Patent Publication Number: US-8972037-B2

Title: Method and system for monitoring batch product manufacturing

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application is related to and claims priority to the provisional U.S. patent application entitled, “METHOD AND SYSTEM FOR MONITORING BATCH PRODUCT MANUFACTURING”, Ser. No. 60/533,498, filing date, Dec. 31, 2003, the disclosure of which is incorporated herein by reference, in its entirety. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to manufacturing processes, and more particularly to monitoring batch manufacturing. 
     2. Background 
     Manufacturing of batch (or bulk) products is common today. Some products within the batch product category are milk, juice, oil, cosmetics, pharmaceuticals and other similar products. The term “batch” means non-discrete. A car in this sense is a discrete product, while milk during manufacturing/processing is a batch product. 
     Monitoring batch product manufacturing is complex and the need to monitor batch processing is compelling today. It is important to have the ability to trace batch products to specific raw material sources and manufacturing units. This is particularly critical if a particular batch of product (for example, milk or any other product) has been contaminated by a terrorist organization. This requires the manufacturing plant to act immediately and with accuracy so that contaminated product can be re-called quickly and efficiently with minimum waste to the businesses that are engaged in batch product manufacturing. Failure to perform this can result in health hazards and/or waste. 
     Conventional batch product manufacturing plants and techniques do not provide a system and/or methodology to track batch products so that various lots can be tracked. Most batch manufacturing plants can be modeled after the ISA S88.01 industry standard (referred to herein as the S88 standard), published by The International Society of Measurement &amp; Control (ISA) and incorporated herein by reference in its entirety. S88 defines a model and methodology for manufacturing plants. A manufacturing unit in a manufacturing plant is a single logical device and a S88 phase is an activity that is performed on a particular unit in a manufacturing process. 
     An example of a prior art system  100  is provided in  FIG. 1A . System  100  has a receiving bay  101  that is used to receive bulk raw products. For example, in a milk bottling/processing plant, the receiving bay will receive raw milk from various farms/trucks. Various trucks from different farms unload milk into bay  101  and the milk is commingled. From bay  101 , raw milk is transferred to a storage unit  102  (may also be referred to “raw silo”). More than one storage unit  102  may be used to store the raw milk. 
     Milk from various storage units  102  is sent to separator(s)  103 . Thereafter, skimmed milk  104  is sent to pasteurizing unit(s)  107  for pasteurizing the milk. Raw cream  105  is sent to cream storage unit(s)  106 . Raw cream is also sent from cream storage unit(s)  106  to pasteurizing unit(s)  107 . Pasteurized milk is then transferred to storage unit(s)  108  and then moved to filing stations  109 . 
     Currently, programmable logic controllers (“PLCs”) are used in the various units described above to collect data. An example of one such PLC is 1756 ControlLogix™ from RockWell Automation™. Typically, these PLCs collect data based on time intervals. The data is captured by an OPC server, which is an industry standard for polling data from PLCs and is incorporated herein by reference in its entirety. An example of this architecture is shown in  FIG. 3A  and is discussed below. 
     If milk gets contaminated and has to be recalled, system  100  cannot trace a particular lot to a defined source. System  100 , when used to recall product will be inaccurate and potentially result in waste. 
     Conventional systems have drawbacks, including the following: 
     Current data collection is performed with a graphical user interface (“GUI”). Data collection schedules are often hard coded and are not flexible. Data is collected based on timestamps at pre-defined intervals. Often correlating data to real events occurs after the fact, which affects the accuracy of the analysis. Therefore, there is a need for a system/methodology that allows efficient and accurate correlation between collected data and real time events in manufacturing plants. 
     Typically, data is collected by PLCs and analyzed by application programs. The collected data has two states (or attributes), for example, data is either known or unknown to the application. When data is being polled from a PLC, a specific value can trigger an event/process, for example, storing information in a database. The process can be triggered multiple times under certain conditions, for example: 
     A data value that is being polled for the value of 1 is initially 0. 
     When this value becomes 1, it triggers a process. 
     The data value becomes unknown due to a problem, for example, a communication problem with the PLC. 
     Data value becomes known again after the problem is fixed and is still 1. 
     Every time this happens, the process is triggered incorrectly. 
     Therefore, there is a need for defining data states such that processes are not triggered incorrectly resulting in waste and inefficiency. 
     Another drawback with current process monitoring techniques is that PLCs are designed and sold by plural manufacturers. This requires the PLC data collection system to customize OPC servers (or any other interface) for every make and model.  FIG. 3A  shows an example of this architecture. PLC 1  and PLC 2  are coupled to OPC server  1 , PLC  3  and PLC 4  are coupled to OPC server  2  and PLC 5  and PLC 6  are coupled to OPC server  3 . Application programs  1 ,  2  and  3  are coupled to OPC servers  1 ,  2  and  3  to analyze and parse the PLC collected data. This system becomes very tedious and expensive in a manufacturing plant that uses PLCs from different vendors. Therefore there is a need to develop a system that is flexible and efficient in handling PLC data from plural vendors. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present invention, a system for monitoring product through a batch manufacturing plant is provided. The system includes, a parallel flow mode when product flows concurrently from at least two units to a single unit; and a serial flow mode where product flows from one unit to another at a given time, wherein the batch manufacturing plant is modeled based on the parallel and serial flow modes. A lot association is built based on product flow and a parent/child record is created for lot association. 
