JP6247597B2 - Control device - Google Patents

Description

  The present invention relates to technology for accessing data in other nodes to which a node is connected via a network.

  In a control system, an application that operates on a processing device (hereinafter referred to as a node) such as a computer or a controller uses data existing in a plurality of other nodes connected to the node via a network at a constant cycle. Operate. Among data used by an application, there is data updated by an application operating on another node. In this case, since the application running on the other node is also running at a constant cycle, the update is performed at a constant cycle.

  The execution result of the application may differ depending on whether the data before update is used or the data after update. Therefore, to use the application stably, always use either data. There is a need.

  As a method for keeping the data quality constant, Patent Document 1 describes a transfer memory system in which data is shared among a plurality of nodes by periodic broadcast transmission.

  In this transfer memory system, by performing broadcast transmission at the timing when the application periodically updates data, the updated data is always shared within the system, so stable application operation Can be realized.

  However, in the technique described in Patent Document 1, since a memory area that can be used for each node is fixed in advance, when the control application updates the system or when the memory area is improved in use. When it is necessary to change the memory usage area of each node, it has been difficult to apply.

  As a technique for solving the problem of Patent Document 1, Patent Document 2 discloses a transfer memory system in which each node stores area management information indicating identification information of a node that secures this area for each area on the memory. Is described.

  By storing the area management information in each node, if the memory use area is changed, the fact is set in the area management information and broadcast communication is performed so that other nodes can also change the area. Notification can be made, and the memory use area can be changed during system operation.

Japanese Patent Laid-Open No. 11-341038 JP 2008-59420 A

  When adding data shared by the system by changing an application on a node that transmits broadcast communication, a memory area for setting the added data is secured by using the technique described in Patent Document 2. And the added data can be shared within the system.

  However, if data that is not shared by the system becomes necessary due to a change in the application on the node that receives the broadcast communication, the data cannot be obtained, so the application cannot be operated correctly. There is sex.

  In order to acquire such data, a query-type data access method that directly requests data from a node having data necessary for the operation of the application can be considered. However, in the query type data access method, since data is requested at the timing of the query source, it is difficult to keep the quality of data obtained as a response constant. If the data quality is not kept constant, the application may not be able to operate stably.

  In order to solve the above-described problem, a control device according to one aspect of the present invention provides communication information indicating a predetermined application execution cycle and a communication plan with another control device connected via a network. A storage unit that stores information, and the application is executed at each application execution cycle, and when the processing request message that is a request for processing is received from the other control device, the processing is executed and the result of the processing is included And a processing unit that executes a response process of transmitting a process response message to the other control device. The processing unit, based on the processing information and the communication information, when the communication condition is to complete the response processing within a predetermined response time and the communication request is received from the other control device Then, it is determined whether or not the communication satisfies the communication condition, and determination information indicating the result of the determination is transmitted to the other control device.

  According to one aspect of the present invention, the control device can complete the time from reception of the request to transmission of the response within a predetermined time.

The structure of the control system of embodiment of this invention is shown. A configuration of the node 100 is shown. The relationship between the application execution period 171 and the application execution time 172 is shown. A response transmission management table 130 and a request transmission management table 140 are shown. The function structure of the communication middleware 160 is shown. The flow of an upper limit reception amount determination process is shown. The sequence of communication processing is shown. The flow of the connection establishment process and data acquisition process in a request source is shown. The flow of the connection establishment process and data acquisition process in a request destination is shown. Indicates the reception timing of the data acquisition request message. The flow of data acquisition processing at the request destination is shown.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings describing the embodiment of the present invention, the same parts are denoted by the same reference numerals, and repeated description thereof will be omitted.

  FIG. 1 shows a configuration of a control system according to an embodiment of the present invention. This control system includes a plurality of nodes 100 (100a, 100b, 100c, 100d). A certain node 100 accesses data stored in another node via the network 114. The number of nodes in the system is not limited to the number illustrated in this figure. For example, each node is a control device that is connected to the control target device and monitors and controls the control target device.

