AU2006336766B2 - Plant control system - Google Patents

Description

1 DESCRIPTION PLANT CONTROL SYSTEM 5 Technical Field The present invention relates to a plant control system, and particularly to an apparatus for performing the creation, display and diagnosis of a plant control program. 10 Background Art Generally, in constructing a plant control system, the system programmer creates, validates, and coordinates a program for automatically operating a plant as the control program for the plant control system, thereafter providing it to 15 the plant operator. At this point, in order to safely control the plant, the system programmer must implement in the control program an interlock condition (approval condition for equipment operation) for activating and operating the plant equipment such as rotary 20 machinery. Since whether the interlock condition is satisfied or not is a natural concern for the plant operator, there is a need for presenting that to the plant operator in an easy-to-understand way. Conventionally, there has been proposed a plant system 25 control system including interlock diagnosis means which updates and displays the satisfaction/unsatisfaction of an interlock condition at a predetermined time point before the present when plant equipment stops, and identifies only a source factor variable of the unsatisfaction to automatically 30 display it by a graphical language even if the interlock circuit is formed in multiple stages (see Japanese Patent Application No. 2004-201978). There has also been proposed a plant control system which operates a function, by which the 35 satisfaction/unsatisfaction of an interlock condition is updated and displayed and, even if the interlock circuit is formed in 2 multiple stages, only a source factor variable of unsatisfaction is identified and automatically displayed by a graphical language, on a general operator display device for supporting the plant operator, making it possible to easily detect the interlock 5 condition which has become unsatisfied out of a large number of interlock conditions in a hierarchical display procedure. Disclosure of the Invention Problems to be Solved by the Invention 10 However, conventional plant control systems have following drawbacks. (a) The interlock diagnosis function, by which the satisfaction/unsatisfaction of an interlock condition is updated and displayed and, even if the interlock circuit is formed in 15 multiple stages, only a source factor variable of the unsatisfaction is identified and automatically displayed by a graphical language, is performed only for the interlock circuit of single plant control means. Therefore, when an interlock condition used by arbitrary 20 plant control means is interfaced as a representative contact by other plant control means connected to a network, it is not possible to monitor the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes the representative contact by the other plant control means. 25 (b) The interlock diagnosis function, by which the satisfaction/unsatisfaction of an interlock condition is updated and displayed and, even if the interlock circuit is formed in multiple stages, only a source factor variable for the unsatisfaction is identified and automatically displayed by a 30 graphical language, detects the contact which has become unsatisfied in first place and displays it on the interlock diagnosis screen. Thus, it is not possible to detect contacts which have become unsatisfied in second, third, ..., or nth place. The present invention has been made in consideration of 35 the above described points, and its object is to provide a plant control system, which has: -3 1) a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact by other plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in 5 other plant control means is also monitored so that each individual interlock condition in the other plant control means is displayed as one of source factor contact of unsatisfaction on the above described interlock diagnosis screen, and 2) a function by which even if the interlock circuit is formed in multiple stages, only a source factor contact of the unsatisfaction is identified so that the 10 contact which has become unsatisfied in first place is detected and displayed on the above described interlock diagnosis screen and, in addition, the contacts which have become unsatisfied in second, third, ..., or nth place are detected and displayed on the above described interlock d agnosis screen. 15 Means for Solving the Problems According to the present invention there is provided a plant control system, comprising: control program editor means for creating a control program including an interlock condition and diagnosis of interlock 20 a plurality of plant control means for executing a program object by said control program; and interlock diagnosis means including a logic operation part and a display part, said interlock diagnosis means having; a function by which the satisfaction/unsatisfaction of an interlock condition 25 at a predetermined time point before the present in arbitrary plant control means is updated and displayed, and even if an interlock circuit is formed in multiple stages, only a source factor contact of unsatisfaction is identified to automatically display an interlock diagnosis screen with a graphic language, and a function by which even when an interlock condition used by arbitrary plant 30 control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each -4 individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is displayed as one of source factor contacts of unsatisfaction on the above described interlock diagnosis screen. 5 Advantages of the Invention As described so far, the present invention is configured such that even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from other plant control means connected to a network, 10 the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is displayed as one of source factor contacts of unsatisfaction on the interlock diagnosis screen, and even if the interlock circuit is formed in 15 5 multiple stages, not only a source factor contact of unsatisfaction which has become unsatisfied in first place, but also the contacts which have become unsatisfied in second, third, ... , or nth place among the source factors of satisfaction 5 are detected and displayed on the interlock diagnosis screen; thus it is made possible to quickly find out the information relating to the interlock condition of a targeted equipment in a large scale plant. 10 Brief Description of the Drawings Figure 1 is a conceptual diagram to show the general configuration of an embodiment 1 of the present invention; Figure 2 is a ladder circuit diagram to show an example of a control program including interlocks; 15 Figure 3 is an explanatory diagram to show an example of the interlock diagnosis screen according to embodiments 1 and 2 of the present invention; Figure 4 is an explanatory diagram to show an example of the interlock diagnosis screen according to embodiments 3 20 and 4 of the present invention; Figure 5 is an explanatory diagram to show an example of the interlock diagnosis screen according to embodiments 5, 6, 7 and 8 of the present invention; Figure 6 is an explanatory diagram to show examples of 25 the HMI screen and the interlock diagnosis screen according to embodiments 9 and 10 of the present invention; Figure 7 is an explanatory diagram to show the interlock diagnosis screen and the manipulation method thereof according to embodiments 11 and 12 of the present invention; and 30 Figure 8 is an explanatory diagram to show examples of the HMI screen and the interlock diagnosis screen according to embodiments 13, 14, 15 and 16 of the present invention. Description of Symbols 35 10 Control program editor means 11 Program compiler 6 12 Ladder/logic formula conversion part 13 Program load client part 20 Interlock diagnosis means 21 Logic formula readout part 5 21 Interlock-state client part 23 Factor-identification logic formula conversion part 24 Logic formula synthesis