WO2000042476A1

WO2000042476A1 - Method of controlling the operation of an industrial plant

Info

Publication number: WO2000042476A1
Application number: PCT/AU2000/000005
Authority: WO
Inventors: Shoni Even-Chaim
Original assignee: Visy R & D Pty Ltd
Priority date: 1999-01-08
Filing date: 2000-01-07
Publication date: 2000-07-20
Also published as: AUPP806699A0

Abstract

A process feedback control system (50) for controlling the operation of an industrial plant (20-23) and method of controlling the operation of an industrial plant, the industrial plant comprising production equipment operable in a plurality of states (60-62; 70-76), and a main control system (30) for selectively altering the state of the production equipment from a current state to a next state upon the occurrence of preselected conditions, the processing feedback control system (50) comprising detection means (35, 36, 55, 120-126) for detecting predefined production events occurring during each current state, and at least one feedback system controller (52) for interrupting the operation of the main control system (30) upon the detection of at least a first of said predefined production events when the current state of the production equipment is in one or more predefined states, so that the production equipment remains in that current state, and for uninterrupting the operation of the main control system (30) when at least a second of said predefined production events is detected subsequent to the first predefined production event during that current state.

Description

METHOD OF CONTROLLING THE OPERATION OF AN INDUSTRIAL PLANT

The present invention relates generally to a method of controlling the operation of industrial plant, and in particular to the control of an industrial plant comprising production equipment operable in a plurality of states, and a control system for selectively altering the state of the production equipment according to the occurrence of predefined events. The present invention will be described with particular reference to the operation of conversion machines within a cardboard box manufacturing plant, but it is to be understood, however, that the invention is not limited to that application and may be used to control the operation of various other production machines and equipment.

A typical cardboard box manufacturing plant will have one or more corrugators that convert rolls of paper into flat sheets of cardboard of varying grades. The newly created stacks of cardboard sheets are moved to a temporary storage area where they are allowed to cure to room temperature before further processing takes place. Stacks of cardboard sheets are eventually transferred to a conversion machine where they are further processed into cardboard boxes before being dispatched to customers. All boxes will generally pass through a conversion machine at least once, and some complicated boxes may pass through multiple conversion machines before being completed, to achieve complicated folding, glueing and printing arrangements, etc. A single sheet of corrugated cardboard fed into the feeder may be turned into several completed boxes by the conversion machine.

In order to assist in the efficient operation of the conversion machines, feedback systems are provided to collect data relating to the various states in which the conversion machine are operable, broadly divided into run time, setup time, downtime and stoptime. Data is also collected about the particular jobs run on each conversion machine.

Existing feedback systems rely heavily upon supervisors and operators of the conversion machines to enter timely and accurate data, for example, as to the shift start/end and job start/end times, job setup times, and reasons for various downtimes and stop times. As a result of the general unreliability of this information, maintenance departments and engineering departments responsible for the maintenance and design of industrial plant equipment have not in the past been able to benefit from an analysis of the data collected.

Moreover, existing feedback systems exchange data with logistics databases and remote servers during the processing of cardboard sheets through the conversion machines. Errors in transporting data, as well as server errors, often corrupt the integrity of data collected by these feedback systems.

There therefore exists a need to collect accurate realtime production and downtime data from plant conversion machines and other production equipment and to analyse this data in order to improve production performance. There is also a need to improve the crew performance of the operators and supervisors responsible for the use of the conversion machines in production by making available shift production and downtime performance data and targets in real time to each crew. There is also a need to improve the integrity and reliability of data flow within existing feedback systems and from these feedback systems to logistics systems within the plant. A need also exists to provide a simple interface for data entry to operators and supervisors, including logging in and out of a shift, job selection and downtime recording.

One aspect of the present invention provides a process feedback control system for controlling the operation of an industrial plant, the industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering the state of the production equipment from a current state to a next state upon the occurrence of preselected conditions, the processing feedback control system comprising detection means for detecting predefined production events occurring during each current state, and at least one feedback system controller for interrupting the operation of the main control system upon the detection of at least a first of said predefined production events when the current state of the production equipment is in one or more predefined states, so that the production equipment remains in that current state, and for uninterrupting the operation of the main control system when at least a second of said predefined production events is detected subsequent to the first predefined production event during that current state.

At least some of the production events may be generated by production equipment actions. Similarly, at least some of the production events may be generated by plant personnel actions.

Configuration information defining said production events may be stored in a memory device associated with the feedback system controller. One or more production characteristics of the industrial plant may also be stored in the memory device. The production characteristics may include information identifying production events that occurred during at least some of said plurality of states.

Conveniently, the feedback system controller may act to periodically transfer the recorded production characteristics to a logistic system in the main control system.

In one embodiment, the feedback system controller may be a programmable state controller. The process feedback control system may further comprise an operator interface system for controlling the operation of the feedback system controller.

Moreover, the process feedback control system may comprise display means for displaying selected production characteristics to plant personnel.

The production equipment may include a plurality of separately operable production machines, the process feedback control system including a separate feedback system controller associated with each such production machine.

In one embodiment, the production machines may be conversion machines for the processing of sheet-like materials into folded containers.

Another aspect of the present invention provides a method of controlling the operation of an industrial plant, the industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering the state of the production equipment from a current state to t a next state upon the occurrence of pre-selected conditions, said method includes the steps of:

(i). detecting the occurrence of predefined production events during each current state, (ii). interrupting the operation of the main control system upon the detection of at least a first of said predefined production events when the current state of the production equipment is in one or more predefined states, so that the production equipment remains in that current state, and (iii). uninterrupting the operation of the main control system when at least a second of the predefined production events is detected subsequent to the first predefined production event during that current state. Yet another aspect of the present invention provides a computer readable memory, encoded with data representing a computer program, for directing the operation of a process feedback control system for controlling the operation of industrial plant, the industrial plant comprising production equipment operable in a plurality of states, and the main control system for selectively altering the state of the production equipment from a current state to a next state upon the occurrence of pre-selected conditions. The encoded computer readable memory comprising means for detecting predefined production events occurring during each current state, means for interrupting the operation of the main control system upon the detection of at least a first of said predefined production events when the current state of said production equipment is in one or more predefined states, so that the production equipment remains in that current state, and means for uninterrupting the operation of said main control system when at least a second of said predefined production events is detected subsequent to said predefined production event during that current state.

A still further aspect of the present invention provides a computer program element comprising computer program code means for a process feedback control system for controlling the operation of the industrial plant, said industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering the state of said production equipment from a current state to a next state upon the occurrence of pre-selected conditions, said computer program means code means causing said process feedback control system to: (i). detect the occurrence of predefined production events during each current state,

(ii). interrupt the operation of the main control system upon the detection of at least a first of said predefined production events when the current state of the production equipment is in one or more predefined states, so that the production equipment remains in that current state, and (iii). uninterrupt the operation of the main control system when at least a second of said predefined production events is detected subsequent to said first predefined production event during that current state.

The following description refers in more detail to various features of the present invention. To facilitate an understanding of the invention, reference is made in the description to the accompanying drawings where the invention illustrated in a preferred embodiment. It is to be understood that the present invention, however, is not limited to that preferred embodiment.

