JP2006086990A - Control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control system ensuring excellent communication efficiency. <P>SOLUTION: The control system is provided with a first control means (102) for selecting the predetermined communication protocol on the basis of transmission information and transmitting the transmission information with a selected predetermined communication protocol and a second control means (103) for receiving the transmission information transmitted with the predetermined communication protocol from the first control means and controlling a control device on the basis of the transmission information received. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a control system including a unit unit including control devices such as a large number of motors and sensors, and a main control unit that transmits commands and the like for controlling the control device to the unit unit.

As an example of a control system, a medium transport apparatus that transports a medium such as paper sheets is known. The media transport device controls multiple unit units (conveying unit, take-in unit, stacking unit) equipped with multiple pulse motors and actuators for media separation and movement, and the operation of the pulse motors and actuators in these unit units. It is comprised by the main control part which issues the control command to perform (refer patent document 1).
JP2001-202588

  In serial communication performed between the main control unit (higher level control device) and the unit unit (lower level control device), a command sent from the main control unit to the unit unit and the processing result of this command are sent from the unit unit to the main control unit. Cyclic communication using the total frame method is adopted for the response (hereinafter referred to as CMD / RES) sent to the communication and the data (hereinafter referred to as DI / O) transmitted between the main control unit and the unit unit. When a control system that transmits data by cyclic communication is incorporated into an event-driven system, there is a problem that a plurality of events cannot be processed simultaneously, resulting in a delay time.

  An object of the present invention is to solve the above-described problems, and is to provide a control system having excellent communication efficiency.

  The control system of the present invention is configured as follows.

  (1) The present invention includes a first control unit that selects a predetermined communication protocol based on the type and state of transmission information, and transmits the transmission information using the selected predetermined communication protocol, and the first control unit. A control system comprising: second control means for receiving transmission information transmitted by a predetermined communication protocol and controlling a control device based on the received transmission information.

  (2) In the control system of the present invention, the first control means for transmitting transmission information and a plurality of control devices having different response speeds are connected, and the transmission information transmitted from the first control means is received. And a second control means for controlling the control device based on the transmission information. The second control means detects the error of the received transmission information, and detects the error by the detection means. And a means for selecting and executing either discarding of the transmission information or a retransmission request for the transmission information according to a response speed of each control device when detected.

  ADVANTAGE OF THE INVENTION According to this invention, the control system excellent in communication efficiency can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a control system according to an example of the present invention. As shown in FIG. 1, the control system includes a main control unit 100A and a unit unit 100B. The main control unit 100 </ b> A includes a control upper CPU 101 and a communication master side CPU 102, and the control upper CPU 101 issues various instructions to the communication master side CPU 102. One unit 100B includes a plurality of slave CPUs 103 (CPU # 1, CPU # 2, CPU # 3, CPU # 4), a photo interrupter 107 controlled by each slave CPU 103, a motor 108, a motor 109, and a solenoid. 110 and the like.

  The communication master side CPU 102 (first control unit) of the main control unit 100A and each slave side CPU 103 (second control unit) of the unit unit 100B are connected by, for example, two transmission paths 105 and 106, and communication Serial communication is controlled by the master side CPU 102 and the slave side CPU 103. The two transmission paths 105 and 106 are selectively used according to the type of transmission information. For example, the transmission path 105 is a dedicated transmission path for command information CMD (COMMAND) and response information RES (RESPONSE) (hereinafter referred to as CMD / RES), and the transmission path 106 is input / output data D (DATA) -I (INPUT). This is a dedicated transmission line for / O (OUTPUT) (hereinafter referred to as DI / O). The two transmission lines 105 and 106 may be physically independent transmission lines (serial cables), or may be logically independent transmission lines. In the case of a logically independent transmission path, for example, different information is transmitted by changing the communication frequency band.

  The upper control CPU 101 gives a general command to drive the photo interrupter 107, the motor 108, the motor 109, and the solenoid 110 of the unit unit 100B. In accordance with the command value, the slave CPU 103 performs detailed control such as driving of the photo interrupter 107, the motor 108, the motor 109, and the solenoid 110.

  Next, the cyclic transmission method and the transient transmission method will be described.

  In the conventional wiring-saving system, both CMD / RES and D-I / O are cyclically transmitted in the total frame method on each transmission path, so when incorporated into an event-driven system, multiple events are processed simultaneously. There was a problem that could not be done. In order to deal with this problem, for example, CMD / RES and DI / O are transmitted using different protocols.

