GB2163928A - Graphics display for a numerical control system - Google Patents

Abstract

A computer numerical control system for controlling the operation of a machine tool in the performance of specified operations with respect to a workpiece includes a software package 321 in the customization machine control logic (MCL) software for generating graphic displays in pseudo real time. A package of subprograms 82, 86 are executed when the machine tool operator requests the display of a display page of machine status information and a routine 82 initializes a predetermined graphic display 88 from display control files 80 of the numerical control (NC) software 24 to the video monitor 18 of a numerical control station. This is followed by a second routine 86 which is executed periodically when the graphic display 88 is active to dynamically update the graphic being displayed. During each of the two routines 82, 86 one or more of six "draw" procedures are called from the display control files 80 of the NC software 24 to produce the desired graphic display 88 such as a horizontal bar graph of the spindle speed of a lathe. <IMAGE>

Description

SPECIFICATION Graphics display generation method for a numerical control system Cross reference to related application This invention relates to U.S. Patent Application Serial No. 415,041, entitled, "Customization Window For A Computer Numerical Control System", filed on September 7, 1982. This related application is owned by the applicants of the present invention and is intended to be incorporated herein by reference.

Background of the invention This invention relates generally to computer numerical control systems for machine tools and more particularly to the graphical display of information related to the operation of such tools and to the machining process.

Numerical control systems for controlling machine tools in accordance with the execution of stored programs in a digital computer are well known. Such systems control the machining operation in response to one or more part programs which are stored in a memory after having been loaded into the memory by a punched tape, for example.Upon demand, the part program directs the machine through a series of fabrication steps.Where, for example, the machine includes a cutting tool, the relative motion between the work piece and the cutting tool is normally along three mutually perpendicular axes in accordance with the part program which dictates the cutting tool motion. Additionally, a computer numerical control (CNC) system might be adapted to control other functions such as tool changes, spindle speed, coolant flow, pallet selection and graphics and message generation.The number and type of functions vary considerably depending upon the type of machine tool being controlled. In the past, control has been performed by dedicated, hard-wired circuits which operate in response to sensed conditions on the machine tool and to commands in the part program.

More recently, however, the logic associated with machine tool control systems has been implemented in a computerized system by means of a set of stored programs, i.e. software, to provide the overall control. The software is tailored for a particular application and may be readily modified on demand to meet specific needs. The addition of programmable control to a numerical control system provides a number of advantages, the first and foremost is that it is only necessary to reprogram the control to enable it to interface with a particular machine tool. Additionally, it is relatively easier for the user to program because of the type of instruction set which is normally employed and the editing features which are normally available.

A computerized numerical control, or simply a CNC, for controlling the operation of a machine tool may include two separate sets of software, namely the "numerical control logic" termed the NC software which is more or less fixed in content and the "machine control logic", termed the MCL program which is flexible and adaptable for customization to a particular machine tool. In the industry this customization is typically carried out by the original equipment manufacturer (OEM).The NC software controls part making, movement of axes, the CRT display and other auxiliary functions while the MCL program primarily, if not exclusively, controls operation of the machine tool. In the above-mentioned U.S. patent application, "Customization Window For A Computer Numerical Control System", there is disclosed, moreover, a software interface, i.e.Customization Window, which is comprised of a group of programs, inputs output arrays and status flags that link the NC software, the MCL program and the machine tool. Use of a customization window gives the OEM, or customer, a high degree of flexibility in adapting a CNC to a particular machine tool. In one aspect, the present invention makes use of a customization window.

Once programmed and operative, computer numerical controls perform their function automatically and substantially without intervention by operating personnel. There is, nevertheless, a need from time to time for the operator (or others) to be able to quickly discern operating results, machining data, machine conditions, and so forth. In short, there is a need for ready communications between the CNC and those having an interest in the controlled process. A typical CNC provides for a great deal of this communication through a visual display on a cathode ray tube (CRT). Much of the displayed information, however, is in the form of textual information which must be read in its entirety for full comprehension.Accordingly, there remains a need for graphics support so that operating personnel can very quickly and easily comprehend operating conditions such as spindle speed, cumulative tool usage, from a quick view of the CRT.

