JP4085286B2 - PLC monitoring system - Google Patents

Description

  The present invention relates to a PLC monitoring system for monitoring a series of time-series bit data corresponding to respective values at each collection time of a plurality of variables collected from a memory of a programmable controller by a data collection unit via an image display. .

  The programmable controller (PLC) is configured by bus-connecting a CPU unit that performs control, a communication unit that performs data communication with the outside, an I / O unit that connects sensors, and the like. The CPU unit includes a microprocessor and a user memory that stores a user program created in advance according to the control content. By executing a predetermined system program, I / O refresh processing, user program execution processing, and peripheral service processing are cyclically executed. This one-round execution cycle is generally called a cycle time. The I / O refresh process is a process in which the PLC CPU unit exchanges IN data and OUT data as control data with the I / O unit via bus communication. The CPU unit includes a memory (for example, an input / output memory, a data memory, etc.) for storing IN data and OUT data as control data. By the way, a data collection unit that can be connected to a PLC is conventionally known. This data collection unit periodically and automatically collects various control data (including the above-mentioned IN data and OUT data. Specifically, for example, on / off data of input / output signals) stored in the memory of the CPU unit. It has a function to do. The data collection unit continues to collect data from the CPU unit at a specified cycle, and stores a series of changes in control data in a time series. The data collection unit may be abbreviated as “SPU”. The data collection unit is connected to the CPU unit by a bus (see Patent Document 1). In addition, it is conventionally known that a series of control data collected by this type of data collection device is monitored by a monitor device such as a display (see Patent Document 2). By storing a series of control data, for example, an on / off signal (time-series bit data string) of an input / output signal that changes in time series can be grasped by a monitor device described later.

  In this type of monitor device, it is common to display a pulse train waveform corresponding to a series of time-series bit data relating to each of a plurality of variables collected by a data collection unit, arranged side by side on a screen of an image display. It is.

  By the way, in order to be able to collect for this type of data collection unit, it is necessary to be treated as control data and variables in the PLC. Furthermore, it is necessary to allocate to the I / O memory and data memory built in the CPU unit, that is, the memory storage area must be uniquely determined. Therefore, for example, when it is desired to collect special data required by calculation between variables in the data collection unit, a new variable is set, and a user program (for example, a ladder program) is set so that the PLC performs calculation between variables. It is necessary to add and modify the program created in the graphic language and to allocate the new variable in the I / O memory or the data memory. The data collection unit also needs to be set so that the new variable is periodically collected from the memory allocation area of the PLC CPU unit, and set so that the monitor device reads and displays the data. .

For example, in general, the PLC data memory defines analog variables such as the number of products and the number of defects, but separately, it tries to acquire analog variables such as the number of non-defective products and the rate of non-defective products. In this case, it is necessary to define arithmetic expressions corresponding to these variables on the PLC side using PLC-specific instruction words. When a specific arithmetic expression is written, “number of non-defective products = number of products−number of defects” and “non-defective product ratio = (number of products−number of defects) ÷ number of products” are generated, which must be written in the user program.
JP 2005-128721 A JP 2003-21650

  However, when the PLC has already shifted to the operating state and is operating normally, new corrections to the user program may cause an increase in cycle time and unexpected malfunctions. Although there is concern and there is such a request, in general, the work is often hesitant. As a result, once it is introduced into the operating state, the user-friendliness on the monitor device side is currently limited.

  The present invention has been made paying attention to the above-mentioned problems, and the object of the present invention is to make no additional changes to the PLC user program even after the PLC has shifted to the operating state. Another object of the present invention is to provide a PLC monitoring system that can generate new information that involves calculation of variables and display the information on a monitor.

  Other objects and operational effects of the present invention will be easily understood by those skilled in the art by referring to the following description of the specification.

The PLC monitor system of the present invention includes a data collection unit that is connectable to the PLC and collects real variable data, and a monitor device connected to the data collection unit through communication.

  The monitor device includes a first means for setting a virtual variable defined by an arithmetic expression using two or more real variables, and an arithmetic expression corresponding to the virtual variable set by the first means as data. A second means of the monitoring device that transmits to the collection unit; a third means of the monitoring device that receives the real variable data string and the virtual variable data string from the data collection unit; a real variable data string and a virtual variable data string; Based on the fourth means of the monitor device stored in the internal table and each real variable data sequence and virtual variable data sequence stored in the internal table, a corresponding waveform display is performed on the screen of the image display of the monitor device. And a fifth means of the monitor device.