part 25 Logic formula/ladder conversion part 30 Database part 10 31 Source file part 32 Object file part 33 Logic formula file part 40 Object memory 41 Data memory 15 42 Code memory 50 Standard processing part 51 Code program server part 52 Program execution processing part 53 Process input/output processing part 20 54 Interlock-state readout server part 60 Screen manipulation/monitoring means 61 Screen program part 62 Database part 25 Best Mode for Carrying Out the Invention Hereinafter, embodiments of the present invention will be described with reference to the appended drawings. Embodiment 1 (Configuration of embodiment 1) 30 First, an embodiment 1 will be described with reference to Figures 1 to 3. Figure 1 is a general block diagram of the embodiment 1 of the present invention, which is generally comprised of the following four parts. Those are, in addition to a plant control 35 system consisting of a controller CONTI as plant control means, a computer COMP as control program creation/display means, a 7 general operator manipulation/display device HMI (human machine interface apparatus) to be operated by the plant operator in the plant operation room, and a LAN (local area network) for connecting the foregoings; a plurality of controllers 5 CONT2, CONT3, ..., CONTn each of which has an equivalent function to that of the controller CONTI, with these plurality of controllers being connected to the LAN. The controller CONTI and CONT2, CONT3, ..., and CONTn are comprised of roughly two parts respectively: an object 10 memory 40 for storing control program objects, and a standard processing part 50 for performing write, read, and execution operations of the control program objects. Further, the object memory 40 is comprised of a data memory 41 and a code memory 42. 15 The data memory 41 includes, in addition to ordinary interlock contacts, internal data of a function block for interlock diagnosis DIAG described below. Moreover, the code memory 42 includes, in addition to ordinary program codes, internal codes of the function block for interlock diagnosis DIAG. 20 The standard processing part 50 is comprised of a program load server part 51 for placing object programs of a control program which is sent via the LAN, into the data memory 41 and the code memory 42, a program execution processing part 52 for executing the control program, i.e. code 25 memory in the controllers CONTI and CONT2, CONT3, ..., and CONTn, a process input/output processing part 53 for supplying the process contact from the plant to the control program, and an interlock-state readout server part 54 for reading the interlock circuit state during the execution of the control 30 program. On the other hand, the computer COMP is comprised of roughly three parts: control program editor means 10 for allowing the system programmer to create control programs, a database part 30 for storing the control programs and logic 35 formulas of interlock, and interlock diagnosis means 20 with which the plant operator knows the cause of the unsatisfaction 8 of an interlock condition. The control program editor means 10 is comprised of a program compiler 11 for converting the source file of a control program into an object file, a ladder (LD)/logic formula 5 conversion part 12 for converting the specified interlock circuit in the control program into a logic formula, and a program load client part 13 for sending the object file of a control program to the controller, as internal processing elements. The database part 30 is comprised of a source file part 31 10 for storing the source file of a control program, an object file part 32 for storing the object file of the control program, and a logic formula file part 33 for storing the logic formulas of the specified interlock circuit. The source file part 31 includes a source of the function block for interlock diagnosis described 15 below. Moreover, the object file part 32 includes the internal data and codes of the function block for interlock diagnosis described below. The interlock diagnosis means 20 is comprised of a logic operation part and a display part. The logic operation part is 20 comprised of a logic formula readout part 21 for reading the logic formula of specified interlock from a file, an interlock-state readout client part 22 for reading out the contact states of the past and the present of specified interlock circuit from the controller, a causal-factor identification logic-formula conversion 25 part 23 for identifying the causal factor of the unsatisfaction of an interlock condition from the logic formula and its contact state, a logic formula synthesis part 24 for synthesizing multi-stage logic formulas into a single logic formula, and a logic formula/ladder (LD) conversion part 25 for depicting a 30 ladder circuit from the logic formulas. The display part displays the operation results by the logic operation part. Further, a general operator manipulation/display device HMI is comprised of roughly two parts: i.e. operator 35 manipulation/monitoring means 60 which is a general function with which the operator manipulates and monitors the plant, 9 and equivalent interlock diagnosis means 20 for performing the same function as that of the interlock diagnosis means provided in the computer COMP. The operator manipulation/monitoring means 60 is 5 comprised of a screen program part 61 for storing screen programs for performing the manipulation/monitoring needed for plant operation, and a database part 62 for storing necessary data for the manipulation/monitoring information. (Operation of embodiment 1) 10 The system programmer creates a control program including interlock circuits for plant equipment by using the control program editor means 10. Figure 2 shows an example of a control program created by using a ladder language specified by JISB3503 (or IEC61131-3), the content of which 15 shows an interlock circuit and an activation circuit for operating a rotary machine M30 in the interlock circuit of the controller CONT1 in the upper tier. There is provided, from top to bottom order in the control programs shown in Figure 2, an interlock circuit for outputting 20 an interlock condition C5, an interlock circuit for outputting the operation condition RUNPRM of M30, and a circuit of M30 operation command M30_RUN. Further, there is provided, in the interlock circuit of the controller CONT2 in the lower tier, a circuit of representative 25 interlock condition X1 for interfacing with the controller CONT1. The interlock circuit of the top most position in this figure is comprised of contacts Bi, B2, B3, B4, and X1, a function block for interlock diagnosis DIAG, and a coil C5, the contact C5 of the coil C5 being inserted into the M30 operation interlock 30 circuit of the second top position. The M30 operation interlock circuit of the second top position is comprised of contacts C1 to C7, a function block for interlock diagnosis DIAG, and a coil RUN_PRM, with the contact RUNPRM of the coil RUNPRM being inserted into the M30 35 operation command circuit of the third top position. The M30 operation circuit is comprised of contacts 10 STARTPB, STARTPRM, STOP_PB, M30_RUN, and RUNRPM as well as a coil M30_RUN. Further, the bottom most interlock circuit is comprised of contacts D1, D2, D3, D4 and D5, a function block for interlock 5 diagnosis DIAG, and a coil X1, the contact X1 of the coil X1 being interfaced with and taken into the top most interlock circuit via the LAN. The interlock circuit is characterized in that it is connected with a function block for interlock diagnosis DIAG 10 before its coil output. Referring back to Figure 1, when the system programmer saves a control program, the control program is stored in the source file part 31 of the database part 30, and the result generated from the source file at the program compiler 11 is stored as an object file 32 of the database part 15 30. At this moment, upon finding a function block for interlock diagnosis, the ladder/logic formula conversion part 12 searches a ladder circuit connected to the input