JP5094243B2 - Communication apparatus and communication system - Google Patents

Description

  The present invention relates to a communication apparatus that performs control communication for controlling FA (Factory Automation) equipment and industrial equipment, and a communication system including the communication apparatus.

  OFDM (Orthogonal Frequency Division Multiplexing) and OFDMA (Orthogonal Frequency Division Multiple Access) used in wireless LAN and power line communications are applied to control communications for controlling industrial equipment such as FA equipment, elevators, and escalators. Technology exists (for example, see Patent Document 1 below).

  When OFDM or OFDMA is used for control communication of FA devices or industrial devices, it is necessary to prepare for a situation where control communication is hindered by the influence of noise or the like emitted from a control target device to a transmission path used for control communication. Generally, the situation where these control communications are hindered is avoided by adopting an adaptive modulation technique based on a training function or transmission path estimation. Further, for example, the one that selects the optimum transmission path by checking the transmission path state in advance as described in Patent Document 2 below can be considered as one of the adaptive modulation techniques.

JP 2005-294991 A JP 2006-129470 A

  However, control communication that employs a training function or adaptive modulation technology has a problem in that the overhead during communication increases, so that it is inefficient for control communication that requires real-time performance (real-time performance is achieved). Was a disadvantageous method). Moreover, it was a disadvantageous method in terms of cost.

  The present invention has been made in view of the above, and an object of the present invention is to obtain a communication device that can be realized at a low cost by suppressing an increase in overhead during control communication and a communication system including the communication device.

  In order to solve the above-described problems and achieve the object, the present invention provides a slave station to which a control target device is connected, or a master station that controls the control target device by communicating with the slave station. A parameter holding means for holding a communication parameter that is preliminarily defined according to an operation state that can be taken by the control target device that continuously operates in accordance with an instruction from a master station, Based on the content of the previous communication performed with the opposite communication device that is the communication partner to control the control target device, the current operation state of the control target device is specified and held in the parameter holding means Communication means that communicates with the opposite communication device using communication parameters corresponding to the specified operation state.

  According to the present invention, each communication device (master station and slave station) prepares a plurality of communication parameter setting patterns in advance and switches them according to the contents of the control communication. Thus, an effect that the overhead that impairs the real-time responsiveness necessary for control communication can be suppressed as in the method of providing a training period of 2 is achieved.

  In addition, the apparatus configuration can be simplified and the cost can be reduced as compared with the method of constantly monitoring the state of the transmission path.

  Embodiments of a communication apparatus according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment.
FIG. 1 is a diagram illustrating a configuration example of a communication system including a communication device according to the present invention. This communication system is composed of a master station 1, a plurality of slave stations 2-1, 2-2,..., And a communication parameter determination device 3, and each device is connected by wire. For communication between the master station 1 and each slave station (slave stations 2-1, 2-2,...), For example, an OFDM scheme or an OFDMA scheme is applied.

  The master station 1 is a control communication device that transmits command data delivered from an upper layer device (not shown) to any one of the slave stations, and passes response data received from each slave station to the upper layer device. . Similarly, each slave station (slave station 2-1, 2-2,...) Passes the command data received from the master station 1 to an upper layer device (not shown) connected to itself. This is a control communication device that transmits response data passed from the layer device to the master station 1. The communication parameter determination device 3 includes a coding method, a modulation / demodulation method, an error correction method, a bit assignment, a tone assignment, a guard interval length, a diversity method, a retransmission method, and the like used when the master station 1 and each slave station perform communication. It is an apparatus for determining a setting value of each parameter for a communication parameter constituted by a plurality of parameters. After determining the communication parameters (each parameter), for example, by communicating with the master station and the slave station, setting values (hereinafter referred to as setting patterns) of the parameters constituting the communication parameters for the master station and the slave station. Called).