In the drawings:

Figure 1 is a schematic diagram of four examples of conversion machines for use in a cardboard box manufacturing plant;

Figure 2 is a schematic diagram of a control system for use in controlling the operation of conversion machines of Figure 1 ;

Figure 3 is a schematic diagram of a process feedback control system for use in monitoring various production characteristics of the conversion machines of Figure 1 when in use and for providing user interaction with the control of the conversion machines;

Figures 4 and 5 are state diagrams showing various operable states of the conversion machines of Figure 1 and various predefined events for causing the changing of the operating state of the conversion machines;

Figures 6 to 11 are examples of operator input and display screens provided by the operator interface system of the process feedback control system of Figure 3 for enabling monitoring and control of the operation of the conversion machines of Figure 1 ; and

Figures 12 A and 12B are two parts of a table summarising an example of valid events forming part of event configuration information used by the control system of Figure 2 and the process feedback control system of Figure 3 to control operation of the conversion machines of Figure 1.

In a typical plant there may be between three and fourteen conversion machines. Although each conversion machine is intended in this example to be used for the processing of cardboard sheets into cardboard boxes, conversion machines may also be used to process other sheet-like material into other folded containers. As seen in Figure 1, some key components of a conversion machine include a pre-feeder 1, a feeder 2, a printing unit 3, a slotter/creaser 4, a die cutter 5, a folder/gluer 6, a stacker/counter ejector 7, a compressor 8, a tie machine 9 and a palletiser 10. The function of each component in Figure 1 is set out below:

Pre-feeder: Feeds stacks of corrugated sheet into the conversion machine. Feeder: Regulates the flow of sheets into the conversion machine.

Printing Unit: Prints the desired pattern on the outside of each sheet in ink using a changeable printing "stereo" which is attached to a rotating drum. Slotter/Creaser: Slots and creases the boxes.

Die Cutter: Cuts the sheets of corrugated cardboard into individual boxes using a changeable "forme" attached to a rotating drum. Folder/Gluer: Folds and glues individual boxes into the required shape.

Stacker/Counter Ejector: Stacks completed boxes into stacks of a pre-determined number

Compression: Compresses folded and glued boxes before they are tied. Tie Machine: Places a plastic strap around a completed bundle of boxes. Palletiser: Stacks completed bundles of boxes into pallets ready for the strapping line.

All conversion machines are not necessarily identical in functionality and level of automation, although there are usually four main types of conversion machine. Figure 1 shows examples of each type, namely a printer 20, a flexo folder/gluer 21, a flexo rotary die cutter 22 and a folder/gluer 23. Each conversion machine includes various ones of components 1 to 10.

Figure 2 shows a control system 30 for controlling the operation of the conversion machines within a cardboard box manufacturing plant. The main components of the control system 30 are a logistics system 31, a logistics interface 32, a supervisory system 33, a "pacesetter" system 34, and machine PLC's 35. The function of these components are set out below:

Logistics System: Controls the planning and scheduling of jobs to be run on each conversion machine. Logistics Interface: Interface between the Logistics system 31 and the remainder of the control system 30. Supervisory System: Maintains a conversion machine job schedule and provides feedback to the Logistics system 31. "Pacesetter" System: Contains configuration information for the control system equipment PLCs 35 and directly controls position encoders used in the conversion machine.

Machine PLC's: Directly controls the operation of each item of equipment in the conversion machine. Figure 3 shows a process feedback control system 50 according to the present invention which includes an interface server 51, and, associated with each conversion machine, a feedback system controller 52, an operator interface system 53 and associated display device 54 and a bar code scanner 55. The function of the interface server 51 is to provide an interface between the feedback system controller 52 of each conversion machine and the logistics system 31 and to transfer information therebetween. There will generally be only one interface server 51 per plant. The function of each feedback system controller 52 is to monitor events generated from plant personnel actions and/or production equipment, and to monitor the flow of execution of jobs selected through the operator interface system 53 on the conversion machine and record and transfer various production characteristics of the industrial plant, such as production and downtime data gathered, to the logistics system 31. There is a dedicated feedback system controller 52 for each conversion machine, which is interfaced by an interface device 36 to the conversion machine control system 30 shown in Figure 2, and to other field devices.

The conversion machine operator interface system 53 is used to provide an operator interface to the process feedback control system of each conversion machine, and enables the following basic functions:

• Shift login/logout.

• Graphical overview of conversion machine.

• Scheduled job selection.

• Manual job entry. • Downtime reason entry.

• Current and previous shift production reporting.

• Current and previous shift downtime reporting.

There may be a separate operator interface system 53 provided for each conversion machine. The interface server 51 and operator interface system 53 may be networked together using the TCP/IP and IPX SPX protocols through an ethernet switch. The switched network may be connected to the main plant wide information systems network to provide access to the logistics system 31 over the ethernet.

The function of the bar code scanner 55 is to identify personnel (i.e. operators, electricians, fitters and supervisors) when they perform work at a conversion machine by scanning a bar coded personnel identification tag. There is a dedicated bar code scanner for each conversion machine, directly connected to the conversion machine feedback system controller. Various other identification systems, such as magnetically or electronically encoded cards, may be used in other embodiments of the invention. Conventional identification methods, such as the entry of a login name and password, may also be used.

The function of the display device 54, together with the operator interface system 53, is to display selected production characteristics to plant personnel. Specifically, the display device 54 provides feedback to the shift crew on the status of operation of each conversion machine. There is a dedicated sixteen character, single line, three colour text message display terminal for each conversion machine, directly connected to the conversion machine feedback system controller.

All production and downtime data for each conversion machine is resident within its associated feedback system controller 52. The local operator interface system 53 provides a mechanism to view and modify data held within the feedback system controller 52.

The feedback system controller 52 and operator interface system 53 may function independently of the feedback system controllers and operator interface systems associated with other conversion machines within the plant under normal circumstances. The only direct interaction between various conversion machines may be for the transfer of jobs between conversion machines, the monitoring of production and downtime statistics for other conversion machines and for the operator interface system of another conversion machine to control the operation of a conversion machine in the event that the local operator interface system has failed. Feedback may be provided to the user to indicate if a requested operation could not be successfully completed.

Each operator interface system 53 may directly communicate only with the feedback system controller 52 of the conversion machine that it is in control of. Information on all other conversion machines may be obtained from the operator interface system controlling that conversion machine, so to reduce the communications overhead of each feedback system controller. The interface between the logistics system 31 and the process feedback control system 50 is through the interface server 51 and all information passed between the systems is held in database tables in the logistics system 31. The transfer of all information between the two systems is through the interface server 51 calling stored procedures in the logistics system 31 database to read/write information from/to the logistics system 31.

An infeed interrupt output from the feedback system controller 52 is connected to the control system 30 via the interface device 36 such that when the output is off, the conversion machine infeed will be interrupted. A key override switch may be provided to enable the conversion machine infeed interrupt to be bypassed. Whilst operating in infeed interrupt bypass mode, the Process Feedback Control System 50 will continue to function normally with the exception that the feed interrupt will be disabled. The feedback system controller 52 may be a programmable state controller or other programmable device, including processing means and a memory device or computer readable memory, encoded with data representing a computer program, for providing the feedback system controller 52 with its functionality.

The overall operation of the method of controlling the operation of the Conversion machines and associated control systems 30 by means of the process feedback control system 50 may be better understood by reference to the state transition diagrams shown in Figures 4 and 5.

The main state transition diagram shown in Figure 4 represents the basic high level function of a production or maintenance shift logging into the process feedback control system 50. At this level, each conversion machine can be considered to be at any one time in either a default conversion machine idle state 60, a production shift state 61 or a maintenance shift state 62. The state of the conversion machine is altered by the occurrence of production events 63 to 66, namely a production shift login or logout event, and a maintenance shift login or logout event.

