1. A plant monitoring and control system comprising: a control unit connected to a measuring instrument and an actuator installed in a plant, the control unit acquiring instrument data from tht measuring instrument and outputting control data to the actuator; and an operator workstation connected to the control unit over ? communication network, the operator workstation acquiring the instrument data measured by the measuring instrument from the control unit anc outputting the control data for the actuator through the control unit to th( actuator, the control data being based on input data from an operator, the operator workstation comprising: a processing unit; a display unit; and a screen display history database for accumulating a history of a screen display displayed on the display unit, wherein the processing unit comprises: a screen display change-point detection unit detecting a change -poim in the screen display displayed on the display unit; a screen display change-point output unit converting display datr displayed on the screen display detected by the screen display change-poini detection unit into text data.' and a history data storage unit storing the text data, into which the display data is converted, as a history of the screen display in the screer display history database.

2. The plant monitoring and control system according to claim 1, wherein after a control input data requisition dialogue box for prompting the operator to input the input data for controlling the actuator is-displayed, when the operator inputs the input data in the control input date requisition dialogue box, the screen display change-point detection unit determines that the control input data requisition dialogue box ts changed and detects, as a change-point, the change in the control input date requisition dialogue box displayed at the time when the operator inputs tht input data, and wherein the screen display change-point output unit converts , into text data in a predetermined format, data including at least display date displayed on the control input data requisition dialogue box, the input date inputted via the control input data requisition dialogue box, idontificatior data for identifying the operator who inputs the input data, and data on ? date and time when the operator inputs the input data.

3. The plant monitoring and control system according to claim 2, wherein after the instrument data acquired from the measuring. instrument via the control unit is displayed on the display unit, when a plant alarm information display is displayed to warn the operator that ar abnormal data is included in the instrument data displayed on the displa} unit, the screen display change-point detection unit determines that the plant alarm information display is changed, and detects the displayed plant alarm information display as a change-point, and wherein the screen display change-point output unit converts, intc text data in a predetermined format, data including at least display date displayed on the plant alarm information display, data type information for identifying a type of the measured data which causes the plant alarm information display to be displayed, a measured value of the abnormal data and data on a date and time when the plant alarm information display it-displayed.

4. The plant monitoring and control system according to any one 01 claims 1 to 3, wherein the processing unit further comprises: a history data retrieval unit searching the screen displa) history database by receiving an input of a search condition and extracting text data matched with the search condition from the screen display history database; and a screen display reproduction unit reproducing an origina screen display for the history of the screen display corresponding to tht extracted text data by using the extracted text data and displaying tht reproduced screen display on the display unit.

5. A method for controlling a screen display history database; in a plant monitoring and control system including: a control unit connected to a measuring instrument and an actuator installed in the plant, the control unit acquiring instrument data from thf measuring instrument and outputting control data to the actuator! and an operator workstation connected to the control unit over t communication network, the operator workstation acquiring the instrumeni data measured by the measuring instrument from the control unit anc outputting the control data for the actuator through the control unit to the actuator, the control data being based on input data from an operator, the operator workstation including: a processing unit; a display unit.' and the screen display history database for accumulating ?, history of a screen display displayed on the display unit, the method executed by the processing unit, comprising the steps of detecting a change-point in the screen display displayed or the display unit,' converting display data displayed on the screen display detected in the detecting step into text data,' and storing the text data, into which the display data is converted as a history of the screen display in the screen display history database.

6. The method for controlling the screen display history database according to claim 5, wherein after a control input data requisition dialogue box for prompting the operator to input the input data for controlling the actuator is displayed, when the operator inputs the input data in the control input date requisition dialogue box, the detecting step executed by the processing unit determines that the control input data requisition dialogue box is changed and detects, as a change-point, the change in the control input date requisition dialogue box displayed at the time when the operator inputs the input data, and wherein the converting step executed by the processing unit converts into text data in a predetermined format, data including at least display date displayed on the control input data requisition dialogue box, the input date inputted via the control input data requisition dialogue box, idontificatior data for identifying the operator who inputs the input data, and data on i date and time when the operator inputs the input data.

7. The method for controlling the screen display history database according to claim 6, wherein after the instrument data acquired from the measuring instrument via the control unit is displayed on the display unit, when a plam alarm information display is displayed to warn the operator that the abnormal data is included in the instrument data displayed on the display unit, the detecting step executed by the processing unit determines that the plant alarm information display is changed, and detects the displayed plam alarm information display as a change-point, and wherein the converting step executed by the processing unit converts into text data in a predetermined format, data including at least display date displayed on the plant alarm information display, data type information foi identifying a type of the measured data which causes the plant alarm information display to be displayed, a measured value of an abnormal data and data on a date and time when the plant alarm information display it-displayed.

8. The method for controlling the screen display history database according to any one of claims 5 to 7, the method executed by the processing unit, further comprising the steps of: searching the screen display history database by receiving ar input of a search condition and extracting text data matched with the search condition from the screen display history database,' and reproducing an original screen display for the history of tht screen display corresponding to the extracted text data by using th( extracted text data and displaying the reproduced screen display on th( display unit. <\. A plant monitoring and control system comprising, substantially as herein described with reference to accompanying drawings and example.