Summary of the invention It is therefore an object of the present invention to provide an improvement in numerical control systems for machine tools.

It is more particularly an object of the invention to provide an improvement in means for displaying information on a graphics display device for a computer numerical control system so that machine tool operators, maintenance personnel and other support personnel can readily and quickly discern the machine tool's operating conditions and performance.

Briefly, the foregoing and other objects are achieved in a computer numerical control system by providing a new package of subprograms included in the portion of the machine control logic (MCL) program made especially accessible for adapting the CNC to a particular machine tool.The subprograms are executed when the machine tool operator requests the display of a display page of machine status information. The subprograms include a routine to initialize a predetermined graphic display from display control files of the numerical control (NC) software.This is followed by a second routine which is executed periodically when the graphic display is active to dynamically update the graphic being displayed.During each of the two routines, one or more of six "draw" procedures are called to produce the desired graphic display.These procedures include moving a graphic cursor to a given location on the CRT screen, drawing a line, drawing a rectangle, drawing an arc, drawing a circle, filling a predetermined area, and clearing an area including the entire screen of the display.

By combining these procedures, graphic representations of physical quantities can be created on the CRT screen. These graphics are of a form which are quickly understood by the viewer. They may be likened somewhat to analog meters in some cases. For example, by combining two contiguous arcs, one may create an analog display of spindle speed as a percentage of full speed. In such a case, the cursor is moved to a specific location, a first arc is then drawn whose magnitude represents actual spindle speed, and then a second arc is drawn contiguous to the first. The two arcs together represent full spindle speed. As spindle speed changes, the arcs vary in angle, one relative to the other The impression created is somewhat like an analog tachometer readout.lt will be seen that bar graphics, pie charts, and various other graphic forms may be created.

Brief description of the drawings While the present invention is defined in the claims annexed to and forming a part of this specification, a better understanding can be had by reference to the following description when taken in conjunction with the accompanying drawings in which; Figure 1 is a simplified diagram illustrative of a known prior art computerized numerical control system (CNC) for controlling a machine tool; Figure 2 is a diagram broadly illustrative of the software included in the CNC system shown in Figure 1; Figure 3 is a block diagram further illustrative of the CNC software shown in Figure 2; Figure 4 is a diagram illustrating the manner in which the machine control (MCL) program is developed; Figure 5 is a block diagram generally illustrative of the sequence of operation of the CNC software;; Figure 6 is a diagram illustrative of the various display page which can be shown on the screen of a cathode ray tube (CRT) located in the numerical control station shown in Figure 1; Figure 7 is a block diagram illustrative of sections of subprograms referred to as "packages" in the OEM MCL program shown in Figure 3; Figure 8 is a block diagram further illustrative of the preferred embodiment of the invention wherein graphics are added to an original equipment manufacturer (OEM) formatted display pages shown on the CRT of the numerical control station shown in Figure 1; and Figure 9 is a flow chart of the method for implementing the graphic display on an OEM display page shown at the numerical control station Detailed description of the preferred embodiment Referring now to the drawings and more particularly to Figure 1, there is disclosed for purposes of illustration the operational environment in which the present invention resides. Figure 1, for example, discloses a computer numerical control (CNC) system for controlling a machine tool 10 and includes three major hardware components. They are: the numerical control station 12, the machine control station 14 and the NC system rack 16 whose purpose is to house the principal printed circuit boards, not shown. Such a configuration is typically illustrative of a Mark Century 2000 computer numerical control system of the General Electric Company.This system is capable of storing entire computer programs and calling them up in a desired sequence, editing programs by the addition or deletion of subprograms in sections or blocks called packages, and thereafter carrying out a complete set of instructions that performs a specific task on a machine tool such as a lathe or milling machine.

The numerical control station 12 includes a video monitor in the form of a cathode ray tube screen display 18 and a keyboard 20 having special function keys to input sets of information, referred to as files, into memory and thereafter command retrieval of file information in a well known manner for program execution.

The machine control station 14 includes a set of manual controls and push buttons 22 which are utilized for machine oriented operator functions such as mode selection, offset access, jog, spindle speed, feed rate, etc.

