Abstract:
A method of acquiring status information of I/O units connected to a numerical controller capable of transmitting status information indicative of particulars of an abnormality occurred in any of the I/O units with less influence on an amount of transmittable information of input/output data. When an abnormality has occurred in the I/O unit, the I/O unit transmits an output signal with a status abnormality notifying bit set to a programmable controller (PC) in the numerical controller. The PC stores information indicative of I/O units in which the status abnormality has occurred as status-abnormality acquiring I/O unit information, in a storage device of the PC. The PC requests the status information to the I/O unit in which the abnormality has occurred according to the status-abnormality acquiring I/O unit information. In response to the request, the I/O unit transmits the status information to the PC.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a method of acquiring status information of external-signal input/output units (hereinafter referred to as I/O units) connected to a numerical controller for controlling a machine tool. In particular, the present invention relates to a method of acquiring status information indicative of abnormalities occurred in the I/O units connected to a programmable controller (PC) provided in the numerical controller. 
         [0003]    2. Description of Related Art 
         [0004]    In order to input/output information between a numerical controller and auxiliary devices of a machine tool, a plurality of I/O units are dependently connected to the numerical controller (see JP11-231923A and JP6-138916A). Usually, input information (i.e. DI data) and output information (i.e. DO data) are transmitted between the numerical controller and the I/O units. Collection of status information as internal information of the I/O units (e.g. an alarm for overheat protection of a DO driver built in the I/O unit) is performed by the numerical controller. 
         [0005]    Conventionally, the status information of the I/O units connected to the numerical controller is transmitted by using an area of the same frame, i.e. a part of the DI data, and therefore there is a problem that an amount of transmittable DI data is decreased by the status information data (see  FIG. 17 ). An alarm procedure such as determining whether the status information included in the DI data is to be used or not and displaying the occurrence of alarm on a display device is dependent on a program (ladder program) prepared by a user. Further, since it is necessary to search the status information of the I/O units by analyzing every DI data, it takes a considerable time to recognize the occurrence of abnormality in the I/O units. Also, there is a problem of increasing a total amount of transmission of the information if the status information is acquired from all of the I/O units. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a method of acquiring status information indicative of abnormality occurred in I/O units without decreasing an amount of transmittable formation of DI and DO data and without greatly increasing a total amount of the transmission due to the status information and without dependence on a user program. 
         [0007]    A method of the present invention acquires status information of I/O units connected to a numerical controller for transmitting input/output information from/to the numerical controller. The method comprises the steps of: storing particulars of an abnormality occurred in any of the I/O units as status information within the I/O unit in which the abnormality has occurred; transmitting a notification of occurrence of the abnormality and information indicative of the I/O unit in which the abnormality has occurred from the I/O unit to the numerical controller; storing the information indicative of the I/O unit in which the abnormality has occurred in the numerical controller; transmitting a request for the status information from the numerical controller to the I/O unit in which the abnormality has occurred; transmitting the status information stored in the I/O unit in which the abnormality has occurred to the numerical controller in response to the request for the status information; and storing the transmitted status information of the I/O unit in the numerical controller. 
         [0008]    The status information may be transmitted with the input information from the I/O unit to the numerical controller as being added to the input information. 
         [0009]    The status information may be transmitted from the I/O unit to the numerical controller as packet information separate from the input/output information. 
         [0010]    The method may further comprise a step of displaying the transmitted status information on a display device of the numerical controller. 
         [0011]    The status information may be acquired from a plurality of I/O units dependently connected to the numerical controller. 
         [0012]    With the above arrangement, the status information of the I/O unit can be acquired without dependence on the user program since the status information is transmitted using an area separate from the DI data in the input signal to be processed independently from the DI data. 
         [0013]    By performing the acquisition of the status information from one I/O unit in one scanning cycle of transmission of the DO/DI data to/from the I/O units, the status information of the I/O units can be acquired without compressing a communication band. 
