JPH07288532A - Simultaneous multiple address communication method - Google Patents

Abstract

PURPOSE:To surely update data while reducing a simultaneous multiple address communication period. CONSTITUTION:A node #00 being a polling master sends a polling command to other nodes #01-#04, other node sends reply data to the polling master with respect to the polling command and the polling master applies simultaneous multiple address communication of data collected from each node as batch data, the node #00 changes an unconditional reply bit provided on the polling command to '1' when a reception error or reception time expiration takes place in the preceding polling and sends the resulting data and the nodes #01-#04 send only a header part as reply data when no state change is caused or the unconditional reply bit is '0' and send reply data when no state change is caused in the reply data while the unconditional reply bit is '1'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast communication method in a local area network (LAN).

[0002]

2. Description of the Related Art Broadcasting is one of the functions of a local area network. This communication function is
Each LAN interface (each called a node) connected on the transmission path has its own output data area, and all nodes share the output data of each node.

In this communication method, a certain node serves as a polling master, and when all output data of each node are collected, all the data are collectively transmitted to all the nodes.

An example of this is shown in FIG. In the figure, the number of nodes is 5
And node # 00 is the polling master node.
Further, the output data of each node is 128 words (1 word = 16 bits), and the minimum data area required for transmission / reception is prepared as 4 headers. This header contains command identification, node identification, transmission size, and the like.

In the broadcast communication procedure, first, a polling command is transmitted from the node # 00 to the node # 01, and the response data from the node # 01 is stored in the node # 00.
Save in 01 data area. FIG. 8 shows the shared data area of each node.

Similarly, the node # 00 has nodes # 02 and #.
A polling command is transmitted to 03 and # 04 and data is received from the node. After that, the data received from each node is transmitted as broadcast data.

[0007]

In conventional broadcast communication, each node transmits all the data defined as the output data area. For example, in FIG. 7, in one round of transmission indicated by the broadcast communication period, the total number of data flowing on the transmission path requires (4 + 132) × 4 words for data collection and 4 + 644 words for collective data, which is a total. In this case, 1188 words are transmitted / received as being fixed every cycle.

Therefore, the broadcast communication cycle is always a constant time except when there is an unconnected node. However, the reply time after sending the polling command is not considered.

From the viewpoint of the host system, the shorter the simultaneous broadcast communication cycle, the shorter the latest data update cycle, which is preferable.

As a method of shortening this broadcast communication cycle, there is a method of omitting the transmission of the response data to the polling command unless the data transmitted by each node last time has changed.

Originally, a node that receives polling from a polling master does not make sense to send output data if the output data sent this time is the same as the output data sent last time. Therefore, if it is the same as the previous value, the output data is not transmitted, and a response is added with the information that the header value is the same as the previous value. As a result, the response data is only 4 words, and as a result, the broadcast period is shortened, and the system performance is improved.

However, this communication method involves a risk that the polling master may miss the response data. If the polling master misses the output data of a node and the state of the output data does not change after that, the node does not send the output data in response to the polling command. You will not be able to permanently collect missed data. The failure to collect the response data means that a reception error of the transmission protocol occurs due to noise or the like on the transmission path.

An object of the present invention is to provide a broadcast communication method for surely updating data while shortening the broadcast communication cycle.

[0014]

According to the present invention, in order to solve the above-mentioned problems, a node which has become a polling master sends a polling command to another node, and another node responds to this polling command. In a broadcast communication method in which response data is transmitted to the polling master, and the polling master broadcasts the data collected from each node to each node as batch data, the polling master sends an unconditional response bit to the polling command. A polling command for a node that has a reception error or a reception timeout in the previous data collection is transmitted by changing the unconditional response bit to "1", and the other node responds to the received polling command. When the data has a state change or when the unconditional response bit is "1" Sends the answer data to the polling master, and transmits only the header portion of the response data to the polling master when when there is no state change in the response data and said unconditional response bit is "0".

Further, according to the present invention, the node which has become a polling master transmits a polling command to another node, and the other node responds to this polling command by sending response data to the polling master. In the broadcast communication method of broadcasting the data collected from each node as a batch data to each node, the polling master communicates with other nodes by the following procedure, and (1) after the completion of transmission of the polling command, First to confirm that another node has started to send output data
Start the timer of.