  That is, the communication master side CPU 102 selects a predetermined communication protocol (transient transmission system or cyclic transmission system) based on the type of transmission information (CMD / RES or DI / O), and selects the predetermined communication selected. Transmission information is transmitted to the slave CPU 103 by the protocol. For example, the communication master side CPU 102 selects a transient transmission method for command transmission, and transmits the command to the slave CPU 103 via the transmission path 105 by the selected transient transmission method. Further, the communication master side CPU 102 selects a cyclic transmission method for data, and transmits the data to the slave side CPU 103 via the transmission path 106 by the selected cyclic transmission method.

  The slave CPU 103 receives a command transmitted by the transient transmission method via the transmission path 105, and controls the motor 108 or the motor 109 based on the received command. Further, the slave side CPU 103 transmits a response corresponding to the received command to the communication master side CPU 102 via the transmission path 105 by the transient transmission method. Further, the slave CPU 103 receives data transmitted by the cyclic transmission method via the transmission path 106 and controls the motors 108 and 109 or the solenoid 110 based on the received data.

  As described above, since the DI / O is always monitored by the control upper CPU 101, it is an object of the cyclic transmission method. At this time, since it is necessary to reduce the amount of overhead data and prevent an increase in traffic, a cyclic transmission method using a total frame method is adopted. FIG. 2 is a diagram illustrating an example of a total frame format. As shown in FIG. 2, the total frame format is composed of a synchronization signal 201 (SYN × 2), a slave CPU connection number 202, a common command 203, and an output data frame 204 from CPU # 1 to CPU #n. ing.

  With regard to CMD / RES, command and response issuance timing is uncertain in the event-driven method. Therefore, when an event occurs, it is transmitted by a transient transmission method using a single packet method. FIG. 3 is a diagram illustrating an example of a single packet format. As shown in FIG. 3, the single packet format includes a synchronization signal 301 (SYN × 2), a slave side CPU address 302, and a CPU setting command 303.

  In this control system, for example, 16 D-I / Os (that is, data input / output devices) can be connected to the slave CPU 103, and the data amount per D-I / O is 1 bit. Therefore, the total D-I / O per one slave CPU 103 is 2 bytes. When a total of 16 slave CPUs 103 are connected, the DI / O transmitted by one cyclic communication is 16 × 2 = 32 bytes. Data that is transmitted by the cyclic transmission method with a total of 40 bytes including the 32 bytes, 6 bytes of the synchronization signal 201 (SYN × 2), 1 byte of the slave CPU connection number 202, and 1 byte of the common command 203. Amount.

  In the transient transmission method based on the single packet method, the synchronization signal 301 is transmitted in 6 bytes (SYN × 2), the slave CPU address 302 is 1 byte, and the CPU setting command 303 is transmitted in 2 bytes in a total of 9 bytes. It becomes the amount of data.

  As described above, a communication system specialized for actuator control can be constructed by preparing a plurality of physical transmission paths and performing communication by changing the protocol for each physical transmission path. Also, one physical transmission line is divided into two logical transmission lines by frequency division, CMD / RES performs transient transmission in a high frequency band, and DI / O cyclic transmission in a low frequency band. By performing this, it is possible to perform effective communication using the cyclic / transient transmission method.

  Next, the CMD / RES variable length total frame method will be described.

  As described above, DI / O is transmitted by the total frame method, and CMD / RES is transmitted by the single packet method. On the other hand, when the number of events occurring simultaneously increases and traffic increases or when a command is issued cyclically, CMD / RES is transmitted in a variable-length total frame method.

  FIG. 4 is a diagram illustrating an example of the format of the variable length total frame method. As shown in FIG. 4, the format of the variable length total frame method includes a synchronization signal 401 (SYN × 2), a device number 402, and a command 404. The device No. 402 designates the connection device of the target slave CPU 103 by the device No. detailed information 403. When a command is to be sent to the connection devices No. 2 and No. 4 of the CPU # 1, the transmission device is designated by setting the bit of the corresponding part of the device No. detailed information 403.