The second diagram shown in Figure 5 is a sub diagram of the state "production shift" in the first diagram and represents the flow of operation when a production shift is operating the relevant conversion machine in one or more run-time states, setup-time states, downtime states and stop-time states. At this level, the conversion machine can be in a no job state 70, a setup state 71, a running with flow state 72, a running with no flow state 73, a stopped infeed interrupt state 74, a stopped state 75, or a setup interrupted state 76. The state of the conversion machine can be altered by the occurrence of production events 77 to 92. The process feedback control system monitors the various operating states of each conversion machine. The production event 63 to 66 and 77 to 92 defined the pre-selected conditions which must occur in order for the control system 30 to cause a particular conversion machine to advance from a current state to a next state of operation.

The configuration information for the process feedback control system 50 is held within a database in the logistics system 31 to enable changes to be made to the operation of the system without the need for re-programming. The configuration information may notably include (i) conversion machine event configuration information, which defines various events which may be detected by each feedback system controller 52, (ii) basic conversion machine configuration information, which defines the basic components constituting each conversion machine, (iii) shift configuration information, which identifies the one or more shifts of operators using each conversion machine, and (iv) operator interface configuration information, which defines the operator interface system used to control the conversion machine.

Figures 12A and 12B summarise an example of some valid events generated by plant personnel actions which form part of the event configuration information for an exemplary conversion machine. These constitute part of the predefined production events which may occur during various ones of the states of operation of the conversion machine shown in Figures 4 and 5. The feedback system controller acts to interrupt the operation of the control system 30 upon detection of one or more of these predefined production events in a particular current state, so that the conversion machine remains in that current state. The feedback system controller 52 only acts to uninterrupt the operation of the control system 30 when a second predefined production event is detected subsequent to the first predefined production event during that current state. For example, once a "wait electrician" event has been generated by a conversion machine operator, the control system acts to interrupt the operation of the conversion machine, until a second event is generated by an electrician/supervisor. Upon detection of this second event, the control system 30 acts to change the current state of the conversion machine to a downtime state.

Changes can only be made to the shift configuration information and conversion machine event configuration information when the system is in the "conversion machine idle" state 60 of the main state transition diagram shown in Figure 4. This is required because changes made on the fly to the system configuration could result in erratic behaviour of the process feedback control system 50 if the current shift or event is not part of the new configuration or the download is aborted.

The basic conversion machine configuration can be updated when the system is in either the "conversion machine idle" state 60 or "maintenance shift" state 62 of the main state transition diagram of Figure 4 or in the "no job" state 70 of the "production shift" state transition sub-diagram of Figure 5. This is required because changes made on the fly to the system configuration with a job in progress could result in erratic behaviour of the process feedback control system 50.

The operator interface system 53 is adapted to allow plant personnel, such as an operator, supervisor or maintenance worker, to request the manual configuration of the process feedback control system 50. When manual system configuration is requested, the supervisor is requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The feedback system controller 52 will then request that the Interface server 51 download the appropriate configuration information. The ability of a user to request full system configuration, "shift configuration" and "conversion machine event configuration" is disabled when the system is in any state other than the "conversion machine idle" state 60 of the main state transition diagram in Figure 4. The ability of a user to request "basic conversion machine configuration" is disabled whenever the system is in the "production shift" state 61 of the main state transition diagram in Figure 4 and there is an active job.

The system may also be automatically configured. When a change is made to any system configuration information in the Logistics system 31, the logistics system 31 will automatically request that the interface server 51 download the new configuration information to the appropriate feedback system controller 52. The logistics system 31 will indicate to the Interface server 51 which information to download for the appropriate conversion machine. The interface server 51 will then indicate to the appropriate feedback system controller 52 that there is new configuration information ready to be read and wait until the feedback system controller requests the configuration information to be downloaded.

When the feedback system controller 52 is restarted following reconfiguration it will return to the "conversion machine idle" state 60 of the main state transition diagram in Figure 4. The system will then check to see if it has a valid "basic conversion machine configuration", "conversion machine event configuration", and "shift configuration". If a valid configuration for any of these does not exist then the feedback system controller 52 will automatically request the appropriate system configuration information from the Logistics system 31. While ever the conversion machine is not fully configured, it will remain locked in the "conversion machine idle" state 60. When the process feedback control system 50 is fully configured, the system will download jobs required to be completed by the conversion machine from the logistics system 31 as required to fully populate the job schedule. The process feedback control system supports a rolling schedule. This means that as a new schedule is sent to the conversion machine, it completely replaces the old schedule, with the exception of the job currently being run on that machine. The schedule is automatically sent from the logistics system 31. Each time the scheduler commits a new schedule it replaces the old schedule completely.

As will be explained below, in order to assist with schedule adherence, an operator is only given permission to start the first job on the schedule. If an operator wants to start a job further into the schedule, the process feedback control system prompts for a supervisor access code to be entered. There is functionality to enter manual jobs, and also to reject jobs if need be from the schedule. These functions can only be performed by a supervisor. The process feedback control system has an option to "enable operator entry" which enables all these functions to be accessed by the operator if required. This can only be activated by the supervisor.

If a shift was previously logged in then an operator will be asked via the operator interface system 53 to confirm that the current shift is correct. If the shift is incorrect then a shift logout will automatically be performed and a "shift logout" event 64 recorded. If there was previously an active job then containing details of the active job will be displayed to an operator by the operator interface system 53 and an operator will be asked to confirm that the active job is correct. If the active job is incorrect then the active job will be completed and a "job complete" record sent to the logistics system 31. If the job schedule is not empty then the job schedule page will be selected on the operator interface system 53 requesting the operator to confirm that the job schedule is correct. If the job schedule is incorrect then a new job schedule will be downloaded from the logistics system 51. If no shift is currently logged in, the system will return to the "conversion machine idle" state 60 and if a maintenance shift was previously logged in, the system will return to the "maintenance shift" state 62. If a production shift is currently logged in, the system will return to either the "stopped", "stopped infeed interrupt", "no job", "setup" or "setup interrupted" states, respectively referenced 75, 74, 70, 71 and 76, depending on whether a job is active or not.

When no shift is logged into the process feedback control system 50, the system will be in the "conversion machine idle" state 60 of the main state transition diagram and the conversion machine infeed will be interrupted. All job selection and production tracking functions on the operator interface system 53 will be disabled in this case and if the system configuration information is not complete, the shift login function will also be disabled on the operator interface system

Conveniently, all shift related functions are performed through the operator interface system 53, in conjunction with the bar code scanner or other operator data input device. A new shift logs into the process feedback control system 50 by a user selecting the shift login function via the operator interface system 53. If a shift is currently logged into the system then the shift logout procedure, as set out below, will first be performed. Following a successful shift logout, the shift login procedure outlined below will be performed.

The user will be requested by the operator interface system 53 to select the shift name and enter their personnel identification number. The user can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The type of login performed depends on the classification of the personnel identification number entered or scanned. If the personnel identification number is that of an "operator" or "supervisor" then event 63 will be detected and a production shift state 61 will be logged in. If the personnel identification number is that of an "electrician" or "fitter" then event 65 will be detected and process feedback control system 50 a maintenance shift (state 62) will be logged in.

