FORTRAN code from a sequential condition group of statements to a constraining condition group of statements. This copying of course could be performed manually, although as noted above the benefits of ensuring consistency and accuracy of the conditions being checked is not as easily maintained when the copying is performed manually. The many features and advantages of the present invention are apparent from the detailed specification, and thus it is intended by the appended claims to cover all such features and advantages of the system which fall within the true spirit and scope of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art from the disclosure of this invention, it is not desired to limit the invention to the exact construction and operation illustrated and described, accordingly, suitable modifications and equivalents may be resorted to, as falling within the scope and spirit of the invention.