JP5140692B2 - Polling transmission system, polling transmission method, and polling transmission program - Google Patents

Description

  The present invention relates to a polling transmission system, a polling transmission method, and a polling transmission program.

  In a transmission system in which a master station as a primary station and a plurality of slave stations as secondary stations are coupled by a communication line, data transmission / reception using a polling method is employed.

  The polling method is a method in which a master station inquires a plurality of slave stations whether there is data to be transmitted. The inquiry is performed by transmitting a polling signal from the master station to each slave station at regular intervals. When there is data to be transmitted in the slave station, the data is transmitted to the master station in the form of a response to the polling signal transmitted from the master station. As a result, even when there is only one communication line connecting the master station and the plurality of slave stations, there is no conflict between the slave stations during data transmission / reception.

  In such a transmission system, it is necessary to perform data transmission in a predetermined band so that the communication line is not overloaded with transmission data from each slave station. Therefore, the amount of data that can be transmitted from the slave station in response to a single inquiry (polling signal) (hereinafter referred to as one-time transmission capacity) is determined in advance, and when transmitting a large amount of data from the same slave station, Data is divided into one transmission capacity for each transmission, and then transmitted to the master station.

  Because of this data division transmission processing, in the polling method in which an inquiry signal is sequentially received from the master station at a constant cycle, if a large amount of data is generated in a short time, the data cannot be sent in one poll and the child is not transmitted. Data waiting for transmission accumulates in the station, and time is required for transmission to the master station.

For example, it is assumed that there will be a failure in the equipment belonging to the downstream system and other related equipment due to the occurrence of a transmission line ground fault or transformer failure in the power system, and a large amount of data will be generated in the same slave station It will be. In addition, the spread of this failure is not limited to the same slave station, but affects neighboring systems, and it is assumed that data is also generated in other slave stations.
In this case, it takes time to transmit data to the master station even in the slave station where the fault has occurred and the slave station that is the destination of the fault. As a result, the collection of the failure information of the slave station is delayed, so that the process of emergency stop of the plant is delayed, and there is a possibility that a secondary failure such as damage to the plant equipment occurs.

In this way, in the polling method that inquires whether there is data to be transmitted from the master station to multiple slave stations, there is a problem that the time criticality cannot be guaranteed in the collection of data waiting for transmission from the slave station. Several techniques have been published so far.
For example, Patent Document 1 describes a technique for collecting necessary information of a system by changing a polling order or a polling cycle according to the importance, priority, and relevance of a main unit as a slave station.

Japanese Patent Laid-Open No. 10-94071

  When polling transmission is performed using the technology described in Patent Document 1, a large amount of data is transmitted from the same slave station at a time, so that transmission waiting data of the slave station where a large amount of data is generated is preferentially collected. This increases the efficiency of information collection for the entire transmission system.

  On the other hand, when highly important data (such as highly urgent failure data) accumulates in the slave station, a mechanism is required to transmit the highly important data with priority over other data. It has been.

  However, in the technique described in Patent Document 1, it is necessary to wait for a time of “data division number × polling period × number of slave stations” at the longest before the polling transmission order comes to highly important data. Even though it is highly important data, there was a waiting for transmission.

  In view of this, the present invention solves the above-described problems and efficiently transmits important data having a large amount of data in a transmission system in which a master station and a plurality of slave stations are coupled by a communication line. With a purpose.