thereof and generates a logic formula for interlock storing it as a logic 20 formula file of the database part 30. After creating and storing control programs, the system programmer performs the writing of these programs into the controller CONT to cause the control programs to be executed. When writing into the controller CONT is performed, internally, 25 the object file 32 of the database part 30 is extracted by the program load client part 13 and delegated to the program load server part 51 of the controller CONT via the LAN; this is received by the program load server 51 and is placed on the data memory 41 and the code memory 42 of the object memory 30 40; and this is further executed by the program execution processing part 52 thereby causing the control program to be executed. The contacts of the interlock circuit and the contacts of the coils are a process contact to be inputted from and 35 outputted to the outside of the controller CONT, which is operated by being supplied from the process input/output part 11 53 to the program execution processing part 52. Figure 3 shows interlock diagnosis screens, where a conventional one in the upper tier and an inventive one in the lower tier are shown in a comparative fashion. First, in the 5 upper tier of Figure 3 is a display example of the conventional interlock diagnosis screen by the interlock diagnosis means 20. In this display example, the logic formula readout part 21 is used to know the address in the controller of the function block for interlock diagnosis from the name of relevant interlock 10 contact, and the address is passed to the interlock-state readout client part 22, which in turn delegates it to the interlock-state readout server part 54 of the controller CONT via the LAN. Thus, by acquiring the internal variables, Permissive (interlock state of the present time) and Time Stamp (the time 15 of occurrence of interlock unsatisfaction at the latest time) of the function block for interlock diagnosis which is being executed, and by displaying this in each field, Live (presentation of interlock unsatisfaction of the present) and Faulted (presentation of interlock unsatisfaction at the latest time), the 20 displaying of the circuit name list of interlock diagnosis targets is realized. In this [Live] column, when the relevant interlock condition is unsatisfied at the present time, an interlock diagram including only the contacts that may have caused the 25 unsatisfaction is displayed as a ladder circuit. Moreover, in [Faulted] column, when the relevant interlock condition is unsatisfied at the latest time, the contact that has become a trigger (primary cause) of the interlock unsatisfaction is displayed in a ladder circuit. 30 On the other hand, in the lower tier of Figure 3, is a display example of the interlock diagnosis screen according to the interlock diagnosis means 20 relating to the interlock circuit shown in Figure 2. Conventionally, when an interlock condition X1 used in 35 the controller CONT1 is interfaced as a representative contact from another controller CONT2 connected to a network, and the 12 representative contact X1 itself is unsatisfied, the state of the representative contact X1 is shown as it is in the interlock diagnosis screen of the controller CONT1, which indicates the interlock unsatisfaction. 5 Here, the interlock diagnosis means 20 tracks the output source of the interlock condition X1 which is interfaced as a representative contact from the other controller CONT2. When this has been taken in from the controller CONT2 to constitute a regular interlock circuit by a function block for interlock 10 diagnosis DIAG, an interlock condition D4 in which the representative contact X1 is unsatisfied in the controller CONT2 is found out in the same way as detecting unsatisfied interlock conditions C3 and C30 in the controller CONT1, and this is displayed in the [Live] column of the interlock diagnosis screen 15 instead of the representative contact X1 from the controller CONT2 which is unsatisfied in the controller CONT1. (Advantages of embodiment 1) As shown in Figure 2, in a conventional apparatus, a unified and simple programming technique in which a function 20 block for interlock diagnosis is inserted into an existing interlock circuit is provided to the system programmer, and also as shown in the [Live] column of the interlock diagnosis screen in the upper tier of Figure 3, the causal contacts and trigger contacts in the event of interlock unsatisfaction at the present time and 25 the latest time are provided to the plant operator as a ladder circuit which can be understood at a glance. That is, a conventional interlock diagnosis function realizes: a plant-operation assist function of briefly answering the question of the plant operator, "why the manipulation target 30 equipment can not be activated, even though the activation button has been pressed?" by presenting an interlock unsatisfaction at the present time; a plant-operation assist function of briefly answering the question of the operator, "Manipulation target equipment has been stopped, and why did 35 it stop?" by presenting an interlock unsatisfaction causal factor at the latest time; and a plant-operation assist function of 13 briefly answering the question of the operator, "Manipulation target equipment has been stopped, and what is the primary cause?" by presenting an interlock unsatisfaction triggering factor at the latest time. 5 In addition to these, the present invention can present an interlock unsatisfaction at the present time. That is, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn 10 which are connected to a network as the plant control means, the output source of this interlock condition is tracked thereby concurrently monitoring the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller. Then, as one of 15 source factor contacts of interlock unsatisfaction in an arbitrary controller which is a monitoring target, it is possible, as with the [Live] column of the interlock diagnosis screen in the lower tier of Figure 3, to present the contact of interlock unsatisfaction at the present time with final individual contacts. 20 Since this will expand the range of monitoring targets and improve the operability of the monitoring function, it is made possible to provide an apparatus which enables to quickly find out the information at present on the interlock condition of a targeted facility, regardless of the constitutional state of the 25 interlock contact which is interfaced between a plurality of controllers in a large scale plant. Embodiment 2 The lower tier of Figure 3 shows a [Faulted] column of the interlock diagnosis screen according to an embodiment 2, 30 i.e. interlock diagnosis means 20 of the present invention. In the above described embodiment 1, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are 35 connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock 14 condition which constitutes a representative contact in the other controller is also monitored and is displayed as one of source factor contacts of interlock unsatisfaction in the arbitrary controller in the [Live] column of the interlock diagnosis screen 5 in the lower tier of Figure 3. On the other hand, the embodiment 2 provides a function in which even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONTI, CONT2, CONT3, ..., 10 CONTn which are connected to the network as the plant control means, the output source of this interlock condition is tracked so that the contact which has become unsatisfied in first place, that is the contact which has become a trigger (primary reason) of interlock unsatisfaction is displayed as a ladder circuit in the 15 [Faulted] column of the interlock diagnosis screen in the lower tier of Figure 3. The interlock diagnosis means 20 tracks the output source of the interlock condition X1 which is interfaced from another controller CONT2 as a representative contact, as with 20 the case of the embodiment 1. When this has been taken in from the controller CONT2 and constitutes a regular interlock circuit by a function block for interlock diagnosis DIAG, the interlock condition D4, in which the representative contact X1 is unsatisfied, is found out in the controller CONT2, in a similar 25 fashion to detect unsatisfied interlock conditions C3 and C30 in the interlock circuit in the controller CONTI, and is displayed as a ladder circuit in the [Faulted] column of the interlock diagnosis screen when this has become a trigger (primary reason) of interlock unsatisfaction. 