The data collection unit includes the first means of the data collection unit that receives the arithmetic expression corresponding to the virtual variable set from the monitor device, and the arithmetic expression received by the first means of the data collection unit . The second means of the data collection unit for generating mapping information for the correspondence between each real variable data string and the address of the real variable in the memory of the PLC, and the PLC memory based on the mapping information in synchronization with the cycle time of the PLC The virtual variable is obtained by substituting the synchronized real data between the third means of the data collection unit for reading the corresponding real data from the data and the third means of the data collection unit and defining the virtual variables. a fourth means of the data acquisition unit for generating a data sequence, the virtual variable data string and PL generated by the fourth means of data collection units A fifth means of the data acquisition unit to transmit the real variable data sequences read to the monitor device from the memory, is provided for.

According to such a configuration, the actual data read by the third means of the data collection unit is substituted into the arithmetic expression defining the virtual variable to generate the virtual variable data string, and the generated virtual variable data string And the actual variable data string read from the memory on the PLC side are transmitted to the monitor device. Therefore, a unique language such as a ladder diagram language is used on the PLC side to define a new variable. Therefore, it is not necessary to add or change the memory allocation, so that the monitoring target data can be expanded without worrying about the delay of the cycle time caused by the addition of the user program.

Further, the data collection unit of the present invention is connected to a PLC that performs control by executing a user program, and periodically reads control data from a memory that stores data of real variables of the PLC , and displays the control data on the display screen. A data collection unit that performs data communication with a monitor device that displays a corresponding waveform, and that stores an arithmetic expression using two or more real variables in the PLC as an arithmetic expression corresponding to a preset virtual variable Means, second means for storing real variable mapping information in the memory on the PLC side based on the arithmetic expression stored in the first means, and storage in the second means in synchronization with the cycle time of the PLC Based on the mapping information, the third means on the PLC side for reading the corresponding real variable data from the PLC memory, and the real variable data read by the third means , A fourth means for generating a virtual variable data string by substituting into the arithmetic expression stored in the first storage means, a virtual variable data string generated by the fourth means, and a read by the second storage means And a fifth means for transmitting the real variable data string to the monitor device.

  According to such a configuration, it is not necessary to add or change memory allocation using a specific language such as a ladder diagram language in the PLC even when defining a new variable. The monitoring target data can be expanded without worrying about the occurrence of time delay.

According to the present invention, the virtual variable data string is generated by substituting the real data read by the third means of the data collection unit into the arithmetic expression defining the virtual variable, and the generated virtual variable data string and the PLC Since the real variable data string read from the memory on the side is transmitted to the monitor device, even when defining a new variable, the PLC side uses a unique language such as a ladder diagram language. Since it is not necessary to add or change the assignment, it is possible to extend the monitoring target data without worrying about the delay of the cycle time caused by the addition of the user program.

  Hereinafter, a preferred embodiment of a PLC monitor system according to the present invention will be described in detail with reference to the accompanying drawings.

  An example of a hardware configuration diagram of a PLC system including a data collection unit is shown in FIG. As shown in the figure, this PLC system is mainly configured by a first PLC 1, a second PLC 5, and a personal computer (hereinafter referred to as a PC) 2. The first PLC 1 and the PC 2 are connected via a communication line 9a, and the first PLC 1 and the second PLC 5 are connected via a communication line 9b.

  The first PLC 1 is configured in a building block type. In this example, the CPU unit 11 that controls the communication, the communication unit 12 that performs data communication with the outside, and the I / O unit 13 that connects the input device or the output device. And a data collection unit (SPU) 14, which are bus-connected via a backplane board.

  As is well known to those skilled in the art, the CPU unit 11 includes a microprocessor that executes general processing, a user program memory that stores user programs, and an I / O memory that stores so-called I / O data. Built-in data memory. Then, the built-in microprocessor of the CPU unit 11 cyclically executes I / O refresh processing, user program execution processing, and peripheral service processing by executing a predetermined system program. At this time, the one-round execution cycle is generally called a cycle time.

