JPH0329340B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a data transmission method in a remote monitoring and control device, and particularly a remote monitoring and control device that transmits data according to the priority order of urgent transmission. The present invention relates to a data transmission method.

[Background of the invention]

There are various configurations of remote monitoring and control devices. Some have a configuration in which separate lines are connected between the master station and the slave stations, and others have a configuration in which a loop-shaped transmission line is connected to the master station and the slave stations.

Figure 1 shows a loop-shaped transmission line 1 connected to one master station 2.
A conventional example is shown in which N slave stations 3 are formed in a loop. This configuration has the advantage that the total length of the transmission line is short because the transmission line is in a loop shape. This is particularly advantageous when the slave stations are arranged in a line. Furthermore, in addition to transmission between the master station and the slave stations, it also has the advantage of allowing communication between the slave stations. This is suitable for communication between slave stations associated with local intelligence.

In such a configuration, in addition to the method of cyclically transmitting data, there is a method of transmitting status change data in which status change data is transmitted only when a data change occurs.

Figure 2 shows a time chart of transmission and reception at that time. Furthermore, the data format flowing through the loop transmission line is shown in FIG. Figure 3 consists of the following contents.

Synchronization: Synchronization code for synchronizing codes.

Data presence/absence: A code that indicates whether data is included in the code.

Type: Code indicating the type of code.

Transmitting station: Code indicating the station where the data was generated.

Receiving station: A code indicating the data receiving station (destination).

Data: A code that indicates data items and their contents. It also includes a data length display. The data length may be fixed or variable.

Now, in Figure 2, both the master station and slave station receive R.
And transmission is indicated by S. Furthermore, within each time span,
The white time width A indicates a code that does not include data, and the time width B with a downward diagonal line to the left indicates a selected code.
The time width C shown in black indicates a reply code, and the time width D shaded downward to the right indicates a command code.

Now, in FIG. 2, when no data is being transmitted on line 1, format A, in which the data presence/absence code is null, flows on the line. The slave station that has the data to be transmitted (slave station 1 in Figure 2) receives this code with no data, changes the data presence code to the data presence code, and also sends the data transmitting station name and receiving station name. and add the data contents. Furthermore, the type is specified as the selection code (in addition to this selection, the type includes reception, transmission, etc.). The code thus obtained flows downstream. Each station is
It is checked whether the receiving station is the same or not. If it is not the receiving station, the data is passed downstream as is. If it is addressed to the receiving station, the display of selection, which is the content of the type described above, is changed to the display of return, and the data is taken in. The type is then sent downstream as a return code. FIG. 2 shows that slave station N is a receiving station. Eventually, this format will go around and return to the transmitting station. The transmitting station checks the content of this return display to see if it is different from the content it transmitted. If it is different, the type code is set as a command code and the code is sent downstream. After these steps are finished,
The master station again displays the data presence/absence code as blank and sends it downstream.

Since this data transmission format performs loop transmission, it is not possible to transmit two or more sets of data at the same time. When data is being transmitted from one station to another, other transmissions must be completed before data can be transmitted. Therefore, as shown in Figure 4,
If data A, B, and C change almost simultaneously in one station, data transmission is performed in the order of A→B→C. For example, if the status change interval for data A, B, and C is 400 ms, and 600 ms from one data transmission procedure, the total transmission time for A, B, and C will be 600 ms x 3 = 1800 ms. becomes.
Note that even if a change in status occurs at a station other than the station where the change in data status of data A, B, or C occurs during the status change interval of data A, B, or C (in Figure 4, data input After the transmission of A, B, and C is completed, the status change data X from the other station will be sent. The time until this X is sent is a long waiting time. This becomes a big problem when this data X is data that needs to be transmitted urgently. Furthermore, it is common for the same station to have three or more data changes, and data X will have an even longer waiting time.

It is also conceivable that A, B, and C change their states at the same time. The fifth figure shows the diagram. If the situation changes simultaneously, A, B, and C can be sent out simultaneously. Therefore, the emergency data X has a waiting time of one cycle (600ms). However, this simultaneous occurrence is a rare phenomenon, and in general, due to the difference in the response delay of devices, cases such as the one shown in FIG. 4 are more common than simultaneous occurrences.

Data that should be sent urgently cannot be delayed. In the past, the amount of data that needed to be sent urgently was not large, but with the development of automatic control functions based on display data from slave stations, and by communicating data between slave stations, Increasingly, local automatic control is being performed. As a result, the amount of data that must be communicated urgently has increased dramatically. The data that should be communicated urgently is data that communicates the failure and the details of the failure when a failure occurs, and is further data that indicates that some kind of constancy should be broken. Therefore, there is a need for a system that can quickly transmit such urgent data with less waiting time.

[Purpose of the invention]

The present invention provides a data transmission method for a remote monitoring and control device that enables priority transmission of emergency data and improves data transmission efficiency.

[Summary of the invention]

The present invention focuses on the fact that when a change occurs in a station, changes occur in multiple items related to the change,
The related items are sent together in one communication procedure.

[Embodiments of the invention]

FIG. 6 shows a flowchart of the process of the present invention. This process is performed internally in both the master station and the slave station.

In FIG. 6, first, a station performs data input/output with an external device (device) connected to its own station. The figure shows only data input. Whether or not this input data is state change data is checked by state change processing, which is processing to determine whether or not the state has changed. If the status change data is present, it is set in a status change data table prepared in advance within the station. The editing process looks at this status change data table, edits the status change data, and sets it in the transmission data table. Then,
In the transmission process, the data set in the transmission data table is sent to the downstream line.

