Abstract:
A system for, and method of, disseminating a functional block to a redundant controller for a real-time process control system and a real-time process control system incorporating the system or the method. In one embodiment, the system includes: (1) a dynamically linkable library object associable with the functional block and (2) a shared memory, associated with at least two nodes of the redundant controller, that receives the dynamically linkable library object and the functional block and provides concurrent access thereto by both the at least two nodes to ensure consistent memory images therefore without requiring one of the at least two nodes to be taken off-line.

Description:
TECHNICAL FIELD OF THE INVENTION 
     The present invention is directed, in general, to real-time process control systems and, more specifically, to a system and method for disseminating functional blocks to an on-line redundant controller of a real-time process control system. 
     BACKGROUND OF THE INVENTION 
     Real-time process control systems were first implemented within a single computer system. As the need to monitor and control more physical devices increased, the complexity and size of the process control systems also increased. With this increased complexity and size came the problem of computer system failures. Computer system failures not only caused downtime, but also included the loss of monitoring and collecting data for that area of the real-time process control system. designated the primary computer at a given time and the other computer is designated the backup computer. If the primary computer failed to operate properly, the backup computer took over the functions of the primary computer. 
     The primary computer transferred the real-time process control data to the backup computer at regular intervals. This kept the backup computer up-to-date in case the backup computer was required to assume the status of primary computer. However, not all information could be transferred while both computers were on-line. 
     Information that could not be transferred on-line included control applications. Control applications consisted of a static set of control algorithms (“static function blocks”) and/or a dynamic set of control algorithms (“dynamic function blocks”) associated with the controller. Static function blocks are associated with the control routines and control definitions contained within the personality of the controller. Dynamic function blocks are associated with the control routines and control definitions contained within the dynamically linked library objects. The static and dynamic function blocks also included information that was related to the control devices associated with the real-time process control system. 
     The dynamically linked. library objects included process control routines and control definitions used to control devices attached to the real-time process control system. In other types of operating systems, the dynamically linked library object are called shared libraries. 
     To modify or add to the existing control routines and control definitions on both computers required several steps. First, the backup computer was taken off-line. The personality and/or dynamically linked library objects were updated on the off-line computer. Next, the off-line computer was brought on-line and was designated the primary computer. Then, the other computer was taken off-line. The personality and/or the dynamically linked library objects were updated on the off-line computer. Then, the computer was brought back on-line as the backup computer. 
     However, this procedure left the redundant computer system vulnerable. If the primary computer failed while the other computer was off-line, the real-time process control data would be lost and the devices could not be controlled until the other computer was brought back on-line. This seriously compromised the integrity and operation of the real-time process control system as a whole. 
     Therefore, what is needed in the art is an improved way to transfer information, such as dynamically linked library objects and static and dynamic functional blocks, between redundant computers while both computers are on-line. 
     SUMMARY OF THE INVENTION 
     To address the above-discussed deficiencies of the prior art, the present invention provides a system for, and method of, disseminating a functional block to a redundant controller for a real-time process control system and a real-time process control system incorporating the system or the method. In one embodiment, the system includes: (1) a dynamically linkable library (perhaps DLL) object associable with the functional block and (2) a shared memory, associated with at least two nodes of the redundant controller, that receives the dynamically linkable library object and the functional block and provides concurrent access thereto by both the at least two nodes to ensure consistent memory images therefore without requiring one of the at least two nodes to be taken off-line. 
     The present invention therefore introduces the broad concept of employing dynamically linkable library objects in combination with shared memory to provide a functional block and dynamically linkable library objects to at least two nodes of a redundant controller without requiring any of the at least two nodes to be taken off-line. Thus, the present invention allows new and/or modified control routines and definitions to be accessible or transferred between at least two nodes of a redundant controller without requiring any of the at least two nodes to be taken off-line. 
     In one embodiment of the present invention, the shared memory is a logical shared memory. Alternatively, the shared memory may be a physical shared memory. In an embodiment to be illustrated and described, the system further includes a controller redundancy synchronization mechanism (CRSM), coupled to the shared memory, that governs consistency between the memory images. The CRSM ensures that the memory of one node matches the memory of the other node, at least to the extent of the shared memory area. 
     In one embodiment of the present invention, the functional block is a part of a functional class. Those skilled in the pertinent art are familiar with the concept of objects and object classes. The present invention advantageously operates within the is environment of object-oriented programming to lend flexibility to the architecture of control software. 