  The I / O unit 13 is connected to a plurality of input devices and output devices (not shown), and includes a memory for storing data corresponding to each device. Then, the input data (including bit variable data that is on / off data and analog variable data that is numerical data) is periodically fetched from the external sensor 4 and stored. Also, output data (including data that is a user program execution result) sent by the IO refresh process of the CPU unit 11 is sent to an external actuator 3 or the like.

  In the I / O refresh process in the CPU unit 11, the microprocessor writes input data from the I / O unit 13 to the corresponding area of the I / O memory via the bus. Further, the microprocessor sends the output data of the corresponding area of the I / O memory to the I / O unit 13 via the bus. In the user program execution process in the CPU unit 11, the microprocessor sequentially executes user instructions of the user program stored in the user program memory. That is, the contents of the input data stored in the I / O memory are referred to and executed according to the user command, and the contents of the memory output data are rewritten based on the execution result.

  In the peripheral service processing in the CPU unit 11, for example, I / O data is exchanged with the second PLC 5 by communicating with the second PLC 5 through the communication unit 12.

  The data collection unit 14 has a built-in processor. When the processor performs the I / O refresh process in the CPU unit 11 described above, the data collection unit 14 reads all the data in the I / O memory from the CPU unit 1 via the bus, Accumulated and stored in a memory in the collection unit (SPU) 14. Instead of reading all the data, only the designated data may be read from the memory of the CPU unit 1 by setting a target to be read to the data collection unit 14 in advance. Note that data collection may be performed, for example, during peripheral service processing instead of being performed during I / O refresh processing of the CPU unit 1, or a separate processing period may be provided before or after user program execution processing. It may be done. In short, any configuration that collects data once per round execution cycle in the CPU unit 1 may be used. Furthermore, the data collection cycle may be lengthened so that data collection is performed once every plural execution cycles in the CPU unit 1 without synchronizing the data collection cycle with the one-round execution cycle in the CPU unit 1.

  Thus, the control data of the CPU unit is collected by the data collection unit 14 and stored and stored in the memory of the data collection unit 14. This collected data is control data of the CPU unit, and includes bit variables and analog variables, or includes input data and output data. The data collection unit 14 has control data on the CPU unit side and memory allocation information for variables. By setting in advance in the data collection unit the information on which memory area of the CPU unit the data to be collected is stored, the data collection unit 14 can collect the collected data periodically from the CPU unit. become. In addition to the memory allocation information, symbol information is preferably registered in the data collection unit 14. The symbol information is information that assists the user in recognizing or specifying certain control data and variables. For example, the symbol information is “input signal from the sensor 4” or “output signal to the actuator 3”. Information. The above-mentioned “production number” and “number of defects” are also symbol information. This symbol information is information represented by a character string, and is sometimes called tag information or a comment (same as the comment 133 in FIG. 9). The collected data is read from the data collection unit 14 and sent to the PC 2 by the communication between the PC 2 and the data collection unit 14 at an appropriate timing.

  The symbol information of the data collected by the data collection unit and the memory allocation information of the CPU unit are registered in advance in the PC 2 (note that the symbol information is used for displaying the comment 133 in FIG. 9 and the memory allocation information is shown in FIG. Used for display of the address 132). The PC 2 acquires the collected data from the data collection unit 14 by communicating with the data collection unit 14 at an appropriate timing. Note that the symbol information and the memory allocation information may be acquired by the PC 2 communicating with the data collection unit 14 instead of registering in advance. The acquired data acquired in this way is stored in a variable table provided in the memory of the PC 2.

  Then, the PC 2 displays a time-series change as a pulse train waveform or an analog waveform on the screen of the image display based on the acquired data, corresponding to each control data (detailed in FIG. 9). . By doing so, the user can visually monitor the control data and various analog data handled by the PLC 1 via the screen of the image display. The first PLC 1 (which may also be referred to as the CPU unit 11) obtains the data of the second PLC 5 by performing the peripheral service process, and the data collection unit 14 collects the data of the PLC 2 via the CPU unit 11. By doing so, the data of the second PLC can be similarly monitored by the PC 2.

  A functional block diagram of the data collection unit 14 is shown in FIG. As shown in the figure, the data collection unit 14 includes a PLC interface 14a, a sampling unit 14b, an arithmetic processing unit 14c, a storage unit 14d, a file management unit 14e, a file writing unit 14f, and a PC interface. 14g.

