Sequence program display device and computer-readable storage medium

Abstract

Provided is a sequence program display device in which a correspondence between variable names conforming to a first notation and symbol names conforming to a second notation is stored and, through execution by one or more processors, a sequence program in which variable names conforming to the first notation are written is obtained, the variable names included in the sequence program are replaced by symbol names conforming to the second notation, and the sequence program with the symbol names conforming to the second notation is displayed.

Description

[Technical Field]

[0001] The present invention relates to a sequence program display device and a computer-readable storage medium. [Background technology]

[0002] A PLC (Programmable Logic Controller) is a control device for manufacturing equipment, etc. It receives signals from input devices, processes them according to a program, and controls output devices connected to the PLC.

[0003] PLCs perform sequence control, which is a control method in which each control step is carried out sequentially according to a predetermined order or procedure. PLC programs are called sequence programs.

[0004] There are several languages ​​for sequence programs. Typical examples include ladder language, structured text (ST) language, function block diagram (FBD) language, and sequential function chart (SFC) language. Even within the same ladder language, specifications may differ depending on the vendor.

[0005] When creating a ladder program, a diagram simulating a circuit using relay contacts and coils is displayed, and a virtual device symbol is placed on each contact and coil. The characters displayed in the input symbol information represent the input device itself or the address where the signal from the input device is input. A device comment associated with the input device may be displayed below the input device symbol (for example, see Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2020-134986 Summary of the Invention [Problem to be solved by the invention]

[0007] In ladder programs, symbol names can be assigned to virtual device symbols. The naming rules for ladder program symbols follow the notation of electrical circuits. However, there is currently a move towards standardizing variable names in accordance with the IEC standard (IEC61131-3). Symbol names based on electronic circuit notation may not conform to the IEC standard. Furthermore, in text-based ST languages, symbols such as "+" and "*" have a textual meaning, so it may not be possible to use symbol names based on electronic circuit notation grammatically.

[0008] Using variable names that comply with the IEC standard improves program compatibility. However, there are users who are familiar with the traditional notation for electrical circuits and who want to continue programming using the notation they created in the past. In the field of sequence programming, there is a demand for a development environment that allows users to create programs that comply with standards while maintaining user operability. [Means for solving the problem]

[0009] A sequence program display device according to one aspect of the present disclosure includes a name memory unit that stores correspondences between variable names conforming to a first notation and symbol names conforming to a second notation, a program acquisition unit that acquires a sequence program written with variable names conforming to the first notation, a name replacement unit that replaces variable names included in the sequence program with symbol names, and a program display unit that displays the sequence program using the symbol names. A storage medium according to one aspect of the present disclosure stores correspondences between variable names conforming to a first notation and symbol names conforming to a second notation, and stores computer-readable instructions that, when executed by one or more processors, acquire a sequence program written with variable names conforming to the first notation, replace the variable names included in the sequence program with symbol names conforming to the second notation, and display the sequence program using the symbol names conforming to the second notation. [Effects of the Invention]

[0010] One aspect of the present invention provides a program development environment that conforms to standards while maintaining user operability. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a block diagram of a sequence program display device according to the first disclosure. [Figure 2] 10 is an example of a sequence program display screen. [Figure 3] 1 is a table illustrating the requirements of the IEC standard. [Figure 4] 1 is an example of a correspondence table between variable names and symbol names. [Figure 5] FIG. 10 is a block diagram of a sequence program display device according to the second disclosure. [Figure 6] 10 is an example of a setting screen for variable names and symbol names. [Figure 7] 1 is an example of a substitution table. [Figure 8] 10 is a flowchart illustrating the operation of the sequence program display device of the second disclosure. [Figure 9A] 10 is an example of a ladder program stored in a program storage unit. [Figure 9B] 1 is an example of a correspondence table between symbol names and variable names. [Figure 9C] 10 is an example of a ladder program displayed on an editing screen. [Figure 10A] 10 is an example of a ladder program editing screen. [Figure 10B]The variable names and symbol names to be added to the correspondence table are shown below. [Figure 10C] 10 is an example of a ladder program stored in a program storage unit. [Figure 10D] 10 is an example of an editing screen for a ladder program after the names have been associated. [Figure 11A] This is an example of a structured text program using variable names. [Figure 11B] 10 is an example of a display screen of a structured text program using symbol names. [Figure 12] FIG. 2 is a diagram illustrating a hardware configuration of a sequence program display device. DETAILED DESCRIPTION OF THE INVENTION

[0012] [First Disclosure] The sequence program display device 100 of the first disclosure will be described below. The sequence program display device 100 of the first disclosure is implemented in an information processing device that displays and edits a sequence program. Examples of the information processing device include, but are not limited to, a numerical control device and a PC (personal computer).