30 Since this will expand the range of monitoring targets and improve the operability of the monitoring function, it is made possible to provide an apparatus which enables to quickly find out the interlock condition which has become unsatisfied in first place for the interlock condition of a targeted facility, 35 regardless of the constitutional state of the interlock contact which is interfaced between a plurality of controllers in a large 15 scale plant. Embodiment 3 Figure 4 shows the content of an embodiment 3, i.e. an interlock diagnosis screen and an operational method thereof 5 according to the present invention. In the above described embodiment 1, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONTI, CONT2, CONT3, ..., CONTn which are 10 connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored and is displayed as one of source factor contacts of interlock unsatisfaction in the arbitrary 15 controller in the [Live] column of the interlock diagnosis screen in the lower tier of Figure 3. Further, in the above described embodiment 2, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in 20 a plurality of controllers CONTI, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored to be displayed as the 25 contact which has become unsatisfied in first place, i.e. the contact which has become a trigger (primary reason) of interlock unsatisfaction as a ladder circuit in the [Faulted] column of the interlock diagnosis screen in the lower tier of Figure 3. 30 In contrast, the embodiment 3 provides a function by which even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONTI, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control 35 means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in 16 the other controller is also monitored so that a variables detailed information (Device Property) opening function relating to the name of contact of interlock unsatisfaction at the present time, and being displayed in the [Live] column of the interlock 5 diagnosis screen, or the name of contact of interlock unsatisfaction at the latest time, and being displayed in the [Faulted] column of the interlock diagnosis screen is selected to open and display a variables detailed information screen of the relevant variable, and also a variables usage portion information 10 (Cross-reference) opening function is selected to open and display a variables usage portion information screen of the relevant variable. Thereby, it is made possible to provide an apparatus which enables the plant operator to extract detailed information 15 relating to individual variables even from a large amount of interlock circuits and to quickly find out the information relating to the interlock condition for a targeted facility thereby quickly determining the cause why the interlock condition has been unsatisfied. 20 Embodiment 4 The interlock diagnosis screen and the manipulation method thereof of Figure 4 show the content of an embodiment 4, following the embodiment 3, of the present invention. In the above described embodiment 3, even when an 25 interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock 30 condition which constitutes a representative contact in the other controller is also monitored so that a variables detailed information (Device Property) opening function relating to the name of contact of interlock unsatisfaction at the present time, displayed in the [Live] column of the interlock diagnosis screen, 35 or the name of contact of interlock unsatisfaction at the latest time, displayed in the [Faulted] column of the interlock 17 diagnosis screen is selected to open and display a variables detailed information screen of the relevant variable, and also a variables usage portion information (Cross-reference) opening function is selected to open and display a variables usage 5 portion information screen of the relevant variable. In contrast, the embodiment 4 provides a function by which even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., 10 CONTn which are connected to the network as the plant control means, the variables usage portion information (Cross-reference) opening function is selected to directly open and display the program, in which the relevant interlock condition D4 is used in for example another controller CONT2, 15 from the variables usage portion information screen which points to the usage portion of the relevant variable. Thereby, it is made possible to provide an apparatus which enables the plant operator to extract detailed information relating to individual variables from an actual program even out 20 of a large amount of interlock circuits and to quickly find out the information relating to the interlock condition for a targeted facility thereby quickly determining the cause why the interlock condition has been unsatisfied. Embodiment 5 25 Figure 5 shows the content of an embodiment 5, i.e. an interlock diagnosis screen of the present invention. In the embodiment 1, in the [Live] column of the interlock diagnosis screen shown in the upper tier of Figure 3, when the relevant interlock condition is unsatisfied at the 30 present time, there is displayed as a ladder circuit an interlock diagram consisting of only the contacts which may be the causal factor, and in the [Faulted] column, when the relevant interlock condition is unsatisfied at the latest time, there is displayed as a ladder circuit the contact which has become a trigger (primary 35 cause) of interlock unsatisfaction. In contrast, the embodiment 5 provides a function by 18 which, when the relevant interlock condition is unsatisfied at the present time, an interlock diagram consisting of only the contacts which may be the causal factor is displayed as a ladder circuit in the [Live] column of the interlock diagnosis screen of 5 Figure 5, and out of these interlock conditions, the contact which has become a trigger (primary cause) of the interlock unsatisfaction at the latest time is displayed as a ladder circuit in the [Faulted](1st) column of the interlock diagnosis screen, and further the interlock diagnosis means 20 tracks, monitors, 10 and memorizes the repeating execution of the controller to display contacts which have become unsatisfied in second, third, ... or nth place, as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc. Thereby, it is possible to provide an apparatus which 15 enables to expand the range of monitoring targets and to improve the operability of the monitoring function thereby allowing the plant operator to quickly find out not only the interlock condition which has become unsatisfied in first place, but also the procedure in which a plurality of interlock 20 conditions become unsatisfied, relating to the interlock conditions of a targeted facility in a large scale plant. Embodiment 6 The interlock diagnosis screen of Figure 5 also shows the content of an embodiment 6 of the present invention. 25 In the embodiment 5, when the relevant interlock condition is unsatisfied at the present time, an interlock diagram consisting of only the contacts which may be the causal factor is displayed as a ladder circuit in the [Live] column of the interlock diagnosis screen of Figure 5, and out of these interlock 30 conditions, the contact which has become a trigger (primary cause) of the interlock unsatisfaction at the latest time is displayed as a ladder circuit in the [Faulted](1st) column of the interlock diagnosis screen, and further the contacts which have become unsatisfied in second, third, ..., or nth place are 35 displayed as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc.

