CONTROL SYSTEM

Abstract: An interactive data processing unit is set in a place distant from a FA control unit so that the interactive data processing unit can directly access a memory in the FA control unit. When a request for access to a memory (3) in CNC (30) is issued in MMC (20), it is outputted to CNC (30) by a remote access control means (1). When an internal data input/output means (2) in CNC (30) receives the access request, direct memory access (DMA) is made for the memory (3). Depending on the request, data are written in the memory, or the designated data are outputted to MMC (20). The remote access control means (1) in MMC (20) receives the inputted data and transfers the data to the device that is the origin of the request. Thus, the accessing of the memory (3) in CNC (30) can be done directly from MMC (20).

Description: The present invention relates to a control system which consists of an FA control unit and an interactive data processing unit for interactively performing data input/output operations, and more specifically, to a control system which allows an improved access from the interactive data processing unit to a memory in the FA control unit. Numerical control systems are equipped with a numerical controller (CNC) and a man-machine interface controller (MMC) which interactively performs data input/output operations and processes the data. The man-machine interface controller has some peripherals such as input devices (e.g., keyboard and mouse) and a display device (e.g., CRT or liquid crystal display) for this interactive operations. In many cases, the numerical controller and man-machine interface controller are installed in a common cabinet and connected with each other by a parallel bus. Thanks to this parallel bus connection, a high-speed data transfer is provided between the numerical controller and man-machine interface controller. On the other hand, however, it is impossible to locate the man-machine interface controller at a distance from the numerical controller because of difficulty in extending the parallel bus. If there was no such a restriction with the location of the man-machine interface controller, it would be possible to place the man-machine interface controller anywhere the machine operator would feel convenient for efficiency of his/her work. For this reason, there has been a demand that the man-machine interface controller and the numerical controller be connected by a long transmission line. One traditional solution for the above demand is such a system that the buses of the two controllers are connected via an RS-232-C line, which is one of the data communications methods standardized by the Electronic Industry Association (EIA) in the United States of America. According to this system configuration, the man-machine interface controller can be located tens of meters away from the numerical controller, and the both processors can exchange data using a predetermined software protocol. For example, when the man-machine interface controller is about to make access to some memory data in the numerical controller, the man-machine interface controller first outputs a data transfer request to the numerical controller via the RS-232-C interface. Upon reception of the data transfer request, the numerical controller parses the request and sends the requested data in its memory back to the man-machine interface controller, thereby allowing the man-machine interface controller to get its desired data. The above-described connection by the RS-232-C interface, however, always takes two steps as follows, when the man-machine interface controller tries to read memory data in the numerical controller. That is, the man-machine interface controller should first issue a data transfer request, and then the processor in the numerical controller must support actual data transfer operations. In other words, the man-machine interface controller cannot directly make access to the memory within the numerical controller. As a result, the man-machine interface controller in need to have some data in the numerical controller should wait for the numerical controller sending the data, thus spending much time to obtain the data. Also, the processor in the numerical controller should take care of the data transfer for the man-machine interface controller in addition to its regular duty, namely, numerical control. And this extra burden of the processor could degrade its processing performance in various areas. As described above, when the man-machine interface controller and the numerical controller are set apart from each other, the conventional numerical control system slows down in its data processing operations due to a lack of direct access capability from the man-machine interface controller to the numerical controller's memory. JP 59144901A discloses a device for generating an emergency stop signal in a robot. EP-A-0380684 discloses a system for remotely diagnosing CNC to diagnose any trouble at a distance. Taking the above into consideration, an object of the present invention is to provide a control system where an interactive data processing unit located away from an FA control unit can make a direct access to a memory in the FA control unit. US-A-3882305 discloses a control system which consists of an FA control unit having a processor and an interactive data processing unit for interactively performing data input/output operations, the control system comprising: remote access control means, provided in said interactive data processing unit, for transmitting an access request to a transmission line and receiving data coming via said transmission line, wherein the