[0013] FIG. 1 is a block diagram of a sequence program display device 100 according to the first disclosure. The sequence program display device 100 of the first disclosure includes a program acquisition unit 1, a program display unit 2, a name replacement unit 3, and a name storage unit 4.

[0014] The program acquisition unit 1 acquires a sequence program. The sequence program may be input by a user through program editing, or an existing sequence program may be acquired.

[0015] The program display unit 2 displays a sequence program on a display unit 70 such as a display. Fig. 2 shows an example of a sequence program display screen. The display screen in Fig. 2 is divided into four display areas, each of which displays a program written in a ladder language, structured text language, function block diagram language, or instruction language.

[0016] Ladder language is a graphic language that has been widely used in Japan for a long time and is suitable for describing sequence processing. The structured text language is a text-based language suitable for describing numerical operations and branching control such as IF statements and FOR statements. Function block diagram language is a graphical language that allows you to connect function block pins together like an electronic circuit diagram. It is suitable for continuous analog signals and allows you to visually check their operation. An instruction language is a textual language, similar to computer assembly language, that describes a series of instructions as a list, and is useful for making applications smaller and faster.

[0017] The number of languages ​​displayed on the display screen of the sequence program does not necessarily have to be four, but may be one or more.

[0018] It is desirable that sequence programs be written in accordance with the IEC standard, which collectively refers to program names, function block names, function names, variable names, and data type names as identifiers.

[0019] According to the IEC standard, identifiers must meet the requirements shown in Figure 3. Specifically, the characters that can be used are English letters (AZ, az) [1 byte per character], numbers (0-9) [1 byte per character], and underscores (_) [1 byte per character] (however, underscores cannot be used consecutively). Uppercase and lowercase letters are not distinguished. The use of reserved words is prohibited.

[0020] The program acquisition unit 1 acquires a sequence program currently being edited or an existing program created in the past. The sequence program acquired by the program acquisition unit 1 is written using variable names, which will be described later.

[0021] The name storage unit 4 stores addresses, symbol names, and variable names in association with each other. An address is a number assigned to an input / output relay, an internal auxiliary relay, a timer, a counter, etc. that can be used in a sequence program. A variable is assigned at least a variable name, and may also be assigned an address. Addresses may also be assigned symbolic names. These symbolic names are names that conform to electronic circuit notation. In the present disclosure, variable names in a sequence program are replaced with symbolic names and displayed, improving visibility for users familiar with programming using electronic circuit notation.

[0022] The name storage unit 4 stores a correspondence table between variable names and symbol names. FIG. 4 is an example of the correspondence table. In the name storage unit 4 of FIG. 4, the variable name "xESP" and the symbol name "*ESP" are assigned to the address "X8.4." The variable name "xpL1" and the symbol name "*+L1" are assigned to the address "G114.0." The variable name "nOT1" and the symbol name "-OT1" are assigned to the address "F126.0."

[0023] The name replacement unit 3 replaces the type of name to be displayed. For example, the name replacement unit replaces the type of name to be displayed for each language of the sequence program. Specifically, it is assumed that a sequence program written in ladder language is replaced with a symbol name and displayed.

[0024] As described above, the sequence program display device 100 of the first disclosure stores, as names of addresses in a sequence program, variable names conforming to the unified IEC standard and symbol names conforming to the notation of electronic circuits.

[0025] Sequence programs are saved using IEC standard variable names and, if necessary, converted to electronic circuit notation for display, improving visibility for users familiar with electronic circuit notation.

[0026] [Second Disclosure] FIG. 5 shows a sequence program display device 100 according to the second disclosure. The sequence program display device 100 of the second disclosure includes a program storage unit 5, a program display unit 2, a name replacement unit 3, a name storage unit 4, an editing operation reception unit 6, a program editing unit 7, and a name management unit 8. The sequence program display device 100 of the second disclosure creates a correspondence table between variable names conforming to the IEC standard and symbol names conforming to the notation of electronic circuits.

