Patent Publication Number: US-2013232423-A1

Title: Display apparatus and operation checking method for the display apparatus

Description:
FIELD 
     The present invention relates to a display apparatus in a system for automatically controlling, with a controller, a robot, a numerical control apparatus, and the like and an operation checking method for the display apparatus. 
     BACKGROUND 
     In a system for automatically controlling, with a controller, a robot, a numerical control apparatus, a machine tool, and the like set in a production line, a display apparatus including a touch panel-equipped liquid crystal display is provided. The display apparatus displays, with a display unit such as a liquid crystal display, operation states (apparatus information) of these external apparatuses controlled by the controller. The display apparatus receives, in an input unit such as a touch panel, an operation input for giving a control instruction to the controller. A user can uniquely create a screen displayed on the display unit using a screen data creating apparatus to match a system for performing control. 
     The user creates a screen using, as components, images representing a switch, a meter, a graph, and the like provided by the screen data creating apparatus. The user associates devices, which are areas in a memory of the controller, with these components. The user performs setting of conditions for changing display of components and device values according to the system for performing control and designation of a processing method for the devices for making it easy to recognize a state of the system for performing control. 
     The display apparatus receives apparatus information of a system that operates according to a program written in the controller. The display apparatus performs display according to the apparatus information. In the display apparatus, display setting information created in advance for the display of the apparatus information is set. 
     In the system of the production line, in some case, the user desires to check contents of display setting information stored in the display apparatus. In the related art, as a method of checking the display setting information, for example, there is a method of connecting the screen data creating apparatus to the display apparatus and reading out the display setting information using the screen data creating apparatus. Like the technologies proposed in Patent Literatures 1 and 2, there is a method of switching a display mode of a screen of the display apparatus from a mode for displaying the operation states to a mode for displaying the display setting information. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Application Laid-open No. 11-45110 
         Patent Literature 2: Japanese Patent Application Laid-open No. 2006-285496 
       
    
     SUMMARY 
     Technical Problem 
     In the method of connecting the screen data creating apparatus to the display apparatus, there is a problem in that, because of concern about security, it is difficult to enable the screen data creating apparatus to be carried into the production line. There is also a problem in that, when the display mode is simply switched to display the display setting information, it is often insufficient for the user to grasp which of problems such as an error in the display setting information and a deficiency of the system occurs. 
     The present invention has been devised in view of the above and it is an object of the present invention to obtain a display apparatus that enables a user to easily and quickly grasp problems such as an error in display setting information and a deficiency of a system and an operation checking method for the display apparatus. 
     Solution to Problem 
     To solve the above problem and attain the above object, a display apparatus according to the present invention includes: a display unit configured to display, about an external apparatus set as a control target by a controller, apparatus information concerning an operation state on a screen; a storing unit configured to store display setting information set for the display of the apparatus information on the display unit; a display-mode switching unit configured to switch the screen to a normal display mode for displaying the apparatus information and a display setting information display mode for displaying the display setting information; a display-setting-information retrieving unit configured to retrieve the display setting information from the storing unit; a display-setting-information displaying unit configured to cause the display setting information specified by the retrieval in the display-setting-information retrieving unit to be displayed on the screen, in the display setting information display mode; a device-value requesting unit configured to request the controller to transmit a device value retained by a device, which is an area in a memory that stores the apparatus information in the controller; a device-value receiving unit configured to receive the device value transmitted by the controller in response to the request by the device-value requesting unit; and a device-value displaying unit configured to cause the device value received by the device-value receiving unit to be displayed on the screen. The device-value requesting unit receives input operation performed according to content of the display setting information displayed by the display-setting-information displaying unit and requests transmission of the device value. 
     Advantageous Effects of Invention 
     The display apparatus according to the present invention displays the display setting information specified by the retrieval and also the device value specified by the display setting information. Therefore, the display apparatus realizes an effect that it is possible to easily and quickly grasp problems such as an error in the display setting information and a deficiency of the system. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of the configurations of a display apparatus and a controller according to a first embodiment. 
         FIG. 2  is a diagram of an example of a format database stored in a nonvolatile memory. 
         FIG. 3  is a diagram of an example of specified contents of values stored in respective items of the format database shown in  FIG. 2 . 
         FIG. 4  is a diagram of an example of a module configuration of a system program in the display apparatus according to the first embodiment. 
         FIG. 5  is a flowchart for explaining a detailed processing procedure by a format retrieving module. 
         FIG. 6  is a diagram of an example of a format database corresponding to display setting information (A), (B), and (C). 
         FIG. 7  is a diagram of a display example of display setting contents in the display setting information (B) and a device value of a word device # 2 . 
         FIG. 8  is a diagram of an example of a module configuration of a system program in a display apparatus according to a second embodiment. 
         FIG. 9  is a flowchart for explaining a detailed processing procedure by a changed content displaying module. 
         FIG. 10  is a diagram of a display example of display setting contents in the display setting information (C) and condition device values of a bit device # 3 . 
         FIG. 11  is a diagram of an example of a device character string database stored in a nonvolatile memory. 
         FIG. 12  is a diagram of an example of specified contents of values stored in respective items of the device character string database shown in  FIG. 11 . 
         FIG. 13  is a diagram of an example of a module configuration of a system program in a display apparatus according to a third embodiment. 
         FIG. 14  is a flowchart for explaining a detailed processing procedure by a device character string displaying module. 
         FIG. 15  is a diagram of an example of a device character string database corresponding to display setting information (A), (B), (C). 
         FIG. 16  is a diagram of a display example of display setting contents in the display setting information (C) and condition device values of a bit device # 3 . 
         FIG. 17  is a diagram of a configuration example of a system of a production line controlled by a controller. 
         FIG. 18  is a block diagram of a hardware configuration of a monitor system for setting display setting information. 
         FIG. 19  is a diagram of an example of allocation of apparatus information and devices. 
         FIG. 20  is a diagram of an example of display setting information stored in a nonvolatile memory. 
         FIG. 21  is a diagram of an example of specified contents of values stored in respective items of the display setting information shown in  FIG. 20 . 
         FIG. 22  is a diagram of areas partitioned in a rectangular shape on a display unit and numerical values affixed to the respective areas. 
         FIG. 23  is a diagram of specified contents of three kinds of display setting information (A), (B), and (C) stored in a nonvolatile memory of the display apparatus. 
         FIG. 24  is a diagram of a display example of display setting contents by the display setting information (B). 
         FIG. 25  is a diagram of a display example of the display setting contents. 
         FIG. 26  is a diagram of a display example of display setting contents by the display setting information (C). 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of a display apparatus and an operation checking method for the display apparatus according to the present invention are explained in detail below based on the drawings. The present invention is not limited by the embodiments. 
     First, with reference to, as an example, a system of a production line controlled by a controller as shown in  FIG. 17 , a related art of a display apparatus used in a system of the production line is explained. A display apparatus  75  is connected to a controller  3 . A conveyor  52  is one of external apparatuses set as control targets by the controller  3 . In the system of the production line, a user operates a touch panel mounted on the display apparatus  75  to thereby switch the operation of the conveyor  52 . A workpiece  53  on the conveyor  52  moves according to the operation of the conveyor  52 . 
     A sensor  51  set in the conveyor  52  detects passage of the workpiece  53 . When detecting the workpiece  53 , the sensor  51  outputs a signal to the controller  3 . A safety door  50  set in the conveyor  52  outputs an opening and closing signal indicating an opening and closing state to the controller  3 . Two programs, i.e., a program for outputting a signal to the conveyor  52  according to an input from the display apparatus  75  and a program for counting inputs from the sensor  51  are written in the controller  3 . 
     The display apparatus  75  receives apparatus information of a system of a production line that operates according to the programs written in the controller  3 . The display apparatus  75  performs display based on display setting information for displaying a state of the apparatus. The display setting information is created in advance to correspond to the apparatus information. The display apparatus  75  receives the opening and closing signal input to the controller  3  from the safety door  50 . The display setting information is set such that a change request for the apparatus information is transmitted from the display apparatus  75  to the controller  3  according to operation by the user only when the safety door  50  is closed. Correspondence between devices, which are areas in the memory of the controller  3 , and apparatus information is described in system specifications  2 . 
     The display setting information is set by a screen data creating apparatus connected to the display apparatus  75 .  FIG. 18  is a block diagram of a hardware configuration of a monitor system for setting the display setting information. The monitor system includes the display apparatus  75 , the controller  3 , and a screen data creating apparatus  26 . 
     The controller  3  includes a memory  4  for storing apparatus information of an external apparatus. A storage area of the memory  4  is partitioned into a plurality of areas referred to as devices. Codes affixed to specify the respective devices are referred to as device codes. The user allocates one or more devices to one kind of apparatus information as storage areas for the apparatus information. 
     As the devices, for example, there are a bit device and a word device. The bit device stores, as device values, bits representing two kinds of states of “0” or “1”. The word device stores, as device values, words representing numbers. In the following explanation, information representing whether a device value stored by a device is a bit or a word is referred to as device type. 