  FIG. 2 shows the configuration of the node 100. The node 100 is a computer such as a controller (control device), a workstation, or a personal computer.

  The node 100 includes, as hardware modules, a storage unit 111 including a volatile / nonvolatile memory and a hard disk device, a processing unit 112 including a central processing unit (CPU), and a communication interface (communication I / F). 113). The communication interface 113 is an interface for connecting to the network 114, and corresponds to a communication interface such as Ethernet (registered trademark) or wireless LAN (Local Area Network). The storage unit 111 stores programs and data. The processing unit 112 executes a program stored in the storage unit 111.

  The storage unit 111 executes the OS 150, the communication middleware 160, and the applications 170 (170a and 170b) as programs. The storage unit 111 further stores a setting file 120, a response transmission management table 130, and a request transmission management table 140 as data. The storage unit 111 further includes a shared memory area 180 that is an area accessible from other nodes.

  The setting file 120 includes an application execution period 171 indicating an execution period of the application 170, an application execution time 172 that is an execution time of the application 170 in the application execution period 171, and data reception request messages received from other nodes. Time required for data acquisition processing until response message transmission (hereinafter referred to as data acquisition processing time), and maximum storage that is the maximum number of messages that can be received by the communication interface 113 and stored in the buffer in the buffer secured by the OS 150 It includes the number of messages and information regarding the node address that uniquely identifies each node 100.

  The data acquisition request message is a message transmitted to the node 100 in the system in order to access the data stored in the storage unit 111 of the node 100. Hereinafter, the node 100 that transmits the data acquisition request message is referred to as a request source, and the node 100 that receives the data acquisition request message is referred to as a request destination.

  The control system of this embodiment and the data acquisition request message transmission / reception method include a single request message method and a periodic request message method.

  In the one-shot request message method, the node 100 that has received the data acquisition request message transmits the data stored in the storage unit 111 as a data acquisition response message each time it is received. Thereby, the request destination can transmit a data acquisition response message in response to the data acquisition request message from the request source.

  On the other hand, in the periodic request message method, the node 100 that has received the data acquisition request message only once transmits a response message spontaneously in the period indicated in the data acquisition request message. As a result, the data acquisition response message can be transmitted at a given cycle after the request source does not transmit the data acquisition request message.

  The data acquisition request message is responded to because of the number of target data to be accessed, the top memory address where the target data is stored in the shared memory area 180 of the request destination, its data size, and the periodic request message method. Includes the cycle for sending messages.

  FIG. 3 shows the relationship between the application execution period 171 and the application execution time 172. As shown in this figure, in general, an application 170 operating on a control system has an application execution period having a fixed application execution time 172 each time an application execution cycle 171 that is a fixed cycle elapses. Operate. When the node 100 executes a plurality of applications 170a and 170b, the application execution period is a period obtained by combining the execution periods of the plurality of applications 170a and 170b. The application execution time 172 in this case is the total of the execution times of the plurality of applications 170a and 170b. In the application execution cycle 171, a period other than the application execution period is called an application standby period.

  When the node 100 receives the data acquisition request message from another node, the node 100 analyzes the data acquisition request message in the application waiting period, acquires the data specified by the data acquisition request message from the storage unit 111, and returns the acquired data as a response. Data acquisition processing to be transmitted to other nodes as a message is performed.

  When the application execution time 172 is shorter than the application execution cycle 171 or when the number of received data acquisition request messages is small, the node 100 can perform data acquisition processing during the application standby period.

  However, when the application execution cycle 171 and the application execution time 172 are almost the same, there is almost no time for performing the data acquisition process, and therefore the node 100 acquires the data acquisition request message received in a certain application execution cycle. Processing may be performed in the next application execution cycle.

  In this case, it is not known whether the timing of data acquisition processing by the request destination is before or after the requested data is updated. Therefore, for example, when the application 170 issues a data acquisition request a plurality of times as in the case of control logic or failure / accident analysis, the expected operation may not be possible due to the difference in the update timing of the data. There are cases where request / response type data access such as is not applicable to the control system.