access request requests an access to an arbitrary address of a memory in said FA control unit; and internal data input/output means provided in said FA control unit, for making access to said memory in response to the access request inputted via said transmission line, writing write-data supplied thereto into said memory, and transmitting read-data read out from the memory to said transmission line. According to the present invention, a control system of this type is characterised in that direct access is made to the arbitrary address of the memory in said FA control unit based on an access request from said remote access control means without intervention by the processor in the FA control unit. The remote access control means is provided in the interactive data processing unit and transmits an access request to a transmission line and receives data arrived therein via the transmission line. This access request is a request of access to arbitrary address of a memory in the FA control unit. The internal data input/output means is provided in the FA control unit and makes a direct access to write or read the memory in response to the access request inputted via the transmission line. It writes the given write-data into the memory when the access is a write-request, while it transmits the read-data to the transmission line when the access request is a read-request. In this way the interactive data processing unit can make access directly to the memory in the FA control unit without any intervention by the processor in the FA control unit. Brief Description of the Drawings FIG. 1 is a block diagram showing a conceptual view of the present invention; FIG. 2 is a total schematic diagram showing a numerical control system according to the present invention; FIG. 3 is a block diagram showing the structure of a numerical control system according to the present invention; FIG. 4 is a circuit diagram of an I/O interface in the MMC; FIG. 5 is a flowchart showing a process of the MMC for sending an access request; FIG. 6 is a flowchart showing a process of the CNC from reception of the access request to delivery of the requested data to the MMC; and FIG. 7 is a flowchart showing a process of the MMC from reception of the data to transfer of the data to the MMC processor. Best Mode for Carrying Out the Invention An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a conceptual view of the present invention. FIG. 1 shows that a man-machine interface controller (MMC) 20 and a numerical controller (CNC) 30 are interconnected by a transmission line 40. When an access request to a memory 3 in the CNC 30 is issued by a certain device in the MMC 20, remote access control means 1 outputs the access request to the CNC 30. In case that it is a write-request, the access request contains write-data and address information to indicate where in the memory 3 the data should be written into. In case of a read-request, the access request contains address information to indicate where in the memory 3 should be read out. Upon reception of such an access request, an internal data input/output means 2 in the CNC 30 makes access to the requested address by performing a direct memory access (DMA) to the memory 3 without any help of the processor in the CNC 30. It writes the data to the memory when the access request is a write-request. On the other hand, when the access request is a read-request, the internal data input/output means 2 outputs the requested data to the MMC 20, and the remote access control means 1 in the MMC 20 receives the data and forwards it to the device which issued the access request. In the way described above, the MMC 20 directly makes access to the memory 3 without any intermediate process by the processor in the CNC 30. FIG. 2 is a total schematic diagram showing a numerical control system according to the present invention. This numerical control system is roughly divided into three constituents: a machine tool 10, a numerical controller 30 integrated in the machine tool 10, and an MMC 20 for remote operations. The machine tool 10 is equipped with a sliding column 11 on its one side. A spindle motor of the machine tool 10 rotates a tool 13 grasped by a chuck 12 and a Z-axis servo motor slides the tool 13 up and down (in Z-axis direction). A table 14 can slide back and forth (in X-axis direction) and also from side to side (in Y-axis direction). A workpiece 15 is mounted on this table 14 for machining. The machine tool 10 and the table 14 are both mounted on a base 16. The operator gives operation commands to the numerical controller 30 via the MMC 20, which is remotely located from the machine tool 10. This MMC 20 has a keyboard 23, a display unit 22, and a floppy disk drive 21, which are controlled by a processor integrated therein. The keyboard 23 is composed of cursor keys, geometrical-element keys, numeric keys and the like, which are used for entering necessary geometry data, machining data, etc. Software for generating part programs can be installed via the floppy disk drive 21. The display unit 22, which is actually a CRT or a liquid crystal display, shows part geometries, machining conditions and the like when the operator interactively creates a part program. The part program finally generated in the MMC 20 will be transferred to the numerical controller 30. In addition to the above, when it become necessary to have some data in the numerical controller 30, the MMC 20 can get the data by making a direct access to the memory in the numerical controller 30. The above-described structural arrangement allows the operator to create a part program with the MMC 20 and transfer it to the numerical