     In the example of the system of the production line shown in  FIG. 17 , an output state of a signal from a controller  3  to the conveyor  52  only has to be capable of representing two states, i.e., presence or absence of an output. Therefore, such information is stored in the bit device. An opening and closing signal from the safety door  50  to the controller  3  only has to be capable of representing two states, i.e., open and close of the safety door  50 . Therefore, the opening and closing signal is stored in the bit device. 
     A value obtained by counting inputs from the sensor  51  in the controller  3  is stored in the word device. In the following explanation, a plurality of bit devices in the memory  4  provided in the controller  3  are referred to as bit devices # 1 , # 2 , . . . and a plurality of word devices in the memory  4  are referred to as word devices # 1 , # 2 , . . . as appropriate. # 1 , # 2 , . . . are device codes. The controller  3  is capable of performing more complicated control by allocating the devices in the memory  4  to a plurality of kinds of apparatus information. 
       FIG. 19  is a diagram of an example of the apparatus information and the devices. A table showing the allocation of the apparatus information and the devices is described in the system specification  2 . In this example, allocation W 1  indicates that an output signal to the conveyor  2  is allocated to the bit device # 1 . Allocation W 2  indicates that a value obtained by counting inputs from the sensor  51  is allocated to the word device # 2 . Allocation W 3  indicates that an opening and closing signal of the safety door  50  is allocated to the bit device # 3 . 
     A program creating apparatus  55  creates a program of the controller  3 . The program creating apparatus  55  is connected to the controller  3 . The program created by the program creating apparatus  55  is transferred to the controller  3 . As the program creating apparatus  55 , a computing apparatus such as a personal computer is used. The program creating apparatus  55  includes a display unit (not shown in the figure) configured to display, for example, a list of device values of the controller  3 . 
     When the devices are used in the program created by the program creating apparatus  55 , to allow the user to easily recognize the device codes, in some case, a character string is allocated to the device codes on the program creating apparatus  55 . For example, if the devices are the bit devices, a character string BIT 1 ,  2 , . . . is used and, if the devices are the word devices, a character string WORD 1 ,  2 , . . . is used instead of the device codes. 
     The screen data creating apparatus  26  is an apparatus that performs creation of screen data including display setting information for displaying apparatus information of an external apparatus in the display apparatus  75  and display setting information output from the display apparatus  75  to the external apparatus via the controller  3 . As the screen data creating apparatus  26 , a computing apparatus such as a personal computer is used. The screen data creating apparatus  26  includes an auxiliary storage device  27  for storing the created screen data. The screen data is data set by the user. The screen data includes, for example, display setting information created by the user, the luminance of a screen, and the volume of a buzzer. 
     The display apparatus  75  includes a display unit  5 , a mode changeover switch  8 , a nonvolatile memory  6 , a screen data creating apparatus interface (hereinafter referred to as creating apparatus I/F)  9 , a controller interface (hereinafter referred to as controller I/F)  10 , a memory  11 , a CPU  78 , and a ROM  31 . 
     The display unit  5  displays, about the conveyor  52 , which is an external apparatus set as a control target by the controller  3 , apparatus information concerning an operation state on a screen. The display unit  5  is, for example, a liquid crystal display. A touch panel  7  is input means for receiving input operation by the user and is attached to the surface of the display unit  5 . The nonvolatile memory  6  is, for example, a flash memory. The nonvolatile memory  6  stores screen data including display setting information. 
     The creating apparatus I/F  9  performs transmission and reception of data between the creating apparatus I/F  9  and the screen data creating apparatus  26 . The controller I/F  10  performs transmission and reception of data between the controller I/F  10  and the controller  3 . The ROM  31  stores a system program. The CPU  78  controls the entire system based on the system program stored in the ROM  31 . The memory  11  functions as a work memory necessary when the CPU  28  executes the system program stored in the ROM  31 . The memory  11  includes a data area, a device type area, and a device code area (all of which are not shown in the figure). 
     The mode changeover switch  8  switches the screen of the display unit  5  to a display mode for displaying apparatus information of an external apparatus and a display mode for displaying display setting information. The system program stored in the ROM  31  can define, as the switching of the modes, specific operation set in advance through the touch panel  7  and a specific input set in advance from the controller  3 . In this case, in the display apparatus  75 , the mode changeover switch  8  can be omitted. 
     Apparatus information displayed by the display apparatus  75  is received from the controller  3 . The controller  3  is indispensable in a monitor system and can be regarded as a part of the display apparatus  75 . 
       FIG. 20  is a diagram of an example of display setting information stored in the nonvolatile memory.  FIG. 21  is a diagram of an example of specified contents of values stored in respective items of the display setting information shown in  FIG. 20 . The user creates display setting information M 1  in the screen data creating apparatus  26 . Areas for storing the display setting information M 1  in the nonvolatile memory  6  include areas for storing an ID number m 1 , a device type m 2 - 1 , a device code m 2 - 2 , a condition device type m 3 - 1 , a condition device code m 3 - 2 , a processing method m 4 , a component m 5 , a format m 7 , and a position m 6 . The display setting information M 1  is present as many as the number of kinds of information created by the user. 
     The ID number m 1  is a number for specifying arbitrary display setting information and is represented by a numerical value. The item of the device type m 2 - 1  indicates whether a device is set as display setting information and indicates, when a device is set, whether the device is a bit device or a word device. 
     The item of the condition device type m 3 - 1  indicates whether a condition device, which is a device in which conditions are stored, is set as display setting information and indicates, when a condition device is set, whether the condition device is a bit device or a word device. In this example, as specified contents of the device type m 2 - 1  and the condition device type m 3 - 1 , “0” represents a bit device, “1” represents a word device, and “−1” represents no setting. 
     The device code m 2 - 2  is a code affixed to each of a plurality of devices present in the memory  4  of the controller  3  and is represented by a numerical value. The condition device code m 3 - 2  is a code affixed to each of a plurality of condition devices present in the memory  4  of the controller  3  and is represented by a numerical value. 
     The item of the processing method m 4  indicates a calculation method in displaying a device value received from the controller  3  on the display unit  5  and a calculation method in transmitting a value input to the touch panel  7  to the controller  3  as a change request for the device value. In this example, as specified contents of the processing method m 4 , “0” represents that a value is not calculated, “1” represents that a value is multiplied by 1000, and “2” represents that a value is divided by 1000. 
     The item of the component m 5  defines whether a change request for a device value is transmitted to the controller, which of a figure and a numerical value is displayed on the display unit  5 , and the shape of the figure when the figure is displayed. In this example, as specified contents of the component m 5 , “1” represents display of a circle, “2” represents display of a numerical value, and “3” represents that a request for changing the device value to “1” or a value processed by the method specified by the processing method m 4  is transmitted to the controller  3 . 
     When the condition device type m 3 - 1  is “0” indicating a bit device, only when a condition device value is “1”, display designated by the item of the component m 5  is performed on the display unit  5  or a change request for a device value is transmitted from the controller I/F  10 . When the condition device type m 3 - 1  is “1” indicating a word device, only when the condition device value is a designated value, display designated by the item of the component m 5  is performed on the display unit  5  or the change request for a device value is transmitted from the controller I/F  10 . In  FIG. 21 , a data area for storing the condition device value is not shown. 
     The item of the position m 6  indicates in which position of the display unit  5  display of the component m 5  is performed. Positions on the display unit  5  are represented by, for example, numerical values 1 to 80 affixed to respective areas partitioned in a rectangular shape as shown in  FIG. 22 . Because the touch panel  7  is laid over the display unit  5 , the numerical values shown in  FIG. 22  represent positions on the touch panel  7  as well. 
     The item of the format m 7  defines a display form of a device value on the display unit  5 . In this example, as specified contents of the format m 7 , “1” represents display in a binary number, “2” represents display in a decimal number, and “3” represents display in a hexadecimal number. In the item of the format m 7 , a color to be displayed on the display unit  5 , the number of digits to be displayed, and the like can be displayed. 
     It is assumed that, in the system of the production line shown in  FIG. 17 , to display apparatus information obtained from the controller  3  on the display apparatus  75 , display setting information (A) and (B) explained below is set in the screen data creating apparatus  26 . It is assumed that, to transmit the apparatus information from the display apparatus  75  to the controller  3 , display setting information (C) explained below is set in the screen data creating apparatus  26 . 
     (A) A state of an output of a signal from the controller  3  to the conveyor  52  is allocated to the bit device # 1  (allocation W 1 ). A device value of the bit device # 1  at the time when the conveyor  52  is operating is represented as “1” and a device value of the bit device # 1  at the time when the conveyor  52  is stopped is represented as “0”. The display unit  5  displays a circle to correspond to the device value “1” of the bit device # 1 . The display unit  5  displays nothing with respect to the device value “0” of the bit device # 1 . 
     (B) A value obtained by counting inputs from the sensor  51  is allocated to the word device # 2  (allocation W 2 ). The display unit  5  displays a numerical value obtained by dividing a production volume of the workpiece  53 , which is a counted value, by 1000. 