In order to solve the above problems, the present invention is a polling transmission system for performing data communication by a polling method between a master station which is a primary station and a plurality of slave stations which are secondary stations,
The slave station includes a priority request unit, a request count calculation unit, a polling processing unit, and a storage unit.
The storage means includes input data to be transmitted to the master station, a priority data parameter for specifying priority data among the input data, and polling for transmitting the priority data and related data. Priority request data that prescribes the number of data communication methods is stored,
The priority data parameter of the storage means includes, for each priority data specified by the priority data parameter, polling of each slave station for transmitting the input data of each slave station related to the priority data Number of times,
The priority request unit detects that the priority data is included in the input data by comparing the input data and the priority data parameter input to the slave station that is the local station,
Based on the detected data amount of the input data in the storage means of the priority data own station and the number of polls of each slave station associated with the priority data parameter , Creating the priority request data as the number of polling of each slave station related to the detected priority data,
When the priority request data is present, the polling processor returns a polling response including the priority request data as a response to the polling request in the polling method received from the master station,
The master station
Until a polling response including the priority request data is received, a slave station is selected one by one according to a predetermined order, and a polling request is transmitted.
When a polling response including the priority request data is received, a polling request corresponding to the number of polling times of each slave station specified by the priority request data is transmitted rather than a process of transmitting a polling request according to the predetermined order. It is characterized by giving priority to processing.
Other means will be described later.

  According to the present invention, it is possible to efficiently transmit important data having a large data amount in a transmission system in which a master station and a plurality of slave stations are coupled by a communication line.

It is explanatory drawing which shows the structural example of the transmission system regarding one Embodiment of this invention, and the example of a format of the polling response signal used with the transmission system. It is a block diagram which shows the internal structural example of the subunit | mobile_unit regarding one Embodiment of this invention. It is explanatory drawing which shows the example of an internal data structure of the slave station regarding one Embodiment of this invention. It is a flowchart which shows operation | movement of the whole transmission system when priority data does not generate | occur | produce in the monitoring control object apparatus regarding one Embodiment of this invention. It is a flowchart which shows operation | movement of the whole transmission system when priority data generate | occur | produces in the monitoring control object apparatus regarding one Embodiment of this invention. It is a flowchart which shows the example of the storage process of the input data buffer which the data input part regarding one Embodiment of this invention performs. It is a flowchart which shows the example of the storage process of the transmission waiting data buffer which the priority request | requirement part regarding one Embodiment of this invention performs. It is a flowchart which shows the example of the polling frequency calculation process which the request frequency calculation part of the sub_station | mobile_unit regarding one Embodiment of this invention performs. It is a flowchart which shows the example of the transmission / reception process of the data which the polling process part regarding one Embodiment of this invention performs.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1A is a diagram illustrating a configuration example of a transmission system. This transmission system is composed of a master station 1 as a primary station and a slave station 2 as a secondary station (slave station 2a, slave station 2b,..., Slave station 2n: n is a natural number). A master station 1 and a slave station 2 are connected on the communication line 3 of the book. The slave station 2 monitors the status of each monitoring control target device 4 accommodated therein, and receives the status change as input data.
Each of these devices (the master station 1, the slave station 2, and the monitoring control target device 4) is configured as a computer having a CPU, a memory, and a network interface, and the CPU reads the program into the memory and executes it. Each process is executed.

The master station 1 is a device that monitors the slave station 2 and transmits a polling request signal as an inquiry signal for inquiring whether there is transmission data to the slave station 2 through the communication line 3 at regular time intervals. The polling request signal is transmitted to each of the slave stations 2 in order according to a prescribed order. When there is transmission waiting data to be transmitted to the master station 1, the slave station 2 that has received the polling request signal addressed to its own station adds the data to the polling response signal and transmits it to the master station 1.
In the following description, a pair of a polling request signal and a polling response signal will be described as a single polling process. In one polling response signal, the amount of data that can be transmitted is limited to a single transmission capacity or less.

  As an example, consider a case where the master station 1 transmits a polling request signal designating the slave station 2a. First, in the slave station 2a that has received the polling request signal addressed to its own station, when there is transmission waiting data to be transmitted to the master station 1, a polling response signal to which transmission waiting data is added is sent via the communication line 3 to the master station. 1 to send. On the other hand, the slave stations 2b to 2n that have received the polling request signal addressed to the other stations discard the polling request signal.

