JP2013229705A - Failure part detection method of ring network in electric injection molding machine - Google Patents

Abstract

In a motor-driven injection molding machine that controls a servo motor and a PWM converter by a ring network, a failure location detection method is provided that can easily estimate a failure location when the network fails.
[Solution]
The controller (5) of the electric injection molding machine (1) is the master station (C), the servo motors (m1, m2,...), And the drive board that controls the PWM converter (2) is the slave station (c1, c2,...). These are connected by a ring network (4) in which packets flow only in one direction. When each slave station (c1, c2,...) Does not receive a packet exceeding a predetermined threshold time, the slave station (c1, c2,...) Waits for a predetermined waiting time set in advance and sends an abnormality occurrence notification packet with its own station ID. Send. The master station (C) estimates the failure location from the received abnormality notification packet.
[Selection] Figure 1

Description

  The present invention is a ring type in which a communication module provided in a controller is a master station, a communication module provided in each of a drive board that controls a servo motor and a PWM converter is a slave station, and packets flow only in one direction. In an electric injection molding machine in which a master station and a slave station are connected by a network, and a servo motor and a PWM converter are controlled by a command from a controller, the present invention relates to a fault location detection method for detecting a fault location in a network. is there.

  The electric injection molding machine includes a mold clamping device, an injection device, an ejector device, and the like, and each of these devices is provided with one or a plurality of servo motors. The electric injection molding machine is supplied with electric power of a three-phase AC voltage, which is converted into a DC voltage by a PWM converter and supplied to each servo amplifier to drive each servo motor. The PWM converter and each servo motor are each provided with a drive board and are controlled by the drive board, and these drive boards are provided with a communication module. A communication module is also provided in the controller of the electric injection molding machine, and each communication module is network-connected. Therefore, each drive board can be controlled by a command from the controller, the PWM converter can be controlled to convert it into a stable desired DC voltage, and the servo motor can be controlled to drive each device. In an apparatus having an inertia member such as a movable platen, kinetic energy is also regenerated into electric power energy when the inertia member is decelerated. That is, a direct current is taken out by the servo motor, and the PWM converter is controlled as necessary to return to a three-phase alternating voltage. Also in this case, the servo amplifier and the PWM converter are controlled in accordance with a command from the controller to each drive board.

  A network having various topologies can be adopted as a network connecting the controller and each communication module of each drive board. For example, a bus type or a star type can be adopted. In a typical form, a bus network is a network connected by a communication line composed of one trunk line and a plurality of branch lines branched from the trunk line. Each node, that is, each communication module is connected to each branch line. Yes. A star network is a network in which communication lines are connected radially to each node from a hub device. In addition, various systems can be adopted as communication systems implemented in these networks. For example, a CSMA / CD system, a token passing system, and the like can be considered. The CSMA / CD method is a method in which each node transmits a packet at an arbitrary timing. In the token passing method, a token circulates on the network, and only the node that captures this token obtains the transmission right and transmits the packet. Is a method for transmitting. The network topology such as the bus type and the star type is excellent, and the communication method such as the CSMA / CD method and the token passing method is also excellent. However, in the bus type, the communication equipment becomes expensive, and in the star type, the communication is concentrated on the hub device and becomes a bottleneck in reliability. An inexpensive, simple and highly reliable network topology is preferable for communication of servo motor and PWM converter drive boards, but a bus type or star type network is not necessarily an optimal network topology. Also, in the communication system, in the CSMA / CD system, when a so-called collision occurs in which the transmission timing overlaps with other nodes, it becomes temporarily impossible to transmit, and in the token passing system, any node temporarily communicates when the token is lost. There is a drawback that can not be. Servo motors and PWM converters are required to have high responsiveness and need to be controlled in real time, so a communication system that does not cause a delay is required.