     (C) An opening and closing signal of the safety door  50  is allocated to the bit device # 3  (allocation W 3 ). A device value of the bit device # 3  at the time when the safety door  50  is closed is represented as “1” and a device value of the bit device # 3  at the time when the safety door  50  is open is represented as “0”. When the device value of the bit device # 3  is “1”, the controller I/F  10  transmits, according to a touch input to the touch panel  7 , a request for changing the device value of the bit device to “1” to the controller  3 . 
       FIG. 23  is a diagram of specified contents of three kinds of display setting information (A), (B), and (C) stored in the nonvolatile memory of the display apparatus. The screen data creating apparatus  26  creates the three kinds of display setting information (A), (B), and (C) corresponding to the respective specified contents. 
     In the system of the production line shown in  FIG. 17 , in some case, the user desires to check contents of display setting information stored in the nonvolatile memory  6  of the display apparatus  75 . The user desires to check the contents, for example, when, although the conveyor  52  is operating, the circle designated by the display setting information (A) is not displayed, when the numerical value designated by the display setting information (B) does not change even if the workpiece  3  passes the sensor  51 , or when the conveyor  52  does not operate even if the user touches the position on the touch panel  7  designated by the display setting information (C). 
     As a first method of checking the display setting information stored in the nonvolatile memory  6 , for example, there is a method of connecting the screen data creating apparatus  26  to the display apparatus  75  and using the screen data creating apparatus  26 . The screen data creating apparatus  26  reads out the display setting information stored in the nonvolatile memory  6  to the auxiliary storage device  27  of the screen data creating apparatus  26  through the creating apparatus I/F  9  of the display apparatus  75 . 
     In the case of the first method of checking the display setting information, the user always carries the screen data creating apparatus  26 . The screen data creating apparatus  26  is connected to the display apparatus  75  to thereby enable anybody to acquire the display setting information from the nonvolatile memory  6 . Therefore, when the screen data creating apparatus  26  is always carried, there is a problem of a concern about security. Therefore, it is difficult to allow the user to carry the screen data creating apparatus  26  into the production line. An inconvenience occurs in that a procedure for obtaining permission for carrying in the screen data creating apparatus  26  takes time. 
     As a second method of checking the display setting information, there is a method of switching the display mode of the screen of the display apparatus  75  from the mode for displaying an operation state to the mode for displaying the display setting information in the same manner as the technologies disclosed in Patent Literatures 1 and 2. 
     In the second method, for example, when the user notices that the numerical value designated by the display setting information (B) does not change even if the workpiece  53  passes the sensor  51 , the user operates the mode changeover switch  8 . Subsequently, the user touches, on the touch panel  7 , the position designated by the display setting information (B) to select the display setting information (B). The CPU  78  of the display apparatus  75  detects a state of the mode changeover switch  8 , retrieves, from the nonvolatile memory  6 , display setting information in which the position m 6  matching the touched position on the touch panel  7  is set, and acquires the display setting information (B). 
     When the CPU  78  reads out the display setting information (B), the display unit  5  displays display setting contents  61  by the display setting information (B), for example, as shown in  FIG. 24 . In the display setting contents  61 , “2” is displayed as the ID number m 1 , wording “word device” is displayed as the device type m 2 - 1 , “# 2 ” is displayed as the device code m 2 - 2 , wording “divide by 1000” is displayed as the processing method m 4 , wording “numerical value” is displayed as the component m 5 , wording “display in a decimal number” is displayed as the format m 7 , and “31” is displayed as the position m 6 . A position  64  on the display unit  5  represents the position m 6  set in the display setting information (B). 
     It is assumed that the display unit  5  displays, for example, display setting contents  62  shown in  FIG. 25 . In the display setting contents  62 , “2” is displayed as the ID number m 1 , wording “word device” is displayed as the device type m 2 - 1 , “# 5 ” is displayed as the device code m 2 - 2 , wording “divide by 1000” is displayed as the processing method m 4 , “numerical value” is displayed as the component m 5 , wording “display in a decimal number” is displayed as the format m 7 , and “31” is displayed as the position m 6 . 
     The user compares the display setting contents  62  with the description of the system specifications  2 . According to the display setting contents  62 , the device type m 2 - 1  is “word device” and the device code m 2 - 2  is “# 5 ”. This indicates that “word device # 5 ” is set in the display setting information (B). On the other hand, in the allocation W 2  of the system specifications  2  shown in  FIG. 19 , “word device # 2 ” is described. The user can notice an error in the display setting information (B) by comparing the display setting contents  62  and the description of the system specifications  2 . 
     In the second method, for example, it is assumed that the user operates the mode changeover switch  8 , touches, on the touch panel  7 , the position designated by the display setting information (C), and selects the display setting information (C). The CPU  78  of the display apparatus  75  reads a state of the mode changeover switch  8 , retrieves, from the nonvolatile memory  6 , display setting information in which the position m 6  matching the touched position on the touch panel  7  is set, and acquires the display setting information (C). 
     When the CPU  78  reads out the display setting information (C), the display unit  5  displays the display setting contents  63  by the display setting information (C), for example, as shown in  FIG. 26 . In the display setting contents  63 , “3” is displayed as the ID number m 1 , wording “bit device” is displayed as the device type m 2 - 1 , “# 1 ” is displayed as the device code m 2 - 2 , wording “bit device” is displayed as the condition device type m 3 - 1 , “# 3 ” is displayed as the condition device code, wording “not calculate” is displayed as the processing method m 4 , wording “transmit “1” to the controller” is displayed as the component m 5 , wording “display in a decimal number” is displayed as the format m 7 , and “80” is displayed as the position m 6 . A position  65  on the display unit  5  represents the position m 6  set in the display setting information (C). The user compares the display setting contents  63  with the description of the system specification  2  and verifies presence or absence of an error in the display setting information (C). 
     In the case of the second method of checking the display setting information, it is likely that an error in the display setting information or a deficiency of the monitor system including the display apparatus  75  is overlooked because of reasons explained below. For example, in the display setting contents  64  shown in  FIG. 24 , the word “divide by 1000” is displayed as the processing method m 4 . Therefore, when a device value of the word device # 2  is smaller than 1000, “0” is displayed in the position  64  of the display unit  5 . 
     When a value obtained by counting inputs from the sensor  51  and dividing the count by 1000 in the controller  3  is already stored in the word device # 2 , to correctly display a value obtained by dividing a production volume by 1000, it is necessary to set “0” in the processing method m 4  to indicate that a value is not calculated. When a value obtained by counting inputs from the sensor  51  is smaller than 1000, the display of the position  64  becomes “0” both when “0” is correctly set in the processing method m 4  and when “2” (divided by 1000) is set in the processing method m 4  by mistake. In this way, it is likely that the user overlooks an error in the processing method m 4 . 
     Further, when communication between the controller I/F  10  and the controller  3  is interrupted because of some cause, the display of the position  64  on the display unit  5  cannot be updated. When the display of the position  64  does not change from “0”, there is also a problem in that the user cannot determine whether the display apparatus  75  has received a device value from the controller  3 . 
     In addition to the second method, the program creating apparatus  55  is connected to the controller  3  and the list of device values of the controller  3  is monitored, whereby it is possible to confirm that a value obtained by counting inputs from the sensor  51  is not stored in the word device # 2 . In this case, as in the case of the use of the screen data creating apparatus  26 , it is difficult to carry the program creating apparatus  55  into the production line because of a concern about security. Even if the program creating apparatus  55  is used, there is still the problem in that the user cannot determine whether the display apparatus  75  has received a device value from the controller  3 . 
     For example, when the connection between the safety door  50  and the controller  3  is interrupted because of some cause, the controller  3  cannot acquire an opening and closing signal from the safety door  50  and a device value of the bit device # 3  of the controller  3  is always “0”. The display apparatus  75  acquires “0” as the device value of the bit device # 3 . Even if the user touches, on the touch panel  7 , the position m 6  set in the display setting information (C), values of the bit device # 3  set in the condition device type m 3 - 1  and the condition device code m 3 - 2  do not change to “1”. 
     Therefore, a request for changing a device value of the bit device # 1  to “1” is not transmitted from the controller  3  and the conveyor  52  does not operate. There is no difference between the display setting contents  63  and the allocation W 3  described in the system specifications  2 . Therefore, the user cannot notice a cause of the non-operation of the conveyor  52 . 
     In this case, the program creating apparatus  55  is connected to the controller  3  and the list of device values of the controller  3  is monitored, whereby the user can confirm that the device value of the bit device # 3  does not change according to opening and closing of the safety door  50 . In this case as well, there is an inconvenience that it is difficult to carry the program creating apparatus  55  into the production line. 
     In this way, when the display setting information is simply displayed, it is insufficient for the user to notice an error in the display setting information and a deficiency of the system including the display apparatus. The inventor has found that means for enabling the user to easily refer to a device value specified by the display setting information is useful in investigating a cause of a deficiency of the system including the display apparatus. 
     First Embodiment 
     In the present invention, a device value obtained by using a device type and a device code of display setting information is used for displaying a component designated by the display setting information. Moreover, the device value itself is displayed together with the display setting information. To assist a user in understanding a displayed device value, a format database is prepared to make it possible to display the device value in an appropriate representation form. Concerning components denoted by reference numerals and signs same as the above, redundant explanation is omitted as appropriate. 