19 In contrast, the embodiment 6 provides a function by which even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, 5 CONTn which are connected to the network as the plant control means, the output source of that interlock condition is tracked to display the contacts which have become unsatisfied in second, third, ..., or nth place, as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ... etc. of the interlock diagnosis 10 screen of Figure 5. The interlock diagnosis means 20, as in the case of the embodiment 1, tracks the output source of the interlock condition X1 which is interfaced as a representative contact from another controller CONT2. 15 When that interlock condition has been taken in from the controller CONT2 and constitutes a regular interlock circuit by a function block for interlock diagnosis DIAG, the interlock condition D4 in which the representative contact X1 is unsatisfied in the controller CONT2 is detected in a similar 20 fashion to detect unsatisfied interlock conditions C3 and C30 in the interlock circuit in the controller CONT1, and is displayed as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ... etc. of the interlock diagnosis screen when that interlock condition has become unsatisfied in second, third, 25 or nth place. Thereby, it is possible to provide an apparatus which enables to expand the range of monitoring targets and to improve the operability of the monitoring function thereby allowing the plant operator to quickly find out not only the 30 interlock condition which has become unsatisfied in first place, but also the procedure in which a plurality of interlock conditions become unsatisfied, relating to the interlock conditions of a targeted facility in a large scale plant, regardless of the constitutional state of the interlock contact which is 35 interfaced between a plurality of controllers in a large scale plant.

