JP2008159004A - Programmable logic controller data trace device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a data trace device 20 tracing data of an array element of array variable even when a suffix of the array variable is variable. <P>SOLUTION: A sampling condition setting section 250 can set the array variable and the suffix variable of the array variable in combination. When the variable used for sampling set by the sampling condition setting section 250 is array variable, an array address arithmetic section 220 calculates the address of the element of the array variable specified with the value of the suffix variable of array variable, and sets it and the value of the suffix variable of the array variable in a sampling executing section 210. The sampling executing section 210 determines the value of the element of the array variable from the address of the element of the array variable, records it and the value of the suffix variable of the array variable in a sampling buffer 230 every sampling period, and displays the recorded value of the element of the array variable and the value of the suffix variable of the array variable every sampling period. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a data trace apparatus that samples and records a specific signal of a programmable logic controller (hereinafter abbreviated as PLC) at a constant period.

  Conventionally, a data trace device that samples and records a specific signal of a PLC at a constant period is used to know a change in the state of the signal of the PLC. In recent years, with improvement in performance of a microprocessor, Patent Document 1 discloses a technique that allows a sequence program to be executed by an interpreter method or a compiler method using a general-purpose microprocessor and to monitor actual data during execution of the sequence program. ing.

  In recent years, PLCs that can create PLC programs that use array variables based on IEC61131-3 have become widespread, and there is an increasing demand for tracing array variables.

  An example of an operation in which a conventional data tracing apparatus traces an array variable will be described with reference to FIGS.

  FIG. 4 is a block diagram showing an embodiment of a conventional PLC and data trace apparatus. 4 includes a PLC execution unit 100 and a data trace unit 200. The PLC execution unit 100 includes a CPU 110, a PLC data memory 120, and a PLC program memory 130. The data trace unit 200 includes a sampling execution unit 210, a sampling buffer 230, a screen control unit 240, a sampling condition setting unit 250, and an operation input control unit 260. The screen control unit 240 is connected to the monitor screen 300 to display a screen, and the operation input control unit 260 is connected to an input device 320 such as a keyboard or a mouse, and receives an input from the input device 320.

  FIG. 5 is a flowchart showing an example of a conventional operation for tracing array variables. The sampling condition setting unit 250 is input to the operation input control unit 260 using the input device 320, and from the array variable name and the number of samplings displayed on the screen control unit 240, the start address of the array, the data type of the array, An array subscript value and the number of times of sampling are obtained, an array element address is obtained from the start address of the array, the data type of the array, and the value of the array subscript, and the sampling execution unit is combined with the number of times of sampling. 210 is set (step S131).

  The sampling execution unit 210 reads the address value of the set array element from the PLC data memory 120, writes it in a predetermined position of the sampling buffer 230 (step S140), and ends the trace when sampling is completed for the set number of times of sampling. To do. If the set number of samplings is not reached, the number of samplings is counted up, and the process returns to step S140 to repeat the sampling (steps S150 and S160).

  FIGS. 6A and 6B are examples of PLC programs using array variables. 6 (a) uses an array variable ARRAYA [] whose subscript is constant = 10 at the second contact from the left bus, and FIG. 6 (b) is a subscript at the second contact from the left bus. Uses the array variable ARRAYB [] with variable = i.

  FIG. 7 shows an example of a screen displaying the result of tracing each variable of the PLC program of FIG. 6A by the conventional data trace apparatus. From the left of the screen example 400, a signal name field 410, a data type field 420, and a trace result field 430 are displayed. A number field 432 for displaying a number for identifying the sampled period is arranged above the trace result field 430, and an input field 434 for displaying the trace result of each variable, an array variable field 436, An output field 438 is arranged. The trace result field 430 can be scrolled horizontally. In the example of FIG. 7, the trace result is displayed as a numerical value, but it is needless to say that the graph can be displayed based on the numerical value.