When a production shift logs into the process feedback control system 50 with no active job, the "no job" state 70 within the "production shift" state transition sub-diagram will become active and all shift related statistics will be reset. When a production shift logs into the process feedback control system 50 with an active job, the "setup" state 71 within the "production shift" state transition sub-diagram will become active, the infeed interrupt to the control system 30 will be removed and all shift related statistics will be reset.

When a maintenance shift logs into the process feedback control system 50, the system will continue to operate in the main state transition diagram within the "maintenance shift" state 62 regardless of whether there is an active job or not. When a shift logs into the system, a "no shift logged in" event will be recorded with the start time as when the previous shift logged out and the end time as the current system time. When a new shift has successfully logged into the system, a "production shift login" event 63 or "maintenance shift login" event 65 will be recorded with the event start and event end times set to the current system time.

A login change in the middle of a shift may be performed by a user via the operator interface system 53, after which if a shift is currently logged into the system then the operator interface system 53 will firstly request the new user to enter their personnel identification number. At this point the user can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The user will then be requested to enter either the personnel identification number of the person who originally logged the shift in or the personnel identification number of a "supervisor". At this point the user can either manually enter their personnel identification number or scan the bar code on their personnel identification tag.

When a login change is performed, no change of state occurs within the process feedback control system and no infeed interrupt is performed.

A shift logs out of the process feedback control system 50 by a user selecting the shift logout function on the operator interface system 53, after which if a shift is currently logged into the system, then a the user will be requested to enter either the personnel identification number of the person who logged the shift in or the personnel identification number of a "supervisor". At this point the user can either manually enter their personnel identification number or scan the bar code on their personnel identification tag.

Each time a shift logout is performed, either a "production shift logout" event 64 or "maintenance shift logout" event 66 will be recorded with the start time set to when the shift logged in and the end time as the current system time. The system will then return to the "conversion machine idle" state 60 of the main state transition diagram with the infeed interrupted.

If there is an active job when a production shift logs out, a "job completed" record will be sent to the logistics system, a "job end" event will be recorded but no change made to the active job, the event start time will be set to the start time of the active job and the event end time to when the shift logged out.

If there is no active job when a production shift logs out, the current event will be recorded with the event start time set to the start time of the event and the event end time to when the shift logged out. The logistics system 31 maintains a rolling schedule of jobs for each conversion machine, which may be updated at any time. When a new job schedule is received by the logistics system 31, the logistics system 31 will lock the existing ob schedule to prevent the process feedback control system 50 from reading new jobs while the schedule is updated. The logistics system 31 will delete the active job from the job schedule and reduce the "quantity scheduled" field by the "quantity produced" field for all jobs since the new scheduling process was commenced. Those jobs for which the "quantity produced" field satisfies the job completion criteria will then be removed from the new job schedule by the logistics system. The logistics system 31 will then overwrite the entire job schedule with the new job schedule with the exception of the active job which will be retained unchanged, set the status of all other jobs to "waiting" and unlock the job schedule. The interface server 51 will then wait until the feedback system controller 52 requests the job schedule information be downloaded.

The feedback system controller 52 will attempt to keep the local job schedule buffer full at all times by always downloading enough jobs to keep the buffer full. If the feedback system controller 52 is about to download a complete new job schedule, it will first erase the entire existing job schedule.

An operator can select a job to run by selecting the "start next job" button 101 or "start job" button 102 on the job schedule page 100 displayed by the operator interface system 53, as seen in Figure 6. The "start job" and "start next job" buttons will only be active when the system is in the "no job" state 70 within the "production shift" state transition sub-diagram of Figure 5.

When the "start next job" button 101 is selected, the operator must then confirm that the next scheduled job from the job schedule is to be started. When the "start job" button 102 is selected, the user will be prompted to enter the number of the job 103 from the job schedule to be started and a the supervisor then requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The feedback system controller will transfer the selected job from the job schedule to become the active job to be completed by the conversion machine.

The manual entry of jobs directly into the process feedback control system 50 through the operator interface system 53 at each conversion machine can normally only be performed by a supervisor. A supervisor can grant manual job entry to an operator by selecting a "enable operator entry" button 104 on the job schedule page. The "enable operator entry" button 104 will be active whenever the system is in the "no job" state 70 within the "production shift" state transition sub-diagram of Figure 5 without manual job entry override enabled. When the "manual job" button 105 is selected, the supervisor will be requested to enter their personnel identification number via the operator interface system. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. To cancel the operator entry, the "cancel operator entry" button 106 on the job schedule page 100 should be selected. The "cancel operator entry" button 106 will be active whenever operator job entry is enabled. Manual job entry will be automatically cancelled when a shift logout is performed.

A user can manually enter a job through the local operator interface system 53 by selecting the "manual job" button on the job schedule page. The "manual job" button 105 will only be active when the system is in the "no job" state 70 within the "production shift" state transition sub-diagram of Figure 5.

If the "manual job" button 105 is selected without operator job entry enabled, the supervisor will be requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The user will then be requested to enter the factory order number 110 and quantity ordered 111. The user can either manually enter the factory order number 110 or scan the factory order number 110 bar code on a job sheet.

If the factory order number 110 entered is in the list of scheduled jobs in the feedback system controller 52, the user will be asked to confirm that the job from the existing schedule is to be started. If the user confirms the job is to be started then the job will be removed from the job schedule and made the active job, otherwise the factory order number 110 entered will be erased.

If the factory order number 110 was not in the list of scheduled jobs in the feedback system controller 52 then the logistics system 31 will be queried to retrieve information on the factory order number 110. If the query to the logistics system succeeds then, the user will be asked to confirm that the scheduled job from the logistics system 31 is to be started. If the user confirms the job is to be started then the job will be made the active job, otherwise the factory order number 110 entered will be erased.

A supervisor can transfer a job from the job schedule of another conversion machine to become the active job on the local conversion machine. The "transfer job" button 107 will only be active when the local process feedback control system 50 is in the "no job" state 70 within the "production shift" state transition sub-diagram of Figure 5 and the job schedule of another conversion machine is selected.

The supervisor must first select the job schedule of the conversion machine containing the job to be transferred. The supervisor then selects the "transfer job" button 107 on that job schedule page. When the "transfer job" button 107 is selected, the user will be prompted to enter the number 103 of the job from the job schedule to be transferred the supervisor requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag and the job will be transferred.

The local feedback system controller will then interact with the remote feedback system controller to delete the selected job from the remote feedback system controller's job schedule and transfer it to become the active job on the local feedback system controller.

An operator can complete a job by selecting the "complete job" button 108 on the job schedule page. The "complete job" button 108 will be active when the system is in the "setup" state 71, "setup interrupted" state 76, "stopped infeed interrupt" state 74 or "stopped" state 75 within the "production shift" state transition sub-diagram of Figure 5. If the operator does not want to complete a job then the operator will be requested to increase the quantity scheduled after which the infeed inhibit will be removed.

When either the "complete job" button 108 is selected or the automatic completion of a job is accepted, the operator will be requested to confirm the job is complete. When a job is completed, the feedback system controller 52 will remove the completed job from the system and send a corresponding signal to the logistics system 31. When the logistics system 31 receives this signal it will remove the job specified from the job schedule for the specified conversion machine. The system will then return to the "no job" state 70 of the "production shift" state transition sub-diagram of Figure 1.