       FIG. 1  is a block diagram of the configurations of a display apparatus and a controller according to the first embodiment. A display apparatus  25  includes the display unit  5 , the touch panel  7 , the mode changeover switch  8 , the nonvolatile memory  6 , the creating apparatus I/F  9 , the controller I/F  10 , the memory  11 , a CPU  28 , and the ROM  31 . 
     In display of display setting information and operation check, the display apparatus  25  according to this embodiment carries out the display of the display setting information and the operation check according to a combination of the display apparatus  25  and the controller  3  without using the screen data creating apparatus  26  and the program creating apparatus  55  (see  FIG. 18 ). The CPU  28  controls the entire system based on a system program stored in the ROM  31 . 
     The memory  11  functions as a work memory necessary when the CPU  28  executes the system program stored in the ROM  31 . The memory  11  includes a data area, a device type area, a device code area, a condition device determination area, a position area, a display setting pointer area, and a format area (all of which are not shown in the figure). 
     The nonvolatile memory  6  functions as a storing unit configured to store screen data including display setting information. The mode changeover switch  8  functions as display mode switching means for switching a screen of the display unit  5  to a normal display mode for displaying apparatus information of an external apparatus and a display setting information display mode for displaying the display setting information. 
     A procedure for operation check for display setting information by the display apparatus  25  according to the present invention is explained. In the present invention, as in the related art, the display setting information is created in the screen data creating apparatus  26 . The display setting information M 1  created in the screen data creating apparatus  26  is stored in the nonvolatile memory  6  through the creating apparatus I/F  9  as shown in  FIG. 20 . The nonvolatile memory  6  further stores a format database obtained by forming format data as a database. 
       FIG. 2  is a diagram of an example of the format database stored in the nonvolatile memory.  FIG. 3  is a diagram of an example of specified contents stored in respective items of the format database shown in  FIG. 2 . Format data F 1  is stored in the nonvolatile memory  6  as a database in advance. The format database F 1  can be created by the user in the screen data creating apparatus  26  and stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . 
     An area for storing the format data F 1  in the nonvolatile memory  6  includes respective areas for storing a device type f 1 - 1 , a device code f 1 - 2 , a first format f 2 - 1 , a second format f 2 - 2 , and a third format f 2 - 3 . The format data F 1  is present by the number of devices used for the display setting information M 1 . The format data F 1  associates the device type f 1 - 1 , the device code f 1 - 2 , and the three formats f 2 - 1 , f 2 - 2 , and f 2 - 3 . The format data F 1  is prepared separately for respective devices. Besides, the format data F 1  can be prepared for a group including a plurality of devices. 
     The item of the device type f 1 - 1  indicates whether a device allocated in the memory  4  of the controller  3  is a bit device or a word device. In this example, as specified contents of the device type f 1 - 1 , “0” represents a bit device and “1” represents a word device. The device code f 2 - 2  is a code affixed to each of devices present in the memory  4  of the controller  3  and is represented by a numerical value. 
     The respective items of the first format f 2 - 1 , the second format f 2 - 2 , and the third format f 2 - 3  define display forms of device values on the display unit  5 . In this example, as specified contents of the first format f 2 - 1 , the second format f 2 - 2 , and the third format f 2 - 3 , “1” represents display in a binary number, “2” represents display in a decimal number, and “3” represents display in a hexadecimal number. In the respective items of the first format f 2 - 1 , the second format f 2 - 2 , and the third format f 2 - 3 , colors to be displayed on the display unit  5 , the numbers of digits to be displayed, and the like can be displayed. The number of formats included in the format data F 1  is not limited to three and only has to be plural. 
       FIG. 4  is a diagram of an example of a module configuration of a system program in the display apparatus according to the first embodiment. In performing check of the display setting information M 1  and the operation of the display apparatus  25 , first, the user operates the mode changeover switch  8  of the display apparatus  25 . When detecting that a state of the mode changeover switch  8  has changed according to the operation by the user, the CPU  28  executes a selecting module S 11 . The selecting module S 11  is a step of storing, when the touch panel  7  of the display apparatus  25  is touched, a numerical value representing a touched position (see  FIG. 22 ) in the position area of the memory  11  to transmit the numerical value to a retrieving module S 12 . 
     In the retrieving module S 12 , which is a display setting information retrieving step, the CPU  28  refers to the position area of the memory  11  and, when receiving the numerical value representing the touched position on the touch panel  7 , retrieves display setting information stored in the nonvolatile memory  6  and specifies the display setting information M 1  in which the position m 6  coinciding with the received numerical value is set. In the retrieving module S 12 , the CPU  28  functions as display setting information retrieving means for retrieving display setting information from the nonvolatile memory  6 . The CPU  28  stores, in the display setting pointer area of the memory  11 , a storing position of the specified display setting information M 1  in the nonvolatile memory  6  and clears the position area of the memory  11 . 
     In a displaying module S 13 , which is a display setting information displaying step, the CPU  28  refers to the storing position of the nonvolatile memory  6  from the display setting pointer area of the memory  11  and instructs, based on the display setting information M 1  of the storing position, the display unit  5  to display display setting contents. In the displaying module S 13 , the CPU  28  functions as display setting information displaying means for causing the display setting information M 1  specified by the retrieval in the retrieving module S 12  to be displayed on the screen in the display setting information display mode. 
     The display unit  5  displays the display setting contents, which are contents of the display setting information. The display unit  5  displays a numerical value as the ID number m 1 . The display unit displays wording “bit device” when the device type m 2 - 1  is “0”, displays wording “word device” when the device type m 2 - 1  is “1”, and displays nothing as the device type m 2 - 1  when the device type m 2 - 1  is “−1”. 
     The display unit  5  displays a numerical value of the device code m 2 - 2  when the device type m 2 - 1  is “0” or “1” and displays nothing as the device type m 2 - 1  when the device type m 2 - 1  is “−1”. The display unit  5  displays wording “condition bit device” when the condition device type m 3 - 1  is “0”, displays wording “condition word device” when the condition device type m 3 - 1  is “1”, and displays nothing as the condition device type m 3 - 1  when the condition device type m 3 - 1  is “−1”. 
     The display unit  5  displays a numerical value of the condition device code m 3 - 2  when the device type m 3 - 1  is “0” or “1” and displays nothing as the condition device code m 3 - 2  when the device type m 3 - 1  is “1”. The display unit  5  displays wording “not calculate” when the processing method m 4  is “0”, displays wording “multiply with 1000” when the processing method m 4  is “1”, and displays wording “divide by 1000” when the processing method m 4  is “2”. 
     The display unit  5  displays wording “display a circle” when the component m 5  is “1”, displays wording “display a numerical value” when the component m 5  is “2”, and displays wording “transmit “1” to the controller” when the component m 5  is “3”. The display unit  5  displays wording “display in a binary number” when the format m 7  is “1”, displays wording “display in a decimal number” when the format m 7  is “2”, and displays wording “display in a hexadecimal number” when the format m 7  is “3”. The display unit  5  displays a numerical value as the position m 6 . 
     In the waiting module S 18 , the CPU  28  stands by for a touch on the touch panel  7  by the user. The CPU  28  stays on standby until the CPU  28  detects that the position of the device code displayed by the display unit  5  in the displaying module S 13  or the position of the condition device code is touched on the touch panel  7 . The user operates the touch panel  7  according to contents of the display setting information displayed on the display unit  5  by the displaying module S 13 . 
     When the position of the device code is touched in the waiting module S 18 , the CPU  28  refers to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11  from the nonvolatile memory  6 . When the device type m 2 - 1  is “0” or “1”, the CPU  28  stores a value of the device type m 2 - 1  in the device type area of the memory  11  and stores a value of the device code m 2 - 2  in the device code area. The CPU  28  stores “0” in the condition device determination area of the memory  11 . 
     When the position of the condition device code is touched in the waiting module S 18 , the CPU  28  refers to the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11  from the nonvolatile memory  6 . When the condition device type m 3 - 1  is “0” or “1”, the CPU  28  stores a value of the condition device type m 3 - 1  in the device type area of the memory  11  and stores a value of the condition device code m 3 - 2  in the device code area. The CPU  28  stores “1” in the condition device determination area of the memory  11 . 
     In a requesting module S 14 , which is a device value requesting step, the CPU  28  requests, through the controller I/F  10 , the controller  3  to transmit a device value. The CPU  28  requests a device value corresponding to the value stored in the device type area and the value stored in the device code area. In the requesting module S 14 , the CPU  28  functions as device value requesting means for requesting the controller  3  to transmit a device value retained by a device, which is an area in the memory  4 . In the requesting module S 14 , the CPU  28  receives input operation performed in the waiting module S 18  and requests transmission of a device value. 
     The controller  3  transmits the device value to the display apparatus  25  in response to the request from the CPU  28 . In a receiving module S 15 , which is a device value receiving step, the CPU  28  receives the device value from the controller  3  via the controller I/F  10  and stores the device value in the data area of the memory  11 . In the receiving module S 15 , the CPU  28  functions as device value receiving means for receiving the device value transmitted by the controller  3  in response to the request in the requesting module S 14 . 