  The PLC interface 14a has a function for connecting to the PLC side. Specifically, the PLC interface 14a is connected to the PLC backplane bus and has a function of performing data communication with the CPU unit 11 and other units. Have. The PC interface 14g has a function for connecting to the PC side, and has a function of connecting to the communication line 9a and performing data communication with the PC 2.

  The sampling unit 14b accesses the CPU unit 11 of the PLC 1 via the PLC interface 14a, thereby periodically and automatically sampling data mapped in advance from the internal I / O memory or data memory of the CPU unit 11. It has a function.

  Of the data sampled in this way, data related to variables (real variables) on the PLC side is sent to the storage unit 14d as it is. On the other hand, for data relating to virtual variables, the arithmetic processing unit 14c performs arithmetic processing by substituting real variables in accordance with an arithmetic expression designated in advance, and the arithmetic result is sent to the storage unit 14d.

  Data corresponding to each of the real variable and the virtual variable stored in the storage unit 14d is transmitted to the PC 2 side via the PC interface 14g by the operation of the file management unit 14e and the file writing unit 14f. As described above, in the data collection unit of the present invention, the data sampled by the sampling unit 14b is stored as it is in the storage unit 14d as data relating to the actual variable. Further, the real variable data to be used for obtaining the virtual variable is also stored once in the storage unit 14d in the same way as the real variable that may be simply collected, and the arithmetic processing unit when necessary to obtain the virtual variable. 14c reads from the storage unit 14d. Note that a real variable that is used only for obtaining a virtual variable is temporarily stored in an internal buffer or the like of the arithmetic processing unit 14c without being stored in the storage unit 14d, and is directly used when performing predetermined arithmetic processing. It can also be. The virtual variable that is the result of the arithmetic processing is written in the storage unit 14d.

  Thereafter, the data corresponding to the real variable and the virtual variable stored in the storage unit 14d is made to appear as if they were real variables by the operation of the file management unit 14e and the file writing unit 14f. The data is transmitted to the PC 2 side.

  A flowchart of the virtual variable setting process executed on the monitor device 2 side is shown in FIG. 2, and an image diagram of the virtual variable setting screen is shown in FIG. By this series of processing, an arithmetic expression related to the virtual variable is programmed, and the arithmetic expression is transmitted to the data collection unit and stored in the storage unit 14d of the data collection unit.

  As shown in the flowchart of FIG. 3, in the virtual variable setting process, first, the “name” and “data type” of a desired virtual variable are set (step 301). This setting operation is performed according to the virtual variable setting screen as shown in FIG.

  The virtual variable setting screen of FIG. 9 is displayed on the screen of the image display device of the PC 2. In this virtual variable setting screen, as shown in FIG. 9, a name display area 101 for displaying the “name” of the virtual variable and a data type display area 102 for displaying the “data type” of the virtual variable. And an arithmetic expression display area 103 for defining the “arithmetic expression” of the virtual variable, and a variable list display that can display a menu of variables (bit variables, analog variables) and virtual variables that can be used for setting the virtual variable. An area 104, an operation key display area 105 displaying various operation keys necessary for setting virtual variables, an OK button 106, and a cancel button 107 are displayed.

  The variable list display area 104 displays “data type”, “address”, and “description” (a character string indicating the meaning content of the variable) corresponding to each variable and virtual variable. Later, as will be described in detail with reference to the flowchart of FIG. 2, an optimal menu display is performed in the variable list display area 104 according to the “data type” set by the user.

  The operation key display area 105 includes a back key 105a, a clear key 105b, a numerical key 105c, a numerical operator key 105d, a logical operator key 105e, and a logical value key 105f.

  Therefore, a user who wants to set a virtual variable while looking at this virtual variable setting screen first uses the word processor function of the personal computer to apply the corresponding virtual variable to each of the name display area 101 and the data type display area 102. Enter a name (for example, “operation time”) and a data type (for example, “REAL”). Thereafter, by moving the cursor up and down in the variable list display area 104 to select a desired variable or virtual variable, and simultaneously operating various keys 105a to 105f displayed in the operation key display area 105, the desired virtual An arithmetic expression corresponding to the variable is created and displayed in the arithmetic expression display area 103. Thereafter, by operating the OK button 106, the virtual variable “operation time” defined by the contents of the arithmetic expression display area 103 is stored in a predetermined area in the memory of the PC.