         [0014]    In a case where abnormalities have occurred in a plurality of I/O units, the status information is acquired in the order of occurrence of the abnormalities registered in storage means to acquire the status information form all of the I/O units in which the abnormalities have occurred. 
         [0015]    By transmitting the status information as packet information separate from the DI data, the status information can be acquired independently of the transmission of the DI data. 
         [0016]    It can be specified in which I/O unit an abnormality has occurred and with which input/output signal the occurrence of an abnormality of the I/O unit is notified by the PC according to the software for the PC, to shorten the time required for investigating a cause of the abnormality in the I/O units. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]      FIG. 1  is a schematic diagram of a numerical controller and I/O units dependently connected to the numerical controller according to an embodiment of the present invention; 
           [0018]      FIG. 2  is a schematic diagram showing an example of notifying a status abnormality in I/O unit to the numerical controller; 
           [0019]      FIG. 3  is a schematic diagram showing an example of requesting status information to the I/O unit; 
           [0020]      FIGS. 4   a - 4   c  are schematic diagrams showing an example of transmitting the status information from the I/O unit to the numerical controller; 
           [0021]      FIG. 5  is a schematic diagram showing an example of occurrence of abnormality in a plurality of I/O units # 2  and # 4 ; 
           [0022]      FIG. 6  is a schematic diagram showing an example of notifying status abnormalities from I/O units # 2  and # 4  to the numerical controller; 
           [0023]      FIG. 7  is a schematic diagram showing an example of storing the status abnormality notifications in the numerical controller; 
           [0024]      FIG. 8  is a schematic diagram showing an example of requesting the status information from the numerical controller to the I/O unit # 2 ; 
           [0025]      FIG. 9  is a schematic diagram showing an example of transmitting the status information from the I/O unit # 2  to the numerical controller; 
           [0026]      FIG. 10  is a schematic diagram showing an example of requesting the status information from the numerical controller to the I/O unit # 4 ; 
           [0027]      FIG. 11  is a schematic diagram showing an example of transmitting the status information from the I/O unit # 4  to the numerical controller; 
           [0028]      FIG. 12  is a schematic diagram showing an example of sending a status information requesting command to the I/O unit # 2 ; 
           [0029]      FIG. 13  is a schematic diagram showing an example of transmitting the status information of the I/O unit # 2  by a separate packet; 
           [0030]      FIG. 14  is a schematic diagram showing an example of a numerical control system in which a plurality of I/O units are dependently connected to a through a communication control device and a communication line; 
           [0031]      FIG. 15  is a flowchart of processing for acquiring status information from one I/O unit; 
           [0032]      FIG. 16  is a flowchart of processing for acquiring status information from a plurality of I/O units; and 
           [0033]      FIG. 17  is a schematic diagram showing an example of prior art in which the status information and the DI data are transmitted in the same frame. 
       
    
    
     DETAILED DESCRIPTION 
       [0034]      FIG. 1  shows a system configuration of a computerized numerical controller (CNC)  6 . The numerical controller  6  is provided with a PC (programmable controller)  7  which is connected to I/O units  1 - 5  via an I/O control circuit  11  and a communication line  24 . The I/O units  1 - 5  are dependently connected to the PC  7  by the communication line  24 . The PC  7  functions as a master device and the I/O units  1 - 5  functions as slave devices. An input signal  27  from any of the I/O units  1 - 5  to the PC  7  comprises frames of a HEAD section, a DI data section, an ALM (alarm) section and a CRC (cycle redundancy check) section. The HEAD section stores information identifying the I/O unit from which the input signal  27  is being sent and a size of sending data, etc., the DI section stores input information operating machine tool such as turning on/off switch, the ALM section stores alarm information such as an alarm of communication error and an error in a parity check of RAM, and the CRC section stores information indicative of irregularity of data of the input signal  27  due to noises, etc. The ALM section as shown in  FIG. 1  consists of eight bits. In order to notify the numerical controller  6  of an occurrence of abnormality, such as alarm for overheat protection of the DO driver, in any of the I/O units  1 - 5  as status abnormality information, a third bit  26  of the ALM section is used as a status abnormality notifying bit. When an abnormality occurs in the I/O unit, a necessary procedure is performed for preventing a secondary damage in the I/O unit. For instance, in a case where a ground fault occurs at an output of the DO driver, an overheat protection function of the DO driver is performed to turn off an output of the DO driver in the I/O unit. 