     In a format retrieving module S 16 , the CPU  28  acquires a value stored in the device type area and a value stored in the device code area of the memory  11  and retrieves, from the format database of the nonvolatile memory  6 , the format data F 1  in which the acquired values and a device type and a device code coincide with each other. The CPU  28  passes a format included in the format data F 1  obtained by the retrieval to a device value displaying module S 17 . 
       FIG. 5  is a flowchart for explaining a detailed processing procedure by the format retrieving module. First, the CPU  28  reads out a value stored in the device type area and a value stored in the device code area of the memory  11  (step S 61 ). The CPU  28  reads out, from the format database of the nonvolatile memory  6 , the format data F 1  in which both of the value of the device type and the value of the device code acquired at step S 61  respectively coincide with the device type f 1 - 1  and the device code f 1 - 2  (step S 62 ). 
     Subsequently, the CPU  28  determines whether a format is stored in the format area of the memory  11  (step S 63 ). When a format is not stored in the format area (No at step S 63 ), the CPU  28  reads out the first format f 2 - 1  in the format data F 1  read out at step S 2  and stores the first format f 2 - 1  in the format area of the memory  11  (step S 64 ). When a format is stored in the format area (Yes at step S 63 ), the CPU  28  reads out the format stored in the format area (step S 65 ). 
     The CPU  28  reads out the first format f 2 - 1  in the format data F 1  present in the nonvolatile memory  6  (step S 66 ). The CPU  28  determines whether the format stored in the format area of the memory  11  and the first format f 2 - 1  read out at step S 66  coincide with each other (step S 67 ). 
     When the format stored in the format area of the memory  11  and the first format f 2 - 1  do not coincide with each other (No at step S 67 ), the CPU  28  reads out the second format f 2 - 2  in the format data F 1  present in the nonvolatile memory  6  (step S 66 ) and carries out determination at step S 67 . When the format stored in the format area of the memory  11  does not coincide with the second format f 2 - 2  either (No at step S 67 ), the CPU  28  carries out the readout at step S 66  and the determination at step S 67  concerning the third format f 2 - 3  as well. In this way, the CPU  28  repeats the determination at step S 67  while sequentially changing the format read out at step S 66  until the format stored in the format area and the format present in the format data F 1  coincide with each other. The order of the formats read out at step S 66  is set in the order of the first format f 2 - 1 , the second format f 2 - 2 , and the third format f 2 - 3 . 
     When the format stored in the format area of the memory  11  and the format present in the format data F 1  coincide with each other (Yes at step S 67 ), the CPU  28  stores the next format of the coinciding format in the format area (step S 68 ). The “next format” is determined, for example, according to the readout order at step S 66 . In this example, when the coinciding format is the first format f 2 - 1 , the CPU  28  stores the second format f 2 - 2 , which is the next format of the first format f 2 - 1 , in the format area. When the coinciding format is the second format f 2 - 2 , the CPU  28  stores the third format f 2 - 3 , which is the next format of the second format f 2 - 2 , in the format area. When the coinciding format is the third format f 2 - 3 , the CPU  28  stores the first format f 2 - 1 , which is the next format of the third format f 2 - 3 , in the format area. 
     In this way, every time the format retrieving module S 16  is executed, the formats are stored in the format area of the memory  11  from the format data F 1  present in the nonvolatile memory  6  in the order of the first format f 2 - 1 , the second format f 2 - 2 , the third format f 2 - 3 , the first format f 2 - 1 , . . . . The format stored in the format area is sequentially changed. 
     In the device value displaying module S 17 , which is a device value displaying step, the CPU  28  causes the display unit  5  to display, according to the format stored in the format area of the memory  11  in the format retrieving module S 16 , the device value stored in the data area of the memory  11  by the receiving module S 15 . In the device value displaying module S 17 , the CPU  28  functions as device value displaying means for causing the device value received in the receiving module S 15  to be displayed on the screen. In the device value displaying module S 17 , the CPU  28  can sequentially change the format of the device value among a plurality of formats of the format data F 1  retrieved from the format database. 
     For example, when a value of the condition device determination area of the memory  11  is “0”, the CPU  28  causes the display unit  5  to display, beside a device code that the displaying module S 13  has caused the display unit  5  to display, a device value according to a format stored in the format area. When the value of the condition device area determination of the memory  11  is “1”, the CPU  28  causes the display unit  5  to display, beside a condition device code that the displaying module S 13  has caused the display unit  5  to display, a device value according to the format stored in the format area. 
     Further, when the value of the condition device determination area of the memory  11  is “0”, the CPU  28  causes the display unit  5  to display a processed value beside a processing method that the displaying module S 13  causes the display unit  5  to display. In this case, the processed value is a value obtained by processing a device value stored in the data area of the memory  11  according to the processing method m 4  present in the display setting information M 1  designated by a storing position stored in the display setting pointer area of the memory  11  in the nonvolatile memory  6 . In such a processed value displaying step, the CPU  28  functions as processed value displaying means for calculating a device value according to the processing method included in the display setting means specified by the retrieval in the retrieving module S 12  and causing the display unit  5  to display a result of the calculation as the processed value. 
     Thereafter, the CPU  28  executes the waiting module S 18  again. The user can request update of the device value displayed on the display unit  5  and change of the format of the device value by touching the device code or the condition device code that the displaying module S 13  has caused the display unit  5  to display. 
     As a specific example, an operation check for the display setting information (B) set in the system of the production line shown in  FIG. 17  is explained. The display setting information (A), (B), and (C) is created by the screen data creating apparatus  26 . The display setting information (A), (B), and (C) created by the screen data creating apparatus  26  is stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . The display setting information (A), (B), and (C) is stored as shown in  FIG. 23  in the nonvolatile memory  6 . 
       FIG. 6  is a diagram of an example of a format database corresponding to the display setting information (A), (B), and (C). When a value of the device type m 2 - 1  or the condition device type m 3 - 1  of the display setting information (A), (B), and (C) is “0” indicating a bit device, the first format f 2 - 1  is set to “1”, the second format f 2 - 2  is set to “−1”, and the third format f 2 - 3  is set to “−1”. When the value of the device type m 2 - 1  or the condition device type m 3 - 1  is “1” indicating a word device, the first format f 2 - 1  is set to “2”, the second format f 2 - 2  is set to “3”, and the third format f 2 - 3  is set to “−1”. 
     The format database is created according to such rules. The created format database is stored in the nonvolatile memory  6 . The ID number m 1  of the display setting information M 1  can be added to format data. In this case, when the same device type and the same device code are present in a plurality of kinds of display setting information, it is possible to create format data for each of the kinds of display setting information. 
     Format data (X) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A). Because a value of the device type m 2 - 1  of the display setting information (A) is “0”, “1” is stored in the first format f 2 - 1 , “−1” is stored in the second format f 2 - 2 , and “−1” is stored in the third format f 2 - 3  of the format data (X). “0”, which is the value of the device type m 2 - 1  of the display setting information (A), is stored in the device type f 1 - 1  of the format data (X). “1”, which is the value of the device code m 2 - 2  of the display setting information (A), is stored in the device code f 1 - 2  of the format data (X). 
     Format data (Y) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (B). Because a value of the device type m 2 - 1  of the display setting information (B) is “1”, “2” is stored in the first format f 2 - 1 , “3” is stored in the second format f 2 - 2 , and “−1” is stored in the third format f 2 - 3  of the format data (Y). “1”, which is the value of the device type m 2 - 1  of the display setting information (B), is stored in the device type f 1 - 1  of the format data (Y). “2”, which is the value of the device code m 2 - 2  of the display setting information (B), is stored in the device code f 1 - 2  of the format data (Y). 
     The values of the device type m 2 - 1  and the device code m 2 - 2  coincide with each other in the display setting information (C) and the display setting information (A). The format data (X) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A) and corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (C) as well. 
     Format data (Z) corresponds to the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting information (C). Because a value of the condition device type m 3 - 1  of the display setting information (C) is “0”, “1” is stored in the first format f 2 - 1 , “−1” is stored in the second format f 2 - 2 , and “−1” is stored in the third format f 2 - 3  of the format data (Z). “0”, which is the value of the device type m 2 - 1  of the display setting information (C), is stored in the device type f 1 - 1  of the format data (Z). “3”, which is the value of the device code m 2 - 2  of the display setting information (C), is stored in the device code f 1 - 2  of the format data (Z). 
     In the operation check for the display setting information (B), first, the user operates the mode changeover switch  8  of the display apparatus  25  and switches the screen from the normal display mode to the display setting information display mode. Subsequently, the user touches the position of a number “31” shown in  FIG. 22  on the touch panel  7  of the display apparatus  25 . The CPU  28  stores the value “31” in the position area of the memory  11 . The CPU  28  retrieves, out of the display setting information stored in the nonvolatile memory  6 , display setting information having the position m 6  coinciding with the value “31” stored in the position area and acquires the display setting information (B). The CPU  28  stores, in the display setting pointer area of the memory  11 , a storing position of the display setting information (B) in the nonvolatile memory  6 . 