  Therefore, the present applicant adopts a ring network for communication between the controller in the electric injection molding machine and the drive board for controlling the servo motor and the PWM converter, and the communication method is the original method described in Patent Document 1. Adopted. More specifically, the ring network has a network topology in which adjacent nodes are connected by communication lines and are connected in a ring shape so as to form a ring shape or a loop shape as a whole. Then, since the communication packet is always transmitted only to the adjacent node, it is not necessary to consider a collision or the like, and a network can be constructed with an inexpensive device. Moreover, the communication system described in Patent Document 1 is as follows. That is, between adjacent nodes, packets are always transmitted from one node to the other, and the packet transmission direction is unidirectional in the entire ring network. The communication module of the controller serves as a master station, and all the communication modules of each drive board communicate as slave stations. The packet sent from the master station toward the first slave station which is the adjacent drive board is a packet including instructions for all other slave stations. When such a packet is received by the first slave station, the first slave station reads only the command addressed to itself and stores it in the memory inside the drive board, and responds to the master station with the command portion addressed to itself. The message is overwritten with the above message, and the packet to the other slave station is left as it is, and the packet is transmitted to the next drive board, that is, the second slave station. In the same manner, the m-th slave station reads only the command addressed to itself from the received packet, saves it in the memory inside the drive board, overwrites the command part with the response message for the master station, The instruction to the slave station and the message addressed to the master station from other slave stations are left as they are and sent to the next (m + 1) th slave station. Finally, the master station receives a packet including responses from all the slave stations. Therefore, every time a packet goes around the ring network, the controller can send commands to all the drive boards and receive responses from all the drive boards, so it is guaranteed that the response is fast and can be controlled in real time. The

JP-A-8-139745

  In the communication between the controller in the electric injection molding machine and the drive board for controlling the servo motor and the PWM converter, if a ring type network is adopted and the communication method described in Patent Document 1 is adopted, the cost can be reduced and the reliability can be reduced. It is possible to perform communication without delay and real-time control. Therefore, there is no particular problem with communication. However, there is room for improvement when a failure occurs. When the communication method described in Patent Document 1 is performed using a ring network, communication of the entire network is stopped when the communication line is disconnected or the communication module fails. In such a case, in order to restore the network, it is necessary to identify the disconnection location and the failed communication module, but it is possible to determine at which location the communication line is disconnected or the communication module has failed. It is not possible to check whether all communication lines and all communication modules are normal. This will take time to restore the network.

  An object of the present invention is to provide a fault location detection method that solves the above-described problems. Specifically, a communication module provided in a controller is used as a master station, and a servo motor and a PWM converter are provided. The communication module provided on each drive board for controlling the slave is a slave station. These master station and slave station are connected by a ring network, and each servo motor and PWM converter are driven by a command from the controller. An object of the electric injection molding machine is to provide a failure location detection method that can easily estimate the failure location when a network fails.

  In order to achieve the above object, the present invention provides a fault location detecting method for detecting a fault location in a network for an electric injection molding machine in which a servo motor and a PWM converter are controlled by a command from a controller by a predetermined network. Configured as The predetermined network is as follows. That is, a communication module provided in the controller is a master station, a servo motor, and a communication module provided in each drive board that controls the PWM converter is a slave station, and these are connected by a ring network. This ring network allows packets to flow only in one direction. In an electric injection molding machine equipped with such a network, when a slave station does not receive a packet after a predetermined threshold time, an abnormality occurrence notification packet with its own station ID is transmitted. Each slave station has a waiting time different from that of the other slave stations, and is configured to wait for the waiting time before transmitting the abnormality occurrence notification packet.

Thus, according to the first aspect of the present invention, in order to achieve the above object, the communication module provided in the controller serves as a master station, and the communication provided in each of the drive boards that control the servo motor and the PWM converter. The slave station is connected to the master station by a ring network in which packets flow only in one direction, and the servo motor and the PWM converter are controlled by a command from the controller. In the electric injection molding machine, when the slave station does not receive a packet beyond a predetermined threshold time, the slave station transmits an abnormality occurrence notification packet with its own station ID. Configured as a method.
According to a second aspect of the present invention, in the method of the first aspect, each of the slave stations has a different waiting time, and waits for the waiting time before transmitting the abnormality occurrence notification packet. The present invention is configured as a failure detection method for a network.

  As described above, according to the present invention, the communication module provided in the controller is the master station, the communication module provided on each of the drive boards that control the servo motor and the PWM converter is the slave station, and the packet is unidirectional. It is configured as a network fault location detection method in an electric injection molding machine in which a master station and a slave station are connected by a ring network that flows only in the motor, and servo motors and PWM converters are controlled by commands from the controller. Yes. In such a ring network, if the communication line is disconnected or the communication module of the slave station fails, the packet does not flow downstream from the failure location, and the master station cannot receive the packet. In this case, it is not known at which position the communication line is disconnected as viewed from the master station or which slave station's communication module is faulty. In the present invention, the slave station is configured to transmit an abnormality occurrence notification packet with the ID of the local station when no packet is received beyond a predetermined threshold time. That is, the slave station that has detected that the packet cannot be received for a predetermined period of time itself transmits an abnormality occurrence notification packet, and the ID of the local station is attached to this packet. The master station receives the error notification packet from one or multiple slave stations, but an error occurs next to the most upstream slave station among the multiple slave stations that transmitted the error notification packet. Can be estimated. That is, it can be estimated that the network is disconnected next to the most upstream child station, or that the communication module of the child station adjacent to the most upstream child station has failed. Therefore, the network can be restored early. According to another invention, different waiting times are set for each of the slave stations, and it is configured to wait for the waiting time before transmitting the abnormality occurrence notification packet. Then, the timing at which each slave station transmits the abnormality occurrence notification packet is surely shifted. The possibility of packet loss due to the coincidence of communication timing can be surely prevented, and reliability is increased.