  At this time, as shown in the flowchart of FIG. 3, when the operator sets “data type”, if the data type is “bit type” (on / off signal), the variable displayed in the variable list display area 104 is All are bit-type (step 303), and thereafter, a desired arithmetic expression can be created while operating the logical arithmetic expression 105e and the logical value key 105f, and this can be registered in a predetermined area of the PC memory ( Step 304).

  On the other hand, if it is determined that the “data type” set by the user is not “bit type” (NO in step 302), all variables displayed in the variable list display area 104 are set to “variable type”. Therefore, the user can generate the four arithmetic expressions while operating the numerical keys 105c and the numerical arithmetic expressions 105d, and register them in a predetermined area of the PC internal memory (step 306).

  In this way, when the virtual variable setting process is completed, the setting information including the arithmetic expression defining each virtual variable thus obtained is transmitted to the data collection unit 14 on the PLC side (step 307). The setting information is conveniently in a file format. The data collection unit 14 receives the setting file via the PC interface 14g and stores it in the storage unit 14d under the control of the file writing unit 14f. If the data collection unit 14 has stored the setting file, the arithmetic expression and other setting information registered in the memory in the PC 2 may be deleted. It should be noted that this series of settings may be performed by another setting tool device (not shown) instead of the PC 2.

  An image diagram of a virtual variable list screen that can be selected for data collection is shown in FIG. As described above, the virtual variable list screen can be displayed on the screen of the image display device of the PC 2 by setting the predetermined display mode. If the arithmetic expression is still registered in the memory in the PC 2 after registering the arithmetic expression, the information of the arithmetic expression can be read from the memory in the PC 2 and displayed again. When the information of the arithmetic expression is deleted from the memory in the PC 2, the arithmetic expression data may be read from the data collection unit and displayed. By observing this list screen, the operator can recognize “name”, “data type”, and “arithmetic expression” of selectable virtual variables. Further, a desired virtual variable to be displayed on the display device may be arbitrarily selected and set based on the list screen. Note that this series of display operations may be performed by another setting tool device (not shown) instead of the PC 2.

  An example of an image diagram of the collection setting screen is shown in FIG. As shown in the figure, the collection setting screen shown in FIG. 10 can be displayed on the screen of the image display device of the PC 2 by setting the display mode to a predetermined mode. This collection setting screen can include not only actual variables selected as data collection targets but also arbitrary virtual variables. Note that this series of display operations may be performed by another setting tool device (not shown) instead of the PC 2. In the example of FIG. 10, the “number of non-defective products” and the “non-defective product rate” correspond to virtual variables.

  Since the virtual variable selected and set in this way is obtained by calculation in the data collection unit, its calculation formula is as if the variable was newly set on the PLC side using the ladder diagram language in the monitoring process. Can be handled.

  Next, FIG. 6 shows a flowchart showing the entire collection processing performed on the data collection unit (SPU) 14 side. When processing is started in the figure, first, setting information (including an arithmetic expression) is read from the storage unit 14d via the file management unit 14e (step 601).

  A detailed flowchart of the setting information read process is shown in FIG. As shown in the figure, in this arithmetic expression reading process, first, virtual variables are read from a setting file (corresponding to the collection setting screen shown in FIG. 10 and the virtual variable list screen shown in FIG. 11) (step 401). ).

  Subsequently, the nesting process of the arithmetic expression of the read virtual variable is decomposed (step 702). Here, each arithmetic expression corresponding to the virtual variable is stored in the arithmetic expression storage table.

  As shown in FIG. 5, a pointer P (n) is attached to each of the real IO value and the virtual variable. For example, the pointer of the actual IO value A is p1, the pointer of the actual IO value B is p2, and so on. Each virtual variable is represented using a pointer indicating the actual IO value. For example, a pointer p11 is attached to the virtual variable A, and this virtual variable A is expressed as an addition result (that is, an addition expression) of a pointer p2 indicating the real IO value B and a pointer p8 indicating the real IO value H. Yes. Similarly, a pointer p31 is attached to the virtual variable C, and an expression for obtaining the virtual variable C is expressed as a product of a pointer p11 indicating the virtual variable A and a pointer p21 indicating the virtual variable B. Therefore, decomposing the arithmetic expression nesting process in step 402 means decomposing the degree of pointer application in the arithmetic expression storage table of FIG.