     In one embodiment of the present invention, one of the at least two nodes is designated a primary node at a given point in time. Any remaining nodes are designated secondary nodes. Of course, the designations may change over time. 
     In one embodiment of the present invention, the dynamically linkable library object is registrable with respect to an operating system governing operation of the at least two nodes. Those skilled in the pertinent art are familiar with the process and objectives of registration. 
     In one embodiment of the present invention, the dynamically linkable library object is synchronized at a selected one of predetermined points-in-execution. The present invention preferably ensures consistency between multiple memory images by ensuring that the memory images at predesignated points-in execution are identical. Of course, consistency can be more rigorous, requiring identity at all shared memory locations. 
     In one embodiment of the present invention, the functional block is a type selected from the group consisting of (1) a static functional block, and (2) a dynamic functional block. In other embodiments of the present invention, the functional block can be other types that allow additional information associated with a real-time process control system to be accessible between the nodes of a redundant controller. 
     In one embodiment of the present invention, the functional block is uninstallable on each of the at least two nodes while the redundant controller is on-line. The present invention allows functional blocks that are unused, or for some other reason, to be uninstalled on each of the redundant controller&#39;s nodes thus saving space and execution time on the redundant controller&#39;s node. 
     The foregoing has outlined, rather broadly, preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 illustrates a block diagram of a real-time process control system that forms one environment within which the present invention can operate; 
     FIG. 2 illustrates a block diagram of the redundant controller of FIG. 1 constructed according to the principles of the present invention. 
     FIG. 3 illustrates a block diagram of a Control Component Library associable with function blocks used by the redundant controller of FIG. 2 constructed according to the principles of the present invention; and 
     FIG. 4 illustrates a flow diagram of a method of the primary node synchronizing the CCL and the associated function blocks of FIG. 3 to the backup node of the redundant controller of FIG.  2 . 
     FIG. 5 illustrates a flow diagram of a method of the backup node of the redundant controller of FIG. 2 receiving synchronization data from the primary node. 
    
    
     DETAILED DESCRIPTION 
     Referring initially to FIG. 1, illustrated is a block diagram of a real-time process control system, generally designated  100 , that forms one environment within which the present invention can operate. The real-time process control system  100  comprises one or more network/bus  110  that interconnects a server  102 , an operator interface  104 , a field unit  106  and a redundant controller  120 . In the illustrated embodiment of the present invention, the real-time process control system  100  may comprise any number of servers  102 , operator interfaces  104 , field units  106  and redundant controllers  120 . 
     The network/bus  110  comprises an industry standard network and industry standard network protocols. The industry standard network protocols, in one embodiment of the present invention, are ETHERNET® and Transmission Control Protocol/Internet Protocol (“TCP/IP”). In an alternate embodiment of the present invention, the network/bus  110  comprises proprietary network and proprietary network protocols. In a third embodiment of the present invention, the network/bus  110  may comprise a combination of industry standard and proprietary networks and network protocols. Wireless communications and fiber optic media may also be used for all or part of the network communications. 
     The server  102  comprises software programs that monitor, process information, and control the physical devices within the real-time process control system  100 . The software programs comprise a requesting program “client,” and a resource program “supplier” and other miscellaneous programs. The client program sends requests to supplier programs to perform specific functions. The supplier programs receive requests and perform the appropriate functions based upon the type of requests sent. The client programs and supplier programs communicate over the network/bus  110  or internally within the server  102 . 
     The operator interface  104  comprises a computer and a display. The operator interface  104  displays information concerning the current state of the system  100 . The operator interface  104  also accepts operator input to perform functions such as controlling a physical device or requesting other information to be displayed on the operator interface&#39;s  104  display. The operator interface  104  may comprise both client programs and supplier programs. The operator interface  104  communicates to other programs over the network/bus  110 . 
     The field unit  106  comprises supplier programs that perform tasks related to the physical devices that make up the real-time process control system  100 . In one embodiment of the present invention, the field unit&#39;s supplier programs collect status information, process data and control the physical devices. In other embodiments, the field unit  106  may perform more or fewer functions than described above. The field unit  106  responds to client&#39;s requests over the network/bus  110 . 