A supervisor can reject a job from the job schedule by highlighting a job on the job schedule 100 and selecting a "reject job" button 109. The "reject job" button 109 will be active when the system is in any state within the "production shift" state transition sub-diagram of Figure 5. When the "reject job" button 109 is selected, the user will be prompted to enter the number of the job from the job schedule to be rejected and the supervisor requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag. The supervisor will then be requested to enter information on why the job has been rejected. The selected job will be removed from the job schedule and the feedback system controller 52 will send a "reject job" signal to the logistics system 31. When the logistics system receives a "reject job" signal, the job rejected will be removed from the job schedule for the specified conversion machine.

"Open time" for a shift is defined as the total time a shift is logged into the system minus all time tracked in events that are classified as "planned downtime", "run time" for a shift is defined as the "open time" for the shift minus all time tracked in events that are classified as "unplanned downtime". "Open time" for a job is defined as the duration of a job from it's start time to end time minus all time tracked in events that are classified as "planned downtime". "Run time" for a job is defined as the "open time" for the job minus all time tracked in events that are classified as "unplanned downtime".

Any event with a duration of less than "y" seconds will not be recorded. The value of "y" is configurable by the user. The time will be recorded against a miscellaneous downtime data field and the contents of a related miscellaneous downtime frequency data field incremented. All events recorded will be recorded with the personnel identification number set to the current logged in operator's personnel identification number, unless otherwise noted, along with the number of kicks for the active job (if any). When the system is in a downtime event in any state of the "production shift" state transition sub- diagram of Figure 5, other than for planned maintenance, the time will be recorded against downtime.

If there is an active job and the job is not in setup, then the system will be in either the "stopped infeed interrupted" state 74 or "stopped" state 75 of the "production shift" state transition sub-diagram of Figure 5. When the system enters the "setup" state 71 of the "production shift" state transition sub-diagram of Figure 5, the start time for the setup will be set to the shift login time if this is the first job in a shift or otherwise to the end time of the previous job. When a job is in the "setup" state 71 and "a" cardboard sheets have been fed into the conversion machine - an event known as a "kick" - are detected as having been made within "b" seconds, the system will detect the event 79 and automatically move to the "running with flow" state 72. The values of "a" and "b" are configurable by the user.

When a job is in the "setup interrupted" state 76 and "a" kicks are detected within "b" seconds, the system will detect the occurrence of the event 92 and automatically move to the "running with flow" state 72. The current event will be recorded with the event start time set to when the event started and the event end time set to the time the first of "a" kicks was detected. When a job moves to the "running with flow" state 72, the event start time will be set to when the setup started and the event end time will be set to the time the first of "a" kicks was detected.

If an operator completes the active job or the shift ends while the system is in the "setup" state 71, the system will automatically move to the "no job" state 70 of the "production shift" state transition sub-diagram of Figure 5. If an operator completes the active job or the shift ends while the system is in the "setup interrupted" state 76, the system will automatically move to the "no job" state 70. The current event will be recorded with the event start time set to when the event started and the event end time set to the time the job was completed or the shift was ended.

When the system moves to the "no job" state 70, a "job in setup" event will be recorded with the event start time set to when the setup started and the event end time set to the time the job was completed or the shift was ended. All downtime events in the "setup interrupted" state 76 will be recorded as downtime for the active job.

When a job is in the "running with flow" state 72 and no infeed kicks are detected within "x" seconds, where the value of "c" is configurable by the user, the system will detect event 80 and move to the "running with no flow" state 73.

If the system is in the "running with no flow" state 73 and an infeed kick is detected within "y" seconds, then the system will detect event 81 and return to the "running with flow" state 72 automatically. All time in the "running with no flow" state 73 plus "x" seconds will be recorded against miscellaneous downtime and the miscellaneous downtime frequency incremented. If the system is in the "running with no flow" state 73 and no infeed kicks are detected within "y" seconds then the system will detect event 82 and move to the "stopped infeed interrupt" state 74 and the infeed will be interrupted. The current event will be "wait downtime reason" with an event start time of when the last infeed kick was detected.

When the system is in the "stopped" state 75 and "c" kicks are detected within "d" seconds, an event 83 will be detected and the job will move to the "running with flow" state 72. When a job moves from the "stopped" state 75 to the "running with flow" state 72 and the duration of the event is greater than or equal to "y" seconds, the current event will be recorded with the event start time set to when the event started and the event end time set to the time the first of "c" kicks occurred. If the event is less than "y" seconds, the time will be recorded against miscellaneous downtime.

A total of seven (7) illuminated push buttons 120 to 126 are located adjacent to each conversion machine to enable an operator to request a specific type of support personnel to attend to the conversion machine. The seven (7) push buttons, in this example, are for supervisor, quality assurance, ink, forme, stereo, fitter and electrician.

The push buttons are active in all states except the "running with flow" state 72 and "running with no flow" state 73. When a push button is depressed, it will be illuminated and will remain illuminated until either the system returns to running or one of the support personnel called arrives to fix the problem.

When the first push button is depressed (if multiple personnel types are called) an appropriate event will be recorded to account for any downtime not yet recorded up until when the push button was depressed. The system will now be prepared to record time against one of the following events "wait forme", "wait ink", "wait stereo", "wait electrician", "wait fitter", "wait quality assurance" or "wait supervisor".

If the system returns to running after support personnel have been called to attend the Conversion machine but without any of those personnel called identifying their arrival to the system, and the event duration is greater than or equal to "y" seconds, an event will be recorded against the first personnel type called. The event start time will be set to when the first call button was pressed (if multiple personnel types are called) and the event end time set to the time the system returned to running. If the event is less than "y" seconds, the time will be recorded against Miscellaneous Downtime. When a support person arrives and determines that they are responsible for resolving the most significant component of any problem then they will identify their arrival at the conversion machine. A support person identifies their arrival by either manually entering their personnel identification number into operator interface system 53 or by scanning the bar code on their personnel identification tag, after which the relevant illuminated push button will be turned off.

If a support person other than one of those that has been called either manually enters or scans their personnel identification number, a prompt will be displayed indicating that and invalid personnel identification number has been entered.

The appropriate "wait forme", "wait ink", "wait stereo", "wait electrician", "wait fitter", "wait quality assurance" or "wait supervisor" event will then be recorded with the personnel identification number set to the support person's personnel identification number. The event start time will be set to when the first call button was pressed and the event end time set to when the support person indicated they arrived.

When a support person identifies that they have arrived to fix any problem, the current event will become one of the following events "forme problem", "ink problem", "stereo problem", "electrical problem", "mechanical problem", "job check" or "supervisor action". The following table summarises the event transitions for each type of personnel:

When the support person has fixed the problem, they will identify this to the system by either manually entering their personnel identification number into the operator interface system 53 or by scanning the bar code on their personnel identification tag.

When a support person finishes fixing a problem, the current event will be recorded with the personnel identification number set to the support person's personnel identification number. The event start time will be set to when the support person indicated they arrived and the event end time set to when the downtime was finished. The current event will then be set to "no crew" and all call lights will be extinguished.

If the system returns to running when the current event is either "forme problem", "ink problem", "stereo problem", "electrical problem", "mechanical problem" or "supervisor action" and the event duration is greater than or equal to "y" seconds, the current event will be recorded with the personnel identification number set to the support person's personal identification number.

The event start time will be set to when the support person indicated they arrived and the event end time set to when the first of "c" kicks occurred. If the event is less than "y" seconds, the time will be recorded against miscellaneous downtime. Under most circumstances, only one (1) support person should identify their arrival to the system for each downtime. However, if multiple support personnel indicate their arrival to the system for a single system downtime then individual events will be recorded to indicate each form of downtime.