     The system also includes a data collection system that collects phase information for every unit and a procedure identifier is used to create a batch identifier, where a batch identifier is associated with each lot on each unit through which product is flowing to and/or from at a given time. 
     In another aspect of the present invention, a method for monitoring batch product manufacturing is provided. The method includes, developing lot association(s) between different phases and units by using a procedure identifier; and creating a batch based on the procedure identifier, where a batch is associated with each lot for each unit through which product flows at a given time. 
     The method also includes, performing trace filtering and/or bulk filtering for a lot of interest. Data is collected from beginning to end of a phase and a parent/child relationship is created for each lot association. If a child has a batch in common with a parent, the child is included in a lot genealogy of the parent. Also, trace genealogy and/or bulk genealogy is used for developing overall lot genealogy. 
     In yet another aspect, a method for monitoring batch manufacturing process is provided. The method includes, using a parallel data flow model for tracking process parameters, where during the parallel data flow product flows from a single unit to other units at a given time; and using a serial data flow model for tracking process parameters, where during the serial data flow, product flows from one unit to another at a given time. 
     The method also includes creating a lot association between different phases and unit by using a procedure identifier; and building a parent/child relationship for each lot association. A lot&#39;s genealogy is developed based on batches that are created using a procedure identifier. 
     In yet another aspect, a system for collecting data in a batch product manufacturing plant is provided. The system includes, a virtual programmable logic controller interface that can collect data from disparate sources and provide a common interface for plural programmable logic controllers (“PLC”). Data is collected from PLCs based on pre-defined rules. The system also includes a phase module that keeps track of plural phases in plural units; a trending module that can collect trending data for various process parameters; and a service monitor module that provides alerts based on certain events. 
     In yet another aspect, programmable logic controller data collection states are provided. The PLC states include a first state where data is known and was previously unknown; a second state where data is known and was previously unknown; and a third state where data is unknown. 
     This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiments thereof, in connection with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing features and other features of the present invention will now be described with reference to the drawings of a preferred embodiment. In the drawings, the same components have the same reference numerals. The illustrated embodiment is intended to illustrate, but not to limit the invention. The drawings include the following Figures: 
         FIG. 1A  shows a prior art system for batch product manufacturing; 
         FIG. 1B  shows a block diagram of a computing system that can implement the various adaptive aspects of the present invention; 
         FIG. 1C  shows the internal architecture of the computing system in  FIG. 1B ; 
         FIG. 1D  shows a parallel and serial product flow model, according to one aspect of the present invention; 
         FIGS. 2A-2B  (referred to herein as  FIG. 2 ) show a block diagram of a batch manufacturing plant, according to one aspect of the present invention; 
         FIG. 3A  shows a block diagram of a prior art system using OPC servers; 
         FIG. 3B  shows a block diagram of a system using a Virtual PLC module, according to one aspect of the present invention; 
         FIG. 3C  shows a topology of the Internet that can be used to implement the process, according to one aspect of the present invention; 
         FIG. 4A  shows a process flow diagram for determining Lot Genealogy, according to one aspect of the present invention; 
         FIG. 4B  shows an example of Lot association, according to one aspect of the present invention; 
         FIG. 4C  shows an example of reducing Lot Association, according to one aspect of the present invention; 
         FIG. 5  shows a block diagram of a system that is used to monitor batch product manufacturing, according to one aspect of the present invention; 
         FIG. 6  is a conceptual module used for the system in  FIG. 5 , according to one aspect of the present invention; and 
         FIG. 7  is a tri-state state diagram for PLC data, according to one aspect of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Definitions: The following definitions are provided as they are typically (but not exclusively) used in the batch product manufacturing environment, implementing the various adaptive aspects of the present invention: 
     “Batch”: Product that flows through one or more units. 
     “Bulk Genealogy”: Lot genealogy where only bulk commingling of product occurs. 
     “CIP”: Clean in place, the abbreviation denotes that Units are cleaned. 
     “Flow Model”: A logical model for product flow within a manufacturing plant. 
     “Full Wash CIP”: A CIP process approved by the Food and Drug Administration for cleaning manufacturing equipment and is designed to remove all residual product and contaminants. This may be used to denote the beginning of a Lot. 
     “HTST”: A “high temperature short time” equipment that is used for pasteurizing milk. 
     “LGTP”: Lot Genealogy and Traceability Process. 
     “Lot”: More than one batch between Lot Generating Event(s) and associated with a manufacturing Unit. 
     “Lot Associations”: Association between Units when product flows from one Unit to another Unit. 
     “Lot Generating Event”: An event that signifies lack of product (including trace amounts) in a Unit, for example, a Full Wash CIP. 
     “Lot Genealogy”: All lots which have contributed to a LOI and all Lots to which an LOI has contributed to are a part of the Lot Genealogy. 
     “Lot of Interest” (“LOI”): This is the origin of a Lot Genealogy. 
