METHOD AND SYSTEM FOR AUTOMATIC GRAPHIC DISPLAY MODIFICATION BASED ON CONTROL PROGRAM MODIFICATION

Abstract: A method and system is disclosed for automatically modifying a graphic display of a diagnostic work station after detecting a probable change to a control program of a coupled programmable control station. The diagnostic work station is programmed to graphically display a representation of the various components of an attached system of automated machinery, their relationship to one another and their state (i.e., ''on'' or ''off'').

Description: METHOD AND SYSTEM FOR AUTOMATIC GRAPHIC DISPLAY MODIFICATION BASED ON CONTROL PROGRAM MODIFICATION Technical Field This invention relates to methods and systems that monitor the operation of manufacturing devices and, particularly, to a method and system for automatically modifying the graphic display of a diagnostic work station upon detecting a change to the logic of the programmable control station being monitored. Background Art A substantial percentage of industrial manufacturing and production is accomplished through the use of automated machinery. This automated machinery is typically controlled by a programmable control station using a program implementing control logic required to perform specific tasks. Although the operation of such automated machinery requires little or no operator intervention, it is still useful to monitor the operation of such machinery to diagnose malfunctions, ensure proper maintenance and control quality. Typically, the operation of the programmable control station, and its coupled automated machinery, is monitored through the use of a diagnostic work station coupled to the programmable control station. In most instances, the diagnostic work station is programmed to display information concerning the status and operation of the coupled programmable control station and associated automated machinery. The display of the diagnostic work station informs operating personnel of fault conditions, device states, signal levels, switch settings and other information useful in diagnosing malfunctions and maintaining appropriate controls on the automated machinery. Often, information regarding the operation of the programmable control station and the automated machinery is presented to the operator of the diagnostic work station through a graphic display representing the logic of the programmable control station and/or the relationships between various elements of the monitored system. Although the use of a diagnostic work station to monitor an attached programmable control station has many advantages, a significant problem can arise when the control logic of the programmable control station is altered. If the programmable control station is placed in operation using modified control logic and the diagnostic work station monitoring the programmable control station is placed in operation using a monitor program which does not account for the modified control logic of the programmable control station, the information displayed by the diagnostic work station could be misleading and erroneous. The prior art has addressed this situation in two ways. FIGURE 1 is a flow chart illustrating a first prior art approach to this situation describing a method of manually modifying the program controlling the diagnostic work station to reflect the modified control logic of the programmable control station. The program controlling the diagnostic work station periodically updates the graphic display of the diagnostic work station to reflect the status of the attached programmable control station and automated machinery. Typically, an operator of the diagnostic work station visually checks the diagnostic work station's graphic display to detect the possibility of an error in the process performed by the programmable control station and the automated machinery. If no error is detected, no action is taken by the operator of the diagnostic work station and the process continues. If, however, the operator of the diagnostic work station detects an error, the operator must investigate whether the error is caused by an equipment failure or a modification of the control logic of the programmable control station. To determine the source of the error, the operator of the diagnostic work station, through inquiries made on the plant floor, must determine whether the control logic of the programmable control station has been modified. If the control logic of the programmable control station has been modified, the process must be shut down. If the control logic of the programmable control station has not been modified, the logic of the current program of the diagnostic work station must be compared to the logic of the prior program of the diagnostic work station, as indicated by a program listing kept on file. If the logic of the program controlling the diagnostic work station has been modified, it must be reviewed, analyzed and reprogrammed to accurately reflect the control logic of the programmable control station. If the logic of the program controlling the diagnostic work station has not been modified, either the responses to inquiries made on the plant floor were erroneous or there is an equipment failure. In either event, the process must be shut down. After shutting down the process, a listing of the current program of the programmable control station must be compared to a listing of the prior program of the programmable control station as indicated by a program listing kept on file. If it is determined that the programmable control station logic has not been modified, the operator of the diagnostic work station can reasonably assume that an equipment failure has caused the error. If it is determined that the logic of the programmable control station has been modified, the current logic of the programmable control station must be reviewed and the program of the diagnostic work station must be altered to reflect those changes in the control logic of the programmable control station in order to accurately monitor the programmable control station. After the diagnostic work station has been reprogrammed, the process may be restarted. FIGURE 2 is a flowchart illustrating the second prior art approach to this situation, describing the method disclosed by U.S.P.N. 4,670,834 of Byal et al. Byal et al. discloses a system and method for automatic diagnostic program modification based on control program modification. The program controlling the diagnostic work station periodically updates the graphic display of the diagnostic work station to reflect the status of the attached programmable control station and automated machinery. The diagnostic work station is attached to a central management information system which is used to detect whether the programmable control station is in run mode. If the programmable control station is in run mode, no action is taken and the process continues. If, however, the programmable control station is not in run mode, the