The functions performed by the CNC shown in Figure 1 are determined by internally stored programs called the CNC software. The CNC software is comprised of three different sets of programs as shown in Figure 2 and includes the numerical control logic 24 (hereinafter referred to as the NC software), the MCL window 26, and the machine control logic 28 (hereinafter referred to as the MCL program). The NC software 24 controls the making of parts, the movement of machine axes, and the display of messages on a cathode ray tube (CRT).

The NC software comprises a fixed or permanent part of the CNC system which normally cannot be changed by the user. The MCL program specifically controls the operation of the machine tool and is comprised of many subprograms, in modular type sections called packages, which allow for user customization by the original equipment manufacturer (OEM). The MCL window 26 comprises a set of software, such as disclosed in the above referenced US patent application, Serial No. 415, 041, that permits the MCL program 28 to communicate with the NC software 24 and provides access to the inputs and outputs of the machine tool 10.

As further shown in Figure 3, the MCL program 28 consists of two parts, the fixed MCL 30 and the customization MCL 32. The customization MCL contains the programs for controlling the operation of the machine tool 10 while using the MCL window 26 software to provide the necessary machine interface. It is the customization MCL 32 that is tailored to customize the CNC for operation in controlling a particular machine tool. The fixed MCL 30, on the other hand, is a set of software whose basic function is to monitor and control the operator devices on the machine control station 14 (Fig ure 1) and is used, as is, for most applications.

The MCL window 26 is comprised of a series of window procedures, and functions 34, status flag arrays 36 and input and output arrays 38 which for the most part cannot be changed so that the integ rity of the NC software cannot be compromised by any of the user programmable functions and pro cedures programmed into the MCL 28.

The NC software 24 is comprised of a plurality of routines for controlling part making 40, axis move ment 42 and operator displays 44 as well as pro viding programs that control spindle motion, -timers, math functions and machine set up data.

The display routines 44 are of particular interest in this invention in that they include routines which permit the customization MCL 32 to optionally se lect or "call" certain display page routines of the NC software for providing the display of desired machine status information to the operator on de mand.

Prior to discussing the invention in detail, the structure of the MCL program 28 will be briefly considered. The MCL program is comprised of an executable sequence of subprograms expressed in a high level computing programming language which resembles a natural language such as Eng lish. This language, called Programmable Control ler Language (PCL), consists of a group of related data and statements similar to PASCAL which are intended to perform a particular operation. Sub programs are created separately and can be used as often as needed to execute either a procedure which performs an operation or a function which performs an operation and returns a value.Each program has an identifier (known as a "call") which, when encountered, causes that program to be executed.Each subprogram is introduced by a declaration followed by any constants, variables, arrays, or enumerated data types it contains. For a Mark Century 2000 CNC, one may refer to a Gen eral Electric publication entitled, "Introduction To PCL/MCL" NEC 1214, November, 1983, for a de tailed explanation of the PCL language. The pres ent invention has particular utility when used in cdnjunction with a Mark Century 2000 CNC al though it will become clear that the invention is not so limited and may be used with other numeri cal control systems as well.

Referring now to Figure 4, customization of the MCL program 28 for the machine tool 10 begins with a system designer entering a series of PCL subprograms, shown by reference numeral 46, into the CNC system via the keyboard 20 of the numeri cal control station 12 where they are fed into a file editor 48. There they are transformed to PCL files where they are stored in a memory, not shown.

The PCL files are also fed to a PCL compiler 52 where they are subsequently translated into machine code and stored as a machine code file 54.

To complete the program processing, the machine code files are next fed to a linker 56 which produces a single machine code file 58. The linked machine code file is then fed to a locator 60 which assigns addresses in a random access memory, not shown, to the information contained in the linker output file and creates a new file 62 containing the RAM memory assignments. The information from the linker file is the final machine code version of the MCL program and is thereafter executed when the machine tool 10 is operated.

With the CNC software, including the MCL program 28, in place as the NC software 24 executes it repeatedly calls the MCL program 28 as shown in Figure 5. Each resulting pass through the MCL program is called a sweep. During each MCL program sweep, the fixed MCL routines first execute to monitor and control the devices of the machine control station 14.This is followed by execution of the customization MCL routines which sequence and call the machine tool subprograms.