10. A method for controlling a screen display history database in a plant monitoring and control system, substantially as herein described with reference to accompanying drawings and example.

PLANT MONITORING AND CONTROL SYSTEM, AND METHOD FOR CONTROLLING SCREEN DISPLAY HISTORY DATABASE
BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION [0001]
The present invention relates to a plant monitoring and control system which monitors and controls operating conditions of a plant anc accumulates histories of screen displays for monitoring and controlling the operating conditions, and a method for controlling a screen display history database in the system.
2. DESCRIPTION OF THE RELATED ART [0002]
In a system for monitoring and controlling a plant, histories of screer displays on a display unit are often stored to analyze the cause of a failure ir the operating conditions of the plant. [0003]
Typically, videotaped screen images of the screen displays on the display unit are stored as the histories of the screen displays Recently some of recorded digital images of the screen displays have been compressec when stored, as disclosed in JPH10-326111A. However, there arises r problem that a large amount of storage capacity is required to store ihi histories of the screen displays as image data in a storage device
Additionally, there arises another problem that searching for imager required for analyzing the cause of a failure in a plant is not an easy task. [0004]
There is another method for analyzing the cause of a failure in tht operating conditions of a plant by using histories of data indicating the operating conditions acquired from the plant, not by using screen images JPH09-054615A discloses an example of a plant data acquiring system which provides easy search for histories of data indicating the operating conditions that an operator wants to acquire, by storing histories of various data indicating the operating conditions of a plant in a database, classifying tht stored data into groups, and creating definitions among the groups anc definitions in one of the groups for analyzing the cause of a failure in tht plant. [0005]
There is yet another method for analyzing the cause of a failure in ?. plant by mainly using histories of operations inputted by operators JP2009-223453A discloses an example of a plant monitoring apparatuf-which provides support for creating operation logs based on measured values-acquired during operation of a plant and on operations inputted by operators The created operation logs are used to analyze the cause of a failure in tht plant.
PROBLEM TO BE SOLVED BY THE INVENTION [0009]
The plant data acquiring system described in JPH09-054615A stores various data acquired during operation of a plant in a history database, anc facilitates the search for data which an operator wants to acquire. However the plant data acquiring system needs to search multiple databases tc acquire data necessary for analyzing the cause of a failure, which indicates the operating conditions at the time when the failure occurs in the plant Thus, searching for the desired data in the plant data acquiring system is-not always a simple task. [0010]
The plant data acquiring system described in JPH09-054615A does not take into account histories of operations for the plant inputted bj operators at all. The plant data acquiring system may reproduce a chari showing measured values over time which indicate an operating condition o: the plant related to a failure in the plant. However, the plant date acquiring system may not show a relation between the chart and operations-inputted by operators. Consequently, the plant data acquiring system is noi convenient for analyzing the cause of a failure in the plant. [0011]
The plant data acquiring system described in JPH09-054615A neither stores nor searches histories of screen displays. Therefore JPH09-054615A does not suggest how to reduce the histories of screer displays. [0012]
The plant monitoring apparatus described in JP2009-223453A
creates operation logs including operations inputted by operators anc measured data indicating the operating conditions related to the operations However, JP2009-223453A does not describe how the operation logs arc searched and used when the cause of a failure in the plant is analyzed. [0013]
As described above, no consideration has been made in conventiona plant monitoring and control systems to provide an efficient way of storing and searching histories of screen displays useful for analyzing the cause of i failure in the operating conditions of a plant.
OBJECT OF THE INVENTION [0014]
Therefore, an object of the present invention is to provide a plam monitoring and control system and a method for controlling a screen displaj history database to enable efficient accumulation and search of histories o; screen displays useful for analyzing the cause of a failure in the operating conditions of a plant. [0015]
To achieve the above object, a plant monitoring and control system o: the present invention has an operator workstation including a screen display history database for accumulating histories of screen displays displayed on t display unit. The operator workstation also includes a processing unii including: a screen display change-point detection unit detecting a change ir a screen display displayed on the display unit; a screen display change-poimoutput unit converting display data displayed on the detected screen displaj into text data; and a history data storage unit storing the resulting text dat? as a history of the screen displays in the screen display history database. [0016]
In the plant monitoring and control system of the present invention the screen display change-point detection unit monitors a control input date requisition dialogue box for receiving control data inputted by an operatoi for controlling an actuator in the plant, and a plant alarm mformatior display which warns an operator that abnormal data is included ir instrument data acquired from a measuring instrument in the plant. The screen display change-point detection unit detects a change or an appearance of the monitored screen displays as a change-point. [0017]
When detecting a change-point, the plant monitoring and contro system of the present invention converts display data displayed on the detected screen display into text data which is stored in the screen displaj history database. Thereby, an amount of data stored in the screen displaj history database is reduced. The screen display history database stores only text data, therefore achieving simple search of the screen displaj history database and reducing processing time required for the search sinct the screen display history database stores no image data and requires n( image processing. [0018]
The plant monitoring and control system of the present, inventior
also enables efficient acquisition of histories of screen displays useful for analyzing the cause of a failure in the operating conditions of the plant, b} monitoring the control input data requisition dialogue box and the plam alarm information display and detecting a change or an appearance of the monitored screen displays.