  Therefore, the control system of the present embodiment transmits the data acquisition request message by the request source so that the request destination can receive the data acquisition request message and transmit the response message within one application execution cycle. Control.

  FIG. 4 shows a response transmission management table 130 and a request transmission management table 140.

  The response transmission management table 130 is a table indicating a data acquisition request message received from another node, and includes an entry for each data acquisition request message. The entry corresponding to one connection includes a request source node address 131, a request head memory address 132, a data size 133, and a response transmission cycle 134. The request source node address 131 indicates the node address of the request source of the data acquisition request message. The node address is, for example, a network address such as an IP (Internet Protocol) address. The request start memory address 132 is included in the data acquisition request message and indicates the start memory address of the acquisition target data. The data size 133 indicates the data size included in the data acquisition request message. The response transmission period 134 is included in the data acquisition request message and indicates the transmission period of the response message. Among these items, the request head memory address 132, the data size 133, and the response transmission cycle 134 are included in the data acquisition request message of the periodic request message method and included in the data acquisition request message of the single request message method. I can't.

  In the periodic request message method, the request destination transmits data corresponding to the size indicated by the data size 133 from the address indicated by the request head memory address 132 as a response message at the period indicated by the response transmission period 134. By using the periodic request message method, if the connection with the request source is established, the request destination does not receive a data acquisition request message from the request source, and the response message is sent every time the response transmission cycle 134 elapses. Can be sent.

  According to this response transmission management table 130, the request destination can manage a plan for reception from the request source.

  The request transmission management table 140 is a table used by a request source for transmission timing control of a data acquisition request message, and includes an entry for each request destination that has established a connection. An entry corresponding to one request destination includes a request destination node address 141 and a request transmission cycle 142. The request destination node address 141 indicates a node address that transmits a data acquisition request message. The request transmission period 142 indicates a period for transmitting a data acquisition request message to the node 100 indicated by the request destination node address 141.

  The request source transmits a data acquisition request message to the node 100 indicated by the request destination node address 141 every request transmission cycle 142. By transmitting the data acquisition request message every elapse of the request transmission cycle 142 received from the request destination by the request source, the number of data acquisition request messages received by the request destination can be limited.

  According to the request transmission management table 140, the request source can manage the transmission plan to the request destination.

  The OS 150 is basic software that comprehensively controls the operation of the node 100.

  FIG. 5 shows a functional configuration of the communication middleware 160.

  The communication middleware 160 controls the transmission timing of the data acquisition request message so that reception of the data acquisition request message and transmission of a response message to the data acquisition request message can be processed within one application execution cycle. The communication middleware 160 includes a message generation / transmission unit 161, a message analysis / reception unit 162, a data acquisition request reception unit 163, a data acquisition unit 164, a periodic data management unit 165, and a bandwidth management unit 166 as modules. including.

  The message generation / transmission unit 161 generates a message according to a command from another module and transmits it through the communication interface 113.

  The message analysis / reception unit 162 receives a message transmitted from another node via the communication interface 113, analyzes the message, and transmits the result to another module according to the analysis result.

  The data acquisition request reception unit 163 receives a data acquisition request from the application 170 and transmits the request to the message generation / transmission unit 161 in accordance with the request transmission cycle 142 indicated in the request transmission management table 140. The message generation / transmission unit 161 transmits a data acquisition request message based on the request, and the message analysis / reception unit 162 receives a response message to the data acquisition request message and sends a response to the data acquisition request as a data acquisition request reception unit. To 163. The data acquisition request reception unit 163 receives the response from the message analysis / reception unit 162 and transmits the response to the corresponding application 170.

  The data acquisition unit 164 acquires data from the storage unit 111 in response to the data acquisition request message received by the message analysis / reception unit 162 and transmits the result to the message generation / transmission unit 161.