  The master station 1 changes the designation destination of the polling request signal in order of the slave station 2a → the slave station 2b →... → the slave station 2n, and transmits the polling request signal in the same manner as the slave station 2a. Collect data from station 2. That is, the master station 1 transmits a polling request signal addressed to each slave station 2 and receives the polling response signal data returned from each slave station 2, so that each slave station 2 holds the data as transmission waiting data. Data collection.

Note that the amount of data that can be transmitted with one polling response signal is limited to a single transmission capacity or less. Therefore, the slave station 2 that wants to transmit data exceeding the one-time transmission capacity as a polling response signal creates a plurality of data blocks less than the one-time transmission capacity by data division processing, and this polling response signal includes that data. Store one of the blocks.
Then, the slave station 2 transmits the next data block when the next polling request signal arrives. The one-time transmission capacity is recorded in advance in a setting file in the slave station 2 or the like.

In the present embodiment, the “number of data divisions” in the data division processing is not the number of times data division processing has been performed, but the number of data blocks generated as a result of the division, and the data blocks are transmitted. To match the number of polls.
For example, when (transmission target data amount) = 26 KB and (single transmission capacity) = 10 KB, this data is divided at two locations every 10 KB, and as a result, three data blocks (10 KB + 10 KB + 6 KB) are generated. Therefore, the number of data divisions and the number of polling in this case are both “3”.

FIG. 1B shows a packet to which priority request data 52 is not added as a format example of the polling response signal. The polling response signal includes a header part 51 and slave station data 53.
The header part 51 includes information on a transmission source and a destination.
The slave station data 53 includes data having a data amount equal to or less than the transmission capacity for one time.

FIG. 1C shows a packet in which priority request data 52 is added to the polling response signal of FIG. 1B as a format example of the polling response signal. The polling response signal includes a header part 51, priority request data 52, and slave station data 53.
The priority request data 52 stores the number of polls requested to the master station 1 for each slave station 2. “0” is set in the slave station 2 that does not require polling.

  FIG. 2 is a block diagram illustrating an internal configuration example of the slave station 2. In the figure, the slave station 2a is taken as an example, but the slave stations 2b to 2n are all assumed to have the same configuration. The slave station 2a includes a data input unit 20, an input data buffer 21, a priority request unit 22, a transmission waiting data buffer 25, a priority request data buffer 26, and a polling processing unit 27. The priority request unit 22 includes a priority data parameter storage unit 23 and a request count calculation unit 24.

The data input unit 20 reads input data from the monitoring control target device 4a and inputs data to the own station.
The input data buffer 21 stores input data input from the data input unit 20.
In the priority data parameter storage unit 23, the number of polls calculated so that the priority data and the data amount associated with each of the slave stations 2 can be efficiently transmitted to the master station 1 is registered in advance. .

The priority request unit 22 compares the data stored in the input data buffer 21 with the priority data parameter storage unit 23, and determines whether or not high-priority data (hereinafter referred to as priority data) exists in the input data buffer 21. Determine whether. Further, priority request data 52 including the number of polls calculated by the request frequency calculation unit 24 is stored in the priority request data buffer 26.
The request count calculation unit 24 refers to the data amount stored in the transmission waiting data buffer 25 and the priority data parameter storage unit 23 and calculates the number of polls to be transmitted to the master station 1.

  The transmission waiting data buffer 25 stores data for refraining from transmission to the master station 1. The priority request data buffer 26 stores priority request data 52 for refraining from transmission to the master station 1. The polling processing unit 27 is connected to the communication line 3 and receives a polling request signal transmitted from the master station 1. Here, when the polling request signal addressed to the own station is received, the transmission waiting data buffer 25 is confirmed, and the data read in order is added to the polling response signal. Further, the priority request data buffer 26 is confirmed, the priority request data 52 read in order is added to the polling response signal, and the polling response signal is transmitted to the master station 1.

FIG. 3 is an explanatory diagram showing an example of the internal data structure of the slave station 2.
In the input data buffer 21 shown in FIG. 3A, data 62 related to the monitoring control target device 4 input from the data input unit 20 is stored for each data ID 61. The data ID 61 is an identifier for making the data 62 individually identifiable. The data 62 stores data to be transmitted to the master station 1.

