SYSTEM FOR PROVIDING OPERATOR DISPLAYS OF DYNAMIC PLANT OPERATION DATA

Abstract: A system for displaying select dynamic process data of plant operations to an operator provides a display of only dynamic data having a predetermined difference between current and stored values. The apparatus comprises means (12) for providing a series of operating plant variables, means (14) for storing the current operating plant variables, display means (18) for displaying the dynamic plant data, and an exception control means (16) for comparing the value of display data on the display means (18) with the current stored data in the storage means (14) against a predeter­ mined value, the exception control means (18) including a control module (20) connected to the display means (18) for displaying any of the stored data that exceeds the predeter­ mined value.

Description: METHODS OF AND SYSTEMS FOR PROVIDING OPERATOR DISPLAYS OF DYNAMIC PLANT OPERATION DATA This invention relates to methods of and systems for providing operator displays of dynamic plant operation data. Control computer systems are commonly used to monitor a number of processes occurring in manufacturing and processing facilities. The monitoring process at a minimum comprises plant data acquisition via a multiplexer, data processing in the computer system, and data display on elements such as cathode ray tubes. Data display on cathode ray tubes include text material comprising alphanumeric description andlor graphic symbols, static displays comprising data independent of plant dynamics, and dynamic displays comprising data, both measured and calculated, which is directly related to plant dynamics. Of these categories, dynamic data display is of paramount importance to operating personnel as it gives the current plant status. To provide the display of dynamic data on a cathode ray tube, process signal data is acquired via a multiplexer, processed in a computer system and usually stored in a data base memory. Dynamic data is then accessed from the data base memory by a display program and transferred to the cathode ray tube. The prevailing practice has been to periodically access and transfer process data to a cathode ray tube at a fixed prespecified time interval known as an update period. This practice is commonly referred to as continuous updating of CRT displays. With this technique, changes in plant status are displayed only after the update period has elapsed, that is, on the next update cycle. This practice is contrary to the needs of operating personnel who sometimes need to know current changes in plant status without delay to prevent a fast moving crisis situation from occurring. Furthermore, updating of all dynamic data on a cathode ray tube display, including data which does not change over an update cycle, increases the volume of data accessed from the data base and transmitted to the CRT, thus increasing system load for display updating. Consequently, system response time for display, time between occurrence of an event in plant and its indication on cathode ray tube, is unnecessarily increased. This further adds to delays in the plant operator's decision making and slows the corrective action process. The probability exists in the prior art that a rapidly changing process variable may not be displayed on the cathode ray tube at all. Thus it is seen that the prior art techniques do not provide for timely updating of cathode ray tube displays. Because of the foregoing, it has become desirable to develop a display update system which provides for minimum display time of critical dynamic data. According to the present invention there is provided a method of providing an operator display of dynamic plant operation data on a cathode ray tube, the method being characterised by: obtaining a value of a displayed dynamic plant data variable from a display; obtaining a current value of the dynamic plant data variable from a current data storage memory; comparing the absolute difference between the value of the displayed dynamic plant variable and the current stored value of the dynamic plant variable; and displaying the currently stored dynamic plant variable if the absolute difference is greater than a predetermined value. According to the present invention there is also provided a system for providing an operator display of dynamic plant operation data, the system being characterised by: means for providing a series of current operating plant variables; storage means for constantly storing the current operating plant variables; display means for displaying the dynamic plant data; and exception control means connected to the variables providing means, the display means and the storage means for comparing the value of data displayed on the display means with the current stored data in the storage means against a predetermined absolute value, the exception control means including a control module connected to the display means for displaying any of the stored data that exceeds the predetermined absolute value of the exception control means. A preferred embodiment of the present invention described hereinbelow can solve or at least alleviate the aforementioned problems associated with the prior art by providing a display system for updating dynamic data on a cathode ray tube display only when the absolute value of the difference between data on the cathode ray tube display and its current value exceeds a predetermined amount. In this manner, data related to all process variables is neither accessed from the data base memory nor transmitted to the operator display unless critical, thus minimizing system response time while updating the operator display with events or changes in plant status as they occur. The invention will now be further described, by way of illustrative and non-limiting example, with reference to the accompanying drawings, in which: Figure 1 is a block diagram of an operator display updating system embodying the present invention; and Figure 2 is a block diagram of an exception update module of the operator display updating system of Figure 1. Figure 1 shows an operator display update system 10 comprising a signal processing module 12, a data base memory module 14, an exception update module 16, and a display update processing module or subsystem 18. In operation, signal values from plant process sensors (not shown) are brought into the signal processing module 12 by commonly known techniques and components. Each signal value is filtered for noise, amplifled and converted to compatible engineering units in the signal processing module 12 by commonly known techniques. Processed signal values are communicated to the data base memory module 14 along link 15 for storage in a known manner. The signal processing module 12 also generates a signal at the end of each processing cycle and communicates it along connecting link 17 to the exception update module 16 by known techniques. Receipt of this signal by the module 16 activates the exception update module 16. With particular reference to Fig. 2, the exception update module 16 is shown as comprising control module 20, access modules 22 and 24, status check module 26, initialization module 28, calculate unit 30, check unit 32, communication facility 34, check module 36, and return unit 38. Signals from the signal processing module 12 of Fig. 1 as received by the control module 20 ofxthe exception update module 16 triggers its execution. Upon this execution of the control module 20, access module 22 accesses a list of the process variables on the operator display and their current value on display from sub-modules D2 and D4 respectively of. the display processor module 18 of Fig. 1 along line 19. The access module 24 next obtains new values for the display from the data base memory 14 along line 21 for each process variable in the list accessed via the access module 22 described above. Next, a check is made whether the exception update module 16 is in execution for the first time by the module 26. If it is in execution for the first time, then all display update band values, accessed by access module 24, are set to zero. If it is not the first time, the module 26 is bypassed and execution goes to module 30. The absolute value of the difference between the new value and the current value on display of a process variable is calculated in module 30, and checked whether it is greater. than the associated display update band in update module 32. If the absolute value is not greater than the display, then execution goes to the check facility module 36; otherwise, a message comprising the process variable identifier, its new value and indicator for detection of exception is formed and communicated to the display executive sub-module D1 of the display processor module 18 (shown in Fig. 1) by the communication facility 34 along line 19, and execution continues at the checking module 36. In the check module 36, a test is made of whether the last process variable in the list obtained via the access module 22 has been processed.¯ If it is not, then execution returns to calculate module 30 for exception update processing of the next process variable in list obtained via access module 24, otherwise execution is returned to exception module control module 20 by the return facility 38. Now returning to Fig. 1, after receiving process variable identifiers, its new value and indicator of exception update detection, display executive sub-module D1 of display processor 18 replaces the existing value in the sub-module D3 by the new value, and outputs it to CRT operator display via display update processor, D4, and CRT driver D5. It should be noted that sub-modules Dl, D2, D3, D4, and D5 of module 18 employ commonly lmown techniques and equipment.