BRIEF DESCRIPTION OF THE DRAWINGS [0020]
FIG. 1 is a diagram showing an exemplary configuration of a plam monitoring and control system according to an embodiment of the present invention!
FIGs. 2A and 2B are illustrations each showing an example of e screen display detected by a screen display change-point detection unit as ? change-point: FIG. 2A is an illustration showing an example of a contro input data requisition dialogue box; and FIG. 2B is an illustration showing an example of a plant alarm information display;
FIGs. 3A and 3B are illustrations each showing an example of screer display change-point data generated by a screen display change-point output unit: FIG. 3A is an illustration showing an example of screen display change-point data generated from the control input data requisition dialogue box shown in FIG. 2A; and FIG. 3B is an illustration showing another example of screen display change-point data generated from the plant alarm information display shown in FIG. 2B;
FIG. 4 is a flowchart showing an exemplary procedure of detecting e
screen display as a change-point and storing the detected change-point in ? screen display history database! and
FIG. 5 is a flowchart showing an exemplary procedure of searching the screen display history database and reproducing a screen display basec on the retrieved history.
BEST MODES FOR CARRYING OUT THE INVENTION [0021]
An embodiment of the present invention will be described in detai with reference to the drawings. [0022]
FIG. 1 is a diagram showing an exemplary configuration of a plant monitoring and control system according to the embodiment of the present invention. As shown in FIG. 1, the plant monitoring and control system 1( includes an operator workstation 20, and one or more of control units 70 each of which is connected to the operator workstation 20 over E communication network 90 to communicate with each other. [0023]
The control units 70 are connected to measuring instruments 8] measuring operating conditions of various devices (not shown) in a plant 80 and to actuators 82 of the devices. The control units 70 acquire data on the operating conditions (e.g., a temperature of a boiler, or an amount o combustion gas flow) from the measuring instruments 81 (e.g., s thermometer for the boiler, or a flowmeter for the combustion gas), anc
output control data (e.g., data on the aperture size of a valve in combustior gas piping) to the actuators 82 (e.g., a motor adjusting the aperture size oV the valve) to control actuation of the actuators 82. [0024]
The operator workstation 20 includes a processing unit 30, a storage unit 40, a display unit 50, and an input unit 60. The processing unit 30 is constituted by, for example, a personal computer or workstation including f central processing unit (CPU) and a memory. The storage unit 40 includes a hard disk unit, the display unit 50 includes a liquid crystal display (LCD) and the input unit 60 includes a keyboard and a mouse, for example. Tht input unit 60 may include a touch panel attached to the display unit 50. [0025]
The processing unit 30 includes functional blocks, such as a plam state acquisition control unit 31, a plant state display control unit 32, i control input data requisition unit 33, a screen display change-poim detection unit 34, a screen display change-point output unit 35, a histon data storage unit 36, a history data retrieval unit 37, and a screen displaj reproduction unit 38. These functional blocks function by executing predetermined programs stored in the memory of the processing unit 30 witr the CPU thereof. [0026]
The storage unit 40 includes a screen display history database 41 which accumulates histories of screen displays displayed on the display unii 50. The detail of the histories stored in the screen display history database
41 will be described in the following description. [0027]
The plant state acquisition control unit 31 acquires instrument date indicating the operating conditions of the plant 80 through the control unh> 70 and the communication network 90. The instrument data is measurec by the measuring instruments 81 every predetermined time interval. The plant state acquisition control unit 31 accumulates the acquired instrumem data in an instrument data history database (not shown) according to tlu type of the data. The plant state acquisition control unit 31 sends contro data inputted by an operator through the input unit 60 and the control input data requisition unit 33 to the control units 70 over the communicatior, network 90. The control units 70 receive the control data, and output it tc the actuators 82 without any change or after it is subjected to calculation as appropriate. [0028]
The plant state display control unit 32 displays the measured valuer of each measuring instrument 81, which are acquired by the plant state acquisition control unit 31, in a chart showing the measured values over time such as a bar chart or a line chart, on the display unit 50 as appropriate tc inform an operator of an operating condition of the plant 80. The plant state display control unit 32 also determines whether or not the instrument data displayed on the display unit 50 includes abnormal data. If abnorma data is included in the instrument data, the plant state display control unit 32 displays alarm information on the display unit 50 to warn the operatoi
that the abnormal state occurs in the plant 80. The instrument data it-determined to be abnormal, for example, in the case where a measured value of the instrument data is greater than a predetermined upper limit or smaller than a predetermined lower limit, or where the measuring instrument 81 measuring the instrument data is out of order. [0029]
The control input data requisition unit 33 receives input date inputted by an operator via the input unit 60, generates control data for the control units 70 and/or the actuators 82 based on the input data, and sends the generated control data through the plant state acquisition control unit 3] to the control units 70. [0030]
The plant state acquisition control unit 31, the plant state displaj control unit 32, and the control input data requisition unit 33 describee above are also included in a typical conventional operator workstation 20 Functional blocks specific to the embodiment of the present invention will be described with reference to FIGs. 2 and 3, as well as FIG. 1. [0031]