  In the priority data parameter storage unit 23 illustrated in FIG. 3B, the predicted polling count 72 of each slave station 2 is stored for each priority data ID 71. The priority data ID 71 is an identifier of data indicating priority data in the data ID 61. Therefore, the data 62 of the record that matches the data ID 61 and the priority data ID 71 is the priority data. A predicted value for each priority data is input to the predicted polling count 72 in advance by an administrator or the like.

In the two data buffers (transmission waiting data buffer 25 and priority request data buffer 26) shown in FIG. 3C, the data in the input data buffer 21 in FIG. 3A and the priority data in FIG. Based on the data in the parameter storage unit 23, the priority request unit 22 sets the data.
The transmission waiting data buffer 25 stores the data 62 of the input data buffer 21 in the order in which the data is input to the input data buffer 21.
The priority request data buffer 26 is based on the polling number of the predicted polling number 72 (variable N described later) and the polling number for transmitting the data amount of the transmission waiting data buffer 25 (variable M described later). The number of polling requests for each slave station 2 is stored as priority request data 52. Note that “0” is set in the priority request data 52 of the slave station 2 that does not request polling.

FIG. 4 is a flowchart showing the operation of the entire transmission system when priority data is not generated in the monitoring control target device 4.
In S101, when control data (measurement value or the like) is generated during normal operation in which an abnormal event such as a failure has not occurred, the monitoring control target device 4 notifies the slave station 2a that is the accommodation destination of the data. .
In S102, the data input unit 20 of the slave station 2a stores the input data from the monitoring control target device 4 in the input data buffer 21 in the input order.
In S103, the priority request unit 22 of the slave station 2a checks that the data ID 61 of the input data buffer 21 does not match the priority data ID 71 of the priority data parameter storage unit 23, and then sets the data 62 of the input data buffer 21 to The data is stored in the transmission wait data buffer 25.
In S104, the master station 1 makes a polling request to the slave station 2a in accordance with a prescribed order.
In S105, the polling processing unit 27 of the slave station 2a stores the data 62 in the transmission waiting data buffer 25 in the slave station data 53 of FIG. A polling response signal is created and a response is sent to the master station 1 that is the polling request source.
The master station 1 and each slave station 2 perform processing of a set of a polling request and a polling response according to a prescribed order. That is, after the master station 1 makes a polling request (S106) / polling response (S107) with the slave station 2b which is the next prescribed order of the slave station 2a, the slave station which is the next prescribed order of the slave station 2b 2n polling request / polling response (S108).

FIG. 5 is a flowchart illustrating the operation of the entire transmission system when priority data is generated in the monitoring control target device 4.
In S200, the monitoring control target device 4 detects the occurrence of an abnormal event such as a failure.
In S201, the monitored control target device 4 acquires (measures) data having a large data amount as priority data (such as data ID 61 = “5” in FIG. 3A) regarding the abnormal event in S200, and the data Is notified to the slave station 2a which is the accommodation destination.
In S202, the data input unit 20 of the slave station 2a stores the input data from the monitoring control target device 4 in the input data buffer 21 in the input order.
In S203, the priority request unit 22 of the slave station 2a checks that the data ID 61 of the input data buffer 21 matches the priority data ID 71 of the priority data parameter storage unit 23, and then sets the data 62 of the input data buffer 21 to The priority request data 52 is created and stored in the priority request data buffer 26 while being stored in the transmission waiting data buffer 25.
In S204, the master station 1 makes a polling request to the slave station 2a in accordance with the prescribed order.
In S205, the polling processing unit 27 of the slave station 2a stores the data 62 in the transmission-waiting data buffer 25 in the slave station data 53 of FIG. 1C as a response to the polling request, and the header unit 51 and S203. The polling response signal attached with the priority request data 52 is generated and responded to the master station 1 which is the polling request source.