It is a network diagram which connects a controller, a PWM converter, and each servomotor in the electric injection molding machine which concerns on embodiment of this invention. In the electric injection molding machine which concerns on embodiment of this invention, it is a figure which shows the packet communicated between a controller, a PWM converter, and each servomotor, The (a) is a packet at the time of a network normal, ) Is a communication text diagram showing a packet when the network is abnormal.

  Hereinafter, this embodiment will be described. The electric injection molding machine 1 according to the present embodiment is also composed of an injection device, a mold clamping device, an ejector device, and the like. These devices are provided with servo motors. For example, the injection device includes an injection primary servo motor m1 for driving the screw in the axial direction and an injection secondary servo motor m2 as shown in FIG. A total of three servo motors are provided, i.e., a metering servo motor m3 for driving the screw in the rotational direction. The mold clamping device and the ejector apparatus are also provided with a mold clamping servomotor m4 and an ejector servomotor m5. The electric injection molding machine 1 is provided with a PWM converter 2, and a three-phase AC voltage 3 supplied from the outside is converted into a predetermined DC voltage. The converted DC voltage is supplied to servo amplifiers that drive the servo motors m1, m2,... And is servoed by drive boards d1, d2,... Provided corresponding to the servo motors m1, m2,. The amplifier is activated to control the servo motors m1, m2,. Since the servo amplifier is composed of a plurality of IGBTs and diodes, the servo amplifier is schematically represented as “IGBT” in FIG. The PWM converter 2 is also provided with a drive substrate d6 so that the PWM converter 2 is controlled.

  In the electric injection molding machine 1 according to the present embodiment, a communication module C, c1, c2,... Is included in each of the controller 5, the PWM converter 2, and the servo motors m1, m2,. Is provided. These communication modules C, c1, c2,... Are connected by a ring network 4. The ring network 4 is also called a loop network, and is as follows in the present embodiment. That is, each of the communication modules C, c1, c2,... Is provided with two terminals, a transmission terminal and a reception terminal. In any two adjacent communication modules, one of the communication modules A communication line is connected from the transmission terminal to the reception terminal of the other communication module. As a result, they are connected in a ring shape as a whole. Therefore, in the ring network 4 according to the present embodiment, packets flow only in one direction. Of the communication modules C, c1, c2,..., The communication module C provided in the controller 5 is a master station C or a primary station, and is provided in the servo motors m1, m2,. The communication modules c 1, c 2,... Are slave stations c 1, c 2,... Or secondary stations, and the master station C transmits data such as commands to the slave stations c 1, c 2,. The master station C receives data such as responses from c2,. The signals of the encoders EC, EC,... Provided in the servomotors m1, m2,... Are input to the slave stations c1, c2,. This packet is sent from the slave stations c1, c2,... To the master station C.

Communication between the controller 5, the PWM converter 2, and the servo motors m1, m2,... In the electric injection molding machine 1 according to the present embodiment will be described. The packet flowing through the ring network 4 at normal time includes data for all the slave stations c1, c2,... As shown in FIG. That is, it includes first slave station communication data, second slave station communication data,..., Nth slave station communication data. .. Are added before and after the communication data of each of the slave stations c1, c2,... So that the communication data of each of the slave stations c1, c2,. It has become. The bit pattern of the flag F is “01111110” in the present embodiment. The communication data of each of the slave stations c1, c2,... Has the same structure. For example, the m-th slave station communication data includes the following information.
・ Mth slave station address A
It is a number for identifying a slave station in the ring network 4 and can also be called an ID.
・ Control bit CB
In order to determine whether the transmission data D is data sent from the master station C to the slave stations c1, c2,... Or data sent from the slave stations c1, c2,. Is a bit. “0” is set when the transmission data D is sent from the master station C to the slave stations c1, c2,..., And “1” is set when the send data D is sent from the slave stations c1, c2,. Is done.
・ Transmission data D
Data sent from the master station C to the slave stations c1, c2,... Or data sent from the slave stations c1, c2,.
・ Check code CC
This is a code for confirming that the bit string composed of the address A, the control bit CB, and the transmission data D is transmitted without error, and a code processed by a checksum is stored for this bit string. On the communication module side on the receiving side, this bit string is processed with a checksum and compared with the check code CC to determine whether or not a transmission error has occurred.