  After receiving the data acquisition request message of the periodic request message method, the periodic data management unit 165 transmits a data acquisition request to the data acquisition unit 164 in accordance with the response transmission period 134 shown in the response transmission management table 130. .

  The bandwidth management unit 166 calculates an upper limit reception packet rate at the time of power activation described later, and controls transmission of a data acquisition request message by another node according to the calculated rate. The upper limit reception packet rate is the number of data acquisition request messages that can be received by the node 100 within the application execution cycle.

  The application 170 operates for each application execution period 171 during the application execution period. The storage unit 111 stores a memory address of data necessary for the operation of the application 170 in the shared memory area 180 of the request destination in the storage unit 111 of another node. The application 170 acquires data from the communication middleware 160 by issuing a data acquisition request designating the memory address of another node to the communication middleware 160. The OS 150 guarantees the operation of the application 170, prioritizes execution of the application 170 over other processing such as data acquisition processing, and executes the application 170 every application execution cycle 171.

  Hereinafter, the operation of the node 100 will be described.

  When the node 100 is powered on, the bandwidth management unit 166 performs an upper limit reception amount determination process for determining the upper limit of the reception amount of the data acquisition request message.

  FIG. 6 shows a flow of the upper limit reception amount determination process.

  After powering on the node 100, the bandwidth management unit 166 reads the setting file 120 stored in the storage unit 111, and information such as an application execution cycle 171, application execution time 172, data acquisition processing time, and the maximum number of messages. Is acquired (S500). If there is information that can be acquired through the OS 150 among these pieces of information, the setting file 120 may not be used and may be acquired through the OS 150.

  Next, the bandwidth management unit 166 calculates the request message processing rate and the buffer overflow prevention rate using the acquired information (S510, S520).

  The request message processing rate is the number of data acquisition request messages that can be subjected to data acquisition processing per unit time. The data acquisition request message received during the application execution cycle is subjected to data acquisition processing during the application standby period. For example, when the unit time is the application execution cycle 171, the application execution cycle 171 is 50 ms, the application execution time 172 is 30 ms, and the data acquisition processing time is 1 ms, the request message processing rate is (application execution cycle 171-application execution time 172 ) ÷ data acquisition processing time ÷ application execution cycle 171 = (50 ms−30 ms) ÷ 1 ms ÷ 50 ms = 20/50 ms. In this case, the node 100 can perform data acquisition processing of up to 20 data acquisition request messages within the application standby period.

  When the node 100 receives the number of messages exceeding the request message processing rate within the application execution cycle, the data acquisition processing may not be completed within the application execution cycle.

  The buffer overflow prevention rate is the number of data acquisition request messages that can be stored in the buffer per unit time during the application execution period. For example, the maximum number of data acquisition request messages that can be stored in the buffer is 90, If the application execution time 172 is 30 ms, the maximum number of stored messages / application execution time 172 = 90/30 ms = 3 / ms = 150/50 ms. In this case, the node 100 can receive up to 150 data acquisition request messages within the application execution period.

  When the node 100 receives the number of messages exceeding the buffer overflow prevention rate during the application execution period, the data acquisition request message cannot be stored in the buffer, and thus the data acquisition request message may be lost.

  After calculating both the request message processing rate and the buffer overflow prevention rate, the bandwidth management unit 166 sets the smaller one of these two rates as the upper limit reception packet rate (S530). For example, in the values of the request message processing rate and the buffer overflow prevention rate, the request message processing rate is set as the upper limit reception packet rate.

  The above is the flow of the bandwidth management unit 166 at the time of power activation. The plurality of nodes 100 operate asynchronously, and the request destination does not know the transmission timing of the data acquisition request message by the request source. That is, the request destination may receive a data acquisition request message during the application execution period, or may receive a data acquisition request message during the application waiting period. According to the flow of the bandwidth management unit 166, the number of data acquisition request messages that can be received in each period is calculated, the smaller one is determined as the upper limit reception packet rate, and the number of data acquisition request messages received within the application execution cycle Is limited below the upper limit received packet rate. Thereby, the time required for the data acquisition process from the reception of the data acquisition request message to the transmission of the response message can be made equal to or shorter than a predetermined response time.