Referring to FIG. 1, the screen display change-point detection unit 3< monitors screen displays on the display unit 50, and detects a change or ar appearance of the monitored screen displays as a change-point. The screer display change-point output unit 35 converts display data displayed on the screen display detected by the screen display change-point detection unit 34 into screen display change-point data represented in text data. The history
data storage unit 36 stores the resulting screen display change-point data as a history of the screen display in the screen display history database 41. [0032]
According to the embodiment of the present invention, the screen display change-point detection unit 34 detects only a change or ar appearance of the screen displays useful for analyzing the cause of a failure in the operating conditions of the plant, not a change in all of the screer displays. Thereby, the amount of histories of screen displays stored in tht screen display history database 41 may be reduced. [0033]
FIGs. 2A and 2B are illustrations each showing an example of i screen display detected by the screen display change-point detection unit at-a change-point^ FIG. 2A is an illustration showing an example of a contro input data requisition dialogue box; and FIG. 2B is an illustration showing an example of a plant alarm information display. [0034]
It is highly possible that a mistake which an operator makes ir inputting control data directly causes a failure in the operating conditions o a plant. Therefore, when an operator inputs control data, the screer display change-point detection unit 34 detects the change in the screer display made by the operator, and stores the display data as a history of tht screen display in the screen display history database 41. [0035]
For example, as shown in FIG. 2A, a control input data requisition
dialogue box 51 is displayed on the display unit 50 to prompt an operator tc input control data. When the operator inputs control data in the contro input data requisition dialogue box 51, the screen display change-poim detection unit 34 detects the change in the control input data requisitior dialogue box 51 as a change-point. [0036]
In the exemplary screen display as shown in FIG. 2A, a plant system diagram display 52 is firstly displayed on the display unit 50 to show ? configuration of the devices and the actuators 82, including connections therebetween. When the operator selects one of the actuators 82 (e.g. "Valve A"), a control input data requisition dialogue box 51 for the selectee actuator 82 ("Valve A") is displayed on the plant system diagram display 52. [0037]
In the control input data requisition dialogue box 51, two buttons ("Automatic" and "Manual" buttons) are displayed to select an operatior mode of "Valve A". When the operator selects the "Manual" button, a slider appears on the control input data requisition dialogue box 51 to adjust the aperture size of "Valve A". For example, after the operator selects the "Manual" button in the control input data requisition dialogue box 51, wher the operator changes the aperture size from 10% to 50%, the screen displaj change-point detection unit 34 detects the change in the control input data requisition dialogue box 51 as a change-point. [0038]
The plant state display control unit 32 receives instrument date
measured by the measuring instrument 81 every short period of time, anc displays a chart, such as a line chart, showing the received instrument data over time in the instrument data display 54 on the display unit 50 as-appropriate (see FIG. 2B). The plant state display control unit 32 updates the instrument data display 54 every time when receiving new instrument data, for example, every other one second. However, the screen displa} change-point detection unit 34 does not detect such change in the instrument data display 54 as a change-point, according to the embodiment. [0039]
This is because the instrument data measured by the measuring instrument 81 at least when the plant normally operates is not always usefu for analyzing the cause of a failure in the operating conditions of the plant The instrument data measured by the measuring instrument 81 every short period of time is stored in the instrument data history database (not shown) Therefore, when, for example, a line chart showing the instrument data needs to be displayed, the histories of the instrument data stored in tht instrument data history database are searched, and a chart, such as a lint chart, for the retrieved data is easily generated and displayed. [0040]
While displaying and updating the instrument data display 54 including a line chart, the plant state display control unit 32 determines whether or not there exists any abnormal data in the instrument data displayed in the instrument data display 54. If it is determined that there exists abnormal data in the instrument data, the plant state display contro
unit 32 displays a plant alarm information display 53 to inform an operatoi that an abnormal state occurs. The screen display change-point detectior unit 34 detects the appearance of the plant alarm information display 53 as i change-point. Instrument data being abnormal means that some failure occurs in the operating conditions of the plant. [0041]
In FIG. 2B, a line chart showing values of "boiler Y temperature' over time is displayed in the instrument data display 54. The plant alarm information display 53 is displayed on the instrument data display 54 wher the "boiler Y temperature" exceeds the upper limit temperature of 200°C. A message for informing an operator that the "boiler Y temperature" i^ abnormal, the measured value of the abnormal "boiler Y temperature", anc the date and time when the abnormal data is acquired are displayed in the plant alarm information display 53. [0042]
FIGs. 3A and 3B are illustrations each showing an example of screer display change-point data generated by the screen display change-poim output unit: FIG. 3A is an illustration showing an example of screen display change-point data generated from the control input data requisition dialogue box 51; and FIG. 3B is an illustration showing another example of screer display change-point data generated from the plant alarm informatior display 53. In the screen display change-point data 51t and 53t, the display data displayed on a screen display detected by the screen displaj change-point detection unit 34 as a change-point is represented in text data
The screen display change-point data 51t and 53t are used for reproducing
the original screen display thereof.