     “Lot Lifetime”: The start and end time for a Lot. The start time is the time when the first product flows since a last Lot Generating Event and the end time is the time of the last product flow before the next Lot Generating Event. 
     “OPC” Server: OPC Sever is an industry standard interface to a server program for polling data from a PLC. 
     “Procedure Id”: A phase identifier that PLC code uses to inform a Data Collection System about the phases, which are on in a particular Unit at a given time 
     “PLC”: Programmable Logic controller, used to control and monitor manufacturing processes and equipment. 
     “Trace Genealogy”: Lot Genealogy where small trace elements co-mingle with the main product. 
     “S88”: Industry Standard for modeling batch manufacturing process. 
     “Unit”: A single device used in a manufacturing plant, for example, a storage tank, a pasteurizer and others. 
     “XML”: Extended Markup Language standard used for describing hierarchical tree structures and incorporated herein by reference in its entirety. 
     Flow Model: 
     In one embodiment of the present invention, a batch flow model is used for monitoring and tracking product through a batch manufacturing plant. The flow model uses parallel and serial product flow modes to determine the progress of a particular phase (for example, an S88 phase) with respect to particular Unit(s).  FIG. 1D  shows an example of the product flow model  110 , which has parallel and serial product flow according to one aspect of the present invention. 
     During parallel product flow, product flows in concurrently from plural units to single unit. An example of this is shown as inputs from Units  118 A and  118 B via paths  120  and  119  sent to Unit  121 . 
     For product transferred out in parallel mode, unit  122  sends product to units  125  and  126 , while product is monitored at locations  124  and  123 , respectively. 
     During serial product flow mode, product flows from a one of many Units to a single Unit. For example, Units  111 ,  111 A and  111 B send product via line  112  one at a time to Unit  113 . Product is metered at location  113 A. 
     In serial flow mode, unit  114  sends product to only one of Units  116 A,  116 B or  116 C through path  117  at a given time. Product is metered at location  115 . 
     Based on flow model  110 , a manufacturing plant can be configured to monitor batch processing and Lot Genealogy. 
     Overall System Example 
       FIG. 2  shows a system according to one embodiment of the present invention, where model  110  is used to efficiently monitor and trace batch product manufacturing. It is assumed that after most Units are fully washed, there is no contamination and that can be the beginning of a Lot. Based on how product moves and when certain units are cleaned, Lot Associations are established. Every Unit has a Lot Identifier (“Lot Id.”). The flow model described above allows one to know, which Unit is operating at a given time. A parent/child record is built for each Lot Association and each Lot can have several batches. Every Lot is time stamped and hence a monitoring system that is described in detail below knows which batch/Lot came first. 
     The LGTP using a data collection system ( FIG. 5 ,  500 ) tracks bulk products within Units by tracking Batches, Lots, Product Flow and Lot Generating Events. The data collection system collects phase information for every unit in compliance with the S88 standard. Programs (or code) in individual PLCs informs the data collection system  500 , which phases are running at a given time in a particular unit by using a Procedure Id. Every phase has an associated integer value (Procedure Id). In one aspect, this value is positive when the phase starts and negative, when the phase ends. 
     Procedure Ids can be used to associate multiple phases on multiple units that are involved in product flow (i.e. Batch). Defining a single phase as a “Parent Phase” performs this and each parent phase can have multiple phases (“child phases”). Procedure Id is used to create a Batch Id in a database ( 520 ,  FIG. 5 ), described below. The Batch is associated with each Lot on each unit through which product is flowing to and/or from. Data collection system  500  determines product flow by using the Flow Model discussed above and by examining the phases that are active for a Batch. 
     Procedure Ids can be messaged between PLCs. For example, an upstream unit ( 204 ,  FIG. 2 ) may start a process and therefore start a phase on a Unit and allocate a Procedure Id for that phase. A downstream unit ( 210 ,  FIG. 2 ) that receives product from the upstream unit is controlled by another PLC. The upstream PLC messages the parent Procedure Id to the downstream unit. 
       FIG. 2  shows various terms that illustrate how Units/Lots/Batches are monitored, according to one aspect of the present invention. For example: 
     “UNLOAD” denotes that product is unloaded; 
     “ONPROD” denotes that product flows through; 
     “XIN_XX”: Indicates that product comes from a certain unit, for example, XIN_RB 1  indicates that product comes from receiving bay  1 ; 
     “XOUT” denotes that product leaves a certain Unit, for example, when product leaves Raw Silo  207 , it is indicated by XOUT, a monitoring point; and 
     “XOUT_HTST 1 ”: Indicates product leaves from a certain unit to another Unit, for example, HTST 1   215 . 
     One or more PLCs are used to monitor the units. For example, a PLC will monitor the “UNLOAD” task from receiving bay  201  and  202 , as described in detail below. 
     Turning in detail to  FIG. 2 , system  200  includes receiving bays  201  and  202  to receive raw product (for example, milk from different sources). CIP  206  indicates when bay  202  is cleaned. This indicates the beginning of a phase. PLCs monitor the “UNLOAD”, task from receiving bays  201  and  202 . 
     Product moves to an intermediate line  203  and from there to raw material storage tanks (raw silo)  207  and  208 . PLCs track product flow from line  203  into tanks  207  and  208  (at XIN_RB 1  and XIN_RB 2 ). 
     Product moves from raw silos  207  and  208  to a transfer line  211  and is monitored by PLCs. Thereafter, raw milk moves to separator  212  and is monitored by PLCs (XIN_XFERLINES). Separator  212  separates cream from the milk and the skimmed milk is moved to pasteurizer (HTST 1 )  216 (XOUT_HTST 1 ), while the cream moves to a cream tank  213  (XOUT_CRM) and then to HTST 1   216 . Again the product movement is monitored. 