  For example, consider a case where 32 control commands are issued simultaneously. When transmission is performed for each single packet in the character synchronization method, an overhead of 32 × number of synchronization signal bits (2 SYNs) = 192 bytes occurs. When this is transferred by the variable total frame method, the overhead is 1 byte of 2 SYNs + the receiving device No frame, and the header portion is suppressed to 7 bytes as a whole, and the communication efficiency can be improved.

  Next, static protocol conversion will be described.

Whether CMD / RES is transmitted by a single packet method or a variable total frame method is determined at the time of system initialization. There are the following two methods for transmission using the variable total frame method.
A first method is a scheduling method. At every sampling time (for example, every 1 [ms]), transmission data is converted into a total frame and communicated. By scheduling and transmitting, the minimum value of the sampling time is guaranteed.

  As a second method, there is a packet number determination method. When the number of transmission data reaches an arbitrary value (for example, 10 CMD / RES are stored in First In First Out memory (FIFO)), the transmission data accumulated in the FIFO is converted into a total frame and communicated. At this time, the sampling time is also set as in the scheduling method. Communication is performed when either the set sampling time or the set number of packets satisfies the condition first. Thereby, both the minimum value of sampling time and the maximum value of data queuing can be guaranteed.

  FIG. 5 is a flowchart illustrating an example of data transmission processing to which the scheduling method and the packet number determination method are applied. For example, assume that the set sampling time value is 1 [ms] and the number of packets is 5. When the communication master side CPU 102 starts a transmission sequence (ST501) and the generation of transmission data is detected (ST502, YES), the number of packets in the FIFO is not changed even when 1 [ms] has not elapsed since the previous transmission. When the number reaches five (ST503, YES), the five pieces of data in the FIFO are converted into a total frame and transmitted (ST504). Even if the generation of transmission data is not detected (ST502, NO), if 1 [ms] has passed since the previous transmission (ST505, YES), even if the number of packets in the FIFO is less than 5, All data is framed and transmitted (ST506).

  If you want to guarantee the minimum sampling time (in the case of transmission information that corresponds to this case), use the scheduling method. If priority is given to real-time performance (in the case of transmission information that corresponds to this case), the packet number determination method is It is valid. That is, based on the type of transmission information, transmission using a scheduling method using a variable total frame or transmission using a packet number determination method using a variable total frame is selected.

  Thus, the communication speed can be optimized by changing the protocol in consideration of overhead.

  Next, dynamic protocol conversion will be described.

  When CMD / RES is communicated by the transient transmission method, if the number of events that occur gradually increases and the traffic increases (when the frequency of transmission information increases), the protocol is changed during the communication, and the total frame method To improve efficiency.

  FIG. 6 is a flowchart for explaining the dynamic protocol conversion. As shown in FIG. 6, first, the communication master side CPU 102 monitors a transmission request (number of transmission packets generated per unit time (occurrence frequency)) from the control upper CPU 101 (ST601), and the number of transmission packets generated is determined. If the threshold is not exceeded (NO in ST602), transmission is performed using a single packet protocol (ST603). If the number of transmitted packets exceeds the threshold (ST602, YES), the protocol is changed from the single packet scheme to the variable total frame scheme. Is changed and transmission is performed (ST604).

  The threshold for the number of transmission packets per unit time and the setting of the variable total frame method are set at the time of initialization. A threshold value (packet / s) is set at the time of initialization, and the type of transmission interrupt is transmitted by a transmission method by hybrid transmission. The slave CPU 103 determines whether the transmitted data is a single packet system or a total frame system based on the packet protocol declaration units 602 and 702 shown in FIGS.

  By dynamically changing the protocol according to the communication traffic, the communication speed for any communication traffic can be optimized.

  FIG. 7 is a diagram illustrating an example of a format of a variable length total frame method corresponding to dynamic protocol conversion. As shown in FIG. 7, the format of the variable length total frame method corresponding to the dynamic protocol conversion includes a synchronization signal 701 (SYN × 2), a communication protocol declaration unit 702, a device No. 703, a common command 704, and CPUs # 1 to # 1. The output data frame 705 up to the CPU #n is configured.

  FIG. 8 is a diagram illustrating an example of a single packet format that supports dynamic protocol conversion. As shown in FIG. 8, the format of the single packet method corresponding to the dynamic protocol conversion includes a synchronization signal 801 (SYN × 2), a communication protocol declaration unit 802, a slave CPU address 803, and a CPU setting command 804. ing.

  Next, transmission information error control will be described.