In the editing process, the item control table and the pending data table are used. The item control table is a table that is set in advance for each input data item, and an example thereof is shown in FIG. Furthermore, the waiting-to-send data table is a table that stores data information that has changed in status but is not yet set in the transmission data table, and an example thereof is shown in FIG.

Further, a status change data table is shown in FIG. 9, and a transmission data table is shown in FIG. 10.

The condition change data table in Figure 9 shows the number of condition change items,
The item and contents are stored for each status change item.

The item control table shown in FIG. 7 consists of small tables for each item, and emergency data, related data, and transmission time limit are set as data for each small table. This urgent data is urgent and high-priority data to be transmitted. Here, emergency data indicates whether or not the data must be transmitted urgently.
Related data refers to data items whose status often changes almost simultaneously when the data changes. If there are multiple items, set multiple items. The transmission time limit indicates the delay time from when a change in status occurs until transmission.

The transmission waiting data table shown in FIG. 8 is made up of small tables for each item, and each small table is made up of related data items and remaining transmission time periods. here,
The related data item indicates a data item related to one status change and whether or not the status has changed. The remaining transmission time limit indicates the remaining time from when a change in status occurs until transmission. If there are multiple related data items, indicate them.

The transmission data table shown in FIG. 10 stores the number of transmission data and the transmission data.

FIG. 11 shows data editing processing. In FIG. 11, when a change in status occurs, the item control table is referred to to determine whether or not the data is emergency data, and if it is emergency data, the data is edited and set in the transmission data table. If the data is not urgent, it is determined whether there is any related data to the data, and if there is no related data, the data is edited and set in the transmission data table.
If there is related data, it searches to see if the item is waiting for status change in the transmission waiting table, and if so, sets the item to status change status. If all of the data groups waiting to be sent have changed their status, the data in that data table is edited and set in the transmission data table. If it is not registered in the transmission waiting table, related data items and transmission time limits are set according to the item control table. This process is also activated at regular intervals, and each time it is activated, the remaining transmission time limit table in the transmission waiting data table is subtracted. If any of the remaining transmission time periods has a value of 0, a data group related to it is edited and set in the transmission data table.

For example, assume that three non-emergency data changes occur in the order of A, B, and C, which are mutually related data but have no other related data. First, the state of A changes, and the contents of the state change are set in the state change data table by the state change process. In the editing process, condition change data A is extracted from the condition change data table, it is learned from the item control table that the related data of A are B and C, and it is checked whether B or C is registered in the transmission waiting table. . If the status of neither B nor C has changed, the related data B and C and the remaining transmission time are set in the transmission waiting table of A. After that, when the status of B changes, it similarly learns that the related data are A and C, and checks whether A or C is already registered in the transmission waiting table. If A is already registered, "changed status" is set in the related item B in A. Furthermore, when the status of C changes, "status changed" is similarly set in the related item C of A in the transmission waiting table. At this time, since all related items of A have become "changed in status", the status change data of A, B, and C are set in the transmission data table and transmitted.

As a result, 3 of A, B, and C are shown in Figure 12.
Status change data can be sent all at once in a short time using one transmission procedure, and thereby other signals X that should be sent urgently can be sent with priority.

FIG. 13 shows the configuration of a station that implements the process of FIG. 6. The slave station 3 includes a receiving section 30, a transmitting section 31, and a processing section 32. The processing section 32 consists of a computer and has various tables as described in FIGS. 7 to 10. The central processing element is the CPU.
The receiving section 30 receives the frame from the upstream line, checks whether the frame is addressed to its own station, and if it is not addressed to its own station, sends it as is to the transmitting section 31 for transmission downstream. If the frame is addressed to the own station, the frame is sent to the processing unit 32.
If it is in data reception mode, the data is taken in, and if it is in data transmission mode, it is processed to include the necessary data. Furthermore, the external device 10
If there is data input/output between the two, the processing section 32 performs the input/output processing, and if it is data input, performs the processing as shown in FIG. As a result of this processing, a new frame is sent to the downstream line via the transmitter 31.

Note that although the data flow is unidirectional, it can also be applied in both directions.

〔Effect of the invention〕

According to the present invention, urgent data is sent with priority and non-urgent data is sent all together in one procedure, so urgent data can be sent immediately and data transmission efficiency can be improved. It became like that.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of a loop-type remote monitoring and control device, Figure 2 is a transmission time chart, Figure 3 is a frame configuration example diagram, Figure 4 is a time chart for transmitting status change data, and Figure 5 is a status change chart. Other time charts for data transmission, Figure 6 is a diagram showing processing within each station, Figures 7 to 10 are diagrams showing various tables, and Figure 11 is a diagram showing processing within each station.
The figure is a flowchart of editing processing, and Figure 12 is a time chart of status change data transmission according to the present invention.
Figure 3 shows an example of the configuration of a slave station. 1... Loop transmission line, 2... Master station, 3... Slave station, 30... Receiving section, 31... Transmitting section, 32...
Processing unit, 10...external device.

Claims (1)

[Scope of Claims] 1. Consists of a loop-shaped transmission line, a master station connected to the line, and a plurality of slave stations connected to the line, with communication between slave stations and slave stations, and slave stations and master stations. In a remote monitoring and control device that transmits data between stations, when the data status changes at each station, it is checked whether or not there is emergency transmission data with a high priority among the status change data, and the emergency transmission data with a high priority is transmitted. If there is data, it is stored in a table, and then the data in the table is immediately sent to the line, and if it is low priority data that does not need to be sent urgently, then related item data is collected into one procedure. A method of transmitting data in a remote monitoring and control device. 2. The data transmission method in a remote monitoring and control device according to claim 1, wherein the emergency transmission data with a high priority is not only condition change data but also related data that occurs subsequent to the condition change.