     Raw condensed tanks  215  and  214  receive raw milk from silos  207  and  208  and are monitored at XIN_RB 1  and XIN_RB 2 . Milk from tanks  214  and  215  is also moved to HTST 1   216 (XIN_RCND). Milk from HTST 1   216  is moved to pasteurized tanks  218  and  219  and then sent to filling station  220 . 
     All along the PLCs monitor product flow through the units and also monitor the phase changes based on model  110 . 
     It is noteworthy that the foregoing illustration is only to provide an example of the adaptive aspects of the present invention. The LGTP, data collection system  500  and the various aspects of the present invention may be implemented in batch manufacturing plants and are not limited to any particular product (for example, milk) process steps, or any particular number of Units or Lots. For example, a plant that is producing juice, oil, cosmetics, pharmaceuticals or any other batch product can easily use the inventive aspects of the present invention. Also, a plant may use any number of tanks and still implement the adaptive aspects of the present invention. 
     The various PLCs, according to the present invention are coupled to OPC servers and plural OPC servers are coupled to a Virtual PLC  503 , as shown in  FIG. 3B . An application program  301  running on a computing system (as described below) coupled to a network (or to the Internet) may analyze data from Virtual PLC  503 . The operation of Virtual PLC  503  is described below in detail with respect to  FIG. 5 . It is noteworthy that the present adaptive aspects of the present invention are not limited to OPC server interface, and instead any other standard or proprietary interface may be used to implement the various adaptive aspects of the present invention. 
     Description of a Computing System and Internet Topology: 
     To facilitate an understanding of the preferred embodiment using the Virtual PLC  503 , the general architecture and operation of a computer system and the Internet will now be described. The specific architecture and operation of the preferred embodiment will then be described with reference to the general architecture. 
       FIG. 1B  is a block diagram of a computing system for performing executable process steps according to one aspect of the present invention.  FIG. 1  includes a host computer  10  and a monitor  11 . Monitor  11  may be a CRT type, a LCD type, or any other type of color or monochrome display. Also provided with computer  10  are a keyboard  13  for entering data and user commands and a pointing device  14  for processing objects displayed on monitor  11 . 
     Computer  10  includes a computer-readable memory medium such as a rotating disk  15  for storing readable data. Besides other programs, disk  15  can store application programs&#39; including web browsers by which computer  10  connects to the Internet and the systems described. 
     According to one aspect of the present invention, computer  10  can also access computer-readable floppy disks storing data files, application program files, and computer executable process steps embodying the present invention or the like via a floppy disk drive  16 . A CD-ROM, or CD R/W (read/write) interface (not shown) may also be provided with computer  10  to access application program files, audio files and data files stored on a CD-ROM. 
     A modem, an integrated services digital network (ISDN) connection, or the like also provides computer  10  with an Internet connection  12  to the World Wide Web (WWW). The Internet connection  12  allows computer  10  to download data files, application program files and computer-executable process steps embodying the present invention. 
     Computer  10  is also provided with external audio speakers  17 A and  17 B to assist a listener to listen to audio files or messages that may be generated based on certain events. 
     It is noteworthy that the present invention is not limited to the  FIG. 1B  architecture. For example, notebook or laptop computers, handheld and/or wireless devices, set-top boxes or any other system capable of running computer-executable process steps may be used to implement the various aspects of the present invention. 
       FIG. 1C  is a block diagram showing the internal functional architecture of computer  10 . As shown in  FIG. 1C , computer  10  includes a CPU  20  for executing computer-executable process steps and interfaces with a computer bus  21 . Also shown in  FIG. 1C  are a video interface  22 , an audio interface  23 , a printer interface  24 , a scanner interface  25 , a WWW interface  26 , a display device interface  27 , a keyboard interface  28 , a pointing device interface  29 , and a rotating disk  15 . 
     As described above, disk  15  stores operating system program files, application program files, web browsers, and other files. Some of these files are stored on disk  15  using an installation program. For example, CPU  20  executes computer-executable process steps of an installation program so that CPU  20  can properly execute the application program. 
     Random access memory (“RAM”)  30  also interfaces to computer bus  21  to provide CPU  20  with access to memory storage. When executing stored computer-executable process steps from disk  15  (or other storage media such as floppy disk  16  or WWW connection  12 ), CPU  20  stores and executes the process steps out of RAM  30 . 
     Read only memory (“ROM”)  31  is provided to store invariant instruction sequences such as start-up instruction sequences or basic input/output operating system (BIOS) sequences for operation of keyboard  13 . 
     Process steps, according to one aspect of the present invention may be performed using the Internet. Data collected by PLCs may be accessed using the Virtual PLC  503  via the Internet. The following provides a brief description of the Internet. 
     The Internet connects thousands of computers world wide through well-known protocols, for example, Transmission Control Protocol (TCP)/Internet Protocol (IP), into a vast network. Information on the Internet is stored world wide as computer files, mostly written in the Hypertext Mark Up Language (“HTML”). Other mark up languages, e.g., Extensible Markup Language as published by W3C Consortium, Version 1, Second Edition, October 2000, ©W3C may also be used. The collection of all such publicly available computer files is known as the World Wide Web (WWW). The WWW is a multimedia-enabled hypertext system used for navigating the Internet and is made up of hundreds of thousands of web pages with images and text and video files, which can be displayed on a computer monitor. Each web page can have connections to other pages, which may be located on any computer connected to the Internet. 