  Focusing on the response frequency of the connected device connected to the slave CPU 103, the control method for the error in the transmission information is changed. The transmission path 105 assigned to the CMD / RES used in the present control system is connected to an actuator having a high response speed and requiring high-precision control, and the transmission path 106 assigned to the DI / O. Is connected to an actuator having a relatively slow response speed. For example, the solenoid 110 is controlled by data transmitted and received on the transmission path 106, and the motors 108 and 109 are controlled by data transmitted and received on the transmission path 105.

  The solenoid response cycle 10 [ms] is a sufficiently large value when viewed from the sampling time 128 [μs] of the current cyclic communication. Even if a transmission error occurs once, the stability of the control system is not lost because it is not the response band of the solenoid. On the other hand, if a transmission error occurs in a motor drive command having a high response frequency and the value is set in the driver, the stability of the control system is significantly impaired.

  FIG. 11 is a flowchart illustrating an example of transmission information error control. As shown in FIG. 11, when the slave side CPU 103 detects a transmission error when receiving data (ST1101) (ST1102, NO), all the data is discarded (ST1103), and the next data is transmitted. wait. On the other hand, when the slave CPU 103 receives a command and detects a transmission error (ST1101) (ST1102, YES), it immediately performs a retransmission procedure (retransmission request) to the communication master side CPU102 (ST1104). The communication master side CPU 102 resends the command. In this way, the stability of the control system can be maintained by changing the error control method according to the type of information to be transmitted (data or command).

  FIG. 9 is a diagram illustrating an example of a format of a total frame method to which an error control code FCS (Frame Check Sequence) based on CRC (Cyclic Redundancy Check) is added. As shown in FIG. 9, the format of the total frame method to which the error control code FCS by CRC is added is the synchronization signal 901 (SYN × 2), the number of slave CPU connections 902, the common command 903, CPU # 1 to CPU #n. Output data frame 904 and error detection signal (FCS) 905.

  FIG. 10 is a diagram illustrating an example of a format of a single packet system to which an error control code FCS by CRC is added. As shown in FIG. 10, the format of the single packet system to which the error control code FCS by CRC is added is a synchronization signal 1001 (SYN × 2), a slave CPU address 1002, a CPU setting command 1003, and an error detection signal (FCS). 1004.

  This embodiment will be summarized below.

  (1) In an event-driven distributed control system, two physical transmission paths are used as a communication method between the host controller and the slave controller, CMD / RES is a transient transmission system, and DI / O is cyclic. By dividing the transmission path according to the type of transmission information as in the transmission method and using an independent protocol for each physical transmission path, communication optimized for mechanical control can be performed. In other words, by having an independent transmission path and protocol according to the type of information to be communicated (CMD / RES, DI / O), it becomes possible to control the actuator and sample the sensor value with a shorter time slice width. , Can perform precise control.

  (2) In an event-driven distributed control system, one physical transmission path is divided into two logical transmission paths by frequency division as a communication method between the host control apparatus and the lower control apparatus, and CMD / RES is high. By performing transient transmission in a frequency band, and performing DI / O cyclic transmission in a low frequency band, communication optimized for mechanical control can be performed.

  (3) In an event-driven distributed control system, CMD / RES is transmitted by a scheduling method using a variable total frame as a communication method between the host controller and the slave controller, so that a large number of events can be generated at a time. Transmission is possible with overhead, and the minimum sampling time can be guaranteed.

  (4) In a distributed control system that is event-driven, a large number of events occur simultaneously by transmitting CMD / RES as a communication method between the host controller and the slave controller using a variable total frame packet number determination method. In addition, transmission can be performed with less overhead, and real-time performance can be guaranteed.

  (5) In the event-driven distributed control system, communication traffic on the CMD / RES line is monitored as a communication method between the host controller and the slave controller, and an increase in network traffic is detected during CMD / RES transient transmission. Then, the protocol is dynamically changed to the variable cyclic method, and if not detected, the communication is performed by the single packet method.

  (6) In a distributed control system in which a plurality of devices having different response frequencies are connected to the lower-level control device, when a communication error is detected as a communication error control method, data is received if it is a command to a device having a low response frequency. If the command is for a device with a high response frequency, the data is retransmitted. That is, by changing the communication error control method according to the response frequency of the device connected to the lower-level control device, stability can be maintained while suppressing an increase in communication traffic.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention in the implementation stage. In addition, the embodiments may be appropriately combined as much as possible, and in that case, the combined effect can be obtained. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the problem described in the column of the problem to be solved by the invention can be solved, and the effect described in the column of the effect of the invention Can be obtained as an invention.