  FIG. 2 is a diagram illustrating a configuration example of a control communication device (corresponding to the above-described master station 1 and each slave station) that is a communication device according to the present invention. The configuration of the master station and each slave station is the same, and only the configuration of the master station 1 is shown in FIG. 2 for simplicity. FIG. 2 shows data (communication parameters, command data, response data) exchanged between each control communication device and the communication parameter determination device 3. Specifically, the communication parameters (communication parameter setting patterns) passed from the communication parameter determination device 3 to the master station 1, the slave stations 2-1 and 2-2 are set as communication parameters 30, 31 and 32, respectively. Similarly, command data passed from the master station 1 to the slave stations 2-1 and 2-2 are command data 41 and 42, respectively, and response data passed from the slave stations 2-1 and 2-2 to the master station 1 is These are response data 51 and 52, respectively.

  Based on FIG. 2, the configuration and operation of the control communication device will be described. The master station 1 (control communication device) includes a transmission unit 11, a parameter holding unit 12, a reception unit 13, and an error detection unit 14. The transmission unit 1 and the reception unit 13 constitute a communication unit, and the error detection unit 14 constitutes a reception result determination unit.

  The transmission unit 11 uses the optimum setting pattern among the plurality of communication parameter setting patterns held by the parameter holding unit 12 in accordance with the state of the transmission path with the counterpart communication device that performs communication. Etc. Specifically, the current state of the transmission path is recognized from the content of the previous control communication with the counterpart communication apparatus, and data and the like are transmitted using a setting pattern corresponding to the transmission path state.

  The parameter holding unit 12 holds an arbitrary number of communication parameter setting patterns received from the communication parameter determination device 3.

  The receiving unit 13 uses the optimum setting pattern among the plurality of communication parameter setting patterns held in the parameter holding unit 12 according to the state of the transmission path between the receiving station and the communication station. Receive. The setting pattern to be used is determined based on the content of the previous control communication, similarly to the transmission unit 11 described above.

  The error detection unit 14 monitors whether or not a reception error such as data transmitted from the slave station has occurred, and passes data for which no reception error has been detected to a higher-layer device.

  Next, the actual control communication operation will be described. Here, an upper layer device is connected to each slave station. Further, FA devices such as motors, sensors, and switches to be controlled, or industrial devices such as elevators and escalators (hereinafter referred to as “elevator”) are connected to the upper layer devices. These are collectively called control target devices). In some cases, a plurality of devices to be controlled are connected to one slave station via an upper layer device.

  Also, when each slave station determines that it is necessary to determine or change the communication parameter setting pattern, such as when the power is turned on or when the number of connected control target devices is detected to change. Communicate with the communication parameter determination device 3 to acquire a communication parameter setting pattern used when communicating with the master station 1. For example, the slave station requests the communication parameter determination device 3 to determine the communication parameter, and the communication parameter determination device 3 is operable with the type and number of devices to be controlled connected to the requesting slave station. Information (such as ON / OFF state), connection distance to the master station 1, and the like are acquired from the slave station, and the requesting slave station communicates with the master station 1 based on the acquired information. Determine the communication parameter setting pattern to be used.

  Note that a plurality of communication parameter setting patterns are determined according to the number of control target devices and the number of operable states of each control target device. The determined communication parameter setting pattern is notified to the requesting slave station and the master station 1, and the master station 1 and the slave station hold the notified communication parameter setting pattern in the parameter holding unit. When determining the communication parameter setting pattern, the communication parameter determination device 3 determines the transmission path state between the slave station and the master station 1 at the time when the communication parameter determination request is received from the slave station and the state (connection of the slave station). The communication parameter setting pattern may be determined based on the type and number of devices to be controlled, the operable state, the connection distance to the master station 1, and the like. However, since the master station 1 and the slave station are connected by wire, if the slave stations are in the same state, it is assumed that the transmission path state is stable (no significant fluctuations). Simulation according to the status of the slave station, that is, simulation with multiple possible conditions such as the connection distance between the master station and the slave station, the type and number of controlled devices connected to the slave station, and the operable state For example, the setting pattern for each condition may be determined in advance. In other words, when a communication parameter determination request is received, a communication parameter setting pattern that matches the state of the requesting slave station may be selected from the setting patterns determined in advance by simulation or the like. Good.