When the priority request data 52 is added to the polling response signal in S205, the master station 1 temporarily suspends the polling process with each slave station 2 according to the specified order, and receives the received priority request data 52. The polling process with each slave station 2 is performed preferentially (as an interrupt process) in accordance with the order and number of times described in.
For example, the priority request data 52 of the polling response signal in FIG. 1C requires polling for priority data “5 times for the slave station 2a and 3 times for the slave station 2n”. Polling five times (S211, priority transmission) and polling the slave station 2n three times (S212, priority transmission). Note that when the priority request data 52 does not need to define the transmission order of the priority data, the order in which the number of polls for each slave station 2 is performed may be any order.

Further, after completing the polling interrupt process for the received priority request data 52, the master station 1 resumes the polling process with each slave station 2 according to the normal prescribed order that has been temporarily suspended. For example, the master station 1 makes a polling request (S206) / polling response (S207) with the slave station 2b which is the next specified order of the slave station 2a.
Thereby, transmission of priority data (S211, S212) can be realized as interrupt processing preferentially without waiting for polling processing (S206, S207) in a normal prescribed order.

FIG. 6 is a flowchart showing an example of storage processing (S102, S202) of the input data buffer 21 executed by the data input unit 20.
The data input unit 20 receives data input from the monitoring control target device 4a (S11). It is determined whether there is a change in the input data (S12), and if there is no conversion, the process returns to S11. If there is a change in the input data, the changed data is stored in the input data buffer 21 (S13).

FIG. 7 is a flowchart showing an example of storage processing (S103, S203) of the transmission waiting data buffer 25 executed by the priority request unit 22.
First, the data ID 61 of the data stored in the input data buffer 21 is compared with the priority data ID 71 of the priority data parameter storage unit 23 (S21), and it is determined whether or not priority data exists in the input data buffer 21. (S22). If it is determined that priority data does not exist, the data in the input data buffer 21 is stored in the transmission wait data buffer 25 (S27).

On the other hand, if it is determined in S22 that priority data exists, each slave station 2 is selected one by one and then a polling count calculation process (details will be described later in FIG. 8) is called (S23) The process is repeated until the slave station has been processed (S24, Yes).
Then, priority request data 52 is created from the polling count calculation result of S23 (S25), and the priority request data 52 is stored in the priority request data buffer 26 (S26). Then, the process proceeds to S27.

  FIG. 8 is a flowchart illustrating an example of the polling count calculation process (S23) executed by the request count calculation unit 24 of the slave station 2a. The processing in FIG. 8 is called after one slave station 2 to be calculated is designated. In the following description, the designated slave station 2 is referred to as designated slave station 2.

The request count calculation unit 24 determines whether or not the designated slave station 2 is its own station (S31). If it is the local station, the transmission wait data buffer 25 is referred to (S32), and it is determined whether or not there is slave data 53 waiting for transmission (S33).
If the slave station data 53 exists in S33, the amount of data waiting for transmission is confirmed, and the number of data divisions is calculated (S34). In the variable “M” indicating the calculated data division number, “M ← data division number” is set (S35). In the present embodiment, the symbol “A ← B” indicates a process of substituting the value B into the variable A.
On the other hand, if there is no data waiting for transmission in S33, or if the designated slave station 2 is not its own station in S31, the data division number “M ← 0” is set (S36).

Next, the polling count corresponding to the designated slave station 2 is acquired from the predicted polling count 72 of the priority data parameter storage unit 23 (S37). Then, the variable “N” indicating the number of polling acquired in S37 is set to “N ← polling number of the corresponding parameter” (S38).
Further, as a calculation result of the number of polling corresponding to the designated slave station 2 of the priority request data 52, the value of “polling number ← M + N” is set (S39).