central management information system uploads the current program controlling the programmable control station and compares this current program with a copy of the prior program controlling the programmable control station. The prior program controlling the programmable control station is retained on file by the central management information system. If the central management information system determines that the current program controlling the programmable control station is the same as the prior program controlling the programmable control station, no action is taken and the process continues. If, however, the current program controlling the programmable control station is different than the prior program controlling the programmable control station, the central management information system automatically analyzes the logic of the current program controlling the programmable control station. The central management information system then creates a new program to control the diagnostic work station based on the current program controlling the programmable control station. Finally, the central management information system downloads the new monitor program to the diagnostic work station, and the process is restarted. Although both of the prior art approaches present a solution to the problem of updating the monitor program of the diagnostic work station to reflect a change in the control program of the programmable control station, each has significant disadvantages. The manual approach illustrated by FIGURE 1 is particularly time-consuming and expensive. This method requires a number of individuals having highly specialized skills to work together to achieve an adequate solution to the problem. The high level of human intervention renders this solution inefficient and undesirable. • The automated approach illustrated by FIGURE 2, also lacks efficiency and economy. This method requires additional equipment, namely a central management information system, to process and analyze the changes in the control program of the programmable control station. In addition, each time the control program of the -programmable control station is modified, a new monitor program for the diagnostic work station must be created and downloaded to the diagnostic work station. «wτnm^τγ of the Invention The present invention described and disclosed herein comprises a method and system of automatically modifying the graphic display of a diagnostic work station upon detecting a change in the control program of a coupled programmable control station. An object of the present invention is to provide a method and system for automatically modifying the graphic display of a diagnostic work station upon detecting a change in the control program of a coupled programmable control station wherein the change in the control program of the programmable control station does not necessitate updating the monitor program of the diagnostic work station. Another object of the present invention is to provide a method and system for automatically modifying the graphic display of a diagnostic work station upon detecting a change in the control program of a coupled programmable control station wherein the method and system will operate within the diagnostic work station, eliminating the need for additional equipment. In carrying out the above objects and other objects of the present invention, a method is provided for automatically modifying the graphic display of a diagnostic work station upon detecting a change in the control program of a coupled programmable control station. The method includes the step of ascertaining whether the programmable control station is in run mode. The method also comprises the step of comparing the current control program with the prior control program upon detecting that the programmable control station is not in run mode. Upon detecting that the current control program is not identical to the prior control program, the method additionally includes the step of ■ analyzing the current control logic to determine the contents of a new graphics display representing the current control logic. The method further includes the step of utilizing the monitor program to cause the diagnostic work station to display the new graphics display. Finally, the diagnostic work station, using the monitor program, displays a modified graphics display representative of the current control logic of the current control program. Further in carrying out the above objects and other objects of the present invention, a system is also provided for carrying out the steps of the above described method. One important feature of the present invention is the ability to couple more than one programmable control station to a single diagnostic work station. In a system with this configuration, the monitor program permits a user of the diagnostic work station to select which coupled programmable control station will be monitored and represented via the graphic display by the monitor program. Another important feature of the present invention is the ability of the monitor program to update a graphic display representing the control logic of the programmable control station and the attached machinery at any time. A user may wish to update the graphic display upon starting a process regardless of whether a change to the control program has actually occurred. This simply configures the graphic display to correctly monitor the newly started process without requiring the creation of a monitor program from scratch. A final important feature of the present invention is the ability of the monitor program to prompt a user of the diagnostic work station upon detecting that a possible control program change has occurred. This allows the user to decide whether he or she wishes to cause the monitor program to update the graphic display. If the user of the diagnostic workstation knows that the control program has not been substantively changed, the user has the option of not causing the monitor program to update the graphic display. The objects, features and advantages of the present invention are readily apparent from the following detailed description of the best mode for carrying out the invention when taken in connection with the accompanying drawings. Brief Description of the Drawings FIGURE 1 is a flow chart illustrating one prior art method of modifying the graphic display of the diagnostic work station to reflect the current control logic of the programmable control station; FIGURE 2 is a flow chart illustrating a second prior art method of modifying the graphic display of the diagnostic work station to reflect the current control logic of the programmable control station; FIGURE 3 is a flow chart illustrating the method of modifying the graphic display of the diagnostic work station to reflect the current control logic of the coupled programmable control station in accordance with the present invention; FIGURE 4 is a block diagram illustrating the hardware