         [0035]      FIG. 2  shows an example of transmitting status abnormality information indicative of an abnormality occurred in the I/O unit # 2  to the PC  7 . As shown in  FIG. 2 , when an abnormality occurred in the I/O unit # 2 , the I/O unit # 2  sets the status abnormality notifying bit in the ALM section of an input signal  28  and sends the input signal  28  to the PC  7 . The ALM section as shown in  FIG. 2  has eight bits in which the third bit is utilized as the status abnormality notifying bit. The use of the third bit as the status abnormality notifying bit is merely an example and another appropriate bit in the ALM section may be used as the status abnormality notifying bit. Upon receipt of the input signal  28  having the ALM section with the status abnormality notifying bit set, the PC  7  specifies the I/O unit # 2  in which an abnormality has occurred based on the information in HEAD section of the input signal  28 , and stores the information, e.g. slave number 2, indicative of the I/O unit in which the abnormality has occurred as status-information acquiring I/O unit information in the RAM  10 . The status-information acquiring I/O unit information may be stored other than in the RAM  10 , but in a register provided in the I/O control circuit  11  shown in  FIG. 1 . 
         [0036]      FIG. 3  shows an example of transmitting a status information request from the PC  7  to the I/O unit # 2  in which an abnormality has occurred. When the PC  7  transmits an output signal  29  to the I/O unit # 2  that is determined as the I/O unit from which the status abnormality notification has been transmitted based on the status-information acquiring I/O unit information, the PC  7  transmits an output signal  29  with the status information requesting bit set. In the example shown in  FIG. 3 , a sixth bit of the HEAD is used as the status information requesting bit. 
         [0037]      FIG. 4   a  shows an example of transmitting the status information from the I/O unit # 2  to the PC  7 . When the I/O unit # 2  receives the output signal  29  having the HEAD section with the status information requesting bit set, the I/O unit # 2  sets a status information transmitting bit in the HEAD section of an input signal  30 , and sends the input signal  30  with the status information added next to the DI data. In the example shown in  FIG. 4   a , the fifth bit of the HEAD section is used as the status information transmitting bit. As shown in  FIG. 4   b , in a state where no abnormality occurred in the I/O unit, the input signal from the I/O unit to the PC  7  consists of a series of frames “HEAD”, “DI data”, “ALM” and “CRC”. 
         [0038]    The output signal from the PC  7  to the I/O unit consists of a series of frames “HEAD”. “DO data”, “ALM” and “CRC”. 
         [0039]      FIG. 4   c  shows an input signal from the I/O unit with the status information added next to the DI data when the status information is required in the case where the abnormality occurred in the I/O unit. In transmitting the status information from the I/O unit to the PC  7 , the status information is added to the input signal after the DI data to consist of a series of five frames. Thus, the status information is requested to only the I/O unit in which an abnormality has occurred, and the status information is acquired from the I/O unit in which the abnormality has occurred, so that the status information is acquired without decreasing communication area in the input signal 
         [0040]      FIG. 5  shows a case where abnormalities have occurred in a plurality of I/O units of # 2  and # 4 . 
         [0041]      FIG. 6  shows that the input signals  31 ,  32  with the status abnormality notifying bit set in the respective ALM frames are transmitted from the I/O units # 2  and # 4  to the PC  7  when abnormalities have occurred in the I/O unit # 2  and the I/O unit # 4 . The HEAD frames of the input signals  31  and  32  store information identifying where the input signals  31  and  32  are being transmitted from. 