  For example, if it is determined that the priority data with the data ID 61 = “5” in FIG. 3A exists (S22, Yes in FIG. 7), the priority request data 52 of the slave station 2a as the designated slave station 2 is transmitted. The sum of the data division amount (M = 3) of the waiting data buffer 25 and (S35 of FIG. 8), the number of times 2 of the slave station 2a of the predicted polling count 72 of the priority data parameter storage unit 23, and S38 of FIG. Is stored in the storage position of the slave station 2a of the priority request data 52 (S39 in FIG. 8).

FIG. 9 is a flowchart illustrating an example of data transmission / reception processing executed by the polling processing unit 27.
First, a polling request signal from the master station 1 is received (S41). This polling request signal is transmitted from the master station 1 in S104 and S204.
It is determined whether or not the priority request data 52 exists in the priority request data buffer 26 (S42). If data exists, the priority request data 52 is read in order, as shown in FIG. It is added to the polling response signal (S43). On the other hand, if the priority request data 52 does not exist in S42, the polling response signal does not add the priority request data 52 as shown in FIG.
Next, it is determined whether or not the slave station data 53 exists in the transmission waiting data buffer 25 (S44). If the slave station data 53 exists, the slave station data 53 is sequentially added to the polling response signal (S45).

  Here, the combination of the priority request data 52 added to the same polling response signal and the slave station data 53 has no particular relationship and is added in the order of reading. And after adding the header part 51 to the polling response signal constructed | assembled by each process of S42-S45, it transmits toward the main | base station 1 (S46). In the process of S46, this polling request signal is transmitted in S105 and S205.

According to the embodiment described above, when the slave station 2 detects the input of the priority data set in the priority data parameter storage unit 23, the slave station 2 sends a response signal with the priority request data 52 added to the master station 1. Send.
The priority request data 52 is a data structure for requesting the master station 1 to interrupt the normal polling order and transmit several consecutive polls.
When the master station 1 detects the priority request data 52 from the response signal, the master station 1 interrupts in the normal polling order and performs the number of times indicated by the priority request data 52 before performing normal polling processing when priority data is not generated. Then, according to the order, the corresponding slave stations are polled and transmitted.
As a result, the priority data is immediately transmitted without waiting for the normal polling order, so that priority data with a high degree of urgency can be quickly transmitted.
Therefore, since the time required for transmitting the priority data can be shortened as “data division number × polling period”, it is possible to increase the priority data throughput of the entire transmission system and to suppress data leakage from the buffer.

Further, the priority request data 52 may include not only the number of polls of the slave station 2 that is the own station but also the number of polls of the slave station 2 that is the other station. For example, a predetermined value stored in the priority data parameter storage unit 23 is substituted for the number of times the other station is polled. This predetermined value is calculated for each priority data ID so that the data capacity can be efficiently transmitted to the master station 1 based on the predicted value of the data capacity generated in the other station in relation to the priority data. This is the number of times (data division number).
For example, when the priority data generated in the own station is the transmission line ground fault data in the power system or the fault data of the transformer failure, it is established as the related data when the operator of the master station 1 issues the next control command. The other station data required as a condition is listed.
Thereby, the data of other stations generated in relation to the priority data generated by the own station can be transmitted immediately without waiting for the normal polling order.

DESCRIPTION OF SYMBOLS 1 Master station 2 Slave station 3 Communication line 4 Monitoring control object apparatus 20 Data input part 21 Input data buffer 22 Priority request part 23 Priority data parameter storage part 24 Request frequency calculation part 25 Transmission waiting data buffer 26 Priority request data buffer 27 Polling process Part 51 Header part 52 Priority request data 53 Slave station data 61 Data ID
62 Data 71 Priority data ID
72 Number of predicted polls

Claims (7)