required for the system of modifying the graphic display the diagnostic work station to reflect the current control logic of the coupled programmable control station in accordance with the present invention; FIGURE 5 is a block diagram illustrating a specific configuration of automated machinery prior to a change in the control logic of the coupled programmable logic controller; and FIGURE 6 is a block diagram illustrating a specific configuration of automated machinery after a change in the control logic of the coupled programmable logic controller. Detailed Description of the Drawing Figures FIGURE 3 illustrates the method of the present invention. At block 300, the monitor program at the diagnostic work station detects whether the programmable control station is in run-mode. If the programmable control station is in run-mode, the monitor program passes control from block 302 to block 312 and continues normal operations by updating the graphic display of the work station to indicate the status of the automated machinery. If the programmable control station has been taken out of run-mode, the monitor program must compare the current control program of the programmable control station with a file copy of the prior control program of the programmable control station as described by block 304. As shown by block 306, if the monitor program determines that no modification of the control program has occurred, the monitor program continues normal operations as described by block 312. If the control program of the programmable control station has been modified, block 308 is performed and the monitor program automatically analyzes the logic of the current control program of the programmable control station. As described by block 310, the monitor program automatically modifies the graphic display of the diagnostic work station to represent the logic of the current control program of the programmable control station. Finally, the monitor program performs the step of block 312 and resumes normal operations by updating the graphic display of the work station to indicate the status of the automated machinery. FIGURE 4 illustrates the hardware needed to monitor and perform typical automated manufacturing operations. In order to simplify the description of the present invention and to provide a concise description of the best mode for practicing this invention, it will be described in connection with a specific example. It should be understood at the outset, however, that this invention can be implemented with different computer equipment and implemented in different software languages. In FIGURE 4, an IBM or compatible personal computer 10, operating as a diagnostic work station and having a monitor program 12 is connected via a communications link 14 to a programmable logic controller 16. The programmable logic controller 16, operating as a programmable control station and having a control program 18, is connected via a communications link 20 to automated machinery 22. The automated machinery 22 can take many forms and perform many functions. For this example, assume that the automated machinery 22 takes the form of a tank-fill system which has been implemented in a plant and that the personal computer 10 is used to monitor the status of the pump in this system. FIGURE 5 illustrates the individual components of the automated machinery for this specific example. The pump 20 is used to pump fluid 22 into a tank 24. The pump 20 is connected to the programmable logic controller 16 via an output line 26. The pump 20 is also connected to the programmable logic controller 16 via first input 28. In addition, the programmable logic controller 16 receives an input from a full switch 30 via an input 32. Output 26, input 28 and input 32 communicate the state of a device as either "on" or "off". In this example, an operator will turn "on" a pump switch 34 which, in turn, turns "on" the pump 20. When the fluid 22 triggers the full switch 30, the pump 20 will be turned "off". In this example, the control program 18 has a very simple function. As long as the state of input 28 is "on", the control program 18 continuously tests the state of the full switch 30. Once the control program 18 determines that the state of the full switch 30 is "on", indicating the tank 24 is full of fluid 22, the control program 18 directs the programmable logic controller 16 to change the state of output 26 from "on" to "off" causing the pump 20 to stop filling the tank 24. Throughout this process the monitor program 12 graphically displays on the personal computer 10 a representation of the various components of the automated machinery 22, their relationship to one another and their state (i.e. "on" or "off"). In this example, the monitor program 12 allows the operator of the personal computer 10 to verify the correct operation of the automated machinery 22. For instance, if the graphic display shows that the full switch 30 is "on" and the pump 20 has not gone "off", the operator of the personal computer must take action to determine and correct the source of the problem. In this case, it is possible that either the full switch 30 or the pump 20 has failed. Continuing with the example, assume that changes are implemented in the automated machinery, as reflected in FIGURE 6. FIGURE 6 illustrates the same configuration of machinery as FIGURE 5 with the addition of a float switch 34 which is connected to the programmable logic controller 16 via input 36. The float switch 34 determines a low level of fluid 22 in the tank 24. The control program 18 is altered to set the state of output 26 to "on", when input 28 is "off", but input 36 is "on". This addition functions to turn the pump "on" when the fluid 22 reaches a sufficiently low level so as to turn float switch 34 on. In order to appropriately alter the control program 18, the process must be temporarily suspended by taking the programmable logic controller 16 out of run mode. As soon as the programmable logic controller 16 has been taken out of run mode, the operator of the personal computer 10 is informed that there may be changes to the control program 18 of the programmable logic controller 16. As soon as the pump process is restarted, the operator of the personal computer 10 instructs the monitor program 12 to analyze the current logic of the control program 18. The monitor program 12 then causes the personal computer 10 to display an updated graphic representation of the process, including the recently added float switch 34. This graphic display is updated automatically, requiring no research of the process logic of the control program 18 and no research into the wiring of either the programmable logical controller 16 or the automated machinery 22. While a preferred embodiment of the subject invention has been shown and described in detail, those skilled in this art will recognize various alternative designs and embodiments for practicing the present invention as defined by the following claims.