The customization MCL program 32 may comprise a number of subprogram packages, each available for individual customization.The number of packages in any particular customization can be increased or decreased depending upon the application at hand. Figure 7 illustrates certain subprogram packages which might typically be available.

The present invention relates to one of the subprogram packages; namely, the MCL display pages 321.By way of illustration, however, the subprogram packages may include: a Power Up Package 322 which includes the start up and safety interlocking routines utilized on the machine during machine start up; a Conveyor Package 323 where all manual and part program control of the convey is included; a Tailstock Package 324 which controls the tailstock on the lathe, a Lubrication Package 325 which implements automatic machine lubrication that must be performed or monitored on a regular basis;Quill Package 326 which controls the tailstock's quill under part program control; a Chuck Package 327 where control of all the clamping and unclamping of the chuck during a part program is implemented; a Tool Turret Package 328 which controls the tool turret on the part program control; a Spindle Package 329 which controls the lathe spindle speed, and a Coolant Package 32iso which controls the machine coolant.

Having thus set forth the operational environment, the details of the subject invention can now be considered. The invention concerns itself with the graphic display of information on the CRT of the video monitor 18 of the numerical control station 12 shown in Figure 1. The keyboard 20 of the numerical control station 12 includes a row of ten keys 66 by which an operator can select any one of ten frequently used main display pages. Each dis play page comprises a raster type of video display and is generated from display control files stored in memory, not shown, forming part of the NC software 24. The row of display page keys 66 is further illustrated in Figure 6. Additional display pages termedsubpages can also be-selected by a set of keys or pushbuttons shown by reference numeral 68 of Figure 1.Four cursor keys are included to provide for up/down and leftlright control of a cursor for data editing and vertical scrolling. The right subpage selections are illustrated just above the row of display page keys 66 while the left subpage selections are illustrated below the row of display page keys and are designated by reference numerals 67 and 69, respectively. The right subpage selections 67 include, for example: "TOOL STATUS"; "PROGRAM POSITION"; "TOOLING DATA", and so on, while the left subpage selections 69 include "TECH STATUS", "PROGRAM PO SITION", and so forth.

The CNC system software, through the Customization MCL 32, provides the machine tool builder or OEM designer with the option to format three "machine" display pages. Thus, the customization can be used to display any desired machine status information for operator or service personnel assistance. These display pages are selectable by the "MACHINE" key 70 and the right and left subpage display page options 72 and 74, respectively, in Figure 6.

Referring now to Figure 8, when the operator selects one of the three machine display pages, the NC software 24is caused to respond to a display page procedure 78 in accordance with whether the page selected is the left, right or main page. Text information, as opposed to graphics, is then called from the display control files 80 where it has been previously stored. The textual information, in proper form, is then coupled to the CRT display 18.

When graphics are to be included as part of the complete CRT display, a "call" embedded in the display control files 80 triggers initiation of those procedures necessary to implement the graphical portion of the display. The display page routine 78 responds to the embedded request for graphics display by initiating a call to the MCL display pages routine 32 through an entry point 79 of the window 26.ln response, -a graphics display change routine 82 is executed. This routine 82 is accessible, e.g., by an original equipment manufacturer adapting a control to a particular machine tool, for customizing the static portion of the graphic display. The customization is written in PCL, as described above.

The graphics display provided by graphics display change routine 82 is static in the sense that once the format and contact of the display are selected, they remain unchanged until recustomized..

The graphic display change routine 82 is able to call upon certain basic graphic functions by way of entry points 83 in window 26. For example, available-to the graphics display change routine 82 are functions to: (1) move the CRT cursor to a particular screen location; (2) draw a line between specified points; (3) draw a rectangle, given opposing corner coordinate points; (4) draw an arc of given radius and angle; (5) draw a circle; (6) fill a particular screen area; and (7) clear a screen area.

Three graphic functions are themselves software routines of a conventional kind which are available upon call from the CNC memory, not shown.

These functions together comprise the graphic display routine 84. Separate window entry points 83 are provided for each graphic function so that each function is available as necessary in making up a custom display.