     A typical Internet user uses a client program called a “Web Browser” to connect to the Internet. A user can connect to the Internet via a proprietary network, such as America Online or CompuServe, or via an Internet Service Provider, e.g., Earthlink. The web browser may run on any computer connected to the Internet. Currently, various browsers are available of which two prominent browsers are Netscape Navigator and Microsoft Internet Explorer. The Web Browser receives and sends requests to a web server and acquires information from the WWW. A web server is a program that, upon receipt of a request, sends the requested data to the requesting user. A standard naming convention known as Uniform Resource Locator (“URL”) has been adopted to represent hypermedia links and links to network services. Most files or services can be represented with a URL. 
     URLs enable Web Browsers to go directly to any file held on any WWW server. Information from the WWW is accessed using well-known protocols, including the Hypertext Transport Protocol (“HTTP”), the Wide Area Information Service (“WAIS”) and the File Transport Protocol (“FTP”), over TCP/IP protocol. The transfer format for standard WWW pages is Hypertext Transfer Protocol (HTTP). 
       FIG. 3C  shows a typical topology of a computer network with computers similar to computer  10 , connected to the Internet. For illustration purposes, three computers X, Y and Z are shown connected to the Internet  32  via WWW interface  26  through a gateway  33 , where gateway  33  can interface N number of computers. 
     WWW interface  26  may be a modem, network interface card or a unit for providing connectivity to other computer systems over a network using protocols such as X.25, Ethernet or TCP/IP, or any device that allows, directly or indirectly, computer-to-computer communications. It is noteworthy that the invention is not limited to a particular number of computers. Any number of computers that can be connected to the Internet  32  or any other computer network may be used. 
       FIG. 3C  further shows a second gateway  35  that connects a network of web servers  36  and  37  to the Internet  32 . Web servers  36  and  37  may be connected with each other over a computer network. 
     Data Collection Conceptual Model: 
       FIG. 6  shows the data collection model  600 , according to one embodiment of the present invention that is incorporated into the system described below with respect to  FIG. 5 . Data collector  602  collects data from data source  601 . Collector  602  sends the information to data collection manager  610 . Adapter  603  is an optional path for a data collector to send data to data collection manager  610  in the event that the data collector  602  cannot interface directly with the collection manager  610 . For example, a data collector  602  that is running on Unix may not be able to communicate with data collection manager  610  that is running on Windows using “COM”. 
     Data collection manager  602  also receives input from a message processor manager  606  and a routing table  611 . Based on the various inputs, data collection manager  610  generates a message that is sent to message sender  604  that generates a message packet. The message packet is sent to a message receiver  605  that moves the packet to message processor manager  606  that sends the message to a message processor  607  and eventually to a database  608 . 
     The various rules that may be used to collect data are described below. 
     Data Collection System: 
       FIG. 5  shows system  500 , according to one embodiment of the present invention that can be used to collect and analyze data to monitor batch processing based on model  110 . Data is collected by PLCs  501  and sent to an OPC server  502 . OPC server  502  is a standard software module that can run on a computing system (for example  10 ) that is coupled to other devices and computing systems over a network (including the Internet). OPC server  502  is designed to receive information from specific PLCs. 
     The collected data is sent to Virtual PLC  503  that is configured by configuration module (or file)  510 . Virtual PLC  503  is a software program running on a computing system (for example system  10 ). In one aspect of the present invention configuration file  510  is based on the XML standard. Configuration file  510  includes information regarding scan rates (i.e. the rate at which data is collected from a PLC), the address from where data is collected and where it needs to be sent after it is collected. 
     Virtual PLC  503  collects data from disparate sources and provides a common interface. Virtual PLC  503  uses virtual memory  510 A that keeps track of data related to particular PLCs. Virtual in this sense means that data does not have to be written at the PLC level and instead is written in memory at computing system  10  or otherwise, and is accessible by Virtual PLC  503 . 
     Virtual PLC  503  uses a table and extracts all the information from a particular PLC. Often, when plural PLCs are operating in a plant, an event that occurs on one PLC will require data from another PLC. Virtual PLC  503  constantly polls all PLCs for data. 
     Also, often data is collected from equipment via software and not by a PLC. To correlate such data to a PLC, often, programmers have to write special conversion routines. Providing virtual memory  510 A eliminates this problem, and hence, there is no need to write to PLC memory. 
     Virtual memory  510 A can also include shadow memory that matches data at the PLC level and collects data in real-time by constantly polling. Hence, there is a copy of PLC data in virtual memory  510 A. 
     Data from Virtual PLC  503  is sent to PLC data Collector module  504 . The data is collected based on various rules  506  that are described below in detail. Rules  506  define data collection rules and the message that is sent to a software application (DCM  507 ) to process the data. Rules  506  are based on Event—Condition—Action, i.e. every statement in the system is of the form: 
     &lt;event&gt; &lt;condition&gt; &lt;action&gt; 
     Example of events is as follows: 
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                   EVERY DAY AT 1:00 PM 
               