  Such a packet is sent as follows. First, since the packet transmitted from the master station C is data for all the slave stations c1, c2,..., All the control bits CB are set to “0” in the first to n slave station communication data. Data such as instructions for the stations c1, c2,... Are stored in the corresponding transmission data D. In the first slave station c1, that is, the first slave station c1, only the first slave station communication data is read, and the transmission data D is stored in the memory in the communication module c1. Then, the data transmitted from the first slave station c1 to the master station C is overwritten on the transmission data D, and the control bit CB is rewritten to “1”. The second to n-th slave station communication data is left as it is, and a packet including the first to n-th slave station communication data is transmitted to the second slave station c2. In the second slave station c2, only the second slave station communication data is read, the transmission data D is stored in the memory in the communication module c2, and the data sent from the second slave station c2 to the master station C is sent. The transmission data D is overwritten, and the control bit CB is rewritten to “1”. The communication data of the other slave stations is left as it is, and a packet including these first to n slave station communication data is transmitted to the third slave station c3. In the same manner, when processing is performed in each of the slave stations c3, c4,..., The packet received by the master station C becomes data from each of the slave stations c1, c2,. All control bits CB of communication data are “1”. In the ring network 4 according to the present embodiment, every time a packet goes around the network, data is sent from the master station C to all the slave stations c1, c2,. The master station C can receive data from c2,. In the present embodiment, such a packet flows on the ring network 4 at regular intervals, for example, every 50 μsec.

  In such a ring network 4, if any of the slave stations c 1, c 2,... Fails or if any communication line is disconnected, no packet flows in the downstream network. For example, when the third slave station c3 fails or when the communication line between the third slave station c3 and the fourth slave station c4 is disconnected, a packet flows through the network after the fourth slave station c4. Absent. As a result, the master station C cannot receive the packet and cannot determine at which location the failure has occurred. In this embodiment, each of the slave stations c1, c2,... Actively transmits an abnormality occurrence notification packet so that the master station C can estimate the failure location.

  Specifically, each slave station c1, c2,... Processes as follows. The slave stations c1, c2,... Constantly confirm the packet reception state. When the slave stations c1, c2,... Do not receive a packet exceeding a predetermined threshold time, for example, 1 millisecond, it is determined that a failure has occurred and is shown in FIG. Anomaly occurrence notification packet is transmitted. The abnormality occurrence notification packet includes an error flag E having a specific bit pattern in addition to the address A of the own station, that is, the ID. For example, when the third slave station c3 fails or when the communication line between the third slave station c3 and the fourth slave station c4 is disconnected, all the slave stations c4, c5, In other words, the abnormality notification packet is transmitted from the fourth slave station c4, the fifth slave station c5,. The master station C receives a plurality of abnormality occurrence notification packets. Then, the master station C can estimate that a failure has occurred on the upstream side of the most upstream slave station c4 among the plurality of slave stations c4, c5,... That have transmitted these packets.

  If an abnormality occurrence notification packet is transmitted simultaneously from a plurality of slave stations c4, c5,..., Packet loss may occur. Therefore, in this embodiment, different waiting times are set in advance for each of the slave stations c1, c2,..., And each of the slave stations c1, c2,. Try to wait. As a result, the timings at which the slave stations c1, c2,... Transmit the abnormality occurrence notification packet can be shifted from each other, and packet loss can be prevented.

DESCRIPTION OF SYMBOLS 1 Electric injection molding machine 2 PWM converter 4 Ring type network 5 Controller m1, m2, ... Servo motor C Master station c1, c2, ... Slave station d1, d2, ... Drive board

Claims (2)

A communication module provided in the controller is a master station, a communication module provided in each of the drive boards that control the servo motor and the PWM converter is a slave station, and the parent network is connected by a ring network in which packets flow only in one direction. In the electric injection molding machine in which the station and the slave station are connected, and the servo motor and the PWM converter are controlled by a command from the controller,
A failure detection method of a network, wherein the slave station transmits an abnormality notification packet with its own ID when no packet is received after a predetermined threshold time.   2. The method according to claim 1, wherein each of the slave stations has a different waiting time, and waits for the waiting time before transmitting the abnormality notification packet. Detection method.

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