Claims: I claim: 1. In a machine information system which includes at least one diagnostic work station coupled to at least one programmable control station, the programmable control station having current control logic expressed by a current control program for operating associated plant machinery, the programmable control station having a run mode, the diagnostic work station having prior control logic for the programmable control station expressed by a prior control program, the diagnostic work station monitoring operation at the programmable control station, a method for automatically modifying a current graphic display of diagnostic information, the current graphic display being produced by a monitor program at the diagnostic work station, the current graphic display representing the current control logic expressed by the current control program, the method comprising the steps of: (a) detecting at the diagnostic work station whether the programmable control station is in said run mode, (b) proceeding to step (g) upon detecting that the programmable control station is in the run mode, (c) upon detecting that the programmable control station is not in the run mode, comparing the current control program with the prior control program, (d) proceeding to step (g) upon detecting that the current control program is identical to the prior control program. (e) upon detecting that the current control program is not identical to the prior control program, analyzing the current control logic to determine the contents of a new graphics display representing the current control logic, (f) utilizing the monitor program to cause the diagnostic work station to display the new graphics display, and (g) utilizing the monitor program to cause the diagnostic work station to display the current control logic of the current control program. 2. The method as claimed in claim 1 wherein the detecting of step (a) could occur upon attaching the diagnostic work station to the programmable control station. 3. The method as claimed in claim 1 or 2 wherein upon detecting that the current control program is not identical to the prior control program in step (e) , the method further including the step of prompting a user of the diagnostic work station for authorization to proceed with analyzing the current control logic to determine the contents of a new graphics display representing the current control logic. 4. The method as claimed in claim 1 wherein the method further includes a step to be performed before step (a) of prompting the user to select which programmable control station to monitor in a system including a diagnostic work station coupled to more than one programmable control station. 5. In a machine information system which includes at least one diagnostic work station having means for graphically displaying data coupled to at least one programmable control station, the programmable control station having current control logic expressed by a current control program for operating associated plant machinery, the programmable control station having a run mode, the diagnostic work station having prior control logic for the programmable control station expressed by a prior control program, the diagnostic work station monitoring operation at the coupled programmable control station, a system for automatically modifying a current graphic display of diagnostic information, the current graphic display being produced by a monitor program at the diagnostic work station, the current graphic display representing the current control logic expressed by the current control program, the system comprising: detecting means for detecting that the programmable control station is in the run mode; means for comparing the current control program with the prior control program to determine whether the current control program is identical to the prior control program; means for analyzing the current control logic to determine the contents of a new graphics display representing the current control logic; means for causing the diagnostic work station to display the new graphics display; and eans for causing the diagnostic work station to display the current control logic of the current control program. 6. The system as claimed in claim 5 wherein the system further includes a means for prompting a user of the diagnostic work station for authorization. 7. The system as claimed in claim 5 or claim 6 wherein the system includes more than one programmable control station and further includes a means for prompting a user of the diagnostic work station to select a programmable control station to monitor.

Inventors: RHOADS MICHAEL N, RHOADS, MICHAEL, N.
Applicants: ELECTRONIC DATA SYST CORP, ELECTRONIC DATA SYSTEMS CORPORATION
Application year: 1993
Main classification: G05B19
IPC codes: G05B19, G05B23