               
                   
                   ON CHANGE &lt;B993/1 - B993/999&gt; 
               
               
                   
                   EVERY 20 seconds 
               
               
                   
                   ON UNKNOWN &lt;N900:1&gt; 
               
               
                   
                   ON KNOWN &lt;Tank5.Temp&gt; 
               
               
                   
                   EVERY MON-FRI AT 12:00 AM 
               
               
                   
                   EVERY 15 minutes SYNCHRONIZED 
               
               
                   
                   EVERY DAY AT 1:00 PM occurs every day at 1:00 p.m. 
               
               
                   
                 ON CHANGE &lt;B993/1 - B993/999&gt; occurs whenever any data 
               
               
                   
                 value within the range B993/1 - B993/999 changes. 
               
               
                   
                   EVERY 20 seconds occurs every 20 seconds. 
               
               
                   
                 ON UNKNOWN &lt;N900:1&gt; occurs when the data at N900:1 is not 
               
               
                   
                 available, usually due to communication failure. 
               
               
                   
                 ON KNOWN &lt;Tank5.Temp&gt; occurs when the data at 
               
               
                   
                 Tank5.Temperature becomes available, usually due to 
               
               
                   
                 reestablished communications. 
               
               
                   
                 EVERY MON-FRI AT 12:00 AM occurs every weekday at 
               
               
                   
                 midnight. 
               
               
                   
                 EVERY 15 minutes SYNCHRONIZED occurs every 15 minutes 
               
               
                   
                 synchronized with the clock, e.g. at 1:00, 1:15, 1:30, 
               
               
                   
                 1:45, 2:00, etc. 
               
               
                   
                   
               
            
           
         
       
     
     Example of conditions is given below: 
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                   WHEN VALUE &gt; 0 AND B144/3 = 1 
               
               
                   
                   WHEN never 
               
               
                   
                   WHEN always 
               
               
                   
                   WHEN ST219:7 &lt;&gt; “ ” 
               
               
                   
                   WHEN VALUE &gt; 0 AND B144/3 = 1 is met when the VALUE 
               
               
                   
                 of a PLC location that triggered the &lt;event&gt; is positive 
               
               
                   
                 AND the value at B144/3 is 1. 
               
               
                   
                   WHEN never is never met. This is useful for 
               
               
                   
                 temporarily removing a condition. 
               
               
                   
                   WHEN always is always met. 
               
               
                   
                   WHEN ST219:7 &lt;&gt; “ ” is met when the string value at 
               
               
                   
                 ST219:7 is NOT empty. 
               
               
                   
                   
               
            
           
         
       
     
     Example of actions is provided below: 
     
       
         
           
               
               
             
               
                   
                   
               
             
            
               
                   
                 SEND BeginProcedure (ADDRESS, 0, ONE INDEXED OFFSET, 
               
               
                   
                 FALSE): 
               
               
                   
                 SEND BeginProcedure (ADDRESS, 0, ONE INDEXED OFFSET, 
               
               
                   
                 FALSE) sends the message BeginProcedure with the specified 
               
               
                   
                 parameters. ADDRESS is the PLC address that triggered the 
               
               
                   
                 &lt;event&gt;. ONE INDEXED OFFSET is the offset within the range 
               
               
                   
                 of addresses specified for the &lt;event&gt; where the first 
               
               
                   
                 item in the range has an offset of 1 (as opposed to Zero 
               
               
                   
                 INDEXED OFFSET which starts at 0). FALSE is the value of 
               
               
                   
                 0. 
               
               
                   
                   (b) SEND ProcedureUnknown (ADDRESS, 0, ONE INDEXED 
               
               
                   
                 OFFSET) 
               
               
                   
                   SEND ProcedureUnknown (ADDRESS, 0, ONE INDEXED 
               
               
                   
                 OFFSET) sends the message ProcedureUnknown with the 
               
               
                   
                 specified parameters. 
               
               
                   
                   
               
            
           
         
       
     
     Messages that can be sent with the SEND command are defined in the rule set by a message definition section marked by [MESSAGE DEFINITION]. This section defines valid messages and their associated parameters and types for the specified Data Processor. 
     The following provides an example of a rule set  506 : 
     
       
         
           
               
             
               
                   
               
             
            
               
                 PROCESSOR = BatchIS 
               
               
                 [MESSAGE DEFINITIONS] 
               
               
                 BeginProcedure(procedureAddress TYPE IS ADDRESS, 
               
               
                 baseProcedureIdOffset TYPE IS NUMBER, procedureId TYPE IS 
               
               
                 NUMBER, previouslyUnknown TYPE IS NUMBER) 
               
               
                 EndProcedure(procedureAddress TYPE IS ADDRESS, 
               
               
                 baseProcedureIdOffset TYPE IS NUMBER, procedureId TYPE IS 
               
               
                 NUMBER, previouslyUnknown TYPE IS NUMBER) 
               