  Subsequently, processing for sorting the processing order of the arithmetic expressions is executed (step 703). In this sort processing, the calculation formulas are sorted so that the calculation processing is performed in advance for the variables used in the subsequent calculation in consideration of the ease of calculation.

  Subsequently, an optimization routine for arithmetic processing is created based on the sorting result (step 704). Here, the “optimization routine” means that when there is the same arithmetic expression (for example, A + B−C) in each arithmetic expression, it is registered as a separate variable and reused in each arithmetic expression, thereby processing time. It means to shorten.

For example, suppose that there is an equation of X = A + BC + DE and an equation of Y = GH + A + BC + F. Among the two expressions, the same arithmetic expression (common expression) is A + B−C, so that it is set as another variable Z,
X = A + BC + DE → X = variable Z + DE
Y = GH + A + BC + F → Y = GH + variable Z + F
As an optimization.

  In the subsequent step 602, mapping information for specifying read data is notified to the PLC (CPU unit) (step 602).

  Thereafter, the data collection unit (SPU) 14 waits for an interrupt for each cycle time from the PLC (CPU) (step 603). In this state, when an interrupt occurs (step 603 YES), the data collection unit (SPU) 14 falls under the mapping area of the PLC that stores the actual data defining each virtual variable through the sampling unit 14b and the PLC interface 14a. Data is read (step 604). The read data is stored in the storage unit 14d. In step 603, instead of the above-described processing contents, processing is performed such that an interrupt timing is generated for each sampling period in which data is collected by the data collection unit, and data is read from the CPU unit by its own interrupt. Also good. Subsequently, the arithmetic processing unit 14c executes arithmetic processing such as substituting the value of the collected data into the arithmetic expression based on the arithmetic expression set in advance corresponding to each virtual variable, and obtains the value of the virtual variable ( Step 605).

  Next, the calculation result thus obtained is stored in a predetermined virtual variable area in the storage unit 14d of the data collection unit (SPU) 14 (step 606). Thereafter, the collection area including the virtual variable area is sampled (step 607), and the collected data is stored in a predetermined file in the memory (step 608). The file storage processing in steps 607 and 608 may be performed for each sampling, or the files may be stored collectively over a plurality of sampling periods.

  Collected data (real variable data) and calculation results (virtual variable data) saved in the file in this way are transmitted to the PC 2 side by communication between the PC 2 and the data collecting unit 14 at an appropriate timing. As described above, it is stored in the internal table in the memory of the PC 2.

  A conceptual diagram showing the relationship between the memory mapping and the collection method is shown in FIG. As shown in the figure, the CPU 11 cyclically executes I / O refresh processing, user program execution processing, and peripheral service processing with a predetermined cycle time.

  The data collection unit 14 collects variable data (bit variable data that is on / off data, analog variable data that is numerical data) specified by the mapping information for each cycle time of the CPU unit 11, and Write to the O variable area.

  On the other hand, on the side of the data collection unit (SPU) 14, in synchronization with each cycle time, the value of the virtual variable is calculated based on the value of the real variable according to a preset arithmetic expression, and this is calculated as the data collection unit (SPU). ) Write to the virtual variable area in 14 memory.

  On the other hand, three types of collection processing (collection A, collection B, and collection C) having independent sampling periods (periods longer than the sampling period synchronized with the cycle time of the CPU unit) are prepared. Through these collection processes, the actual variables in the actual variable area on the CPU unit side are independently collected and stored in the actual variable area of the data collection unit 14. Then, the virtual variable is obtained by substituting the real variable into the arithmetic expression, and stored in the virtual variable area of the data collection unit 14. This is because the data to be collected is to be monitored with a short sampling period synchronized with the cycle time of the CPU unit, or to be monitored with a sampling period longer than the cycle time of the CPU unit (for example, 100 ms). In addition, there are cases where data that is to be monitored with a longer sampling period (1 s) may coexist.

  The real variable data collected in this way and the virtual variable obtained by the arithmetic expression are stored in a file and transferred to the PC 2 side as necessary. Thereafter, on the PC 2 side, a waveform diagram can be displayed over a plurality of lines as shown in FIG. 12 on the screen of the image display device based on the data strings corresponding to the real variables and the virtual variables. Thus, monitoring according to appropriate monitoring items in accordance with each control target device is possible.