[0043]
As shown in FIG. 3A, the screen display change-point data 51i generated from the control input data requisition dialogue box 51 includes text data, for example, indicating that the control input data requisitior dialogue box 51 shows data on "Valve A", and "Automatic" and "Manual buttons and a slider in a form of a bar chart for adjusting the aperture size o: the valve are displayed in the control input data requisition dialogue box 51 The text data in the screen display change-point data 5 It corresponds to the display data displayed on the control input data requisition dialogue box 51. [0044]
The screen display change-point data 51t also include? text date which represents control data inputted by an operator via the control inpui data requisition dialogue box 51, such as "Status: OFF->ON" of the item "Button 1" and "Status: 10->50" of the item "Bar Chart 1". The screer display change-point data 5 It also includes data which is not necessarih displayed in the control input data requisition dialogue box 51, such at "Operator: Ichiro" which is identification data for identifying an operator who inputted the control data, and "Time: 2010/01/01, 12:10:20" which is date/time data on the date and time when the screen display change-poim detection unit 34 detected the change in the control input data requisitior dialogue box 51 as a change-point. [0045]

As shown in FIG. 3B, the screen display change-point data 53i generated from the plant alarm information display 53 includes text data as follows. An alarm message displayed in the plant alarm information display 53 is represented as "Warning Message: boiler Y temperature is abnormal!!" Data type information for identifying the type of the instrument data which caused the plant alarm information display 53 to bt displayed is included as "Name: boiler Y temperature". The measured value of the boiler temperature determined to be abnormal is included as "Temperature: 205". Date/time data for representing the date and time when the screen display change-point detection unit 34 detected the appearance of the plant alarm information display 53 as a change-point is included as "Time: 2010/01/01, 15:30:20". Identification data for identifying an operator monitoring the boiler is included as "Operator: Jiro". [0046]
In the screen display change-point data 53t as shown in FIG. 3B, th( item "Line Chart Type" includes text data for reproducing the instrumem data display 54 at the time when the plant alarm information display 53 was displayed. The text data includes "boiler Y temperature" which is data type information for representing the type of the instrument data displayed in tht instrument data display 54, "Line Chart" which represents the chart type "X: Time, Y Temperature" which represents the data types of the x and j axes of the chart, and "Time Range: 2010/01/01, 15:00:00 - 15:30:20" which represents a range for displaying values. [0047]
Values of "boiler Y temperature" measured over time are not includec in the screen display change-point data 53t. A line chart showing the measured values of "boiler Y temperature" may be reproduced by acquiring; the histories of the measured values of "boiler Y temperature" from the instrument data history database. Therefore, the text data following tht item "Line Chart Type" may include only information on the type of a chan showing the measured values. [0048]
Alternatively, no text data following the item "Line Chart Type" may be included in the screen display change-point data 53t. The reproducec instrument data display 54 as well as the reproduced plant alarm information display 53 are useful for analyzing the cause of a failure in tht operating conditions of the plant. However, if the type of the reproducec chart is not necessarily the same as that of the original chart at the time when the plant alarm information display 53 was displayed, a chart showing, the measured values over time may be easily reproduced by acquiring th( measured values displayed when the plant alarm information display 53 wat displayed from the instrument data history database. [0049]
The screen display change-point output unit 35 generates the screer display change-point data 5It and 53t described above from the control input data requisition dialogue box 51 and the plant alarm information display 53 respectively. The screen display change-point data 51t and 53t may bf generated by using source programs for displaying the control input data
requisition dialogue box 51 and the plant alarm information display 53 The source programs include data names and input parameter names foi displaying the control input data requisition dialogue box 51 and the plant alarm information display 53. To generate the screen display change-poim data 5It and 53t, these data names and input parameter names may be usee without any change or to acquire data necessary for the generation. [0050]
The history data storage unit 36 stores the screen display change-point data 51t and 53t generated by the screen display change-poim output unit 35 as a history of the screen displays. [0051]