               
                 ProcedureUnknown(procedureAddress TYPE IS ADDRESS, 
               
               
                 baseProcedureIdOffset TYPE IS NUMBER, procedureId TYPE IS 
               
               
                 NUMBER) 
               
               
                 BeginPhase(phaseAddress TYPE IS ADDRESS, procedureId TYPE 
               
               
                 IS NUMBER, parameters TYPE IS ADDRESS_LIST, 
               
               
                 previouslyUnknown TYPE IS NUMBER) 
               
               
                 EndPhase(phaseAddress TYPE IS ADDRESS, procedureId TYPE IS 
               
               
                 NUMBER, parameters TYPE IS ADDRESS_LIST, previouslyUnknown 
               
               
                 TYPE IS NUMBER) 
               
               
                 PhaseUnknown(phaseAddress TYPE IS ADDRESS) 
               
               
                 ////////////////////////////////////////////////////////// 
               
               
                 // 
               
               
                 // WFF rules 
               
               
                 ////////////////////////////////////////////////////////// 
               
               
                 / 
               
               
                 {WFF} 
               
               
                 [RULES] 
               
               
                 ON CHANGE &lt;B993/1 - B993/999&gt; 
               
               
                 WHEN VALUE = 1 SEND BeginProcedure (ADDRESS, 0, ONE 
               
               
                 INDEXED OFFSET, FALSE) 
               
               
                 WHEN VALUE = 0 SEND EndProcedure (ADDRESS, 0, ONE INDEXED 
               
               
                 OFFSET, FALSE) 
               
               
                 ON KNOWN &lt;B993/1 - B993/999&gt; 
               
               
                 WHEN VALUE = 1 SEND BeginProcedure (ADDRESS, 0, ONE 
               
               
                 INDEXED OFFSET, TRUE) 
               
               
                 WHEN VALUE = 0 SEND EndProcedure (ADDRESS, 0, ONE INDEXED 
               
               
                 OFFSET, TRUE) 
               
               
                 ON UNKNOWN &lt;B993/1 - B993/999&gt; 
               
               
                 WHEN always SEND ProcedureUnknown (ADDRESS, 0, ONE INDEXED 
               
               
                 OFFSET) 
               
               
                 ON CHANGE &lt;N900:1&gt; 
               
               
                 WHEN VALUE &gt; 0 SEND BeginPhase(ADDRESS, ABS_VALUE, &lt;&gt;, 
               
               
                 FALSE) 
               
               
                 WHEN VALUE &lt; 0 SEND EndPhase(ADDRESS, ABS_VALUE,  
               
               
                 &lt;ST409:0, ST419:10, ST409:7, ST409:8&gt;, FALSE) 
               
               
                 ON KNOWN &lt;N900:1&gt; 
               
               
                 WHEN VALUE &gt; 0 SEND BeginPhase(ADDRESS, ABS_VALUE, &lt;&gt;, 
               
               
                 TRUE) 
               
               
                 WHEN VALUE &lt; 0 SEND EndPhase(ADDRESS, ABS_VALUE,  
               
               
                 &lt;ST409:0, ST419:10, ST409:7, ST409:8&gt;, TRUE) 
               
               
                 ON UNKNOWN &lt;N900:1&gt; 
               
               
                 WHEN always SEND PhaseUnknown(ADDRESS) 
               
               
                   
               
            
           
         
       
     