[0027] The program storage unit 5 stores existing sequence programs. The sequence programs are written in one or more languages. Addresses in the sequence programs are given variable names conforming to the IEC standard, symbol names written in accordance with electronic circuit notation, or both.

[0028] The name replacement unit 3 replaces the type of name to be displayed. For example, the type of name to be displayed is replaced for each language. Specifically, in a sequence program written in ladder language, the name is replaced with a symbolic name and displayed, but in a language other than ladder language, the sequence program is displayed without being replaced with a symbolic name.

[0029] The name storage unit 4 stores addresses, symbol names, and variable names in association with each other. As mentioned above, addresses are numbers assigned to input / output relays, internal auxiliary relays, timers, counters, etc. that can be used in sequence programs. At least a variable name is assigned to an address. A symbol name may also be assigned to an address. The symbol name is a name that conforms to the notation of electronic circuits.

[0030] The program display unit 2 displays the sequence program on a display such as a monitor. The sequence program can be displayed in multiple languages. It is also possible to insert structured text language into ladder language, input ladder language output into function blocks, and display a combination of multiple languages.

[0031] When the variable names in the sequence program and the names displayed on the screen are replaced with symbol names, the name replacement can be visually indicated by decoration. Methods of decoration include text color, background color, the presence or absence of a frame, and a popup when the mouse is over.

[0032] The editing operation reception unit 6 receives edits to the sequence program. As mentioned above, a sequence program can be written in multiple languages. The notation may differ depending on the language and may also differ depending on the manufacturer of the PLC (Programmable Logic Controller) that runs the sequence program. The name management unit 8, which will be described later, replaces address names with names that comply with the IEC standard.

[0033] The name management unit 8 creates a correspondence table and replaces names in the sequence program. In creating the correspondence table, the symbol names of the sequence program are replaced with variable names conforming to the IEC standard and stored in the program storage unit 5, and the symbol names are associated with the variable names. Specifically, the system reads symbol names from the sequence program, determines whether the symbol names conform to the IEC standard, and if the symbol names in the ladder program do not conform to the IEC standard, prompts the user to register variable names that conform to the IEC standard. Figure 6 shows an example of a setting screen for variable names and symbol names. Using the setting screen, symbol names can be associated with variable names.

[0034] The name management unit 8 also replaces names in the sequence program. If an existing sequence program is written using symbol names, or if a symbol name is entered while editing the sequence program, the name management unit 8 refers to the correspondence table, rewrites the symbol name of the sequence program into a variable name, and stores it in the program storage unit 5.

[0035] The name management unit 8 may include a substitution table for characters and character strings. FIG. 7 is an example of a substitution table. As mentioned above, the IEC standard has a rule that symbols other than the underscore cannot be used. The substitution table specifies the characters to be replaced with characters that are not allowed in the IEC standard. According to the substitution table in FIG. 7, "*" is replaced with "x", "-" is replaced with "_", and "+" is replaced with "p". According to the substitution table, the symbol name "*ESP-X" is replaced with the variable name "xESP_X". The association between symbol names and variable names can be performed automatically by the name management unit 8, or manually by the user visually checking the variable names.

[0036] The substitution table may incorporate a naming convention. By following predefined naming conventions, it becomes possible to guess to some extent the meaning, function, and usage of variables, improving the efficiency of debugging, corrections, and additional development. When multiple people are developing, naming variables according to a unified standard improves the readability and visibility of each other's code, improving development efficiency and maintainability. By incorporating a substitution table into the naming rules, it is possible to automatically create variable names that conform to the naming rules, or to present candidates for variable names that conform to the naming rules to the user.

[0037] The name replacement unit 3 replaces the name to be displayed in accordance with the language of the sequence program displayed on the display unit 70. Specifically, when a sequence program in ladder language is displayed, the name to be displayed is replaced with a symbol name.

[0038] FIG. 8 is a flowchart illustrating the operation of the sequence program display device 100 of the second disclosure.

[0039] The sequence program display device 100 acquires a sequence program from the editing operation receiving unit 6 or the program storage unit 5 (step S1). When a symbol name is input by an editing operation or when a symbol name exists in an existing program, the name management unit 8 determines whether or not this symbol name complies with the IEC standard (step S2).