As described above, when an operator inputs control data through the control input data requisition dialogue box 51 after the control input date requisition dialogue box 51 is displayed, or when the plant alarm information display 53 is displayed, that is, on an event-driven basis, this change-point in the screen display is accumulated as a history of the screer display in the screen display history database 41. Therefore, the amount o: the histories of the screen displays stored in the screen display histon database 41 is substantially reduced. [0052]
The history data retrieval unit 37 receives a search key inputted vif the input unit 60 by an operator, searches the screen display histon database 41 based on the inputted search key, and extracts text date matched with the search key from the histories of the screen displays
Since all of the histories of the screen displays accumulated in the screen display history database 41 are stored in text, the histories of the screer displays may be searched by simply searching text data of the histories anc by determining whether or not the date/time data or the measured value of ? history is in a specified range, for example. [0053]
The screen display reproduction unit 38 reproduces the origina control input data requisition dialogue box 51 or the original plant alarm information display 53 based on the extracted screen display change-poim data 51t or 53t, which is a history of the screen display retrieved by tht history data retrieval unit 37, and displays the reproduced screen display or the display unit 50. This process of the screen display reproduction unit 3b may be performed by executing programs for displaying the control inpui data requisition dialogue box 51 and the plant alarm information display 5[ with input parameters required for executing the programs. These inpui parameters are acquired from the retrieved screen display change-point datf. 51t or 53t. [0054]
As described above, the history data retrieval unit 37 searches onl\ text data. Therefore, the processing time required for the search executec by the history data retrieval unit 37 is substantially reduced compared with that for histories of the screen displays including image data. Additionally an operator inputs just a keyword, which is any text without any restriction to search the screen display history database 41. Furthermore, analyzing
the cause of a failure in the operating conditions of the plant requires onh the screen display history database 41 to be searched at the first stage tc acquire data relating to an event which may cause a failure, such as a screer display, inputted control data or a measured value, date/time data, and identification data for identifying an operator. Consequently, the histories-of the screen displays stored in text improve the efficiency of the search o: the histories of the screen displays as well as the efficiency of the analysis o: the failure in the operating conditions of the plant. [0055]
With reference to FIGs. 4 and 5 as well as FIGs. 1 to 3 as appropriate the process flow performed in the plant monitoring and control system 1( according to the embodiment of the present invention will be described tc explain the above description on a step-bystep basis. FIG. 4 is a flowchan showing an exemplary procedure of detecting a screen display as f change-point and storing the detected change-point in the screen displaj history database. FIG. 5 is a flowchart showing an exemplary procedure o; searching the screen display history database and reproducing a screer display based on the retrieved history. [0056]
In the procedure as shown in FIG. 4, the processing unit 30 detects f change-point in the screen display displayed on the display unit 50, converts the display data displayed on the detected screen display into text data, anc stores the resulting text data in the screen display history database 41. [0057]
First, the processing unit 30 determines whether or not a control input data requisition dialogue box 51 is displayed on the display unit 5( (Step S10). If the control input data requisition dialogue box 51 is displayec (Yes in Step SIO), the processing unit 30 determines whether or not ar operator inputs control data through the control input data requisitior dialogue box 51 (Step Sll). If the processing unit 30 receives no input o control data (No in Step Sll), the processing unit 30 repeats tht determination in Step Sll until receiving an input through the control inpui data requisition dialogue box 51. [0058]
If the processing unit 30 receives control data inputted by the operator (Yes in Step Sll), the processing unit 30 acquires display dat? displayed on the control input data requisition dialogue box 51 at that timt (Step S12). The processing unit 30 may acquire the display data from e source program for displaying the control input data requisition dialogue bo> 51, as described above. [0059]
The processing unit 30 receives the control data inputted through tht control input data requisition dialogue box 51 by an operator (Step Si3) acquires the identification data for identifying the operator who inputted tht control data (Step S14). and also acquires the current date and time (Step Si5). This identification data is used for uniquely identifying an operator The identification data may be a user ID previously inputted by the operator under the control of an authentication unit (not shown), or persona
information of the operator corresponding to the user ID, such as an operator
name.