  The bandwidth management unit 166 uses the number of data acquisition request messages that can be processed during the application execution period within a predetermined measurement time as the request message processing rate, and obtains data that can be received during the application standby period within the measurement time. The number of request messages may be the buffer overflow prevention rate, and the number of data acquisition request messages that can be processed within the measurement time may be the upper limit reception packet rate. In this case, the bandwidth management unit 166 may use the measurement time as the application execution cycle.

  Since the transmission processing time for transmitting the data acquisition request message is smaller than the application execution time and the data acquisition processing time, and the influence on other processing is small, the node 100 uses the transmission processing for calculating the request message processing rate. There is no need to consider time. Further, the node 100 may calculate the request message processing rate by subtracting a preset transmission processing time from the length of the application waiting period.

  Hereinafter, a communication process in which the target data is acquired by the node 100a as the request source communicating with the node 100b as the request destination will be described.

  FIG. 7 shows a communication processing sequence.

  The application 170a operating on the node 100a transmits a data acquisition request to the communication middleware 160 (S610). In this request, the node address of the request destination and the memory address storing the target data are designated. In the case of the periodic request message method, the data acquisition request further specifies a response transmission cycle that is a data acquisition cycle.

  The communication middleware 160 that has received the data acquisition request performs connection establishment processing as necessary (S700). Details of the connection establishment process will be described later. Through the connection establishment process, the node 100b determines whether or not the upper limit received packet rate calculated for power activation exceeds the request from the node 100a. This prevents the operation of the node 100 that has already established a connection with the node 100b from being affected.

  If it is difficult to establish a connection as a result of the connection establishment process (S700) (No in S720), the communication middleware 160 notifies the application 170a that data cannot be obtained (S820).

  If the connection can be established as a result of the connection establishment process (S700) (Yes in S720), the communication middleware 160 executes a data acquisition process for accessing the data stored in the storage unit 111 of the node 100b (S800). A data acquisition response as the execution result is notified to the application 170a (S820). In the case of the periodic request message method, S800 and S820 are repeatedly performed.

  According to the above communication processing, the request source establishes a connection by communication with the request destination, and if the connection is established, data can be acquired from the request destination.

  FIG. 8 shows a flow of connection establishment processing and data acquisition processing at the request source.

  In the connection establishment process (S700), when receiving the data acquisition request from the application 170a, the data acquisition request receiving unit 163 of the communication middleware 160 of the node 100a analyzes the received content and refers to the request transmission management table 140 (S710). , S712).

  If the request transmission management table 140 includes the node address of the request destination, the data acquisition request receiving unit 163 determines that the connection has been established (Yes in S714), and executes the data acquisition process (S810 and later). To do.

  When the request transmission management table 140 does not include the node address of the request destination, the data acquisition request reception unit 163 determines that the connection has not been established (No in S714), and executes the connection process. The message generation / transmission unit 161 generates a connection establishment request message and transmits the connection establishment request message to the node 100b (S716).

  After transmitting the connection establishment request message, the message analysis / reception unit 162 receives and analyzes the connection establishment response message corresponding to the request (S718). If it is determined that the connection can be established (Yes in S720), The data acquisition request reception unit 163 sets the request destination node address 141 and the request transmission cycle 141 included in the response in the request transmission management table 140, and proceeds to data acquisition processing (S810 and subsequent steps).

  As a result of the analysis, when it is determined that connection establishment is difficult (No in S720), the data acquisition request receiving unit 163 notifies the application 170a that data acquisition is not possible (S820).

  The above is the description of the connection establishment process in the requesting node 100a. Next, the data acquisition process (S800) in the node 100a will be described.

  The data acquisition request reception unit 163 of the communication middleware 160 refers to the request transmission cycle 142 included in the request transmission management table 140 and determines whether it is time to transmit the data acquisition request message (S810).