  In the conventional data trace apparatus, in the case of the PLC program of FIG. 6A, the sampling condition setting unit 250 performs sampling from the address at which the first element of the array is stored, the value of the array subscript, and the data type of the array. Since the address for storing the element and the data type of the array element can be obtained, the data trace of the array variable = ARRAYA [10] can be performed, but the array variable = ARRAYB [i of the PLC program in FIG. ], The value of the subscript of the array is the value of variable = i and may change during sampling, so data tracing could not be performed.

JP 2005-115969 A

  Since the conventional data trace apparatus 20 cannot specify the address of the array element of the array variable when the subscript of the array variable in the PLC program is a variable, the data of the array element of the array variable can be specified only when the subscript is a constant. There was a problem that tracing could not be performed.

  The present invention has been made under the circumstances described above, and an object of the present invention is to provide a data trace apparatus 20 that can perform data tracing of array elements of array variables even when the subscript of the array variable is a variable. Is to provide.

  In order to achieve the above object, a data trace device according to the present invention samples and stores variable logic controller variable values at a constant period, and the data trace device performs sampling and A sampling condition setting unit that sets sampling start and end conditions, a sampling execution unit that performs sampling according to the conditions set in the sampling condition setting unit, and an array that calculates an address of an array variable on which the sampling execution unit performs sampling An address calculation unit, and a sampling buffer for storing the sampling result of the sampling execution unit, the sampling condition setting unit can be set by combining an array variable and a subscript variable of the array variable, the array address calculation unit, Sampling conditions When the sampling variable set in the setting section is an array variable, calculate the address of the element of the array variable specified by the value of the subscript variable of the array variable, along with the value of the subscript variable of the array variable Set in the sampling execution unit, the sampling execution unit obtains the value of the element of the array variable from the address of the element of the array variable, and records the value of the subscript variable of the array variable in the sampling buffer for each sampling period The recorded element value of the array variable and the value of the subscript variable of the array variable are displayed side by side for each sampling period.

  By using the present invention, the following effects can be obtained. That is, even when the subscript of the array variable is a variable, it is possible to perform data trace of the element of the array variable, so that it is easy to analyze the actual operation of the PLC program including the array variable. For example, an effective PLC program using array variables can be built in the following cases.

  The operation mode (operation mode / pause mode / emergency stop mode, etc.) to be controlled is assigned as the value of the subscript variable of the array variable, and the PLC program mode can be switched at once by changing the value of the subscript variable. It can be easily realized. In this way, if the subscript of an array variable is used as a variable, the same variable can have multiple meanings. In such a case, according to the present invention, even when the subscript of the array variable is a variable, debugging can be performed using the data trace function. Therefore, it is very easy to debug the program when the array variable is used in the PLC program. The effect which becomes can be acquired.

  Hereinafter, an embodiment of the present invention (hereinafter referred to as an embodiment) will be described with reference to FIGS.

  FIG. 1 is a block configuration diagram showing the PLC 10 and the data trace device 20 of this embodiment corresponding to FIG. In addition, the same code | symbol is attached | subjected to the same structure location and description is abbreviate | omitted. In the present embodiment, an array address calculation unit 220 is newly added.

  FIG. 2 is a flowchart showing an example of operations of the sampling execution unit 210 and the array address calculation unit 220 in the data trace apparatus 20 according to the present embodiment. In addition, the same code | symbol is attached | subjected to the same structure location as FIG. 5, and description is abbreviate | omitted.

  When the variable to be sampled is an array variable, the sampling condition setting unit 250 stores an address that stores the first element of the array, an array data type, an array subscript value, or an array subscript value. The data type of the subscript type of the array and the number of samplings are obtained and set in the array address calculation unit 220. Whether the array subscript is a constant (numeric value) or a variable is set in the data type of the array subscript type. In the case of a variable, the subscript data type is set. (Step S100).

  The array address calculation unit 220 determines whether the set array index is a constant or a variable. If it is a variable, the process proceeds to step S120. If it is a constant, the process proceeds to step S130 (step S110).