When a second or subsequent support person who has been called indicates their arrival to the system, the current event will be recorded with the personnel identification number set to the original support person's personnel identification number. The event start time will be set to when the original support person indicated they arrived and the event end time set to when the current support person indicated they arrived. The current event will then become either "forme problem", "ink problem", "stereo problem", "electrical problem", "mechanical problem", "job check" or "supervisor action" depending on the type of support person.

When the system is in any state within the "production shift" state transition sub-diagram other than "running with flow" state 72 and "running with no flow", a user can change the current through an event screen on the operator interface system 53.

If the exit permission field for the current event does not allow an operator to exit the event, then the supervisor will be requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag.

The event screen will display a list of all events that can be entered by an operator based on the entry permission field for each event type defined in the logistics system. When a new event is selected from the list and the duration of the existing event is greater than or equal to "y" seconds, the current event will be recorded with the personnel identification number set to the operator or supervisors personnel identification number as appropriate. The event start time will be set to original event start time and the event end time set to the current system time. If the current event is less than "y" seconds, the time will be recorded against miscellaneous downtime. The current event will then be set to the event selected by the operator or supervisor.

When the system is in any state within the "production shift" state transition sub-diagram other than "running with flow" state 72 and "running with no flow" state 73, a user can complete the current event through the event screen.

If the exit permission field for the current event does not allow an operator to exit the event then, the supervisor will be requested to enter their personnel identification number. The supervisor can either manually enter their personnel identification number or scan the bar code on their personnel identification tag.

If the duration of the existing event is greater than or equal to "y" seconds, the current event will be recorded with the personnel identification number set to the operator or supervisors personnel identification number as appropriate. The event start time will be set to original event start time and the event end time set to the current system time. If the current event is less than "y" seconds, the time will be recorded against miscellaneous downtime.

If the system is in the "setup interrupted" state 76, the system will return to the "setup" state 71 of the "production shift" state transition sub-diagram and there will be no current downtime event. If the system is any state other than the "setup interrupted" state 76 of the "production shift" state transition sub- diagram, the current event will become "wait downtime reason" and the system will be in the "stopped infeed interrupted" state of the "production shift" state transition sub-diagram.

All boxes produced when a job is active are counted and recorded against the active job. The number of boxes produced will be based on the number of kicks at the infeed to the conversion machine.

When boxes are produced with a production shift logged into the system and an active job, all boxes produced when the system is in the "setup" state 71 will be recorded against setup number of boxes. All boxes produced when the system is in the "running with flow" state 72 will be recorded against run number of boxes. When boxes are produced when a maintenance shift is logged into the system and a job is active, all boxes produced will be recorded against maintenance number of boxes.

When quality assurance has been requested to be performed on a job, the infeed will be interrupted as soon as the job enters the "running with flow" state 72 in the "production shift" state transition sub-diagram for the first time. The "stopped infeed interrupt" state 74 within "production shift" state transition sub- diagram will become active and the current event will be "wait quality assurance".

The text message display 54 at each conversion machine has three different modes of operation depending on the status of operation of the conversion machine as detailed below. In each mode of operation, the text message display will scroll each message left to right across the display (if longer than 16 characters) and scroll between messages vertically ten ( 10) seconds after each message has been fully displayed. When the conversion machine is in either the "running with flow" state 72 or "running with no flow" state 73, the following information will be displayed: 1. Current Job Running Speed in Kicks/Open Hour

2. Shift To Date Running Speed in Kicks/Open Hour

3. "Running Behind/On/Ahead Of Target"

Whether the conversion machine is running behind/on/ahead of target is be determined based on whether the shift to date running speed is less than the slow running percentage of target below the target kicks/open hour, greater than the fast running percentage of target above the target kicks/open hour or between the two (2) set points.

When the conversion machine is in the "setup" state 71 , the following information will be displayed: 1. Target Setup Time 2. Current Setup Time 3. Product Description

When the conversion machine is in any state other than "running with flow" state 72, "running with no flow" state 73 or "setup" state 71, the following information will be displayed:

1. Current Event Description and Duration

If the system is waiting on support personnel to attend to the conversion machine then multiple events may be active, all of which should be displayed. This mode of operation is also active when the conversion machine is in the "conversion machine idle" and "maintenance shift" states of the main state transition diagram.

A total of fourteen screens are available to be displayed on the operator interface system 53 to provide an effective operator interface for users to interact with the process feedback control system 50. The first nine of these screens - namely, conversion machine overview, job selection, scheduled job details, event entry, conversion machine configuration, event configuration, alarms, event history and job history - enable various conversion machine control functions to be performed by the user. The remaining five screens - namely, job progress trend, job downtime, shift performance report, shift progress trend and shift downtime - enable the monitoring of various production reporting statistics for a conversion machine.

1. Conversion machine Overview

The purpose of this screen is to display a graphical overview of the conversion machine selected and provide details on the active job. Figure 7 shows an example of this screen. The following factory order information will be displayed for the active job: 1. Factory Order Number

2. Customer Number

3. Customer Name

4. Customer Requested Delivery Date

5. Product Code 6. Product Description

7. Scheduled Start Time

8. Quantity Ordered

9. Quantity Already Manufactured

10. Quantity Scheduled

The following active job progress statistics will be displayed:

1. Number Of Kicks

2. Quantity Of Boxes Manufactured

3. Total Setup Time 4. Target Setup Time 5. Total Run Time

6. Total Open Time

7. Total Downtime

8. Downtime % Of Open Time

9. Target Downtime % Of Open Time

10. Average Speed Kicks/Run Hour

11. Target Speed Kicks/Run Hour

12. Average Speed Kicks/Open Hour

13. Target Speed Kicks/Open Hour

2. Job Selection

This purpose of this screen is to provide details on the logistics job schedule for the conversion machine selected and allow a user to start, reject and complete jobs.

The logistics job schedule for the conversion machine will be displayed as a vertical list of scheduled jobs in sequence with "page down" and "page up" buttons to navigate through the list. The following information will be displayed for each scheduled job: 1. Factory Order Number

2. Customer Name

3. Product Description

4. Scheduled Start Time

5. Quantity Scheduled

A user can view the details on a job from the job schedule by selecting the "job details" button adjacent to each job. When the "job details" button is selected, the scheduled job details screen will be displayed. The "start next job", "start job" "transfer job", "manual job", "manual job entry override", "cancel manual job entry override", "complete job" and "reject job" buttons whose functionality has previously been described in the document will be located on this screen.

3. Scheduled Job Details

This screen will display all details received from the logistics system on the scheduled job selected from the job selection screen. The following information will be displayed for the job selected:

1. Factory Order Number

2. Customer Number

3. Customer Name

4. Customer Requested Delivery Date 5. Product Code

6. Product Description

7. Scheduled Start Time

8. Quantity Ordered

9. Quantity Already Manufactured 10. Quantity Scheduled

11. Target Setup Time

12. Target Downtime % Of Open Time

13. Target Speed Kicks/Run Hour

14. Target Speed Kicks/Open Hour 15. Forme

16. Stereo No 1

17. Stereo No 2

18. Stereo No 3

19. Stereo No 4 4. Event Entry

This screen will allow a user to enter new events, indicate the arrival of service personnel and the completion of service work. The screen will display the current event code, event description, event start time, factory order number and number of kicks.