Claims: CLAIMS 1. A method of providing an operator display of dynamic plant operation data on a cathode ray tube, the method being characterised by: obtaining a value of a displayed dynamic plant data variable from a display (18); obtaining a current value of the dynamic plant data variable from a current data storage memory (14); comparing the absolute difference between the value of the displayed dynamic plant variable and the current stored value of the dynamic plant variable; and displaying the currently stored dynamic plant variable if the absolute difference is greater than a predetermined value. 2. A method according to claim 1, including calculating the absolute difference between the value of a displayed second variable and a currently stored value thereof if the absolute difference between the first-mentioned displayed variable and its current value is less than a predetermined value. 3. A system for providing an operator display of dynamic plant operation data, the system being characterised by: means (12) for providing a series of current operating plant variables; storage means (14) for constantly storing the current operating plant variables; display means (18) for displaying the dynamic plant data; and exception control means (16) connected to the variables providing means (12), the display means (18) and the storage means (14) for comparing the value of data displayed on the display means with the current stored data in the storage means (14) against a predetermined absolute value, the exception control means (16) including a control module connected to the display means (18) for displaying any of the stored data that exceeds the predetermined absolute value of the exception control means.

Inventors: AGARWAL, SURESH C., JANECEK, EDWARD D., KEYES, MARION A., SCHOEFFLER, JAMES D., WILLEY, MICHAEL S.
Applicants: THE BABCOCK & WILCOX COMPANY
Application year: 1983
Main classification: G06F15
IPC codes: G06F3, E02D29, G05B23, E04F19, G06F17