  When it is determined that it is time to transmit (Yes in S810), the message generation / transmission unit 161 generates and transmits a data acquisition request message (S812).

  When the message analysis / reception unit 162 receives and analyzes the response message to the transmitted data acquisition request message (S814), the data acquisition request reception unit 163 notifies the application 170a of the result (S820).

  On the other hand, when it is determined that it is not the timing to transmit the data acquisition request message (No in S810), the data acquisition request reception unit 163 enters a wait state for the data acquisition request message, and receives from the application 170a or another application. It waits for a data acquisition request (S816).

  According to the above processing of the request source, if the connection with the request destination is not established, the connection can be established and the request transmission cycle can be received from the request destination. Thereby, the request source can transmit the data acquisition request message according to the request transmission cycle.

  FIG. 9 shows a flow of connection establishment processing and data acquisition processing at the request destination.

  When the message analysis / reception unit 162 receives the connection establishment request message from the node 100a (Yes in S750), the message management / notification unit 162 notifies the bandwidth management unit 166 to that effect, and the bandwidth management unit 166 that has received the notification transmits the response transmission management table 130. (S752), the total of the number of data acquisition request messages received by the established connection and the received connection establishment request message is calculated, and the received packet rate which is the total number of messages per unit time is calculated. It is calculated, and it is determined whether or not the calculated received packet rate exceeds the upper limit received packet rate (S754). The number of data acquisition request messages is, for example, the number of entries in the response transmission management table 130. The unit time is, for example, the application execution cycle 171.

  If it is determined that the received packet rate does not exceed the upper limit received packet rate (No in S754), the message generation / transmission unit 161 transmits a connection establishment response message indicating the request transmission cycle (S756), and performs processing. The process proceeds to S750.

  When it is determined that the received packet rate exceeds the upper limit received packet rate (Yes in S754), the message generation / transmission unit 161 transmits a connection establishment response message indicating that the connection cannot be established (S758), and performs processing. The process proceeds to S750.

  The above is the description of the connection establishment process in the requested node 100b. Next, the data acquisition process (S800) in the node 100b will be described.

  When the message analysis / reception unit 162 receives the data acquisition request message (in the case of No in S750) instead of the connection establishment request message (in the case of No in S750), the message analysis / reception unit 162 notifies the data acquisition unit 164 to that effect. Upon receiving the notification, the data acquisition unit 164 acquires the corresponding data from the request-destination shared memory area 180 (S854), and the message generation / transmission unit 161 transmits a response including the acquired data to the node 100a ( S856), the process proceeds to S750 of the connection establishment process.

  Further, the periodic data management unit 165 refers to the response transmission management table 130 and determines whether or not it is time to transmit the periodic data, that is, whether or not the response transmission period 134 has elapsed since the previous transmission of the periodic data. (S858). The periodic data is a response message that the request destination transmits every response transmission period 134 in the periodic request message method.

  As a result of the determination, if it is determined that it is time to transmit the periodic data (Yes in S858), the data acquisition unit 164 is notified of this. The data acquisition unit 164 that has received the notification acquires the corresponding data from the shared memory area 180 of the request destination (S854), and the message generation / transmission unit 161 transmits a response including the acquired data to the node 100a (S856). .

  In S858, when it is determined that it is not the timing for transmitting the periodic data (No in S858), the periodic data management unit 165 waits until the timing for transmitting the periodic data is reached.

  According to the above processing of the request destination, whether or not to establish a connection based on the number of data acquisition request messages received within the application execution period 171 when a connection establishment request message is received from the request source. Can be determined. As a result, the number of data acquisition request messages received within the application execution cycle 171 can be limited, and a response message delay due to an increase in the number of data acquisition request messages can be prevented. In addition, when a request destination receives a data acquisition request message of a periodic request message method together with connection establishment, it can transmit a response message every response transmission period 134 without receiving a data acquisition request message thereafter. .

  With the above operation, the node 100a can acquire the target data stored in the node 100b.