20 Embodiment 7 The interlock diagnosis screen of Figure 5 also shows an embodiment 7 of the present invention. In the embodiment 6, even when an interlock condition 5 used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the output source of that interlock condition is tracked to display the contacts which have 10 become unsatisfied in second, third, ..., or nth place are displayed as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ... etc. of the interlock diagnosis screen in Figure 5. The embodiment 7 provides a function by which when an 15 interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock 20 condition which constitutes a representative contact in the other controller is also monitored so that even when those interlock conditions become unsatisfied in second, third, ..., or nth place, a variables detailed information (Device Property) opening function relating to the name of contact of interlock 25 unsatisfaction, displayed as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc. of the interlock diagnosis screen is selected to open and display a variables detailed information screen of the relevant variable, and also a variables usage portion information (Cross-reference) opening 30 function is selected to open and display a variables usage portion information screen of the relevant variable. Thereby, it is made possible to provide an apparatus which enables the plant operator to extract detailed information relating to individual variables even from a large amount of 35 interlock circuits and to quickly find out the procedure in which a plurality of interlock conditions become unsatisfied regardless 21 of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, as well as to quickly find out the information relating to the interlock condition of a targeted facility thereby quickly determining the 5 cause why the interlock condition is unsatisfied. Embodiment 8 The interlock diagnosis screen of Figure 5 also shows an embodiment 8 of the present invention. In the embodiment 7, when an interlock condition used 10 by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition 15 which constitutes a representative contact in the other controller is also monitored so that even when those become unsatisfied in second, third, ..., or nth place, a variables detailed information (Device Property) opening function relating to the name of contact of interlock unsatisfaction, displayed as a 20 ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ... etc. of the interlock diagnosis screen is selected to open and display a variables detailed information screen of the relevant variable, and also a variables usage portion information (Cross-reference) opening function is 25 selected to open and display a variables usage portion information screen of the relevant variable. In contrast, the embodiment 8 provides a function by which when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another 30 controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored so that even when those 35 interlock conditions become unsatisfied in second, third, ..., or nth place, a variables detailed information (Device Property) 22 opening function relating to the name of contact of interlock unsatisfaction, displayed in a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc. of the interlock diagnosis screen is selected to directly open and display, for 5 example, the program in which relevant interlock condition D4 is used in the other controller CONT2, from a variables usage portion information screen which points to the usage portion of the relevant variable. Thereby, it is made possible to provide an apparatus 10 which enables the plant operator to extract detailed information relating to individual variables even from a large amount of interlock circuits and to quickly find out the information relating to the interlock condition for a targeted facility thereby quickly determining the cause why the interlock condition has been 15 unsatisfied. Thereby, there is provided an apparatus which enables to expand the range of monitoring targets and to improve the operability of the monitoring function thereby allowing the plant operator to extract, from an actual program, detailed 20 information relating to individual variables even from a large amount of interlock circuits in a large scale plant and to quickly find out the procedure in which a plurality of interlock conditions become unsatisfied, as well as to quickly find out the information relating to the interlock condition of a targeted 25 facility regardless of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, thereby quickly determining the cause why the interlock condition is unsatisfied. Embodiment 9 30 Figure 6 shows an embodiment 9, i.e. an HMI screen and interlock diagnosis screen of the present invention. In the embodiment 1, in the [Live] column of the interlock diagnosis screen in the lower tier of Figure 3, even when an interlock condition used by an arbitrary controller is 35 interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn 23 which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored to be displayed as one of 5 source factor contacts of interlock unsatisfaction in the arbitrary controller, on the computer COMP of the control program creation/display means. In contrast, in the embodiment 9, the function of the embodiment 1 is performed on a general operator 10 manipulation/display device HMI. The operator manipulation/display device HMI has a display function of the interlock diagnosis screen shown in Figure 3 since it includes interlock diagnosis means 20 equivalent to that provided in the computer COMP. 15 Then, since the interlock diagnosis means 20 of the operator manipulation/display device HMI refers the list of the interlock conditions, i.e. coil variables stored as the logic formula file of the database part 30 of the computer COMP via the LAN, in a same way that the interlock diagnosis means 20 of 20 the computer COMP refers the logic formula file of the database part 30, it is possible to display the circuit name list of the interlock diagnosis targets and the interlock diagnosis screen selected therefrom on the plant manipulation/monitoring screen. 25 Figure 6 shows a case in which, on a general operator manipulation/display device HMI to be manipulated by the operator in the plant operation room, an interlock circuit which has been unsatisfied is selected from the circuit name list screen of the interlock diagnosis targets on the plant 30 manipulation/monitoring screen to be used by the operator for manipulating/monitoring the plant, thereby displaying a relevant interlock diagnosis screen. Thus, as shown in Figure 6, in a general operator manipulation/display device HMI to be manipulated by the 35 operator, a function of displaying the circuit list of the interlock diagnosis targets by the interlock diagnosis means and an 24 interlock diagnosis screen is added to an example of the plant manipulation/monitoring screen provided by the operator manipulation/monitoring means so that the plant operator can directly monitor the state of interlock unsatisfaction only by the 5 operator manipulation/display device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or without assistance by the system programmer. Further, the screen program of the interlock monitoring 10 screen which used to be specially created in the operator manipulation/monitoring means will become unnecessary, and thus it becomes possible to consistently display the latest interlock state without making changes in the screen program of the operator manipulation/monitoring means even when 15 modifications, additions, or elimination of the interlock associated with the alteration of the facility take place. Embodiment 10 Figure 6 also shows an embodiment 10, i.e. an HMI screen and an interlock diagnosis screen of the present 20 invention. In the embodiment 2, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONTI, CONT2, CONT3, ..., CONTn which are connected to the 25 network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored tracing the output source of the interlock condition so that the contact which has become 30 unsatisfied in first place, that is, the contact which has become a trigger (primary reason) of interlock unsatisfaction, is displayed as a ladder circuit in the [Faulted] column of the interlock diagnosis screen in the lower tier of Figure 3. In contrast, in the embodiment 10, the function of the 35 embodiment 2 is performed by a general operator manipulation/display device HMI as in the case of the 25 embodiment 9. Thus it is possible to provide an apparatus which enables to expand the range of interlock monitoring targets and to improve the operability of the monitoring function, and 5 regardless of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, allows the plant operator to quickly find out the interlock condition which has become unsatisfied in first place regarding the interlock condition of the targeted facility through only the 10 operator manipulation/display device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing or without assistance by the system programmer. Embodiment 11 15 Figure 7 shows an embodiment 11, i.e. an interlock diagnosis screen and the manipulation method thereof of the present invention. In the embodiment 3, even when an interlock condition used by an arbitrary controller is interfaced as a representative 20 contact from another controller in a plurality of controllers CONTI, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other 25 controller is also monitored so that a variables detailed information (Device Property) opening function relating to the name of contact of interlock unsatisfaction at the present time displayed in the [Live] column of the interlock diagnosis screen, or the name of contact of interlock unsatisfaction at the latest 30 time displayed in the [Faulted] column of the interlock diagnosis screen is selected to open and display a variables detailed information screen of the relevant variable, and also the variables usage portion information (Cross-reference) opening function is selected to open and display a variables usage 35 portion information screen of the relevant variable. In contrast, in the embodiment 11, the function of the 26 embodiment 3 is performed by a general operator manipulation/display device HMI as in the case of the embodiment 9. Thereby, it is possible to provide an apparatus which 5 enables the plant operator to extract detailed information relating to individual variables even from a large amount of interlock circuits through only the operator manipulation/display device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system 10 programmer during designing, or without assistance by the system programmer, and to quickly find out the information relating to the interlock condition of a targeted facility thereby quickly determining the cause why the interlock condition has been unsatisfied. 15 Embodiment 12 Figure 7 shows an embodiment 12, i.e. an interlock diagnosis screen and the manipulation method thereof of the present invention. In the embodiment 4, even when an interlock condition 20 used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, a variables usage portion information (Cross-reference) opening function is selected to 25 directly open and display the program, in which relevant interlock condition D4 is used in for example another controller CONT2, from a variables usage portion information screen which points to the usage portion of the relevant variable. In contrast, in the embodiment 12, the function of the 30 embodiment 4 is performed by a general operator manipulation/display device HMI as in the case of the embodiment 9. Thereby, it is possible to provide an apparatus which enables the plant operator to extract detailed information 35 relating to individual variables even from a large amount of interlock circuits through only an operator manipulation/display 27 device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or without assistance by the system programmer, and to quickly find out the information 5 relating to the interlock condition of a targeted facility thereby quickly determining the cause why the interlock condition has been unsatisfied. Embodiment 13 Figure 8 shows the embodiment 13, i.e. an HMI screen 10 and an interlock diagnosis screen thereof of the present invention. In the embodiment 5, when the relevant interlock condition is unsatisfied at the present time, an interlock diagram consisting of only the contacts which may be the causal 15 factor is displayed as a ladder circuit in the [Live] column of the interlock diagnosis screen of Figure 5, and out of these interlock conditions, the contact which has become a trigger (primary cause) of the interlock unsatisfaction at the latest time is displayed as a ladder circuit in the [Faulted](1st) column, and 20 further the contacts which have become unsatisfied in second, third, ..., or nth place are displayed as a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc. In contrast, in the embodiment 13, the function of the embodiment 5 is performed by a general operator 25 manipulation/display device HMI as in the case of the embodiment 9. Thus it is possible to provide an apparatus which enables to expand the range of the monitoring targets and to improve the operability of the monitoring function and, through only the 30 operator manipulation/display device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or without assistance by the system programmer, allows the plant operator to quickly find out not only the interlock condition 35 which has become unsatisfied in first place, but also the procedure in which a plurality of interlock conditions become 28 unsatisfied, regarding the interlock condition of a targeted facility in a large scale plant. Embodiment 14 Figure 8 also shows an embodiment 14, i.e. an HMI 5 screen and an interlock diagnosis screen of the present invention. In the embodiment 6, even when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers 10 CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the output source of the interlock condition is tracked to display the contacts which have become unsatisfied in second, third, ..., or nth place are displayed as a ladder circuit in each of the columns 15 [Faulted](2nd), [Faulted](3rd), ...etc. of the interlock diagnosis screen of Figure 5. In contrast, in an embodiment 14, the function of the embodiment 6 is performed by a general operator manipulation/display device HMI as in the case of the 20 embodiment 13. Thus it is possible to provide an apparatus which enables to expand the range of the monitoring targets and improve the operability of the monitoring function and, through only the operator manipulation/display device HMI to be normally used 25 by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or without assistance by the system programmer, and regardless of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, allows the plant 30 operator to quickly find out the interlock condition which has become unsatisfied in first place as well as the procedure in which a plurality of interlock conditions become unsatisfied regarding the interlock condition of a targeted facility in a large scale plant. 35 Embodiment 15 Figure 8 also shows an embodiment 15, i.e. an HMI 29 screen and an interlock diagnosis screen of the present invention. In the embodiment 7, when an interlock condition used by an arbitrary controller is interfaced as a representative 5 contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other 10 controller is monitored so that even when those interlock conditions become unsatisfied in second, third, ..., or nth place, a variables detailed information (Device Property) opening function relating to the name of contact of interlock unsatisfaction displayed as a ladder circuit in each of the 15 columns [Faulted](2nd), [Faulted](3rd), ... etc. of the interlock diagnosis screen of Figure 5 is selected to open and display a variables detailed information screen of the relevant variable, and also a variables usage portion information (Cross-reference) opening function is selected to open and display a variables 20 usage portion information screen of the relevant variable. Thus it is possible to provide an apparatus which enables to expand the range of the monitoring targets and to improve the operability of the monitoring function and, through only the operator manipulation/display device HMI to be normally used 25 by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or without assistance by the system programmer, allows the plant operator to extract detailed information relating to individual variables even from a large amount of interlock circuits in a 30 large scale plant, and regardless of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, to quickly find out the information relating to the interlock condition of the targeted facility while quickly finding out the procedure in which a plurality of interlock conditions 35 become unsatisfied, thereby making it possible to determine the cause why the interlock condition has become unsatisfied.