[0060]
The processing unit 30 generates the screen display change-poim data 5 It as shown in FIG. 3A, based on the display data displayed on the control input data requisition dialogue box 51, the control data inputted through the control input data requisition dialogue box 51, the identification data on the operator, and the date/time data for the operation as describee above (Step S16). [0061]
If the processing unit 30 determines that no control input dat? requisition dialogue box 51 is displayed (No in Step S10), the processing unii 30 determines whether or not a plant alarm information display 53 is displayed (Step S21). If no plant alarm information display 53 is displayec (No in Step S2l), the process returns back to Step 10. [0062]
If the processing unit 30 determines that the plant alarm informatior display 53 is displayed (Yes in Step S21), the processing unit 30 acquires the display data displayed on the plant alarm information display 53 (Step S22) The processing unit 30 may acquire the display data from a source program for displaying the plant alarm information display 53, as described above. [0063]
The processing unit 30 acquires data items shown in a chart foi instrument data displayed in the instrument data display 54 on which tht
plant alarm information display 53 is displayed (Step S23). The processing unit 30 also acquires the current date and time (Step S24). The processing unit 30 may also acquire the identification data for identifying an operator who is responsible for monitoring the instrument data. [0064]
The processing unit 30 generates the screen display change-point data 53t as shown in FIG. 3B based on the display data displayed on the plant alarm information display 53, the data items shown in the chan displayed in the instrument data display 54 which cause the plant alarm information display 53 to be displayed, the date/time data, and tht identification data on the operator as described above (Step S25). [0065]
After Step S16 or S25, the processing unit 30 stores the screer display change-point data 51t or 53t generated in Step S16 or S25, in tht screen display history database 41 as a history of the screen displays (Stej S27). [0066]
In the above procedure, the screen display change-point detectior unit 34 performs Steps S10, Sll, and S21. The screen display change-poim output unit 35 performs Steps S12 to S16 and Steps S22 to S25. The histon data storage unit 36 performs Step S27. [0067]
As described above with reference to FIG. 4, the histories of tht screen displays represented in text data are stored in the screen display
history database 41. To search the screen display history database 41 anc reproduce the screen display acquired by the search, the procedure as showr in FIG. 5 is performed. [0068]
As shown in FIG. 5, the processing unit 30 receives a search kej inputted by an operator via the input unit 60 (Step S30), searches the screer display history database 41 with the search key (Step S31), and extracts text data matched with the search key from the histories of the screen displays The search key is any text without any restriction, or text representing ?. range of the date/time or measured values. [0069]
The processing unit 30 searches the screen display history database 41 with the search key in Step S31, and determines whether or not any date matched with the search key is extracted from the histories of the screer displays (Step S32). If data matched with the search key is extracted from the histories of the screen displays (Yes in Step S32), the processmg unit 3( determines whether or not the extracted data corresponds to the screer display change-point data 51t generated from the control input data requisition dialogue box 51 (Step S33). If no data matched with the search key is extracted (No in Step S32), the processing unit 30 ends the process. [0070]
If the processing unit 30 determines that the extracted date corresponds to the screen display change-point data 51t generated from tht control input data requisition dialogue box 51 in Step S33 (Yes in Step S33)
the processing unit 30 reproduces the control input data requisition dialogue box 51 from the extracted screen display change-point data 51t, and displays the reproduced control input data requisition dialogue box 51 on the display unit 50 (Step S34). [0071]
If the processing unit 30 determines that the extracted data does not correspond to the screen display change-point data 51t generated from tht control input data requisition dialogue box 51 in Step S33 (No in Step S33) that is, if the processing unit 30 determines that the extracted date corresponds to the screen display change-point data 53t generated from the plant alarm information display 53, the processing unit 30 reproduces tht plant alarm information display 53 and the instrument data display 54 from the extracted screen display change-point data 53t, and displays tht reproduced screen displays on the display unit 50 (Step S35). Wher displaying the instrument data display 54, the processing unit 30 acquires measured values required for displaying a chart from the instrument date history database, not from the screen display history database 41. [0072]
In the above procedure, the history data retrieval unit 37 performs Steps S30 to S32. The screen display reproduction unit 38 performs Steps S33 to S35. [0073]
According to the embodiment of the present invention, the histories of the screen displays stored in the screen display history database 41 art
those of only screen displays useful for analyzing the cause of a failure in tht operating conditions of the plant, for example, the control input dat? requisition dialogue box 51 for receiving an input of control data from ar operator and the alarm information display 53 for warning an operator thai abnormal data is included in instrument data. Thereby, the amount of the histories of the screen displays stored in the screen display history database 41 is substantially reduced. [0074]
The display data displayed on the screen display is converted intc text data, and the resulting text data is stored in the screen display histon database 41 as a history of the screen display. Thereby, the screen display history database 41 may be easily searched with, for example, a keyworc which is any text without any restriction. Additionally, the screen display history database 41 does not require processing of searching image data therefore reducing the processing time required for the search of the screer display history database 41 executed by the processing unit 30. [0075]
As a result, the plant monitoring and control system 10 enablee efficient accumulation and search of the histories of the screen displays useful for analyzing the cause of a failure in the operating condit ions of tht plant in the screen display history database 41. [0076]
According to the embodiment described above, the processing unit 3( of the operator workstation 20 (see FIG. l) is constituted by a single persona
computer or workstation. However, the processing unit 30 may bt constituted by multiple personal computers and workstations. For exampk a personal computer or workstation may perform the functional blocks specific to the embodiment of the present invention, that is, the screer display change-point detection unit 34, the screen display change-poim output unit 35, the history data storage unit 36, the history data retrieval unit 37, and the screen display reproduction unit 38, and another personal computer or workstation may perform the functional blocks which are also included in a conventional operator workstation 20, that is, the plant state acquisition control unit 31, the plant state display control unit 32, and the control input data requisition unit 33.

I CLAIM:
1. A plant monitoring and control system comprising:
a control unit connected to a measuring instrument and an actuator installed in a plant, the control unit acquiring instrument data from tht measuring instrument and outputting control data to the actuator; and
an operator workstation connected to the control unit over ? communication network, the operator workstation acquiring the instrument data measured by the measuring instrument from the control unit anc outputting the control data for the actuator through the control unit to th( actuator, the control data being based on input data from an operator, the operator workstation comprising: a processing unit; a display unit; and
a screen display history database for accumulating a history of a screen display displayed on the display unit,
wherein the processing unit comprises:
a screen display change-point detection unit detecting a change -poim in the screen display displayed on the display unit;
a screen display change-point output unit converting display datr displayed on the screen display detected by the screen display change-poini detection unit into text data.' and
a history data storage unit storing the text data, into which the display data is converted, as a history of the screen display in the screer display history database.