[0040] If the symbol name complies with the IEC standard (step S3; Yes), the name management unit 8 uses the symbol name as the variable name (step S4). If the symbol name does not comply with the IEC standard (step S3; No), the name management unit 8 displays a variable name setting screen such as that shown in Fig. 6 and prompts the user to set the variable name (step S5).

[0041] When the user sets the variable name, the name storage unit 4 adds the set symbol name and variable name to the correspondence table (step S6). Note that in step S5, the symbol name may be replaced using a replacement table, and candidates for variable names in accordance with the IEC standard may be presented to the user, and the user's selection may be accepted.

[0042] The name management unit 8 rewrites the names attached to the addresses of the sequence program into variable names conforming to the IEC standard and stores them in the program storage unit 5 (step S7). At this time, the names attached to the addresses of the sequence program are rewritten into variable names conforming to the IEC standard, but symbol names conforming to the notation for electronic circuits are displayed on the display screen of the sequence program (step S8).

[0043] A specific example of the operation of the sequence program display device 100 will be described with reference to FIGS. (1) An example of replacing the display of an existing sequence program will be described. Here, it is assumed that the sequence program is written using variable names and that the correspondence between symbol names and variable names has been completed. The display replacement is performed by both the sequence program display device of the first disclosure and the sequence program display device of the second disclosure.

[0044] 9A is a ladder program stored in program storage unit 5. In this ladder program, the variable name of the a terminal on the input bus side is "xESP_X," the variable name of the second a terminal is "READY," and the variable name of the output on the output bus side is "xESP_G."

[0045] The name replacement unit 3 replaces the name to be displayed depending on the language of the sequence program displayed on the display unit 70. In this example, the name of a sequence program written in ladder language is replaced. FIG. 9B shows an example of a correspondence table between symbol names and variable names. In this correspondence table, the variable name "xESP_X" at address "x8.4" is replaced with the symbol name "*ESP-X", and the variable name "xESP_G" at address "G8.4" is replaced with the symbol name "*ESP-G".

[0046] The name replacement unit 3 replaces the variable names of the sequence program written in ladder language with symbol names, and the program display unit 2 displays the replaced symbol names on an editing screen for the sequence program. Figure 9C shows the ladder program displayed on the editing screen. In Figure 9C, the variable name "xESP_X" of the a-contact on the input bus side is displayed with the symbol name "*ESP-X." Also, the variable name "xESP_G" of the output on the output bus side is displayed with the symbol name "*ESP-G."

[0047] In the display screen of Fig. 9C, the symbol names "*ESP-X" and "*ESP-G" are displayed in light blue. In the display screen of Fig. 9C, the character color of the symbol names is used to indicate that the symbol names are different from the variable names of the sequence program. In addition to the character color, the difference between the displayed symbol names and the variable names of the sequence program may be indicated by using the background color of the characters or by displaying a frame around the characters.

[0048] (2) Next, an example of creating a correspondence table between symbol names and variable names and rewriting a sequence program while editing the sequence program will be described. FIG. 10A is an example of a ladder program editing screen. In the ladder program being edited, the symbol name "*ESP-X" has been entered into terminal a on the input bus side. The name management unit 8 determines whether the symbol name entered into the editing screen complies with the IEC standard. The symbol name "READY" can be used in the IEC standard, so it is used as a variable name as is. The symbols "*" and "-" cannot be used in the IEC standard, so the name management unit 8 prompts the user to enter a variable name. To enter the variable name, for example, a variable name and symbol name setting screen shown in FIG. 6 is displayed. The user sets a variable name that corresponds to the symbol name. The correspondence between the symbol name and the variable name is added to a correspondence table. FIG. 10B shows an example of variable names, symbol names, and addresses added to the correspondence table.

[0049] The name management unit 8 rewrites the symbol names of the ladder program as variable names and stores them in the program storage unit 5. The ladder program stored in the program storage unit 5 looks like Figure 10C. The a-contact on the input bus side has been rewritten to the variable name "xESP_X".

[0050] Figure 10D shows the ladder program editing screen after the names have been associated. The editing screen displays the symbol name "*ESP-X" entered by the user as is. The symbol name text is displayed in light blue, indicating that the variable name and symbol name are different.