controller 30. It also allows the numerical controller 30 to perform the desired machining operations, making the tool 13 engaged with the workpiece 15 by controlling the sliding column 11 and table 14 of the machine tool 10. FIG. 3 is a block diagram showing the structure of the numerical control system according to the present invention. This figure can be roughly divided into two parts, namely, the MMC 20 and the CNC 30. While a processor 31 controls various devices on a bus 35 in the CNC 30, a processor 24 controls various devices on a bus 29 in the MMC 20. The MMC 20 and the CNC 30 are interconnected by a transmission line 40, which serves as a medium of data communications. Note that the bus 35 in the CNC 30 is a multi-master bus which permits some devices other than the processor 31 to become a bus master. The CNC 30 is under the total control of the processor 31. A RAM 32 stores various data or I/O signals. A non-volatile memory 33 is organized by some CMOS memory devices backed up by batteries, where system parameters, pitch error compensation data, tool offset data and the like are retained even after the main power is lost. Axis control circuits 36 receive axis motion commands from the processor 31 and output the commands to servo amplifiers 37. The servo amplifiers 37, in response to those motion commands, drive servo motors integrated in the machine tool 10. A programmable machine controller (PMC) 38 receives control signals such as T-function (Tool selection command) signals at the time of execution of the part programs. The PMC 38 processes those control signals according to its sequence program and produces operation command signals, thereby controlling the machine tool 10. The PMC 38 also receives status signals from the machine tool 10 and provides input signals to the processor 31 after processing them with the sequence program. Further, an I/O interface 34 on the bus 35 is in charge of data communication with the MMC 20. In response to an access request from the MMC 20 targeting the RAM 32, the I/O interface 34 makes a direct memory access (DMA) to read or write data in the RAM 32. When the access request is a read-request, the I/O interface 34 sends the read data to the MMC 20. On the other hand, when the access request is a write-request, it writes the arrived data into the RAM 32. The I/O interface 34 also performs data conversion from parallel to serial when outputting data on the bus 35 to the MMC 20, and from serial to parallel when receiving the inbound signals from the MMC 20. The MMC 20 executes interactive processing programs invoking some interactive data input screens, where the operator can set various machining operations and data using a menu provided therein. The processor 24 displays such menu-style input screens on a display unit 22 via a graphics control circuit 22a, and according to the data thereby entered, it generates part programs as well as displaying total tool paths in a background animation. Various data required for this interactive processing are stored in a RAM 25. Composed of battery-backed CMOS memory devices, a non-volatile memory 26 is provided for storing application programs, part programs and the like which must be retained even when the main power is removed. A video RAM (VRAM) 27 works as a high-speed RAM to store graphics data for animation which will simulate a machining process of the machine tool 10 according to the part programs which have been compiled as NC program statements and stored in the non-volatile memory 26. The graphics control circuit 22a converts the graphics data in the VRAM 27 into video signals and outputs them to the display unit 22. For data exchange purposes such as loading software or saving various data, there is provided a floppy disk drive 21 with an FDD interface 21a to read and write floppy disks. The graphics control circuit 22a converts digital information produced by the processor 24 and the like into the video signals and provides them to the display unit 22. CRT or liquid crystal display is a suitable device for the display unit 22. A keyboard interface 23a supports data transfer control between the keyboard 23 and the processor 24. The keyboard 23 consists of symbol keys, numeric keys and the like for entering geometry data and NC data necessary for the machine operations. The I/O interface 28, in response to an access request from a certain device in the MMC 20 targeting the RAM 32 in the CNC 30, converts the parallel access request into serial signals and sends them to the CNC 30. It also receives the serial signals sent from the CNC 30 converting them into parallel signals. The transmission line 40, which connects between the I/O interface 28 in the MMC 20 and the I/O interface 34 in the CNC 30, can be 20 to 50 meters long as well as allowing a high-speed data transmission at about 25 Mbps. FIG. 4 is a circuit diagram of the I/O interface 28 in the MMC. The access request signal which has reached the I/O interface 28 via the bus 29 is accepted by a parallel bus interface 281. When the access request is a read-request, its signal is applied to a selector 283. When it is a write request, the data is written into a write buffer 282, which can store a plurality of data and outputs the data in the first-in-first-out manner. The output of the write buffer 282 is supplied to the selector 283. The selector 283 receives a read-request or a write-request and then simply outputs the access request to the next stage. When it has received both requests at a time, the selector 283 will output the read-request before the write-request. A parallel-to-serial converter (P/S) 284 converts the parallel input signal