  Next, the monitoring process will be described. A general flowchart of the entire monitoring process is shown in FIG.

  In the figure, when processing is started, first, arithmetic expression read processing is executed (step 301). In the subsequent step 302, each variable data read from the data collection unit (SPU) 14 of the PLC 1 and stored in the internal table or database is read.

  FIG. 4 shows a general flowchart of the entire monitoring process executed on the monitor device 2 side. As shown in the figure, when the monitoring process is started, first, by communicating with the data collection unit (SPU) 14, the corresponding data (actual variable) is stored from the storage unit 14d of the data collection unit (SPU) 14. , Including virtual variables) is executed (step 401). This processing may be configured such that the PC 2 makes a data transfer request to the data collection unit 14 and receives a reply, or the data collection unit 14 independently transmits data and receives it.

  Subsequently, the data read from the data collection unit (SPU) 14 of the PLC 1 is stored in an internal table in the memory of the PC 2 (step 402). Subsequently, the data (including real variables and virtual variables) stored in the internal table is displayed on the screen 100 of the image display device of the PC 2 by the processing of the processor inside the PC 2.

  FIG. 12 shows an image diagram of the entire monitor screen at this time. As shown in the figure, the entire monitor screen 100 includes a bit variable waveform display area 110, an analog variable waveform display area 120, a bit variable related information display area 130, and an analog variable related information display area 140. It is out.

  Display rows corresponding to L1 to L16 are set in the bit variable waveform display area 110, and each display row can display a pulse train waveform corresponding to a data train corresponding to each of 16 bit variables. ing. On the other hand, in the analog variable waveform display area 120, analog variable waveforms corresponding to a predetermined number of analog variables are respectively drawn with lines having unique colors.

  In the bit variable related information display area 130, a check box column 131 for setting each display row to be active or non-active, a color box column 132 representing a variable color corresponding to each display row, An address / comment display column 133 that can alternatively display an address or comment corresponding to each variable, and an on / off color box that indicates an on / off state at the time point indicated by the cursor line 111 in each display row L1 to L16 in two colors. Similarly, an ON / OFF character string 135 indicating the ON / OFF state as either ON / OFF, and an ON / OFF time column 136 indicating the ON time or the OFF time of the OFF pulse indicated by the cursor line 111 are provided. It has been.

  Similarly, in the analog variable related information display area 140, a check box column 141 for setting the display of each analog variable to either active or inactive, a color box column 142 indicating the line color of each variable, A comment column 143 for displaying a description (comment) of the variable and a numerical value box column 144 indicating the value of each variable at the time point indicated by the cursor line 111 are provided.

  In particular, in connection with the present invention, virtual variables corresponding to “number of non-defective products” and “non-defective product ratio” are displayed in the comment column. Correspondingly, the analog variable waveform display area 120 indicates the number of products to be produced. A corresponding waveform 121, a waveform 122 corresponding to the number of non-defective products, and a waveform 123 corresponding to the number of defects are displayed. The number of non-defective products in the waveform 122 is a value obtained by the calculation formula = number of products−number of defects in the PC 2. As shown by these waveforms, the transition of the relationship among the number of productions, the number of defects, and the number of non-defective products can be observed. It should be noted that the non-defective product rate of the virtual variable is a value obtained by the equation: (production number−number of defects) ÷ production number. When displaying in the analog variable waveform display area 120, the vertical axis may be a ratio, with the lowest point being 0% and the highest point being 100%.

  Needless to say, the virtual variable data is uniquely generated on the PC 2 side and does not exist in the memory on the PLC 1 side. Further, it is not obtained by calculation on the PC 2 side. As described above, according to the present invention, virtual variable data can be handled as if a variable was newly set in the ladder diagram language or the like on the PLC 1 side. By observing the change over time via the monitor screen, it becomes possible to derive the optimum virtual variable for maintenance of the production facility and failure cause analysis.

  According to the present invention, a virtual variable data string is generated by substituting real data read by the third means on the PLC side into an arithmetic expression that defines a virtual variable, and the generated virtual variable data string and the PLC side Since the real variable data string read from the memory is sent to the monitor device, even when defining a new variable, memory allocation is performed using a specific language such as a ladder diagram language on the PLC side. Since it is not necessary to add or change the data to be monitored, it is possible to extend the monitoring target data without worrying about the delay of the cycle time caused by the addition of the user program.