[0051] The substitution of symbol names with variable names may be performed automatically using the substitution table in Fig. 7. Alternatively, candidates for variable names to be substituted may be automatically created using the substitution table, and the created candidates may be presented to the user, who may then select a variable name from the presented candidates.

[0052] (3) Next, an example of replacing the display of a structured text language will be described. Here, it is assumed that the correspondence between symbol names and variable names has been completed.

[0053] The structured text program is stored in the program storage unit 5. The structured text program stored in the program storage unit 5 is written with variable names that comply with the IEC standard. FIG. 11A is an example of a display screen of a structured program using variable names. In Figure 11A, syntax such as "IF," "THEN," and "END_IF" are displayed in red, variables such as "xESP_X," "READY," and "xESP_G" are displayed in light blue, operators such as ":=" are displayed in white, and reserved words such as "TRUE" are displayed in blue.

[0054] 11B is an example of a display screen of a structured text program using symbol names. The name replacement unit 3 reads the correspondence table and replaces the symbol names with variable names. The symbol name "*ESP-X" is displayed in the display area for the variable name "xESP_X," and the symbol name "*ESP-G" is displayed in the table area for the variable name "xESP_G."

[0055] The display screen of Figure 11B may visually indicate that the symbol names and variable names are different. For example, the background color of the display area for symbol names such as "*ESP-X" and "*ESP-G" may be changed. Also, a pop-up that appears when the mouse is hovered over the symbol names may be used to indicate that the symbol names and variable names are different.

[0056] As described above, the sequence program display device 100 of the second disclosure determines whether the address name (symbol name) entered during editing of a sequence program complies with the IEC standard, and if the symbol name does not comply with the IEC standard, it is associated with a variable name that complies with the IEC standard.

[0057] In the sequence program display device 100 of the second disclosure, when the name of an input address is associated with a variable name, the name of the address in the sequence program being edited is rewritten to the corresponding variable name and stored in the program storage unit 5.

[0058] The sequence program display device 100 of the first disclosure and the sequence program display device 100 of the second disclosure are provided with a substitution table and perform substitution of symbol names and variable names. The substitution of symbol names and variable names may be performed automatically, or candidates for substituted variable names may be presented to the user to prompt the user to select one.

[0059] The sequence program display device 100 of the first disclosure improves the visibility of a program by displaying the sequence program using symbol names that are familiar to a particular user. For example, even if the symbol names of an actual sequence program are replaced with variable names in order to comply with the IEC standard, the symbol names assigned when the program was edited are displayed, allowing the user to view the program without being bothered by differences in names.

[0060] The sequence program display device 100 of the second disclosure can associate symbol names and variable names that are input at the same time as editing a sequence program. Once the association is established, the next time a symbol name is input, the symbol name is automatically rewritten as a variable name. Furthermore, it is possible to associate symbol names and variable names for sequence programs created in the past, and to rewrite the associated symbol names as variable names.

[0061] In the sequence program display device 100 of the second disclosure, the symbol names of the sequence program stored in the program storage unit 5 can be replaced with variable names while the symbol names are displayed on the sequence program editing screen. Because the symbol names are displayed on the sequence program editing screen, the user can create a program without being bothered by differences in names. Furthermore, because the symbol names of the created sequence program are automatically rewritten as variable names, a program that complies with the IEC standard can be created.

[0062] [Hardware configuration] The hardware configuration of the sequence program display device 100 will be described with reference to Fig. 12. The CPU 111 provided in the sequence program display device 100 is a processor that controls the entire sequence program display device 100. The CPU 111 reads a system program processed in a ROM 112 via a bus, and controls the entire sequence program display device 100 in accordance with the system program. The RAM 113 temporarily stores temporary calculation data, display data, various data input by the user via the input unit 71, etc.

[0063] The display unit 70 is a monitor or the like attached to the sequence program display device 100. The display unit 70 displays an operation screen, a setting screen, and the like of the sequence program display device 100.

[0064] The input unit 71 is a keyboard, a touch panel, or the like that is integrated with the display unit 70 or is separate from the display unit 70. The user operates the input unit 71 to input data to the screen displayed on the display unit 70. The display unit 70 and the input unit 71 may be mobile terminals.