     The redundant controller  120  comprises a primary node  122  and a backup node  124 . In the redundant controller  120 , if the primary node  122  fails to operate correctly, the backup node  124  assumes the role of the primary node and takes over the primary&#39;s nodes functions. In an alternate embodiment, the redundant controller  120  may comprise more than two nodes. 
     Each of the redundant controller&#39;s nodes comprise programs that perform specific tasks such as collecting status information, processing data and controlling physical devices. Both the primary node  122  and the backup node  124  respond to client&#39;s requests over the network/bus  110 . Also, the primary node  122  is coupled to the backup node  124  via a redundancy link through which the nodes share information. 
     Referring now to FIG. 2, illustrated is a block diagram of the redundant controller  120  of FIG. 1 constructed according to the principles of the present invention. In one embodiment of the present invention, the redundant controller  120  has at least two nodes, the primary node  122  and the backup node  124 . The primary node  122  and the backup node  124  are coupled to the shared memory  210 . In the illustrated embodiment of the present invention, the shared memory  210  is logical shared memory and is located in each node of the redundant controller  120 . Even though the shared memory is shown located in each node, the concept of using memory that is shared between each of the nodes of the redundant controller  120  is not limited by the location or the number of nodes illustrated in FIG.  2 . In an alternate embodiment, the shared memory  210  is physical shared memory. 
     Coupled to the shared memory  210  is a controller redundancy synchronization mechanism (“CRSM”)  220 . The CRSM  220  governs the consistency between the memory images in the primary node  122  and the backup node  124  and is conventional. The CRSM  220  also ensures that the memory of one node matches the memory of the other node, at least to the extent of the shared memory area. In ensuring the consistency of memory images, the CRSM  220  will synchronize the memory images at predetermined point-in-execution. A “predetermined point-in-execution” is a point common to both the primary node&#39;s and backup node&#39;s execution where synchronization of memory can be performed. The predetermined point-in-execution points ensure that each node is using the same information prior to performing certain functions. 
     One skilled in the art should know that the present invention is not limited to a redundant controller with only two nodes. In another embodiment of the present invention, the redundant controller may have more than two nodes and the shared memory is coupled between all the nodes. Also, other embodiments of the present invention may have more capabilities than described above. 
     Referring now to FIG. 3, illustrated is a block diagram of a Control Component Library (“CCL”)  310  associable with function blocks  320  used by the redundant controller of FIG. 2 constructed according to the principles of the present invention. CCLs are specialized Dynamically Linked Library (“DLL”) objects for control functions used within the real-time process control system  100 . CCLs are loaded into shared memory  210  on the primary controller  122  and transferred to the shared memory  210  on the backup controller  124  by the CRSM  220 . CCLs are also registrable and unregistrable with respect to the operating systems governing the operation of the redundant controller  120 . Those skilled in the pertinent art are familiar with the concept and use of DLL objects, registration of DLLs and control functions. 
     Associable with the CCL  310  are function blocks  320 . The function blocks  320  comprise information concerning processing of sensors, controllable devices or other components within the real-time process control system  100 . The function blocks  320  are instantiated into shared memory  210  and also contain and/or reference pointers into a CCL object&#39;s control functions. In one embodiment of the present invention, the function blocks  320  are objects that are part of a functional class. In another embodiment of the present invention, each of the instantiated function blocks  320  can be either a static or a dynamic function block. Those skilled in the pertinent art are familiar with the concept of objects, object classes and function blocks and their use in real-time process control system. 
     The redundant controller&#39;s primary node  122  and backup node  124  both use and maintain the CCL  310  and the associable function blocks  320 . In an alternate embodiment of the present invention, the primary node  122  uses the CCL  310  and the backup node  124  does not use the CCL  310  until the backup node  124  transitions into the primary role. 
     The CRSM  220  synchronizes the CCL  310  and the associable function blocks  320  between the primary node  122  and the backup node  124 . In one embodiment of the present invention, the instantiated functional blocks  320  and the CCL  310  must reside in the same logical shared memory location on both the primary node  122  and the backup node  124  since the functional blocks  320  contain and/or reference pointers into the CCL  310 . In a second embodiment of the present invention, each of instantiated function blocks  320  can be located anywhere in shared memory. 
     In one embodiment of the present invention, the CCL  310  can be uninstalled on the primary node  122  and the backup node  124  while they are on-line. A CCL may be uninstalled when the CCL is no longer referenced by a function block. In other embodiments of the present invention, other criteria for determining when to uninstall an associable function block may be used. In a second embodiment of the present invention, the function blocks  320  can be uninstalled on the primary node  122  and the backup node  124  while they are on-line. 