  As described above, when the request destination that has received the connection establishment request message determines to establish a connection, the application 170 transmits a connection establishment response message indicating the request transmission cycle, so that the application 170 in the shared memory area 180 The timing of transmitting the data acquisition response message can be kept constant with respect to the timing of updating the data.

  In addition, the request destination limits the amount of data acquisition request messages received from other nodes by determining whether or not to establish a newly requested connection based on information on connections that have already been established. be able to. Further, the response process from the reception of the data acquisition request message to the transmission of the data acquisition response message by the request destination can be completed within a predetermined response time. As a result, the timing at which the data acquisition request message is received can be kept constant with respect to the timing at which the requested application 170 updates the data in the shared memory area 180. Also, by setting the response time as the application execution cycle, the amount of data acquisition request messages that can be processed within the application execution cycle can be limited.

  FIG. 10 shows the reception timing of the data acquisition request message.

  Depending on the reception timing of the data acquisition request message, such as when the request destination receives a data acquisition request message just before the end of the application execution cycle, the data acquisition process is interrupted during the data acquisition process, and the data acquisition process is interrupted. Data acquisition processing may be resumed after the execution period. Thus, when the data acquisition process extends over the next application execution cycle, the target data may be updated by the application. Here, a data acquisition process for detecting a case where the data acquisition process extends over the next application execution cycle will be described.

  FIG. 11 shows the flow of data acquisition processing at the request destination.

  The message analysis / reception unit 162 of the requesting node 100b receives the data acquisition request message from the requesting node 100a (S850), analyzes the message (S852), and then the data acquisition unit 164 is a processing unit. The current time is confirmed using a clock included in 112, etc., and stored in the storage unit 111 as time A (S1000).

  Next, the data acquisition unit 164 acquires the corresponding data from the requested shared memory area 180 (S854).

  After data acquisition, the data acquisition unit 164 confirms the current time, and compares the time B with the time A (S1010, S1020), as in S1000.

  As a result of the comparison, if the difference between the two times is longer than the application execution time 172 (Yes in S1020), the data acquisition unit 164 determines that the application 170 has been executed during the data acquisition process, and an error occurs. A response is transmitted to the node 100a (S1030), and the process proceeds to S750 described above.

  As a result of the comparison, if the difference between the two times is shorter than the application execution time 172 (No in S1020), the data acquisition unit 164 determines that the data acquisition process has been performed normally, and uses the acquired data as a response. (S1040), and the process proceeds to S750 described above.

  According to this data acquisition process, it is possible to determine whether or not the application has been executed during the data acquisition process by checking the time before the data acquisition and the time after the data acquisition.

  The process requested by the request message from the other node is not only the transmission of the data stored in the shared memory area 180, but also other processes such as the calculation using the data and the transmission of the calculation result. good. A data acquisition request message may be used instead of the connection establishment request message. In the periodic request message, a connection establishment request message may be used instead of the data acquisition request message.

  As described above, an error is transmitted to the request source when the timing at which the request destination application 170 updates the data in the shared memory area 180 and the timing at which the data acquisition request message is received are different. Therefore, it is possible to prevent the request source from using incorrect data. Further, the request source can acquire the requested data within a certain application execution cycle within the cycle, and can ensure that the acquired data is the data updated within the cycle.