5. Convention Machine Configuration

This screen will display the current basic conversion machine and shift configuration information for the conversion machine selected. Figure 8 shows an example of this screen.

6. Event Configuration

This screen will display the event configuration for the conversion machine selected.

7. Alarms

The purpose of the alarms screen is to display a list of the active and previous alarms for the conversion machine selected. The user will be able to acknowledge alarms individually or acknowledge all alarms at once.

8. Event History

This screen will display a list of the events for the conversion machine selected.

The event history for the conversion machine will be displayed as a vertical list of events in chronological order (most recent first) with "page down" and "page up" buttons to navigate through the list. The following information will be displayed for each event:

1. Event Description

2. Factory Order Number

3. Number Of Kicks 4. Personnel Identification Number 5. Event Start Time

6. Event End Time

9. Job History This screen will display a list of the completed jobs for the conversion machine selected. The job history for the conversion machine will be displayed as a vertical list of jobs in chronological order (most recent first) with "page down" and "page up" buttons to navigate through the list. The following information will be displayed for each job: 1. Factory Order Number

2. Production Work Centre

3. Scheduled Work Centre

4. Setup Number Of Kicks

5. Maintenance Number Of Kicks 6. Run Number Of Kicks

7. Quantity Manufactured

8. Setup Start Time

9. Setup End Time

10. Job End Time 11. Miscellaneous Downtime Time

12. Miscellaneous Downtime Frequency

13. Comment

Each Feedback system controller 52 will calculate and maintain basic production reporting statistics for the conversion machine that it is controlling. This information will be able to be viewed from the local operator Interface system 53 to provide immediate feedback to plant personnel on operation of the conversion machine. For the active job, the production statistics detailed below will be calculated and maintained by the feedback system controller 52, which can be viewed from the operator interface system 53. Each time a new job is started the active job statistics will be reset to zero.

1. Number Of Kicks

2. Quantity Of Boxes Manufactured

3. Total Setup Time

4. Total Run Time 5. Total Open Time

6. Total Downtime

7. Downtime % Of Open Time

8. Average Speed Kicks/Run Hour

9. Average Speed Kicks/Open Hour The total downtime and number of occurrences for each downtime event type including miscellaneous downtime will be accumulated for the active job and all four shifts. Each time a new "production shift" logs into the system, the downtime event statistics for the current shift will be reset to zero. Each time a new job is started, the downtime event statistics for the active job will be reset to zero.

For each of the four possible shifts, the statistics detailed below will be calculated for production shifts only and maintained for the each shift, month to date for each shift and month to date total for all shifts. Each time a new shift is started the last shift statistics for that shift will be set to zero and when the first shift starts after 12:00am on the first day of each month, the month to date statistics for all shifts will be set to zero.

1. Total Setup Time 2. Setup Time % of Open Time 3. Average Setup Time

4. No Off Setups

5. Total Run Time

6. Run Time % of Open Time 7. Run Speed Kicks/Run Hour

8. Total Kicks

9. Total Downtime Time

10. Downtime % of Open Time

11. Average Downtime Duration 12. No Off Downtime Events

13. Total Open Hours

14. Open Time % Of Shift Time

15. Run Speed Kicks/Open Hour

16. % Waste Boxes of Total Boxes

A following screen will be devoted to providing reporting and trending of the operation of the operations feedback system as described below:

1. Job Trend This screen will display a trend of the average speed in kicks/run hour and kicks/open hour against the target speed in kicks/run hour and kicks/open hour for the active job. Figure 9 shows an example of this screen. The average speeds will be calculated and the trend updated every minute.

2. Job Downtime

This screen will display a bar chart of the total downtime for each downtime event type expressed as a percentage of total downtime including miscellaneous downtime for the active job. Figure 10 shows an example of this screen. The total downtime will be calculated and the trend updated every minute. 3. Shift Performance Report

The purpose of this screen is to display shift performance statistics for each conversion machine. Figure 11 shows an example of this screen. The following statistics will be displayed for the shift selected, month to date for the shift selected and month to date total for all shifts:

Waste Statistics:

% Waste Boxes of Total Boxes Setup Statistics: Total Setup Time

Setup Time % of Open Time

Average Setup Time

No Of Setups

Target Setup Time

Run Statistics:

Total Run Hours

Run Time % of Open Time

Speed Kicks/Run Hour Total Kicks

Target Speed Kicks/Run Hour

Downtime Statistics:

Total Downtime Hours Downtime % of Open Time

Average Duration No Downtime Events Target Downtime % of Open Time

Open Statistics: Total Open Hours % Of Shift Hours Speed Kicks/Open Hour Total Kicks Target Speed Kicks/Open Hour

4. Shift Progress Trend

This screen will display a trend of the average speed in kicks/run hour and kicks/open hour against the target speed in kicks/run hour and kicks/open hour for the current "production shift". The average speeds will be calculated and the trend updated every minute.

5. Shift Downtime

This screen will display a bar chart of the total downtime for each downtime event type expressed as a percentage of total downtime including miscellaneous downtime for the current "production shift". The total downtime will be calculated and the trend updated every minute.

It can be seen from the foregoing that the present invention enables the supervisory aspects of process control, job measuring and productivity feedback for production equipment within an industrial plant to be carried out. The process feedback control system ensures that real time feedback is provided to operators, supervisors and other plant personnel, both by shift and by job. Each shift has the ability to view performance statistics for themselves whilst the conversion machine is running, for other shifts on the same machine, or any other machine in the industrial plant.

The process feedback control system interrupts the feed of the conversion machine to ensure that operators, supervisors, maintenance personnel and other plant personnel perform actions to indicate what is happening on a conversion machine. As has been seen above, the feed will be disabled if there is no shift logged into record feedback against, there is no job selected to record feedback against, the machine has stopped running due to a particular cause of downtime, or the selected quantity of feeds has been attained, for example.

The process feedback control system features full redundancy since data provided to each machine from the logistics system 31 is buffered in the interface 32. If for some reason the logistics system 31 is inoperable or unavailable, job scheduling and other data provided in the buffer will ensure that the conversion machine remains operable and no data is lost.

In order to assist with an understanding of the foregoing embodiment of the invention, a typical system flow will now be described. Initially, an operator or supervisor may start the shift, and know carton may be fed through the conversion machine until this is done. Until a shift is logged in, the display device 54 will display the message "no shift logged in for xxx minutes". This enables a supervisor to ensure that a shift does login at a correct time.

If there is a job left setup on the machine, the process feedback control system 50 automatically starts counting setup time against this job. The customer name and product description, target setup time for this job (based on available product/work centre history) and actual setup time so far will be displayed. If there is no job setup, the process feedback control system will automatically change state to the no job state 70. The display device 54 will the display "no job for xx minutes xx seconds" and the feed to the Conversion machine will be disabled until the operator selects the appropriate job. All time experienced in the "no job" state 70 will then be retrospectively allocated to setup time for the job selected. The process control feedback system remains in setup mode until x boxes are run through the machine in y time and an event 79 is detected. These parameters are configurable by the plant personnel. Upon meeting this condition, the process feedback control system shifts to the running with flow state 72, and the display device 54 displays the customer name, product description, the kicks per open hour for this job as well as the kicks per open hour of the shift.