     One skilled in the art should know that the present invention is not limited to the three function blocks and the one CCL described. In another embodiment of the present invention, the there can be more than three or fewer function blocks associable with a CCL. In a third embodiment of the present invention, the function blocks may be contained within the CCL. 
     Referring now to FIG. 4, illustrated is a flow diagram of a method of the primary node  122  synchronizing the CCL and the associated function blocks of FIG. 3 to the backup node  124  of the redundant controller of FIG.  2 . In FIG. 4, the CRSM  220  first performs initialization in a step  402 . 
     After initialization, the CRSM  220  examines the execution of the primary node  122  for a point-in-execution synchronization point in a decisional step  404 . If the primary node  122  has not reached a point-in-execution synchronization point, the CRSM  220  returns to determine if a point-in-execution synchronization point has been reached in the decisional step  404 . 
     If the CRSM  220  determines that a point-in-execution synchronization point has been reached by the primary node  122 , the CRSM  220  retrieves the CCLs  310  and the associable function blocks  320  that are associated with this particular point-in-execution synchronization point from shared memory in a step  406 . 
     Next, the CRSM  220  transfers the CCLs  310  and the associable function blocks  320  from the primary node  122  to the backup node  124  in a step  408 . Once the CRSM  220  has transferred the CCLs  310  and the associable function blocks  320  to the backup node  124 , the CRSM  220  then returns to examine the primary node  122  execution for the next point-in-execution synchronization point in the decisional step  404 . 
     In another embodiment of the present invention, the CRSM  220  also transfers information from the primary node  122  to the backup node  124  that allows unused or not-in-use CCLs  310  to be uninstalled on the backup node  124 . In a third embodiment of the present invention, the CRSM  220  transfers also transfers information that allows the CCLs  310  to be uninstalled on the backup node  124  based upon predetermined criteria. 
     Referring now to FIG. 5, illustrated is a flow diagram of a method of the backup node  124  of the redundant controller of FIG.  2  receiving synchronization data from the primary node  122 . In FIG. 5, the CRSM  220  first performs initialization in a step  502 . 
     After initialization, the CRSM  220  examines the execution of the backup node  124  for a point-in-execution synchronization point in a decisional step  504 . If the backup node  124  has not reached a point-in-execution synchronization point, the CRSM  220  returns to determine if a point-in-execution synchronization point has been reached in the decisional step  504 . 
     If the CRSM  220  determines that a point-in-execution synchronization point has been reached by the backup node  124 , the CRSM  220  receives the synchronization data from the primary node  122  in a step  506 . In one embodiment of the present invention, the synchronization data comprises the CCLs  310  and the associable function blocks  320 . In another embodiment of the present invention, the synchronization data can comprise other information in addition to the CCLs  310  and the associable function blocks  320 . 
     Next, the CRSM  220  updates the backup node&#39;s shared memory with the synchronization data in a step  508 . The update process may include registering the transferred CCLs  310  and the associable function blocks  320  with the operating system if needed. The update processes may also include instantiating the function blocks  320  in shared memory. In another embodiment of the present invention, the backup node  124  also saves the synchronization data to a local storage device associated with the backup node  124 . Once the backup node  124  has received the synchronization data, the CRSM  220  then returns to examine the backup node  124  execution for the next point-in-execution synchronization point in the decisional step  504 . 
     In another embodiment of the present invention, the backup node  124  receives information from the primary node  122  to uninstall one or more CCLs  310 . Once this type of information is received, the CRSM  220  uninstalls the specified associable function of blocks  320  on the backup node  124 . In a third embodiment of the present invention, the backup node  124  receives and processes uninstall CCLs  310  commands. 
     One skilled in the art should know that the present invention is not limited to transferring information from the primary node to the backup node. In another embodiment of the present invention, the synchronization of node information can occur in both directions. In a second embodiment of the present invention, any one of the redundant controller&#39;s nodes may perform the synchronization of information between the nodes. Also, the present invention is not limited to only synchronizing CCLs and function blocks between nodes. Other embodiments of the present invention may have additional or fewer steps than described above in FIG.  4  and FIG.  5 . 
     Although the present invention has been described in detail, those skilled in the art should understand that they can make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.