2. The plant monitoring and control system according to claim 1,
wherein after a control input data requisition dialogue box for
prompting the operator to input the input data for controlling the actuator is-displayed, when the operator inputs the input data in the control input date requisition dialogue box, the screen display change-point detection unit determines that the control input data requisition dialogue box ts changed and detects, as a change-point, the change in the control input date requisition dialogue box displayed at the time when the operator inputs tht input data, and
wherein the screen display change-point output unit converts , into text data in a predetermined format, data including at least display date displayed on the control input data requisition dialogue box, the input date inputted via the control input data requisition dialogue box, idontificatior data for identifying the operator who inputs the input data, and data on ? date and time when the operator inputs the input data.
3. The plant monitoring and control system according to claim 2,
wherein after the instrument data acquired from the measuring.
instrument via the control unit is displayed on the display unit, when a plant alarm information display is displayed to warn the operator that ar abnormal data is included in the instrument data displayed on the displa} unit, the screen display change-point detection unit determines that the plant alarm information display is changed, and detects the displayed plant alarm information display as a change-point, and
wherein the screen display change-point output unit converts, intc
text data in a predetermined format, data including at least display date displayed on the plant alarm information display, data type information for identifying a type of the measured data which causes the plant alarm information display to be displayed, a measured value of the abnormal data and data on a date and time when the plant alarm information display it-displayed.
4. The plant monitoring and control system according to any one 01
claims 1 to 3,
wherein the processing unit further comprises:
a history data retrieval unit searching the screen displa) history database by receiving an input of a search condition and extracting text data matched with the search condition from the screen display history database; and
a screen display reproduction unit reproducing an origina screen display for the history of the screen display corresponding to tht extracted text data by using the extracted text data and displaying tht reproduced screen display on the display unit.
5. A method for controlling a screen display history database; in a plant
monitoring and control system including:
a control unit connected to a measuring instrument and an actuator installed in the plant, the control unit acquiring instrument data from thf measuring instrument and outputting control data to the actuator! and
an operator workstation connected to the control unit over t communication network, the operator workstation acquiring the instrumeni
data measured by the measuring instrument from the control unit anc outputting the control data for the actuator through the control unit to the actuator, the control data being based on input data from an operator, the operator workstation including:
a processing unit;
a display unit.' and
the screen display history database for accumulating ?, history of a screen display displayed on the display unit,
the method executed by the processing unit, comprising the steps of
detecting a change-point in the screen display displayed or the display unit,'
converting display data displayed on the screen display detected in the detecting step into text data,' and
storing the text data, into which the display data is converted
as a history of the screen display in the screen display history database.
6. The method for controlling the screen display history database
according to claim 5,
wherein after a control input data requisition dialogue box for prompting the operator to input the input data for controlling the actuator is displayed, when the operator inputs the input data in the control input date requisition dialogue box, the detecting step executed by the processing unit determines that the control input data requisition dialogue box is changed and detects, as a change-point, the change in the control input date requisition dialogue box displayed at the time when the operator inputs the
input data, and
wherein the converting step executed by the processing unit converts into text data in a predetermined format, data including at least display date displayed on the control input data requisition dialogue box, the input date inputted via the control input data requisition dialogue box, idontificatior data for identifying the operator who inputs the input data, and data on i date and time when the operator inputs the input data.
7. The method for controlling the screen display history database
according to claim 6,
wherein after the instrument data acquired from the measuring instrument via the control unit is displayed on the display unit, when a plam alarm information display is displayed to warn the operator that the abnormal data is included in the instrument data displayed on the display unit, the detecting step executed by the processing unit determines that the plant alarm information display is changed, and detects the displayed plam alarm information display as a change-point, and
wherein the converting step executed by the processing unit converts into text data in a predetermined format, data including at least display date displayed on the plant alarm information display, data type information foi identifying a type of the measured data which causes the plant alarm information display to be displayed, a measured value of an abnormal data and data on a date and time when the plant alarm information display it-displayed.
8. The method for controlling the screen display history database
according to any one of claims 5 to 7,
the method executed by the processing unit, further comprising the steps of:
searching the screen display history database by receiving ar input of a search condition and extracting text data matched with the search condition from the screen display history database,' and
reproducing an original screen display for the history of tht screen display corresponding to the extracted text data by using th( extracted text data and displaying the reproduced screen display on th( display unit.
<\. A plant monitoring and control system comprising, substantially as herein described with reference to accompanying drawings and example.
10. A method for controlling a screen display history database in a plant monitoring and control system, substantially as herein described with reference to accompanying drawings and example.