     Data collected from module  504  is then sent to a data collection manager (DCM”)  507  that receives routing information from a routing table  509 . DCM  507  can also receive data from non-PLC sources  507 A and provides a common interface for data collection from plural and disparate sources. For example, data may be collected by a computing system ( 10 ) or an embedded system (not shown). 
     Routing table  509  has entries that include the destination and transport information for messages. This information is used by DCM  507  to send a message to message sender  508 . In one aspect, the message may be in the XML format. 
     Message sender  508  forwards the message to Message Queuing system (“MQ”)  511 . In one aspect of the present invention, MQ  511  is a standard system that is provided by Microsoft Corporation™ that is incorporated herein by reference in its entirety. MQ  511  stores the messages in queue(s)  512  and when needed, it pulls the message from queue(s)  512 . 
     Message receiver  518  receives the messages from module  511  and sends it to data manager  517 . Data manager  517  interacts with routing table  509 , a phase module  516  and a trending module  519 . Data manager  517  pulls the messages from message receiver  518  as a transaction. All transactions are coordinated by distributed transaction coordinator (“DTC”)  514 . In one aspect of the present invention, DTC  514  is provided by Microsoft Corporation™ that is incorporated herein by reference in its entirety. 
     DTC  514  coordinates multiple transactions. For example, DTC  514  coordinates a transaction between say phase module  516  and/or trending module  519  with SQL server  521  and also coordinates the transaction between DCM  517  and phase module  516  and/or trending module  519 . It is noteworthy that the present invention is not limited to coordinating transactions involving any particular number/type of modules 
     Phase module  516  keeps track of plural S88 phases in plural units and collects discrete information. This information is stored in database  520  that includes SQL server  521 . It is noteworthy that the present invention is not limited to any particular database technology (for example, the SQL technology) and any other database system may be used SQL server  521  stores various procedures and can command phase module  516  to move Lot Associations, and phase information. 
     It is noteworthy that database  520  may be coupled to the Internet or any other network in a computing system (for example,  10 ). 
     Trending module  519  collects trending data continuously. This can include information on parameters in plural units. 
     System  500  also includes a service monitor  524  that provides alerts  525  (for example emails) upon certain events (for example, if temperature changes in a storage unit). Service monitor  524  receives input from various modules, for example, virtual PLC  503 , data manager  517 , trending module  526 , phase module  516  and data collection manager  507 . 
     Service manager  526  provides configuration information to module  523  that is sent to monitoring module  524 . This establishes the base line for sending alerts  525 . 
     Determining Lot Genealogy: Lot Genealogy involves a LOI and all the descendants and ancestors. A parent/child relationship occurs, when product flows from one Unit to another. Although product may flow from one Lot to another, it does not mean that the Lot is a part of a particular genealogy. The LOI&#39;s Batches are used to determine which Lots are to be included in its genealogy. Since a Lot contains Batches, which determines when and where product flow has occurred, the Batches are important to Lot Genealogy process. 
     In one embodiment of the present invention, Lot Associations are maintained (in database  520 ) and a LOI is chosen from Lot Associations. The Batches are compared to each child Lot. If a child has batches in common, then it is included in the genealogy and then a new list of batches is build per the following rules: 
     For Trace Genealogy or Units that store products: 
     A new list of batches is created from the child Lot&#39;s batches without earlier batches from descendants and later batches for ancestors. An earlier batch is one that came before the earliest batch in the new list of batches. A later batch is one that came after the latest batch in the new list. 
     For Bulk Genealogy and Units that do not store products: 
     A new list of batches is created from the intersection of the parent and child batches. If there are no batches in common, then the child and its subsequent associations are removed from the genealogy. 
     The new list of batches is passed on recursively for each remaining child. 
       FIG. 4A  shows a flow diagram of a process according to one aspect of the present invention to monitor batch processing. The process tracks lots within manufacturing units by tracking Batches, Lots, Product Flow and lot generating Events. This is achieved by collecting phase information for every Unit. 
     Turning in detail to step S 400 , the process develops lot associations, as described above. Lot associations are developed between different phases and different units and not to product itself. This is helpful because product mostly moves from one unit to another. This is achieved by using a Procedure Id, which is then used to create a Batch. The Batch is then associated with each lot in each Unit that product is flowing from, to or through. This is achieved by examining every phase that is active for a Batch.  FIG. 4B  shows an example of various units and how product is flowing. Product is transferred into Unit A and then transferred to Unit B, and from Unit B, product moves to Unit D. This occurs after any transfer takes place between Unit B and C. The parameters in Unit A are tracked and a Lot Association is developed between A and B. Lot Association is also created between B and D. If A is the lot of interest, then the transfer of product from B to C is not considered to be a part of Lot A&#39;s genealogy. In one aspect of the present invention, a tree like structure is used for Lot Associations. 
     In step S 401 , the process allows a user to select a particular LOI. This can be achieved by using a user interface at computing system  10 . 
     In step S 402 , the process performs trace genealogy filtering, as described above. Trace filtering monitors small “trace’ amount commingling to the main product. This eliminates unnecessary associations so that the overall tracking process is efficient. 
     In step S 403 , bulk filtering is performed to optimize the overall tracking process, where Bulk Genealogy, bulk commingling of product occurs. Once again redundant associations are eliminated and only useful information is used.  FIG. 4C  shows a flow diagram for eliminating redundant associations for bulk filtering. Unit E sends product only to Unit C, via unit B. Unit A sends product to Unit D via unit B. For all transfers from A to D, only trace amount commingling occurs in Unit B since B does not store product. Therefore, for bulk filtering, the association between B and C is eliminated. 
     In step S 404 , the process outputs Lot Genealogy. 
     In one aspect of the present invention, data is collected from the beginning of a phase (for example, an S88 phase) and stops collecting data at the end of the phase. In this way information is directly related to a unit or a particular operation. Hence, only important (phase related) information is monitored and analyzed, making the overall monitoring process efficient and cost-effective. 
     In another aspect of the present invention, three states are available for PLC data, namely, data is known and was previously known, data is known and was previously unknown and data is unknown.  FIG. 7  shows a data state diagram with three data states State  0   701 , State  1   702  and State  703 . 
     A data value that is being polled for the value of 1 is initially set to unknown (State  0   701 ). 
     When the data value becomes known, it goes to State  1   702 . 
     The data value becomes Unknown  701 , for example, due to communication problem with a PLC it goes back to State  0   701 . 
     The data value becomes Known ( 702 ) again and it is still 1 (State  1 ,  702 ). Then it goes to State  2   703  until the data goes bad. 
     The process is now triggered again, but it has added information that it was “Previously Unknown”. This added information helps in avoiding unnecessary event triggers. This avoids double triggering of a process/event when data is unavailable. 
     While the present invention is described above with respect to what is currently considered its preferred embodiments, it is to be understood that the invention is not limited to that described above. To the contrary, the invention is intended to cover various modifications and equivalent arrangements within the spirit and scope of the appended claims.