It is a hardware block diagram of the PLC system containing a data collection unit. It is a functional block diagram of a data collection unit. It is a flowchart of a virtual variable setting process. It is the general flowchart of the whole monitor process. It is a block diagram of an arithmetic expression storage table. It is a flowchart which shows the whole collection process. It is a detailed flowchart of a setting information reading process. It is a conceptual diagram which shows the relationship between memory mapping and a collection system. It is an image figure of a virtual variable setting screen. It is an image figure of a collection screen. It is an image figure of a virtual variable list screen. It is an image figure of the whole monitor screen.

Explanation of symbols

1 First PLC
2 PC
3 Actuator 4 Sensor 5 Second PLC
6 Analog I / O unit 7 Digital I / O unit 11 CPU unit 12 Communication unit 13 I / O unit 14 Data collection unit (SPU)
14a PLC interface 14b Sampling unit 14c Operation processing unit 14d Storage unit 14e File management unit 14f File writing unit 14g PC interface 51 CPU unit 52 Communication unit 53 I / O unit 100 Display screen 101 Name display area 102 Data type display area 103 Operation Expression display area 104 Variable list display area 105 Operation key display area 106 OK button 107 Cancel button 110 Bit variable waveform display area 120 Analog variable waveform display area 130 Bit variable related information display area 140 Analog variable related information display area

Claims (3)

A data collection unit that is connectable to the PLC and collects real variable data; and a monitor device connected to the data collection unit via communication,
In the monitor device,
A first means of a monitor device for setting a virtual variable defined by an arithmetic expression using two or more real variables;
A second means of the monitor device for transmitting an arithmetic expression corresponding to the virtual variable set by the first means to the data collection unit;
A third means of the monitoring device for receiving the real variable data string and the virtual variable data string from the data collection unit;
A fourth means of the monitoring device for storing the real variable data string and the virtual variable data string in the internal table;
And a fifth means of the monitor device for displaying the corresponding waveform on the screen of the image display device of the monitor device based on each real variable data string and virtual variable data string stored in the internal table. ,
The data collection unit includes
A first means of a data collection unit for receiving an arithmetic expression corresponding to a virtual variable set from a monitor device;
Second means of the data collection unit for generating mapping information about the correspondence between each real variable data string included in the arithmetic expression received by the first means of the data collection unit and the address of the real variable in the PLC memory; ,
In synchronization with the PLC cycle time, and the third means of the data collection unit to read out the actual data corresponding from the memory of the PLC on the basis of the mapping information,
Read the third means of the data collection unit, and the fourth means of a data acquisition unit for generating a virtual variable data sequence are substituted into the calculation equation for defining a virtual variable actual data together with synchronized,
A fifth means of the data acquisition unit that transmits the real variable data sequences read from the virtual variable data string and the PLC memory generated by the fourth means of the data collection unit to the monitor device, is provided A PLC monitoring system characterized by the above. Monitor device and data that are connected to a PLC that executes control by executing a user program, periodically reads control data from a memory that stores data of real variables of the PLC , and displays a corresponding waveform on the display screen A data collection unit for communication,
First means for storing an arithmetic expression using two or more real variables in the PLC in correspondence with a preset virtual variable;
Second means for storing mapping information about correspondence between each real variable data string included in the arithmetic expression stored in the first means and the address of the real variable in the PLC memory;
Third means for reading out data of the corresponding real variable from the memory of the PLC based on the mapping information stored in the second means in synchronization with the cycle time of the PLC;
Is read out by the third means, the fourth means for generating a data each other real variable synchronized, virtual variable data sequence by substituting the stored arithmetic expression in the first storage means,
A fifth means for transmitting the virtual variable data string generated by the fourth means and the real variable data string read by the second storage means to the monitor device is provided. Data collection unit.   The first means includes an arithmetic expression using a set virtual variable in the stored arithmetic expression,
  The fourth means has a function of substituting a virtual variable generated by substituting data of synchronized real variables into an arithmetic expression, and generating as another virtual variable by substituting into the arithmetic expression using the virtual variable, The data collection unit according to claim 2.

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