30 Embodiment 16 Figure 8 also shows an embodiment 16, i.e. an HMI screen and an interlock diagnosis screen of the present invention. 5 In the embodiment 8, when an interlock condition used by an arbitrary controller is interfaced as a representative contact from another controller in a plurality of controllers CONT1, CONT2, CONT3, ..., CONTn which are connected to the network as the plant control means, the state of 10 satisfaction/unsatisfaction of each individual interlock condition which constitutes a representative contact in the other controller is also monitored so that even when those become unsatisfied in second, third, ..., or nth place, a variables usage portion information (Cross-reference) opening function to the 15 name of contact of interlock unsatisfaction displayed in a ladder circuit in each of the columns [Faulted](2nd), [Faulted](3rd), ...etc. of the interlock diagnosis screen is selected to directly open and display, for example, the program in which relevant interlock condition D4 is used in the other controller CONT2 20 from a variables usage portion information screen which points to the usage portion of the relevant variable. Thereby, it is made possible to provide an apparatus which enables the plant operator to extract detailed information relating to individual variables from actual programs even out of 25 a large amount of interlock circuits and to quickly find out the information relating to the interlock condition for a targeted facility thereby quickly determining the cause why the interlock condition has become unsatisfied. Thus it is possible to provide an apparatus which enables 30 to expand the range of the monitoring targets and improve the operability of the monitoring function and, through only the operator manipulation/display device HMI to be normally used by the plant operator, without manipulating the computer COMP to be used by the system programmer during designing, or 35 without assistance by the system programmer, allows the plant operator to extract detailed information relating to individual - 31 variables from an actual program even out of a large amount of interlock circuits in a large scale plant, and regardless of the constitutional state of the interlock contacts which are interfaced between a plurality of controllers, to quickly find out the information relating to the interlock condition of the targeted facility while 5 quickly finding out the procedure in which a plurality of interlock conditions become unsatisfied, thereby making it possible to determine the cause why the interlock condition has become unsatisfied. The reference in this specification to any prior publication (or information derived from it), or to any matter which is known, is not, and should not be taken 10 as an acknowledgment or admission or any form of suggestion that that prior publication (or information derived from it) or known matter forms part of the common general knowledge in the field of endeavour to which this specification relates. Throughout this specification and tie claims which follow, unless the 15 context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims (17)