     The CPU  28  reads out, from the nonvolatile memory  6 , the display setting information (B) designated by the storing position stored in the display setting pointer area. The CPU  28  causes the display unit  5  to display “2” as the ID number m 1 , display wording “word device” as the device type m 2 - 1 , display “# 2 ” as the device code m 2 - 2 , display wording “divide by 1000” as the processing method m 4 , display wording “numerical value” as the component m 5 , display wording “display in decimal number” as the format m 7 , and display “31” as the position m 6 . 
     When recognizing that the position of a device code displayed earlier is touched, the CPU  28  reads out, from the nonvolatile memory  6 , the value “1” of the device type m 2 - 1  and the value “2” of the device code m 2 - 2  of the display setting information (B) designated by the storing position stored in the display setting pointer area. The CPU  28  stores “1” in the device type area, stores “2” in the device code area, and stores “0” in the condition device determination area of the memory  11 . 
     Subsequently, the CPU  28  requests, through the controller I/F  10 , the controller  3  for a device value of the word device # 2 , which is a device corresponding to the value “1” of the device type area and the value “2” of the device code area of the memory  11 . The CPU  28  stores, in the data area of the memory  11 , the device value of the word device # 2  received from the controller  3  through the controller I/F  10 . 
     The CPU  28  reads out the value “1” stored in the device type area and the value “2” stored in the device code area of the memory  11 . The CPU  28  retrieves, from the format database stored in the nonvolatile memory  6 , format data including the device type f 1 - 1  and the device code f 1 - 2  coinciding with these values and obtains the format data (Y). Because a format is not stored in the format area of the memory  11 , the CPU  28  stores, in the format area of the memory  11 , the value “2” of the first format f 2 - 1  within the format data (Y). 
     Because the value of the condition device determination area of the memory  11  is “0”, the CPU  28  reads out a device value of the “word device # 2 ” from the data area of the memory  11 . Because the value “2” stored in the format area of the memory  11  designates display in a decimal number, the CPU  28  displays the read-out device value in a decimal number. The display unit  5  displays the device value beside the device code. 
       FIG. 7  is a diagram of a display example of display setting contents in the display setting information (B) and a device value of the word device # 2 . The display unit  5  displays, together with the display setting contents  61  of the display setting information (B), a device value  70  of the word device # 2  used in the display setting information (B). In this example, the device value  70  is “100”. A processed value  17  is a value obtained by processing the device value  70  of the word device # 2  according to “divide by 1000”, which is the processing method m 4  in the display setting information (B). 
     When the display of the position  64  of “31” on the display unit  5  shown in  FIG. 7  does not change from “0” during the operation of the system of the production line shown in  FIG. 17 , the user cannot determine from only the display of the position  64  whether this is because the device value of the word device # 2  is smaller than 1000 or because the communication between the display apparatus  25  and the controller  3  has been interrupted. 
     In this embodiment, the device value  70  is displayed as “100” by the device value displaying means. Therefore, the user can recognize that the display of the position  64  does not change from “0” because the device value of the word device # 2  is smaller than 1000 and that the display apparatus  25  can receive the device value from the controller  3 . Because “0”, which is the processed value  17  by the processing method designated by the display setting information (B), and the value “0” displayed in the position  64  coincide with each other, the user can confirm that there is no problem in contents of the display setting information (B). 
     As explained above, the display apparatus  25  displays, together with the display setting information specified by the retrieval, the device value specified by the display setting information. In this embodiment, it is possible to check the display setting information and a deficiency of the system including the display apparatus without using a screen data creating apparatus and a program creating apparatus. Consequently, there is an effect that it is possible to easily and quickly grasp problems such as an error in the display setting information and a deficiency of the system, which are hard to determine only with the display of the display setting information. 
     For example, when display of a numerical value in the display unit  5  is limited to maximum four digits, it is assumed that a device value of the word device # 2  is a decimal number “10000”. In the display setting information (B), a value stored in the second format f 2 - 2 , which is the next format of the first format f 2 - 1 , is “3”, which indicates display in a hexadecimal number. When the user touches a position where a device code is displayed on the touch panel  7 , the CPU  28  causes the display unit  5  to display, as the device value of the word device # 2 , “2710” obtained by converting the decimal number “10000” into a hexadecimal number. Because the number of display digits can be adjusted as appropriate in this way, the user can correctly grasp the device number. 
     Second Embodiment 
     In a second embodiment, functions different from the functions in the first embodiment are explained. Components same as the components in the first embodiment are denoted by the same reference numerals and signs. Redundant explanation of the components is omitted as appropriate. All of the block configuration shown in  FIG. 1 , the format database shown in  FIG. 2 , and the specified contents shown in  FIG. 3  are the same in the second embodiment. 
       FIG. 8  is a diagram of an example of a module configuration of a system program in a display apparatus according to a second embodiment. The selecting module S 11 , the retrieving module S 12 , and the displaying module S 13  are operations same as the operations in the first embodiment. 
     In an input waiting module S 36 , the CPU  28  stays on standby until the CPU  28  detects that a position designated by display setting information has been touched on the touch panel  7 . When detecting that the position designated by the position setting information has been touched, the CPU  28  retrieves, from the display setting information stored in the nonvolatile memory  6 , display setting information having the position m 6  coinciding with a numerical value representing the touched position (see  FIG. 22 ). The CPU  28  stores, in the display setting pointer area of the memory  11 , a storing position of the retrieved display setting information M 1  in the nonvolatile memory  6 . 
     In a change content displaying module S 37 , which is a device value change content displaying step, the CPU  28  reads out the condition device type m 3 - 1 , the condition device code m 3 - 2 , the processing method m 4 , and the component m 5  from the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11 . The CPU  28  acquires change content of a device value transmitted to the controller  3  and causes the display unit  5  to display the change content of the device value. In the change content displaying module S 37 , the CPU  28  functions as device value change content displaying means for causing change content designated concerning the change of the device value specified from the display setting information to be displayed on the screen. Thereafter, the CPU  28  executes the input waiting module S 36  again. 
       FIG. 9  is a flowchart for explaining a detailed processing procedure by the change content displaying module. First, the CPU  28  reads out the condition device type m 3 - 1  and the condition device code m 3 - 2  from the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11  (step S 81 ). 
     Subsequently, the CPU  28  determines whether a condition device type is set (step S 82 ). When the condition device type is set (Yes at step S 82 ), i.e., in this example, when the condition device type m 3 - 1  is “0” or “1”, the CPU  28  stores a value of the condition device type m 3 - 1  in the device type area of the memory  11 . The CPU  28  stores a value of the condition device code m 3 - 2  in the device code area of the memory  11 . 
     After storing the values in the device type area and the device code area of the memory  11 , the CPU  28  requests, through the controller I/F  10 , the controller  3  for a condition device value. The CPU  28  acquires the condition device value through the controller I/F  10  by receiving the condition device value from the controller  3  (step S 83 ). The CPU  28  stores the acquired condition device value in the data area of the memory  11 . 
     When the condition device type is not set (No at step S 82 ), i.e., in this example, when the value of the condition device type m 3 - 1  is “−1”, the CPU  28  executes processing at step S 85  without acquiring the condition device value. 
     After acquiring the condition device value at step S 83  and storing the condition device value in the data area of the memory  11 , the CPU  28  determines whether the value of the condition device stored in the data area is the value set in the display setting information M 1  (step S 84 ). When the value of the condition device type m 3 - 1  is “0” indicating a bit device, the CPU  28  determines whether the condition device value is “1”. When the value of the condition device type  3   m - 1  is “1” indicating a word device, the CPU  28  determines whether the value of the data area is the same as the condition device value specified in the display setting information M 1 . 
     When the condition device value stored in the data area is the value set in the display setting information M 1  (Yes at step S 84 ), the CPU  28  reads out a value of the processing method m 4  of the display setting information M 1  (step S 85 ). When the value of the processing method m 4  is “1” or “2”, the CPU  28  calculates, with a calculation method corresponding to the processing method m 4 , a device value before processing for transmitting a change request to the controller  3  according to designation by the component m 5  of the display setting information M 1  (step S 86 ). The CPU  28  stores a processed value obtained by the calculation in the data area of the memory  11 . When the value of the processing method m 4  is “0”, the CPU  28  directly stores, in the data area of the memory  11 , the device value before processing for transmitting the change request to the controller  3  according to the designation by the component m 5  of the display setting information M 1 . 
     Subsequently, the CPU  28  reads out the device type m 2 - 1  and the device code m 2 - 2  from the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11 . The CPU  28  stores a value of the read-out device type m 2 - 1  in the device type area of the memory  11 . The CPU  28  stores the read-out device code m 2 - 2  in the device code area of the memory  11 . 