The graphic display routines 84 are merged with the textual material through the display control files 80 and then displayed on the CRT 18.

The static portion of the graphic display provides a background or framework from which to display real time operating data in graphical form. The graphics display update routine 86 provides this dynamic operating data on a virtual real time basis. When in the display page mode, the display page procedure 78 makes a periodic call, e.g., every 150 milliseconds through window entry point 81 to the graphics display update routine 86. The routine 86 is tailored to sample the required information which is inherently available within the numerical control system. For example, for a lathe, information is readily available on real time spindle speed. That information is simply scaled by the graphics display update routine 86 which then imitates one or more of the graphic functions (through entry points 83) so that it is displayed in proportion to the actual real time value.

Thus, the graphics display update routine 86 functions substantially identically to the graphics display change routine 82 except that the latter is repeatedly called and is tailored to include immediate operating data. The static and dynamic graphics thus produced are merged with the text material through the display control files 80 and the display page routine 78 for presentation on the CRT.

It will be helpful to an understanding of the invention to discuss a typical graphic display that might be desired. For example to create a bar graph of spindle speed for a lathe as a percentage of maximum spindle speed, the customization MCL 32 is simply tailored to create two contiguous rectangles such as is illustrated on the CRT 18 of Figure 8 by reference numeral 88. Although there may be a static portion to the overall display, the bar graph to be created is composed essentially of all real time repetitively updated data. Since the static and dynamic portions are achieved by quite similar progressions, it is sufficient to discuss only the dynamic portion of the graphics to be displayed.

For creating. the bar graph of Figure 8, the display page routine 78 calls, through MCL window entry point 81, the graphics display update routine 86 every 150 milliseconds. The graphics display update routine 86 has available, from the control system, real time data on the lathe spindle speed.

This information is scaled and then draw commands are issued in accordance with the scaled information. Four commands, for example, are necessary: (1) > move the cursor to a preselected left-hand lower corner starting point for a first rectangle; (2) draw the first rectangle to a right-hand upper corner ending point, where such point is a function of actual spindle speed; (3) again move the cursor to the left-hand, lower corner starting point for a second rectangle such that the second rectangle begins where the first rectangle ends; and (4) then draw the second rectangle to righthand upper corner ending point representing maximum spindle speed. Thus, as spindle speed increases or decreases, the two rectangles increase and/or decrease in length accordingly. The visual appearance is that of a bar graph depicting actual spindle speed.

Appendix I is a PCL program for creating a bar graph as described above. Routines for supplying the window calls for generating the graphics are contained in Appendix II hereto.

Referring now to Figure 9, shown thereat is a flow chart illustrative of the operational steps implemented in software for generating graphics on the customization OEM MCL display pages displayed on the video monitor 18. The first step is shown by reference numeral 90 and comprises a call for one of the three "machine" display pages via the MCL display page package 32 upon an operator requesting a particular MCL display page.

This, as it will be recalled, results from an operator activating one of the keys included in the keyboard sets 66 and 68 of the numerical control station 12 (Figure 1).Next a test is made for the existence and availability of a particular page as evidenced by step 92. Next values of the desired parameters which are to be the subject of a graphic display are obtained as shown by step 94.

Having determined the display page and the parameter values, a call to display the display page is issued, whereupon the display page routine 78 is executed as shown by step 96. The initialization portion of the graphic generation is next executed (step 98) followed by a periodic updating of the graphic display as evidenced by step 100. During each of the graphic generation steps 98 and 100, there are program calls 82 and 86 from the customization MCL program 32 to execute seven draw procedures 102, 104 ... 114 with the appropriate parameters to produce the desired graphical displays by implementing the seven functions disclosed previously such as: move the graphic cursor to a given location, draw a rectangle, etc.

Thus what has been shown and described is a method and means for generating graphics on a numerical control machine tool display monitor in response to operator request for display of an OEM display page.