  Next, when the array subscript is a variable, the array address calculation unit 220 adds the subscript value from the PLC data memory 120 based on the address for storing the set array subscript value and the data type of the subscript. The character value is read out and obtained (step S120). That is, the array address calculation unit 220 accesses an address in which the value of the array subscript in the PLC data memory 120 is stored, and based on the data type of the subscript (data size, etc.) The subscript value is read out and obtained.

  Further, an address for storing the array element to be sampled is obtained from the obtained subscript value, the address for storing the first element of the array, and the data type of the array. For example, if the obtained subscript value is i = 5, the address of the first element is 1000, and the subscript is an integer greater than or equal to 0, if the data type of the array is address 1 for array element 1, By adding the subscript value to the address of the head element, the address of the array element to be sampled is obtained as address 1005. Similarly, when the subscript is a constant, the address for storing the array element is obtained. The obtained array element address is set in the sampling execution unit 210 together with the subscript value. (Step S130).

  The sampling execution unit 210 reads the array element value from the PLC data memory 120 from the set array element address, writes it to the predetermined position of the sampling buffer 230 together with the subscript value, and performs sampling for the set number of times of sampling. When the process is finished, the trace is finished (step S150).

  If the set number of samplings has not been reached, the number of samplings is counted up, the process returns to step S110 and the sampling is repeated (steps S150 and S160).

  FIG. 3 shows an example of a screen displaying the result of tracing each variable of the PLC program of FIG. 6B by the data trace apparatus of the present invention, as compared with FIG. The screen shows a signal name field 410, a data type field 420, and a trace result field 430. In addition to the input field 434, the array variable field 436, and the output field 438, the trace result field 430 shows a subscript variable field 437 in which the subscript variable = i of the array variable = ARRAYB [i] is displayed.

  As described above, according to the present invention, when an array variable is sampled, the value of the address for storing the array element is calculated every time sampling is performed. Therefore, even when the subscript of the array variable is a variable, data tracing can be performed. Is possible. Although the above is an example of a one-dimensional array, data trace can be performed in the same way for a multidimensional array even when the subscript of the array variable is a variable.

It is a block block diagram which shows an example of PLC and the data trace apparatus in this invention. It is a flowchart which shows an example of operation | movement of the sampling execution part 210 and the arrangement | sequence address calculating part 220 of the data trace apparatus in this invention. It is an example of the monitor screen which displayed the sampling result of the data trace apparatus in this invention. It is a block block diagram which shows an example of the conventional PLC and a data trace apparatus. It is a flowchart which shows an example of operation | movement of the sampling execution part 210 and the arrangement | sequence address calculating part 220 of the conventional data trace apparatus. It is an example of a PLC program including an array variable. It is an example of the monitor screen which displayed the sampling result of the conventional data trace apparatus.

Explanation of symbols

  10 PLC, 20 data trace device, 100 PLC execution unit, 110 CPU, 120 PLC data memory, 130 PLC program memory, 200 data trace unit, 210 sampling execution unit, 220 array address calculation unit, 230 sampling buffer, 240 screen control unit 250 sampling condition setting unit 260 operation input control unit 300 monitor screen 320 input device.

Claims (1)

In a data trace device that samples and stores the value of a variable of a programmable logic controller at a constant cycle,
A sampling condition setting section for setting variables for sampling and sampling start and end conditions;
A sampling execution unit that performs sampling according to the conditions set in the sampling condition setting unit;
An array address calculation unit for calculating an address of an array variable to be sampled by the sampling execution unit;
A sampling buffer for storing the sampling result of the sampling execution unit;
With
The sampling condition setting unit can be set by combining an array variable and a subscript variable of the array variable,
The array address calculation unit calculates the address of the element of the array variable specified by the value of the subscript variable of the array variable when the sampling variable set in the sampling condition setting unit is an array variable. Set in the sampling execution unit together with the value of the subscript variable of the array variable,
The sampling execution unit obtains the value of the element of the array variable from the address of the element of the array variable, records the value of the subscript variable of the array variable in the sampling buffer for each sampling period, and records the recorded array Displaying the value of the variable element and the value of the subscript variable of the array variable side by side for each sampling period;
A data trace apparatus for a programmable logic controller.

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