     The CPU  28  retrieves, from the format database stored in the nonvolatile memory  6 , format data including the device type f 1 - 1  coinciding with the value stored in the device type area and the device code f 1 - 2  coinciding with the value stored in the device code area. The CPU  28  acquires a format from the retrieved format data (step S 87 ) and stores the format in the format area of the memory  11 . The acquisition of the format by the retrieval of the format data at step S 87  and the storage of the format in the format area are the same as the format retrieving module S 16  in the first embodiment (see  FIG. 4 ). 
     Subsequently, the CPU  28  causes the display unit  5  to display the device value stored in the data area of the memory  11  according to the format stored in the format area of the memory  11 . The display unit  5  displays the device value beside the display of “component” among the display setting contents. 
     When the condition device value is not the value set in the display setting information (No at step S 84 ), the CPU  28  causes the display unit  5  to display a message “no transmission” beside the display of “component” on the display unit  5  (step S 89 ). 
     As a specific example, an operation check for the display setting information (C) set in the system of the production line shown in  FIG. 17  is explained. The display setting information (A), (B), and (C) is created by the screen data creating apparatus  26 . The display setting information (A), (B), and (C) created by the screen data creating apparatus  26  is stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . The display setting information (A), (B), and (C) is stored as shown in  FIG. 23  in the nonvolatile memory  6 . 
     It is assumed that a format database corresponding to the display setting information (A), (B), and (C) is the same as the format database in the first embodiment shown in  FIG. 6 . The format data (X) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A) and the display setting information (C). The format data (Y) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (B). The format data (Z) corresponds to the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting information (C). 
     In the operation check for the display setting information (C), first, the user operates the mode changeover switch  8  of the display apparatus  25  and switches the display of the screen from the normal display mode to the display setting information display mode. Subsequently, the user touches the position of a number “80” shown in  FIG. 22  on the touch panel  7  of the display apparatus  25 . The CPU  28  stores the value “80” in the position area of the memory  11 . The CPU  28  retrieves, out of the display setting information stored in the nonvolatile memory  6 , display setting information having the position m 6  coinciding with the value “80” stored in the position area and acquires the display setting information (C). The CPU  28  stores, in the display setting pointer area of the memory  11 , a storing position of the display setting information (C) in the nonvolatile memory  6 . 
     The CPU  28  reads out, from the nonvolatile memory  6 , the display setting information (C) designated by the storing position stored in the display setting pointer area. The CPU  28  causes the display unit  5  to display “3” as the ID number m 1 , display wording “bit device” as the device type m 2 - 1 , display “# 1 ” as the device code m 2 - 2 , display wording “bit device” as the condition device type m 3 - 1 , display “# 3 ” as the condition device code m 3 - 2 , display wording “not calculate” as the processing method m 4 , display wording “transmit “1” to the controller” as the component m 5 , and display “80” as the position m 6 . 
     When detecting that the position of the number “80” is further touched on the touch panel  7 , the CPU  28  retrieves display setting information in which the position m 5  is “80” out of the display setting information stored in the nonvolatile memory  6  and acquires the display setting information (C). The CPU  28  stores, in the display setting pointer area of the memory  11 , the storing position of the display setting information (C) in the nonvolatile memory  6 . 
     Further, the CPU  28  reads out, from the nonvolatile memory  6 , a value “0” of the condition device type m 3 - 1  and a value “3” of the condition device code m 3 - 2  of the display setting information (C) designated by the storing position stored in the display setting pointer area. Because the value of the condition device type m 3 - 1  is a value other than “−1” indicating no setting, the CPU  28  stores the value “0” of the condition device type m 3 - 1  in the device type area of the memory  11  and stores the value “3” of the condition device code m 3 - 2  in the device code area of the memory  11 . 
     The CPU  28  requests, through the controller I/F  10 , the controller  3  for a condition device value of the bit device # 3 , which is a condition device corresponding to the value “0” of the device type area and the value “3” of the device code area of the memory  11 . The CPU  28  stores, in the data area of the memory  11 , the condition device value of the bit device # 3  received from the controller  3  through the controller I/F  10 . 
     When the condition device value of the bit device # 3  is “0”, the condition device value does not correspond to a value for executing operation designated by the component m 5  of the display setting information (C). In this case, the CPU  28  causes the display unit  5  to display wording “no transmission” beside wording “components” in the display unit  5 . 
       FIG. 10  is a diagram of a display example of display setting contents in the display setting information (C) and a condition device value of the bit device # 3 . The display unit  5  displays, together with display setting contents  170  of the display setting information (C), device value change content  126  designated in the display setting information (C). In this example, a condition device value of the bit device # 3  used in the display setting information (C) is “0” and the device value change content  126  is “not transmission”. 
     In this embodiment, when the conveyor  52  does not operate even if the user touches the position  65  on the touch panel  7 , the user can recognize, referring to the device value change content  126 , whether the display apparatus  25  has requested the controller  3  to change a device value. When recognizing that the change of the device value has not been requested, the user can realize early solution of a problem by investigating a condition device for changing the device value. In this embodiment, as in the first embodiment, it is possible to easily and quickly grasp problems such as an error in the display setting information and a deficiency of the system. 
     Third Embodiment 
     In a third embodiment, functions different from the functions in the first embodiment are explained. Components same as the components in the first embodiment are denoted by the same reference numerals and signs. Redundant explanation of the components is omitted as appropriate. All of the block configuration shown in  FIG. 1 , the format database shown in  FIG. 2 , and the specified contents shown in  FIG. 3  are the same in the third embodiment. 
       FIG. 11  is a diagram of an example of a device character string database stored in a nonvolatile memory.  FIG. 12  is a diagram of an example of specified contents of values stored in respective items of the device character string database shown in  FIG. 11 . The device character string database is a database of device character string data for converting a device code into a character string. 
     Device character string data N 1  is stored in the nonvolatile memory  6  as a database in advance. The device character string data N 1  can be created by a user in the screen data creating apparatus  26  and stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . 
     An area for storing the device character string data N 1  in the nonvolatile memory  6  includes areas for storing a device type n 1 - 1 , a device code n 1 - 2 , and a character string n 2 . The device character string data N 1  is present by the number of devices used in display setting information. 
     The device type n 1 - 1  corresponds to the device type m 2 - 1  or the condition device type m 3 - 1  of the display setting information M 1 . A value of the device type n 1 - 1  is the same as a value of the device type m 2 - 1  or a value of the condition device type m 3 - 1  of the display setting information M 1 . The device code n 1 - 2  corresponds to the device code m 2 - 2  or the condition device code m 3 - 2  of the display setting information M 1 . A value of the device code n 1 - 2  is the same as a value of the device code m 2 - 2  or a value of the condition device code m 3 - 2  of the display setting information M 1 . 
     The character string n 2  is a character string for specifying the device code n 1 - 2 . The character string n 2  can be used in the program creating apparatus  55  instead of a device code as a character string for specifying the device code. The character string n 2  can be set as an arbitrary character string as well for the user to specify the device code n 1 - 2 . 
       FIG. 13  is a diagram of an example of a module configuration of a system program in a display apparatus according to the third embodiment. The selecting module S 11 , the retrieving module S 12 , and the displaying module S 13  are operations same as the operations in the first embodiment. 
     In a device character string displaying module S 23 , the CPU  28  acquires the device type m 2 - 1  and the device code m 2 - 2  or the condition device type m 3 - 1  and the condition device code m 3 - 2  from the display setting information M 1  designated by a storing position stored in the display setting pointer area of the memory  11 . The CPU  28  retrieves, in the device character string data stored in the nonvolatile memory  6 , device character string data including the device type n 1 - 1  and the device code n 1 - 2  coinciding with the thus acquired device type m 2 - 1  and the device code m 2 - 2  or the condition device type m 3 - 1  and the condition device code m 3 - 2 . 
     Further, the CPU  28  causes the display unit  5  to display the character string n 2  of the device character string data N 1  obtained by the retrieval. In the device character string displaying module S 23 , which is a device character string displaying step, the CPU  28  functions as device character string displaying means for displaying a character string retrieved from the device character string database using a device code included in display setting information specified by retrieval in the retrieving module S 12 . 
       FIG. 14  is a flowchart for explaining a detailed processing procedure by the device character string displaying module. First, the CPU  28  reads out the device type m 2 - 1  and the device code m 2 - 2  from the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11  (step S 71 ). 
     The CPU  28  retrieves, from the device character string database of the nonvolatile memory  6 , the device character string data N 1  in which both values of the device type m 2 - 1  and the device code m 2 - 2  acquired at step S 71  respectively coincide with the device type n 1 - 1  and the device code n 1 - 2  and acquires the device character string data N 1  (step S 72 ). 
     The CPU  28  reads out the character string n 2  of the device character string data N 1  acquired at step S 72  (step S 73 ). The CPU  28  causes the display unit  5  to display the character string n 2  read out at step S 73  (step S 74 ). 
     Subsequently, the CPU  28  reads out the condition device type m 3 - 1  and the condition device code m 3 - 2  from the display setting information M 1  designated by the storing position stored in the display setting pointer area of the memory  11  (step S 75 ). 