to the serial output signal. A driver 285 amplifies this output signal for sending it to the CNC 30. On the other hand, an incoming signal from the CNC 30 is supplied to the serial-to-parallel converter (S/P) 287 via a receiver 288, where the signal is converted from serial to parallel. After passing through an error check circuit 286 for inspection of its data integrity, the parallel output signal reaches the parallel bus interface 281, which outputs the signal to the bus 29. The following will explain a procedure of the MMC processor to make access to the CNC's RAM in the above-described numerical control system. For ease of explanation, the procedure is divided into the following three processes: a transmission process of an access request from the MMC to the CNC, a process of the CNC from reception of the access request to delivery of the requested data to the MMC, and a process of the MMC from reception of the data to transmission of the data to MMC processor. FIG. 5 is a flowchart showing the process of the MMC to transmit an access request. Note that it is the remote access control means 1 previously described in FIG. 1 that performs the detailed process steps shown in this flowchart. [S1] The remote access control means 1 accepts an access request which has come from the processor via the bus 29 requesting an access to the RAM 32 in the CNC (see FIG. 3). [S2] It is determined whether the access request is a read-request or not. If it is, the procedure goes to step S6. Otherwise, the access request is taken as a write-request and the procedure goes to step S3 for data writing. [S3] The write-data is stored into the write buffer. [S4] It is checked whether any read-request is available or not. If it is available, the procedure repeats step S4. If there is no read-request, the procedure proceeds to step S5. Since the MMC processor has nothing to do but wait until the data becomes ready to read after sending the read-request, it is desirable to fetch the data as quickly as possible. This is the reason why the read-request is given priority over the write-request. [S5] The remote access control means 1 outputs the write-data in the buffer together with the access request (i.e., the write-request). [S6] The access request signals, which contain the write-data in case of a write-request, are converted from parallel to serial. [S7] The remote access control means 1 sends out the access request to the CNC. (The procedure continues toward "A" in FIG. 6.) The access request produced by the processor in the MMC is thereby transmitted to the CNC.FIG. 6 is a flowchart showing the process of the CNC from reception of the access request to delivery of the requested data to the MMC. Note that it is the internal data input/output means 2 previously described in FIG. 1 that performs the detailed process steps shown in this flowchart. [S8] The internal data input/output means 2 accepts the access request transferred from the MMC. [S9] The access request signals are converted from serial to parallel. [S10] It is determined whether the access request is a read-request or not. If it is, the procedure goes to step S12. Otherwise, the procedure goes to step S11. [S11] The data contained in the access request is written into the RAM and the procedure is terminated here. Note that the access to the RAM is performed by means of DMA without intervention of the CNC processor. [S12] The internal data input/output means 2 reads out the data from the RAM specified by the access request. This access to the RAM is also performed by DMA. [S13] The output data signals are converted from parallel to serial. [S14] The internal data input/output means 2 transmits the output data to the MMC. (The procedure continues toward "B" in FIG. 7.) In the way described above, the internal data input/output means 2 directly writes data when the access request is a write-request. When it is a read-request, the internal data input/output means 2 directly fetches the data and transfers it to the MMC.FIG. 7 is a flowchart showing a process of the MMC from reception of the data to transmission of the data to MMC processor. It is the remote access control means 1 previously described in FIG. 1 that performs the detailed process steps shown in this flowchart. [S15] The remote access control means 1 accepts the data transferred from the CNC. [S16] The data signals are converted from serial to parallel. [S17] Through the error check, it is inspected whether the data has been destroyed or not during transmission. If any error is found, the procedure goes to step S18, and if not, to step S19. [S18] The remote access control means 1 resends the access request and the procedure goes back to step S2. [S19] The remote access control means 1 transfers the data to the processor in the MMC. (The procedure goes to "A" in FIG. 5.) That concludes the whole procedure for the access request issued by the MMC processor to make access to the RAM in the CNC. As described above, the access request sent from the MMC to the CNC is handled by the internal data input/output means 2 which makes a direct access to the memory without intervention of the processor in the CNC. Thanks to this configuration, the processor in the MMC can have access directly to the CNC in the same way as access to the memory of its own. Besides allowing a high-speed access from the MMC to the CNC, the present invention avoids any extra task of the CNC processor regarding the access, which results in a great throughput of the total numerical control system. In addition to the above, since the present invention connect between the MMC and CNC with a high-speed data communications system whose