  Next, as an example, control communication between the master station 1 and the slave station 2-1 that is performed when a motor (not shown) is connected to an upper layer device to which the slave station 2-1 is connected. The operation is shown. It should be noted that this motor changes its operating state only in accordance with an instruction from the master station 1 except when an abnormality such as a sudden stop of power supply occurs. That is, once an instruction is received, the same operation state is continued until the next instruction is received.

  Assuming a situation in which the rotation of the motor is turned on or off from an upper layer device to which the parent station 1 is connected, the motor is turned on via the parent station 1 from the upper layer device (the upper layer device on the parent station side). Information to be instructed is transmitted as command data 41 to the slave station 2-1. Further, the motor starts to operate according to the command data 41 transferred from the slave station 2-1 to the upper layer device (slave station side upper layer device). The master station 1 recognizes the operation state of the motor from the contents of the previous control communication operation with the slave station 2-1 (the contents of the previously transmitted command data 41 or the previously received response data 51). Therefore, communication is performed using a communication parameter (communication parameter setting pattern) that provides the highest transmission rate according to the operating state.

  When the above-described control communication is performed and the motor starts operation, motor noise is superimposed on the communication path between the master station 1 and the slave station 2-1, and communication between the master station 1 and the slave station 2-1 is performed. There may be a situation in which an adverse effect occurs and communication that is possible without any problem when the motor is OFF cannot be communicated when it is ON.

  However, if the communication parameter determination device 3 prepares optimal communication parameter setting patterns for each of the motor OFF and ON in advance and notifies them to the master station 1 and the slave station 2-1, the transmission unit 11 and the receiving unit 13 are transmitted or received in the setting pattern for when the motor is OFF until the time when the control communication for turning ON is executed. It can be changed to send or receive with a setting pattern. As a result, a situation that adversely affects communication between the master station 1 and the slave station 2-1 does not occur. That is, communication is performed with an optimal communication parameter setting pattern according to the transmission path state, and it is possible to avoid the situation where communication between the master station 1 and the slave station 2-1 becomes impossible.

  Next, as an example different from the above, a function in which the motor connected to the upper layer device of the slave station 2-1 autonomously turns on / off depending on the state of the sensor connected to the same upper layer device. In other words, the control communication operation between the master station 1 and the slave station 2-1 when there is a possibility that the operation state may change without receiving an instruction from the master station 1 will be described.

  In this case, since the motor operating state changes even if control communication is not performed between the master station 1 and the slave station, the transmitter 11 and the receiver 13 of the master station 1 know the motor operating state in advance. I can't. As a result, in the worst case, there may be a situation where communication is suddenly interrupted.

  However, the receiving unit 13 of the master station 1 enables reception with both communication parameter setting patterns when the motor is OFF and ON, and detects an error so as to select the reception result of the one that has successfully communicated. By configuring the unit 14, it is possible to prevent communication between the master station 1 and the slave station 2-1 from being interrupted. Specifically, when there is a possibility that the motor is autonomously turned on / off other than the instruction by the command data 41 transmitted from the master station 1 on the slave station side, the receiver 13 of the master station 1 12, using both the communication parameter setting pattern used for communication when the motor connected to the slave station 2-1 is ON and the communication parameter setting pattern used for communication when OFF is used. The received signal is demodulated and the two obtained reception results (received data) are output to the error detection unit 14. Then, the error detection unit 14 selects the one that can be normally received and passes it to the upper layer apparatus. If there are a plurality of items that can be normally received, one of them is selected and passed to the upper layer apparatus.

  In addition, in the case of a system configuration in which a mode in which the operating state is changed according to an instruction from the master station and a mode in which the slave station can change the operating state autonomously can be selected, the master station and the slave station are currently selected. Recognize the mode and perform the operation according to the selected mode (in the case where the operation state can be changed autonomously on the slave station side, reception processing is performed with all available communication parameter setting patterns) .