A polling transmission system that performs data communication between a master station that is a primary station and a plurality of slave stations that are secondary stations by a polling method,
The slave station includes a priority request unit, a request count calculation unit, a polling processing unit, and a storage unit.
The storage means includes input data to be transmitted to the master station, a priority data parameter for specifying priority data among the input data, and polling for transmitting the priority data and related data. Priority request data that prescribes the number of data communication methods is stored,
The priority data parameter of the storage means includes, for each priority data specified by the priority data parameter, polling of each slave station for transmitting the input data of each slave station related to the priority data Number of times,
The priority requesting unit detects that the priority data is included in the input data by comparing the input data input to the slave station that is the local station and the priority data parameter,
The request count calculation unit is based on the detected amount of input data in the storage means of the priority data own station and the polling count of each slave station associated with the priority data parameter. , Creating the priority request data as the number of polling of each slave station related to the detected priority data,
When the priority request data exists, the polling processing unit returns a polling response including the priority request data as a response to the polling request in the polling method received from the master station,
The master station is
Until a polling response including the priority request data is received, a slave station is selected one by one according to a predetermined order, and a polling request is transmitted.
When a polling response including the priority request data is received, a polling request corresponding to the number of polling times of each slave station specified by the priority request data is transmitted rather than a process of transmitting a polling request according to the predetermined order. A polling transmission system characterized by prioritizing processing. When the request count calculation unit calculates the polling count of each slave station,
Corresponding to the priority data parameter and the number of data divisions, which is the result of dividing the data amount of the input data input to the slave station, which is its own station, by the amount of data that can be transmitted in one polling response The sum of the polling count of the local station is the polling count in the priority request data of the local station,
2. The polling transmission system according to claim 1, wherein the number of polling of the other station as each of the slave stations associated with the priority data parameter is set as the number of polling in the priority request data of the other station. When the priority request unit detects that the priority data is included in the input data, the priority ID is stored in the storage unit as the data ID of the input data stored in the storage unit and the priority data parameter. The polling transmission system according to claim 1 or 2, wherein the stored data ID of the priority data is compared, and when the data IDs coincide with each other, the input data is detected as the priority data. A polling transmission method by a polling transmission system that performs data communication by a polling method between a master station that is a primary station and a plurality of slave stations that are secondary stations,
The slave station includes a priority request unit, a request count calculation unit, a polling processing unit, and a storage unit.
The storage means includes input data to be transmitted to the master station, a priority data parameter for specifying priority data among the input data, and polling for transmitting the priority data and related data. Priority request data that prescribes the number of data communication methods is stored,
The priority data parameter of the storage means includes, for each priority data specified by the priority data parameter, polling of each slave station for transmitting the input data of each slave station related to the priority data Number of times,
The priority requesting unit detects that the priority data is included in the input data by comparing the input data input to the slave station that is the local station and the priority data parameter,
The request count calculation unit is based on the detected amount of input data in the storage means of the priority data own station and the polling count of each slave station associated with the priority data parameter. , Creating the priority request data as the number of polling of each slave station related to the detected priority data,
When the priority request data exists, the polling processing unit returns a polling response including the priority request data as a response to the polling request in the polling method received from the master station,
The master station is
Until a polling response including the priority request data is received, a slave station is selected one by one according to a predetermined order, and a polling request is transmitted.
When a polling response including the priority request data is received, a polling request corresponding to the number of polling times of each slave station specified by the priority request data is transmitted rather than a process of transmitting a polling request according to the predetermined order. A polling transmission method characterized by prioritizing processing. When the request count calculation unit calculates the polling count of each slave station,
Corresponding to the priority data parameter and the number of data divisions, which is the result of dividing the data amount of the input data input to the slave station, which is its own station, by the amount of data that can be transmitted in one polling response The sum of the polling count of the local station is the polling count in the priority request data of the local station,
5. The polling transmission method according to claim 4, wherein a polling count of the other station as each of the slave stations associated with the priority data parameter is set as a polling count in the priority request data of the other station. When the priority request unit detects that the priority data is included in the input data, the priority ID is stored in the storage unit as the data ID of the input data stored in the storage unit and the priority data parameter. 6. The polling transmission method according to claim 4, wherein the stored data ID of the priority data is compared, and when the data IDs coincide with each other, the input data is detected as the priority data. 7.   A polling transmission program for causing the master station and the slave station to execute the polling transmission method according to any one of claims 4 to 6.

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