The process feedback control system now remains in the running with flow state 72 measuring kicks over time. If the conversion machine stops running, the state of the machine will pass to the running with no flow state 73 and, if the short downtime exceeds y seconds (typically 90 seconds), then the state will move to stopped infeed interrupt state 74 and the feed to the conversion machine interrupted. The operator will then be prompted for the downtime reason. The machine will not start again until the event 84 of entering an appropriate downtime reason has been carried out by the operator. The operator can enter the downtime reason during the downtime. Once the downtime reason has been entered, the display device 54 will display the downtime reason together with the time spent in the downtime. The feed will then be re-enabled and the machine will pass into the stop state 75.

The process feedback control system will return to the running with flow state 72 once x kicks in y time have been recorded. The short downtimes are accumulated by job and sent back to the logistics system 31 as a total miscellaneous downtime for that job, together with the frequency of short stops.

Upon reaching the scheduled number of through put or boxes processed by the machine, the process feedback control system will automatically interrupt the feed, and promptly ask the operator whether the job is to be ended or to be overrun.

From the foregoing, it can also be seen that the process feedback control system 50 enables various levels of security to be defined for categories of plant personnel who can access the different downtimes on the system. For example, an operator is unable to select a downtime of "mechanical", but can select instead a downtime of "waiting for a fitter". When this downtime is selected, a box appears prompting a fitter to scan their ID code via the bar code scanner 55. The process feedback control system goes into the downtime state of "waiting for fitter" and a message is displayed on the display device 54 together with the amount of time spent waiting for a fitter. If the operator starts running the conversion machine again in this mode, then the process feedback control system will return to the run state 72. If the process feedback control system is in "waiting for fitter" mode, and the fitter scans their card, the system will automatically change state from "waiting for fitter" to "mechanical problem". The system remains in the "mechanical problem" state until the fitter scans their ID card again, to indicate that the service has been completed, or until the machine starts running. Once the fitter scans their ID card to indicate that the service is completed, the system changes state again from "mechanical" to "no crew". If the machine starts running immediately, say within 90 seconds, after the services has been completed, the "no crew" downtime will not be recorded. Accordingly, various production characteristics recorded by the process feedback control system, such as the time spent in current operating states, or between events occurring within a particular state, may be attributed to various free determined categories, including categories associated with different types of plant personnel.

It can also be seen from the foregoing that the process feedback control system displays targets against jobs for setup times, and runtimes. Historical downtime information by job is also displayed.

Many other variations may be made to the above described components and arrangements without departing from the spirit or ambit of the invention. For example, the steps of interrupting the operation of the control equipment when the production equipment is in a current state, and not leaving that state until predefined plant personnel actions and/or production events occur may be extended to use by quality assurance plant personnel. In one embodiment, all jobs flagged as "new jobs" by the logistics system 31 may be automatically stopped at the end of the set-up state 71, and automatically pushed into a wait- for-QA (Quality Assurance) state, quality assurance plant personnel would then be required to confirm that set-up had been performed correctly, before authorising the control system to proceed to a next state. Similar quality assurance checks may be performed at other of the states shown in Figures 4 and 5

Claims

CLAIMS:

1. A process feedback control system for controlling the operation of an industrial plant, said industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering said state of said production equipment from a current state to a next state upon the occurrence of pre-selected conditions, said process feedback control system comprising: detection means for detecting predefined production events occurring during each current state, and at least one feedback system controller for interrupting the operation of said main control system upon the detection of at least a first of said predefined production events when the current state of said production equipment is in one or more predefined states, so that the production equipment remains in that current state, and for uninterrupting the operation of said main control system when at least a second of said predefined production events is detected subsequent to said first predefined production event during that current state.

2. A process feedback control system according to claim 1 , wherein at least some of said production events are generated by production equipment actions.

3. A process feedback control system according to either one of claims 1 or 2, wherein at least some of said production events are generated by plant personnel actions.

4. A process feedback control system according to any one of the preceding claims, wherein configuration information defining said production events is stored in a memory device associated with said feedback system controller.

5. A process feedback control system according to claim 4, wherein one or more production characteristics of said industrial plant are stored in said memory device.

6. A process feedback control system according to claim 5, wherein said production characteristics include information identifying production events that occur during at least some of said plurality of states.

7. A process feedback control system according to either of claims 5 or 6, wherein said feedback system controller acts to periodically transfer said recorded production characteristics to a logistics system in said main control system.

8. A process feedback control system according to any one of the preceding claims, wherein said feedback system controller is a programmable state controller.

9. A process feedback control system according to any one of the preceding claims, and further comprising an operator interface system for controlling the operation of said feedback system controller.

10. A process feedback control system according to any one of the preceding claims, and further comprising display means for displaying selected production characteristics to plant personnel.

11. A process feedback control system according to any one of the preceding claims, wherein said production equipment includes a plurality of separately operable production machines, said process feedback control system including a separate feedback system controller associated with each production machine.

12. A process feedback control system according to any one of the preceding claims, wherein said production machines are conversion machines for the processing of sheet-like material into folded containers.

13. A method of controlling the operation of an industrial plant, said industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering said state of said production equipment from a current state to a next state upon the occurrence of pre-selected conditions, said method including the steps of: (i) detecting the occurrence of predefined production events during each current state,

(ii) interrupting the operation of said main control system upon the detection of at least a first of said predefined production events when the current state of said production equipment is in one or more predefined states, so that the production equipment remains in that current state, and

(iii) uninterrupting the operation of said main control system when at least a second of said predefined production events is detected subsequent to said first predefined production event during that current state.

14. A method according to claim 13, wherein at least some of said production events are generated by production equipment actions.

15. A method according to either one of claims 13 or 14, wherein at least some of said production events are generated by plant personnel actions.

16. A method according to any one of claims 13 to 15, and further including the step of storing configuration information defining said production events in a memory device associated with said feedback system controller.

17. A method according to claim 16, and further including the step of storing one or more production characteristics of said industrial plant in said memory device.

18. A method according to claim 17, wherein said production characteristics include information identifying production events that occur during at least some of said plurality of states.

19. A method according to either of claims 17 or 18, and further including the step of periodically transfer said recorded production characteristics to a logistics system in said main control system.

20. A method according to any one of claims 13 to 19, and further including the step of displaying selected production characteristics to plant personnel.

21. A computer readable memory, encoded with data representing a computer program, for directing the operation of a process feedback control system for controlling the operation of an industrial plant, said industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering said state of said production equipment from a current state to a next state upon the occurrence of pre-selected conditions, said encoded computer readable memory comprising: means for detecting predefined production events occurring during each current state, means for interrupting the operation of said main control system upon the detection of at least a first of said predefined production events when the current state of said production equipment is in one or more predefined states, so that the production equipment remains in that current state, and means for uninterrupting the operation of said main control system when at least a second of said predefined production events is detected subsequent to said first predefined production event during that current state.

22. A computer program element comprising computer program code means for a process feedback control system for controlling the operation of an industrial plant, said industrial plant comprising production equipment operable in a plurality of states, and a main control system for selectively altering said state of said production equipment from a current state to a next state upon the occurrence of pre-selected conditions, said computer program code means causing said process feedback control system to:

(i) detect the occurrence of predefined production events during each current state,

(ii) interrupt the operation of said main control system upon the detection of at least a first of said predefined production events when the current state of said production equipment is in one or more predefined states, so that the production equipment remains in that current state, and

(iii) uninterrupt the operation of said main control system when at least a second of said predefined production events is detected subsequent to said first predefined production event during that current state.