It is a figure which shows schematic structure of the control system of an example of this invention. It is a figure which shows an example of the format of a total frame system. It is a figure which shows an example of the format of a single packet system. It is a figure which shows an example of the format of a variable-length total frame. It is a flowchart which shows an example of the data transmission process to which the scheduling system and the packet number determination system are applied. It is a flowchart for demonstrating dynamic protocol conversion. It is a figure which shows an example of the format of the variable-length total frame corresponding to dynamic protocol conversion. It is a figure which shows an example of the format of the single packet system corresponding to dynamic protocol conversion. It is a figure which shows an example of the format of the total frame system which added the error control code FCS by CRC. It is a figure which shows an example of the format of the single packet system which added the error control code FCS by CRC. FIG. 11 is a flowchart illustrating an example of transmission information error control.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100A ... Main control part, 100B ... Unit part, 101 ... Upper CPU for control, 102 ... Communication master side CPU, 103 ... Slave side CPU, 105, 106 ... Transmission path, 107 ... Photo interrupter, 108 ... Motor, 109 ... Motor 110 ... Solenoid

Claims (11)

A first control means for selecting a predetermined communication protocol based on the type and state of the transmission information, and transmitting the transmission information using the selected predetermined communication protocol;
Second control means for receiving transmission information transmitted by a predetermined communication protocol from the first control means, and controlling a control device based on the received transmission information;
A control system characterized by comprising:   The first control means selects a transient transmission method when transmitting the first transmission information, transmits the first transmission information according to the selected transient transmission method, and cyclically transmits the second transmission information. The control system according to claim 1, wherein a transmission method is selected, and the second transmission information is transmitted by the selected cyclic transmission method.   The first control means and the second control means are connected, and a plurality of transmission paths that are selectively used according to the type of transmission information are provided. Control system.   The control system according to claim 3, wherein the plurality of transmission paths are physically independent transmission paths.   The control system according to claim 3, wherein the plurality of transmission lines are logically independent transmission lines.   The first control means selects a transient transmission scheme to which the first frequency band is applied when transmitting the first transmission information, transmits the first transmission information by the selected transient transmission scheme, Selecting a cyclic transmission method to which a second frequency band different from the first frequency band is applied when transmitting the transmission information, and transmitting the second transmission information by the selected cyclic transmission method. The control system according to claim 1 or 5, characterized in that The first control means selects a transmission to which a scheduling method using a variable total frame is applied based on a type of transmission information, and transmits the transmission information by a transmission using a scheduling method using the selected variable total frame. And
2. The control according to claim 1, wherein the second control unit receives the transmission information by transmission to which a scheduling method using the variable total frame is applied, and controls a control device based on the transmission information. system. The first control means selects transmission to which a packet number determination method using a variable total frame is applied based on the type of transmission information, and transmits the transmission information by transmission using the selected packet number determination method using the variable total frame. Transmit
The said 2nd control means receives the said transmission information by transmission which applied the packet number determination system by the said variable total frame, and controls a control apparatus based on the said transmission information, The control apparatus of Claim 1 characterized by the above-mentioned. Control system.   The first control means monitors the occurrence frequency of transmission information to the second control means, and selects either transmission using a single packet system or transmission using a variable total frame system based on the monitoring result The control system according to claim 1, wherein the transmission information is transmitted by selected transmission. First control means for transmitting transmission information;
A plurality of control devices having different response speeds connected thereto, receiving transmission information transmitted from the first control unit, and controlling the control device based on the transmission information;
With
The second control means detects the error of the received transmission information, and when the detection means detects an error, discards the transmission information or transmits the transmission information according to the response speed of each control device. And a means for selecting and executing one of information retransmission requests. The control device includes the first control device capable of responding to a first response speed, and the second control device capable of responding to a second response speed that is faster than the first response speed. ,
The first control means transmits first transmission information for a first control device and second transmission information for a second control device,
The second control means discards the first transmission information based on the error detection of the first transmission information by the detection means, and the second transmission information based on the error detection of the second transmission information. The control system according to claim 10, wherein the first control unit is requested to retransmit the data.

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