While there has been shown and described what is at present considered to be the preferred embodiment of the invention, modifications thereto will readily occur to those skilled in the art. It is not desired, therefore, that the invention be limited to the specific implementations shown and described, but it is intended to cover all such modifications, alterations and changes falling within the spirit and scope of the invention as defined in the appended

Claims (18)

claims. CLAIMS

1. A method of controlling the operation of a computer numerical control (CNC) system for displaying predetermined information relating to the operation of a machining system in the form of graphics, comprising the steps of: a) requesting the display of a raster type of display on operator viewable display apparatus; b) determining values of said predetermined information about to be displayed; c) initially generating a graphic of said predetermined information; and d) periodically updating the generation of said graphic for displaying changing values of said predetermined information.

2. The method of claim 1 wherein said predetermined information comprises maching status information.

3. The method of claim 1 or 2 wherein said raster type of display comprises one of a plurality of display pages generated on a video monitor for displaying machine status information specified by the original equipment manufacturer.

4. The method of claim 1, 2, or 3, wherein said predetermined display page additionally includes message information in alphanumeric form.

5. The method of claim 1 wherein said steps of generating and updating said graphic selectively includes the steps of moving a graphic cursor to a given location, drawing a line, drawing a rectangle, drawing an arc, drawing a circle, filling a predetermined area of said graphic location, and clearing a predetermined area of said graphic location.

6. The method of claim 5 wherein said CNC system includes software implemented numerical control logic (NC) and machine control logic (MCL) sections and wherein said step of requesting said display page comprises requesting an MCL display page of predetermined machine status information.

7. The method of claim 6 wherein said step of requesting an MCL display page further comprises including a call in display control files of the NC section for the generation of graphics, said NC section responding to said call and initiating a call to the MCL section, said MCL section executing one or more routines including calls back to the NC section for producing said graphics.

8. The method of claim 7 wherein said CNC additionally includes a software implemented interface providing a communication link between said NC section and said MCL section and the input output device of said machining system, and wherein said step of making execution calls comprises transmitting said calls through said interface.

9. The method of claim 8 wherein said MCL section includes a software implemented customization section programmable by the original equipment manufacturer and said software execution calls for a graphic display originate from a subprogram package of the customization MCL section.

10. The method of claim 9 wherein said display apparatus comprises a video type monitor including a viewing section and wherein said steps of generating and updating said graphic selectively includes the steps of moving a graphic cursor to a given location on said viewing screen, drawing a line of predetermined length, drawing a rectangle of predetermined size, drawing an arc of predetermined length, drawing a circle of predetermined diameter, filling a predetermined area of said screen, and clearing a predetermined area of said screen.

11. A numerical control system for controlling a machine tool including means for displaying information to an operator and comprising: numerical control logic (NC) software and machine control logic (MCL) software respectively including first and second sets of stored computer programs executable upon demand to control the operation of said system, said first set of programs being operable when called to access and read a display control file, couple signals to said displaying means for providing a display of textual information to the operator, and initiating a call to said second set of programs to generate a graphics display; said second set of programs including a set of subprograms being executed in response to said call to generate calls back to said first set of programs for displaying predetermined information in the form of said graphics display.

12. The system as defined by claim 11 and wherein said second set of programs is partially comprised, at least, of a plurality of subprogram packages which can be customized by an original equipment manufacturer.

13. The system as defined by claim 12 wherein said subprogram packages include a package for calling at least one graphic display in the form of a display page of machine status information.

14. The system as defined by claim 13 wherein said package calling for said graphic display includes a first subprogram for initially calling for the generation of a graphic display and a second subprogram for periodically updating the graphic display initially generated, including the clearing of said graphic displays from a screen.

15. The system as defined by claim 14 wherein both said subprograms include routines for calling the programs of the NC and wherein the programs of the NC include routines for implementing the movement of a graphic cursor, the drawing of a line, the drawing of a rectangle, the drawing of an arc, the drawing of a circle, the filling in of a predetermined area, and the clearing of a predetermined area as well as the entire graphic display.

16. The system as defined by claim 15 and wherein said system additionally includes an interface comprised of third set of stored programs, a plurality of status flags and a set of inputloutput arrays, said interface linking said first and second sets of programs and the machine tool and wherein program calls between said first and second sets of programs are communicated through said interface.

17. A method according to claim 1, substantially as herein described with reference to and as shown in the accompanying drawings.

18. A system according to claim 11, substantially as herein described with reference to and as shown in the accompanying drawings.