  As described above, in the present embodiment, each control communication device (master station and slave station) prepares a plurality of communication parameter setting patterns in advance, and switches and uses them according to the contents of the control communication. It was. As a result, it is possible to suppress the occurrence of overhead that impairs the real-time responsiveness required for control communication as in the conventional method of providing a training period. In addition, the configuration of the apparatus can be simplified and the cost can be reduced as compared with a method of constantly monitoring the state of the transmission path.

  In addition, by providing the parameter holding unit 12 that holds an arbitrary number of communication parameter setting patterns, not only a simple state of ON / OFF but also a device to be controlled has a plurality of operation states, that is, It is also possible to cope with a case where there are a plurality of states controlled by the command data 41 and 42 or notified by the response data 51 and 52.

  In the configuration example shown in FIG. 1, the communication parameter determination device 3 is a device different from the master station 1 and the slave stations 2-1 and 2-2, but this is the operating state of the device to be controlled. In the process for predetermining the communication parameter setting pattern corresponding to each command data or response data, it is considered that conventional training or processing for grasping the state of the transmission path is necessary. This is because it is disadvantageous in terms of cost to have each child station. If there is no problem in cost, the communication parameter determination device 3 may be built in the master station or the slave station.

  As described above, the communication device according to the present invention is useful for control communication for controlling industrial equipment, and in particular, when controlling an actuator such as a motor, while suppressing an increase in overhead during communication. This is suitable for performing control communication with optimal communication parameters according to the operating state of each device.

It is a figure which shows the structural example of the communication system containing the communication apparatus concerning this invention. It is a figure which shows the structural example and control communication operation | movement of a communication apparatus concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master station 2-1, 2-2 Slave station 3 Communication parameter determination apparatus 11 Transmission part 12 Parameter holding part 13 Reception part 14 Error detection part 30, 31, 32 Communication parameter 41, 42 Command data 51, 52 Response data

Claims (4)

A communication device that operates as a slave station to which a control target device is connected, or a master station that controls the control target device by performing communication with the slave station,
Communication parameters defined in advance according to the operating states that can be taken by the controlled device that operates continuously according to instructions from the master station, and a setting pattern for each operating state of communication parameters configured by a plurality of parameters Parameter holding means for holding
Based on the content of the previous communication performed with the opposite communication device that is the communication partner for controlling the control target device, the current operation state of the control target device is specified, and the parameter holding means A communication means for communicating with the opposite communication device with communication parameters corresponding to the identified operating state being held;
Equipped with a,
When the communication means transmits a response to the operation state change instruction command or receives a response to the operation state change instruction command, the communication means sets a communication parameter in a setting pattern corresponding to the operation state indicated by the change instruction command. change to a communication apparatus according to claim Rukoto. The control target device is an actuator,
The communication apparatus according to claim 1, wherein a state that the control target device can take is a state in which the actuator is generating a constant power or a state in which the actuator is stopped. further,
A reception result determining means for determining whether or not the communication means has normally received the signal transmitted from the opposite communication device;
With
When a signal is transmitted from the opposite communication device in a state where the operation state of the control target device cannot be specified,
The communication means receives all of the communication parameters that can be used for communication with the opposite communication device among the communication parameters held by the parameter holding means, and receives signals transmitted from the opposite communication device. The process is executed the same number of times as the number of communication parameters,
The reception result determination unit selects a reception result that has been successfully received as a final reception result from reception results obtained by the communication unit executing reception processing. Or the communication apparatus of 2. A plurality of slave stations configured by the communication device according to claim 1, 2, or 3 ,
A master station configured by the communication device according to claim 1, 2, or 3 ,
When receiving a request for the slave station or al communication parameters, based on the type and the possible motions state of the control target devices connected to the slave station, and communicates with the slave station and the slave station determining communication parameters master station uses a communication parameter determination unit communication parameters the determined notifies the relevant slave station and the master station,
A communication system comprising:

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