1. A plant control system, comprising: control program editor means for creating a control program including an interlock condition and diagnosis of interlock; a plurality of plant control means for executing a program object by said control program; and interlock diagnosis means including a logic operation part and a display part, said interlock diagnosis means having; a function by which the satisfaction/unsatisfaction of an interlock condition at a predetermined time point before the present in arbitrary plant control means is updated and displayed, and even if an interlock circuit is formed in multiple stages, only a source factor contact of unsatisfaction is identified to automatically display an interlock diagnosis screen with a graphic language, and a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is displayed as one of source factor contacts of unsatisfaction on the above described interlock diagnosis screen.

2. The plant control system according to claim 1, characterized in that said interlock diagnosis means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that the contact which has become unsatisfied in first place including each individual interlock 33 condition in the other plant control means is detected and displayed on said interlock diagnosis screen.

3. The plant control system according to claim 1, characterized in that said interlock diagnosis means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that the detailed information of each individual interlock condition in the other plant control means is displayed as one of source factor contacts of unsatisfaction, and the program portion at which the source factor contact to have become unsatisfied is used in the other plant control means are presented.

4. The plant control system according to claim 1, characterized in that said interlock diagnosis means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in another plant control means is one of source factor contacts of unsatisfaction, and the relevant program in which that contact is used in the other plant control means is directly displayed.

5. The plant control system according to claim 1, characterized in that said interlock diagnosis means has a function by which even if the interlock circuit is formed in multiple stages, only a source factor contact of unsatisfaction is identified and the contact which has become unsatisfied in first place is detected to be displayed on said interlock diagnosis screen, and in 34 addition, the contacts which have become unsatisfied in second, third, ..., or nth place are detected to be displayed on said interlock diagnosis screen.

6. The plant control system according to claim 5, characterized in that said interlock diagnosis means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is displayed as a detection target contact when having become unsatisfied in second, third, ..., or nth place, on said interlock diagnosis screen.

7. The plant control system according to claim 6, characterized in that said interlock diagnosis means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that when each individual interlock condition in the other plant control means has become unsatisfied in second, third, ..., or nth place and is displayed on said interlock diagnosis screen, the detailed information thereof and the program portion at which the source factor contact which has become unsatisfied is used in the other plant control means are directly presented by a display function of source factor contact which indicates that said interlock condition has become unsatisfied in second, third, ..., or nth place.

8. The plant control system according to claim 6, characterized in that said interlock diagnosis means has a function by which 35 even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that when each individual interlock condition in the other plant control means has become unsatisfied in second, third, ..., or nth place and is displayed on said interlock diagnosis screen, the relevant program in which the contact is used in the other plant control means is directly displayed by a display function of source factor contact which indicates that said interlock condition has become unsatisfied in second, third, ..., or nth place.

9. The plant control system according to claim 1, characterized by comprising: operator manipulation/monitoring means which comprises the functions of said interlock diagnosis means on a general operator manipulation/display device to be manipulated by the plant operator in the plant operation room, and is capable of displaying said interlock diagnosis screen, and a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is included as one of source factor contacts of unsatisfaction and said interlock diagnosis screen is displayed on the screen of said operator manipulation/display device.

10. The plant control system according to claim 9, characterized in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative 36 contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that the contact which has become unsatisfied in first place including each individual interlock condition in the other plant control means is detected, and said interlock diagnosis screen is displayed on the screen of said operator manipulation/display device.

11. The plant control system according to claim 9, characterized in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored to present the detailed information of each individual interlock condition in the other plant control means as one of source factor contacts of unsatisfaction, and the program portion at which the source factor contact to have become unsatisfied is used in the other plant control means on the screen of said operator manipulation/display device.

12. The plant control system according to claim 9, characterized in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in another plant control means is one of source factor contacts of unsatisfaction, and the relevant program in which that contact is used in the other plant 37 control means is directly displayed on the screen of said operator manipulation/display device.

13. The plant control system according to claim 9, characterized in that said operator manipulation/monitoring means has a function by which even if an interlock circuit is formed in multiple stages, only a source factor contact of unsatisfaction is identified and the contact which has become unsatisfied in first place is detected to display said interlock diagnosis screen on the screen of said operator manipulation/display device, and in addition, the contacts which have become unsatisfied in second, third, ..., or nth place are detected to display said interlock diagnosis screen on the screen of said operator manipulation/display device.

14. The plant control system according to claim 13, characterized in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative contact in the other plant control means is also monitored so that each individual interlock condition in the other plant control means is a detection target contact when having become unsatisfied in second, third, ..., or nth place, and said interlock diagnosis screen is displayed on the screen of said operator manipulation/display device.

15. The plant control system according to claim 14, characterized in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition constituting a representative -38 contact in the other plant control means is also monitored so that when each individual interlock condition in the other plant control means has become unsatisfied in second, third, ..., or nth place and is displayed on said interlock diagnosis screen, the detailed information thereof and the program portion at 5 which the source factor contact which has become unsatisfied is used in the other plant control means are directly presented on the screen of said operator manipulation/display device by a display function of source factor contact which indicates that said interlock condition has become unsatisfied in second, third, or nth place. 10

16. The plant control system according to claim 14, characterised in that said operator manipulation/monitoring means has a function by which even when an interlock condition used by arbitrary plant control means is interfaced as a representative contact from another plant control means connected to a network, the state of satisfaction/unsatisfaction of each individual interlock condition 15 constituting a representative contact in the other plant control means is also monitored so that when each individual interlock condition in the other plant control means has become unsatisfied in second, third, ..., or nth place and is displayed on said interlock diagnosis screen, the relevant program in which the contact is used in the other plant control means is directly displayed on the screen of said 20 operator manipulation/display device by a display function of source factor contact which indicates that said interlock condition has become unsatisfied in second, third, ... , or nth place.

17. A plant control system substantially as hereinbefore described with reference to the accompanying drawings. 25