     The CPU  28  determines whether a condition device type is set (step S 76 ). When the condition device type is set (Yes at step S 76 ), i.e., in this example, when the condition device type m 3 - 1  is “0” or “1”, the CPU  28  retrieves the device character string data N 1  in which both values of the condition device type m 3 - 1  and the condition device code m 3 - 2  acquired at step S 75  respectively coincide with the device type n 1 - 1  and the device code n 1 - 2  from the device character string database in the non-volatile memory  6 , and acquires the device character string data N 1  (step S 77 ). 
     The CPU  28  reads out, concerning a condition device, the character string n 2  of the device character string data N 1  acquired at step S 77  (step S 78 ). The CPU  28  causes, concerning the condition device, the display unit  5  to display the character string n 2  read out at step S 78  (step S 79 ) and ends the processing. 
     When there is no setting of a condition device type (No at step S 76 ), i.e., in this example, a value of the condition device type m 3 - 1  is “−1”, the CPU  28  ends the processing without performing readout of a character string related to the condition device and display of the character string on the display unit  5 . 
     The waiting module S 18 , the requesting module S 14 , the receiving module S 15 , the format retrieving module S 16 , and the device value displaying module S 17  are the same as those in the first embodiment. 
     As a specific example, an operation check for the display setting information (C) set in the system of the production line shown in  FIG. 17  is explained. The display setting information (A), (B), and (C) is created by the screen data creating apparatus  26 . The display setting information (A), (B), and (C) created by the screen data creating apparatus  26  is stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . The display setting information (A), (B), and (C) is stored as shown in  FIG. 23  in the nonvolatile memory  6 . 
     It is assumed that a format database corresponding to the display setting information (A), (B), and (C) is the same as the format database in the first embodiment shown in  FIG. 6 . The format data (X) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A) and the display setting information (C). The format data (Y) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (B). The format data (Z) corresponds to the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting information (C). 
       FIG. 15  is a diagram of an example of a device character string database corresponding to the display setting information (A), (B), and (C). Device character string data (P) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A). “0” is stored in the device type n 1 - 1  and “1” is stored in the device code n 1 - 2 . “BIT 1 ” is set in the character string n 2  of the device character string data (P) as a character string for specifying the device code “1”. 
     Device character string data (Q) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (B). “1” is stored in the device type n 1 - 1  and “2” is stored in the device code n 1 - 2 . “WORD 2 ” is set in the character string n 2  of the device character string data (Q) as a character string for specifying the device code “2”. 
     The values of the device type m 2 - 1  and the device code m 2 - 2  coincide with each other in the display setting information (C) and the display setting information (A). The device character string data (P) corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (A) and corresponds to the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (C) as well. 
     Device character string data (R) corresponds to the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting condition (C). “0” is stored in the device type n 1 - 1  and “3” is stored in the device code n 1 - 2 . “Safety door opening and closing signal” is set in the character string n 2  of the device character string data (R) as a character string for specifying the device code “3”. It is assumed that the device character string data (P), (Q), and (R) are created by the user in the screen data creating apparatus  26  and stored in the nonvolatile memory  6  via the creating apparatus I/F  9 . 
     In the operation check for the display setting information (C), first, the user operates the mode changeover switch  8  of the display apparatus  25  and switches the display of the screen from the normal display mode to the display setting information display mode. Subsequently, the user touches the position of the number “80” shown in  FIG. 22  on the touch panel  7  of the display apparatus  25 . The CPU  28  stores the value “80” in the position area of the memory  11 . The CPU  28  retrieves, out of the display setting information stored in the nonvolatile memory  6 , display setting information having the position m 6  coinciding with the value “80” stored in the position area and acquires the display setting information (C). The CPU  28  stores, in the display setting pointer area of the memory  11 , a storing position of the display setting information (C) in the nonvolatile memory  6 . 
     The CPU  28  reads out, from the nonvolatile memory  6 , the display setting information (C) designated by the storing position stored in the display setting pointer area. The CPU  28  causes the display unit  5  to display “3” as the ID number m 1 , display wording “bit device” as the device type m 2 - 1 , display “# 1 ” as the device code m 2 - 2 , display wording “bit device” as the condition device type m 3 - 1 , display “# 3 ” as the condition device code m 3 - 2 , display wording “not calculate” as the processing method m 4 , display wording “transmit “1” to the controller” as the component m 5 , and display “80” as the position m 6 . 
     The CPU  28  reads out the device type m 2 - 1  and the device code m 2 - 2  of the display setting information (C) from the nonvolatile memory  6 . The CPU  28  retrieves, from the device character string database stored in the nonvolatile memory  6 , device character string data including the device type m 2 - 1  and the device code m 2 - 2  coinciding with the device type m 2 - 1  and the device code m 2 - 2  read out from the nonvolatile memory  6  and obtains the device character string data (P). The CPU  28  obtains the character string n 2  “BIT 1 ” from the acquired device character string data (P) and causes the display unit  5  to display the character string n 2  “BIT 1 ”. 
     Subsequently, the CPU  28  reads out the condition device type m 3 - 1  and the condition device code m 3 - 2  of the display setting information (C). Because the value of the condition device type m 3 - 1  is a value other than “−1” indicating no setting, the CPU  28  retrieves, from the device character string database stored in the nonvolatile memory  6 , device character string data including the device type n 1 - 1  and the device code n 1 - 2  coinciding with the condition device type m 3 - 1  and the condition device code m 3 - 2  read out from the nonvolatile memory  6  and obtains the device character string data (R). The CPU  28  acquires the character string n 2  “safety door opening and closing signal” from the obtained device character string data (R) and causes the display unit  5  to display the character string n 2  “safety door opening and closing signal”. 
     When recognizing that the position of a device code displayed earlier is touched, the CPU  28  reads out, from the nonvolatile memory  6 , the value “0” of the condition device type m 3 - 1  and the value “3” of the condition device code m 3 - 2  of the display setting information (C) designated by the storing position stored in the display setting pointer area. The CPU  28  stores “0” in the device type area, stores “3” in the device code area, and stores “1” in the condition device determination area of the memory  11 . 
     Subsequently, the CPU  28  requests, through the controller I/F  10 , the controller  3  to transmit a condition device value of the bit device # 3 , which is a condition device corresponding to the value “0” of the device type area and the value “3” of the device code area of the memory  11 . The CPU  28  stores, in the data area of the memory  11 , the condition device value of the bit device # 3  received from the controller  3  through the controller I/F  10 . 
     The CPU  28  reads out the value “0” stored in the device type area and the value “3” stored in the device code area of the memory  11 . The CPU  28  retrieves, from the format database stored in the nonvolatile memory  6 , format data including the device type f 1 - 1  and the device code f 1 - 2  coinciding with these values and obtains the format data (Z). Because a format is not stored in the format area of the memory  11 , the CPU  28  stores, in the format area of the memory  11 , the value “1” of the first format f 2 - 1  within the format data (Z). 
     Because the value of the condition device determination area of the memory  11  is “0”, the CPU  28  reads out a condition device value of the bit device # 3  from the data area of the memory  11 . Because the value “1” stored in the format area of the memory  11  designates display in a binary number, the CPU  28  displays the read-out condition device value in a binary number. The display unit  5  displays the condition device value beside the condition device code. 
       FIG. 16  is a diagram of a display example of display setting contents in the display setting information (C) and a condition device value of the bit device # 3 . The display unit  5  displays, together with the display setting contents  61  of the display setting information (C), a device value  72 , which is a condition device value of the bit device # 3  used in the display setting information (C). In this example, the device value  72  is “0”. 
     In the system of the production line shown in  FIG. 17 , when the conveyor  52  does not operate even if the user touches the position  65  on the touch panel  7 , the user can recognize that the condition device value is “0” referring to the device value  72 . The user can recognize that the condition device is an opening and closing signal of the safety door  50  referring to display setting content  160 . Consequently, the user can easily grasp that the user should check an opening and closing state of the safety door  50 . Further, when the safety door  50  is closed, the user can easily grasp that a connection state between the bit device # 3  and the safety door  50  should be checked. In this embodiment, as in the embodiments explained above, it is possible to easily and quickly grasp problems such as an error in display setting information and a deficiency of a system. 
     The display apparatus and the operation checking method for the display apparatus according to the present invention is not limited to the application to the system of the production line explained above. The above explanation concerning the system of the production line is an example. The display apparatus and the operation checking method for the display apparatus can be applied to other systems as appropriate. 
     REFERENCE SIGNS LIST 
     
         
         
           
               3  controller 
               4  memory 
               5  display unit 
               6  non-volatile memory 
               7  touch panel 
               8  mode changeover switch 
               9  creating apparatus I/F 
               10  controller I/F 
               11  memory 
               17  processed value 
               25  display apparatus 
               28  CPU 
               50  safety door 
               70  device value 
               126  device value change content 
             F 1  format data 
             M 1  display setting information 
             N 1  device character string data 
             S 11  selecting module 
             S 12  retrieving module 
             S 13  displaying module 
             S 14  requesting module 
             S 15  receiving module 
             S 16  format retrieving module 
             S 17  device value displaying module 
             S 18  waiting module 
             S 23  device character string displaying module 
             S 36  input waiting module 
             S 37  change content displaying module