[0065] The nonvolatile memory 114 is a memory that retains its stored state even when the power to the sequence program display device 100 is turned off, for example, by being backed up by a battery (not shown). The nonvolatile memory 114 stores workpiece shape data, tool shape data, tool path data, and machining programs. The nonvolatile memory 114 stores programs read from external devices via an interface (not shown), programs input via the input unit 71, and various data acquired from each unit of the sequence program display device 100, machine tools, etc. (e.g., setting parameters acquired from machine tools). The programs and various data stored in the nonvolatile memory 114 may be expanded into the RAM 113 when executed / used. In addition, various system programs are pre-written in the ROM 112. [Explanation of symbols]

[0066] 100 Sequence program display device 1 Program Acquisition Department 2 Program display section 3 Name replacement part 4 Name storage section 5 Program memory section 6 Editing operation reception section 7 Program Editorial Department 8 Name management department 70 Display section 71 Input section 111 CPU 112 ROM 113 RAM 114 Non-volatile memory

Claims

1. a name storage unit that stores correspondence between variable names conforming to the first notation and symbol names conforming to the second notation; a program acquisition unit that acquires a sequence program written with variable names conforming to the first notation; a name replacement unit that replaces variable names included in the sequence program with the symbol names; a program display unit that displays the sequence program using the symbol name; Equipped with when the program display unit replaces variable names of a sequence program with symbol names and displays them, the displayed symbol names are displayed in an ornamented manner. Sequence program display device.

2. A name storage unit that stores correspondence between variable names conforming to a first notation and symbol names conforming to a second notation; a program acquisition unit that acquires a sequence program written with variable names conforming to the first notation; a name replacement unit that replaces variable names included in the sequence program with the symbol names; a program display unit that displays the sequence program using the symbol name; Equipped with the program acquisition unit is an editing operation reception unit that receives an editing operation of a sequence program, a name management unit that determines whether the symbol name accepted by the editing operation accepting unit conforms to the first notation, and if the symbol name does not conform to the first notation, rewrites the symbol name of the sequence program being edited into a variable name that conforms to the first notation; Equipped with A sequence program display device, wherein if the symbol name does not conform to the first notation, the name management unit accepts the setting of a variable name for the symbol name accepted by the editing operation acceptance unit, and stores the correspondence between the symbol name and the variable name in the name memory unit.

3. A name storage unit that stores correspondence between variable names conforming to a first notation and symbol names conforming to a second notation; a program acquisition unit that acquires a sequence program written with variable names conforming to the first notation; a name replacement unit that replaces variable names included in the sequence program with the symbol names; a program display unit that displays the sequence program using the symbol name; the program acquisition unit is an editing operation reception unit that receives an editing operation of a sequence program, a name management unit that determines whether the symbol name accepted by the editing operation accepting unit conforms to the first notation, and if the symbol name does not conform to the first notation, rewrites the symbol name of the sequence program being edited into a variable name that conforms to the first notation; Equipped with the program acquisition unit is a program storage unit that stores an existing sequence program, a name management unit that determines whether or not a symbol name included in the existing sequence program conforms to the first notation, and if the symbol name does not conform to the first notation, rewrites the symbol name of the existing sequence program to a variable name that conforms to the first notation; Equipped with A sequence program display device in which, if the symbol name does not conform to the first notation, the name management unit accepts the setting of a variable name for the symbol name included in the existing sequence program and stores the correspondence between the symbol name and the variable name in the name memory unit.

4. A sequence program display device as described in claim 2 or 3, wherein the name management unit stores a substitution table for the first notation and the second notation, and uses the substitution table to replace the symbol name with the variable name.

5. A sequence program display device as described in claim 2 or 3, wherein when the program display unit replaces variable names of a sequence program with symbol names and displays them, the displayed symbol names are decorated and displayed.

6. The sequence program can be written in multiple languages, the name replacement unit replaces variable names included in a sequence program written in a specific language with symbol names conforming to the second notation; 4. The sequence program display device according to claim 1, wherein said program display unit displays said sequence program written in said specific language using said symbol names.

7. A method for storing correspondence between variable names conforming to the first notation and symbol names conforming to the second notation; When executed by one or more processors, acquiring a sequence program written with variable names conforming to the first notation; replacing variable names included in the sequence program with symbol names conforming to the second notation; Displayed by a symbol name according to the second notation, When the display replaces variable names of the sequence program with symbol names, the symbol names are displayed in an ornamented form. A storage medium that stores instructions readable by the processor.

Images