transmission line is so extendible, the MMC can be located at a distance from the CNC, thereby enabling the operator to check some data on the display screen or operate the keyboard in any place convenient for his/her work. Further, in addition to the aforementioned floppy disk drive, other peripheral devices such as a printer can be connected to the MMC. The present invention makes it possible to set those devices necessary for the operator at a convenient place for his/her work. Incidentally, the above-described embodiment has shown a numerical controller for an example of the FA controllers, however, it is possible to apply the present invention to other controllers if they have a multi-master bus. A robot controller, for example, is included in such FA controllers, and in this application, the operator can carry out his/her task outside the working area of the robot, thereby keeping the operator's safety. As for the interactive data processing unit, the above description exemplified an MMC, however, it is also possible to apply the present invention to any unit having a processor. Thus, a general-purpose personal computer, for example, can serve as the interactive data processing unit, and in that case, it is possible to use a variety of peripheral units (e.g., a hard disk drive and printer) for personal computers at a distance from the FA control unit. The interactive data processing unit includes a teaching pendant for robot. This teaching pendant is used for on-line programming of the robot motion by manually operating the robot. By applying the present invention to the teaching pendant, the operator can manipulate the robot from a distance. For further variations, if both the FA control unit and interactive data processing unit are equipped with the remote access control means and internal data input/output means, the FA control unit will be able to make a direct access to the memory in the interactive data processing unit. The above long discussion will be summarized as follows. According to the present invention, the remote access control means performs a long-distance transfer of the access request from the interactive data processing unit to the memory within the FA control unit, and the internal data input/output means in the FA control unit makes a direct access to the memory. Thanks to this configuration the interactive data processing unit, even if it is placed away from the FA control unit, can have access directly to the memory within the FA control unit at a high speed in spite of the long distance.

Claims: A control system which consists of an FA control unit (30) having a processor (31) and an interactive data processing unit (20) for interactively performing data input/output operations, the control system comprising: remote access control means (1), provided in said interactive data processing unit, for transmitting an access request to a transmission line (40) and receiving data coming via said transmission line, wherein the access request requests an access to an arbitrary address of a memory (3) in said FA control unit; and internal data input/output means (2) provided in said FA control unit, for making access to said memory in response to the access request inputted via said transmission line, writing write-data supplied thereto into said memory, and transmitting read-data read out from the memory to said transmission line; characterised in that direct access is made to the arbitrary address of the memory (3) in said FA control unit (30) based on an access request from said remote access control means (1) without intervention by the processor (31) in the FA control unit. A control system according to claim 1, further comprising parallel/serial converting means (284) providing at both ends of said transmission line (40), for converting an outgoing signal from parallel to serial and converting an incoming signal from serial to parallel. A control system according to claim 1, further comprising: further remote access control means (1), provided in said FA control unit (30), for transmitting an FA access request to said transmission line (40) and receiving data coming via said transmission line, wherein the FA access request requests an access to an arbitrary address of a further memory (3) in said interactive data processing unit; and further internal data input/output means (2), provided in said interactive data processing unit (20), for making a direct access to said further memory in said interactive data processing unit in response to the FA access request inputted via said transmission line, writing further write-data supplied thereto into said further memory, and transmitting further read-data read out from said further memory to said transmission line. A control system according to claim 1, wherein said FA control unit (30) is a numerical controller. A control system according to claim 1, wherein said FA control unit (30) is a robot controller. A control system according to claim 1, wherein said interactive data processing unit (20) is a man-machine interface controller. A control system according to claim 1, wherein said interactive data processing unit (20) is a personal computer. A control system according to claim 1, wherein said memory (3) is a random access memory (RAM). A control system according to claim 1, wherein said interactive data processing unit (20) is a teaching pendant for robot.

Inventors: KINOSHITA JIRO, KUBO Y, KINOSHITA,JIRO, KUBO, Y., KINOSHITA,Jiro, Fanuc Mansion Harimomi 6-210, KUBO, Y., Fanuc Mansion Harimomi 11-602
Applicants: FANUC LTD, FANUC LTD.
Application year: 1995
Main classification: G05B19
IPC codes: G05B19, B25J13, B25J9