         [0042]      FIG. 7  shows that the information specifying the I/O units # 2  and # 4  in which abnormalities have occurred is stored in the PC  7 . When the PC  7  receives the input signals  31 ,  32  having ALM frames with the status abnormality notifying bits set, the PC  7  specifies the I/O unit # 2  and the I/O unit # 4  based on the information in the HEAD frames of the input signals  31 ,  32 , respectively, and stores information indicative of the I/O units in which the abnormalities have occurred, in the RAM  10  of the PC  7  as the status-information acquiring I/O unit information. 
         [0043]      FIG. 8  shows an example of transmitting status information requests from the PC  7  to the I/O unit # 2  in the case where abnormalities have occurred in the plurality of I/O units # 2  and # 4 . When the PC  7  is to send an output signal  33  to the I/O unit # 2  from which the status abnormality notification has been transmitted, the PC  7  sends the output signal  33  with the status information requesting bit set in the HEAD frame of the output signal  33  according to the status-information acquiring I/O unit information. 
         [0044]      FIG. 9  shows an example of transmitting the status information from the I/O unit # 2  to the PC  7  in the case where abnormalities have occurred in the I/O units # 2  and # 4 . When the I/O unit # 2  receives the output signal  33  having the HEAD frame with the status information requesting bit set, the I/O unit # 2  sets the status information notifying bit in the HEAD frame of an input signal  34  and transmits an input signal  34  with the status information added next to the DI data. Then, the status information from the I/O unit # 2  is stored in the RAM  10  of the PC  7 . 
         [0045]      FIG. 10  shows an example of transmitting the status information request from the PC  7  to the I/O unit # 4  in the case where abnormalities have occurred in the I/O units # 2  and # 4 . When the PC  7  is to send an output signal  35  to the I/O unit # 4  from which the status abnormality notification has been transmitted, the PC  7  sends the output signal  35  with the status information requesting bit set in the HEAD frame of the output signal  35  in accordance with the stored status-information acquiring I/O unit information. 
         [0046]      FIG. 11  shows an example of transmitting the status information from the I/O unit # 4  to the PC  7 . When the I/O unit # 4  receives the output signal  35  having the HEAD frame with the status information requesting bit set, the I/O unit # 4  sets the status information notifying bit in the HEAD frame of an input signal  36  and sends the input signal  36  with the status information added next to the DI data. Then, the status information from the I/O unit # 4  is stored in the RAM  10  of the PC  7 . The processing is successively performed for all of the I/O units which are specified to be the I/O unit in which the abnormality have occurred based on the status-information acquiring I/O unit information. 
         [0047]      FIGS. 12 and 13  show an embodiment in which status information is transmitted by a separate packet. When an abnormality occurs in any of the I/O units, the occurrence of abnormality is notified to the PC  7  using the status abnormality notifying bit, and the status-information acquiring I/O unit information is stored in the RAM  10  in the same manner as the above embodiments. The procedure of transmission of the DI data and the DO data for each of the I/O units is completed in one scanning cycle, the PC  7  sends a status information request command to each of the I/O units specified by the status-information acquiring I/O unit information (e.g. slave numbers) stored in the RAM  10 , independently and separately from the transmission of the DI data and the DO data. The I/O unit which receives the status information request command, transmits the status information to the PC  7 . Since the status information request command and the status information of the I/O unit are transmitted independently from the transmission of the DI data and the DO data which are regularly performed each scanning cycle, the request and collection of the status information of the I/O units are performed giving priority to the transmission of the DI data and the DO data. 
         [0048]      FIG. 14  shows an example of system configuration in which a PC  7  is provided in a numerical controller  6  and a plurality of I/O units are connected to the PC  7  through a communication controller  39  and a communication line  24 . The communication controller  39  connected to the PC  7  reduces a load of the CPU  8  in the PC  7  and prevents lowering of performance of numerical control of the numerical controller  6 . 
         [0049]      FIG. 15  is a flow diagram of processing for acquiring the status information of one I/O unit, and  FIG. 16  is a flow diagram of acquiring the status information from the plurality of I/O units.