  Terms for the expression of the present invention will be described. The node 100b or the like may be used as the control device. As another control device, the node 100a or the like may be used. As the application execution cycle, an application execution cycle 171 or the like may be used. The storage unit 111 or the like may be used as the storage unit. The processing unit 112 or the like may be used as the processing unit. As the processing information, the setting file 120 or the like may be used. As the communication information, the response transmission management table 130, the request transmission management table 140, etc. may be used. A connection or the like may be used as the communication and the second communication. As the process, a process for obtaining data stored in the shared memory area 180 may be used. A connection establishment response message or the like may be used as the determination information. A connection establishment request message or the like may be used as the communication request message and the second communication request message. A data acquisition request message or the like may be used as the processing request message and the second processing request message. A data acquisition response message or the like may be used as the processing response message. As the reception time, a unit time, an application execution cycle, or the like may be used. The upper limit reception packet rate or the like may be used as the upper limit reception number. As the number of receptions, the number of data acquisition request messages may be used. A request message processing rate or the like may be used as the upper limit response processing number. A buffer overflow prevention rate or the like may be used as the upper limit storage number. An application execution period or the like may be used as the operation period. An application waiting time or the like may be used as a period other than the operation period. An application execution time 172 or the like may be used as the operation time. A processing time or the like may be used as the response processing time. The request transmission cycle 142 or the like may be used as the request transmission cycle and the second request transmission cycle. The response transmission cycle 134 or the like may be used as the response transmission cycle.

  The embodiment has been specifically described above, but the present invention is not limited to the above disclosure, and it goes without saying that various modifications can be made without departing from the spirit of the embodiment.

DESCRIPTION OF SYMBOLS 100 ... Node 111 ... Memory | storage part 112 ... Processing part 113 ... Communication interface 114 ... Network 120 ... Setting file 130 ... Response transmission management table 140 ... Request transmission management table 150 ... OS 160 ... Communication middleware 170 ... Application 180 ... Shared memory area

Claims (7)

A storage unit for storing processing information indicating a predetermined application execution cycle and communication information indicating a plan of communication with another control apparatus connected via a network;
The application is executed at each application execution cycle, and a processing response message including a result of the processing is executed to the other control device when the processing request message which is a processing request is received from the other control device. A processing unit for executing a response process to be transmitted;
With
The processor is
Based on the processing information and the communication information when the communication processing is received from the other control device, and the response processing is completed within a response time that is a predetermined application execution cycle. Determining whether or not the communication satisfies the communication condition, and transmitting determination information indicating the result of the determination to the other control device ,
When a communication request message that is a request for the communication is received from the other control device, it is determined whether the communication satisfies the communication condition,
In order for the communication to satisfy the communication condition, an upper limit reception number that is the number of processing request messages that can be received within a reception time that is a predetermined application execution cycle is calculated,
When the communication request message is received from the other control device, a reception number that is the number of processing request messages scheduled to be received within the reception time is calculated based on the communication information, and the reception number is the upper limit The communication condition must be less than the number of receptions,
The processing information further includes an operation time that is the length of the operation period of the application within the application execution cycle, and a response processing time that is the length of the response processing time,
The processing unit calculates an upper limit response process number that is the number of response processes that can be executed in a period other than the operation period within the application execution cycle, and determines an upper limit reception number based on the upper limit response process number.
Control device. The processing information further includes an upper limit storage number that is the number of processing request messages that can be received and stored during the operation period,
The processing unit determines an upper limit reception number based on the upper limit storage number.
The control device according to claim 1 . The processing unit determines the smaller of the upper limit response processing number and the upper limit storage number as the upper limit reception number,
The control device according to claim 2 . When it is determined that the communication satisfies the communication condition, the processing unit transmits information indicating a request transmission cycle, which is a transmission cycle of a processing request message, to the other control device,
The processing request message is transmitted from the other control device for each request transmission cycle.
The control device according to claim 3 . The processing unit measures a processing time from a time at which the processing request message is received to a time at which the processing is completed, determines whether the processing time is longer than the operation time, and the processing time When it is determined that the operation time is longer, a response indicating an error is transmitted to the other control device.
The control device according to claim 4 . The processing unit transmits a second communication request message requesting second communication to the other control device, and the second control device determines that the second communication satisfies the communication condition, and sets a second request transmission cycle. When receiving the information indicating from the other control device, the second processing request message is transmitted to the other control device every second request transmission cycle.
The control device according to claim 1 . When it is determined that the communication satisfies the communication condition and information indicating a response transmission period is received from the other control device, the processing unit executes the process for each response transmission period, and the result of the process A processing response message indicating
The control device according to claim 1.

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