(2) When data from the other node is not being received when the first timer times out, it is determined that the output data has no change in state to the other node, and a polling command is transmitted to the next node. To do.

(3) When data from the other node is not being received when the first timer times out, the time-up counter for the other node is incremented by 1, and the number of times of the counter exceeds the set number. In this case, the other node is recognized as unconnected.

(4) The second timer is started during the reception of the response data from the other node, and the response data is fetched when the reception is completed before the time up of the second timer, and Clear the time-up counter to 0 and check the connection.

(5) When the second timer times out, the time-up counter is incremented by +1.

The other node transmits response data when the output data has a state change at the time of receiving the polling command, and does not transmit the response data when the output data has no state change. It is characterized in that the response data is transmitted only once when the number of times lower than the set number continues.

[0021]

[Action]

(First invention) In response to the reception of the polling command, the other node basically transmits only the header part as response data when the state change does not occur, thereby reducing the amount of transmission data for data collection.

The node that has become the polling master changes the unconditional response bit provided in the polling command when a reception error or reception timeout occurs in the previous polling, and the other nodes do not change the state of the response data. In this case, the response data is transmitted so that the data can be updated even if the polling master misses the data.

(Second aspect) In response to the reception of the polling command, another node basically does not transmit the response data when the state change does not occur, and reduces the amount of data transmission for data collection.

Further, the other node transmits the response data only once when the number of times of not transmitting the response data is lower than the number of times of no reception on the polling command side, so that the polling master side connects to the node concerned. Enable confirmation and data update.

That is, if the node that has become the polling master does not respond to the polling command,
Whether the node is not connected or whether the output data has no change in state is recognized by whether or not the response data is not received and the set number of times is exceeded.

Further, when the polling master misses the received data due to the transmission protocol error, the polling master obtains the reception from the other node at a number lower than the set number of times even if the state of the output data is not changed at the other node. Update the data.

[0027]

【Example】

(First Embodiment) FIG. 1 shows a procedure in which a node serving as a polling master receives data from another node. Further, FIG. 2 shows a procedure in which a node other than the polling master transmits response data to the polling command.

In FIG. 1, when the polling master sends a polling command, an unconditional response bit is prepared in its header part. When transmitting the polling command, the polling master sets the unconditional response bit of the header to "0" (step S1) and checks whether a reception error or a reception timeout has occurred at the previous polling (step S2). ), When a reception error occurs or a reception timeout occurs, the unconditional response bit is set to "1" (step S3).

When there is no reception error or no reception timeout, the unconditional response bit remains "0".

The polling master transmits a polling command as header data obtained by processing the unconditional response bit (step S4).

For the transmission of this polling command,
It is checked whether or not a response is received from the destination node (step S5), and if there is no response, a reception error or reception timeout for the node is stored (step S6).

When the response is received, the storage of the reception error and the reception timeout for the node is reset (step S7).

On the other hand, the node receiving the polling command checks whether the unconditional response bit included in its header is "1" when the polling command is received (step S11), as shown in FIG. (Step S12), when the unconditional response bit is "0", it is checked whether or not there is a state change in the output data of this time compared to the previous time (step S13). If there is no state change, the state of the output data is changed. Only the header part carrying the unchanged information is transmitted (step S14).

The unconditional response bit in step S12 is 1
Or when there is a state change in the output data in step S13, the regular output data is transmitted together with the header (step S15).

According to the present embodiment, the node which has become the polling master, when transmitting the polling command,
When there is a reception error or reception timeout in the previous polling process, the unconditional response bit in the header part is set to "1" and transmitted. That is, when the node that has become the polling master misses the response data in the previous polling, it sets the unconditional response bit in the next polling for that node.

When the data to be transmitted this time is the same as the data transmitted last time, the node receiving this polling command basically performs processing of transmitting only the header but not the output data, but unconditionally in the header part. When the response bit is set to "1", the output data is transmitted even if there is no state change.

FIG. 3 shows an example of the simultaneous broadcast communication procedure of this embodiment. When sending a polling command from node # 00, which has become the polling master, to nodes # 01 to # 04 and collecting its response data, there must be no previous reception error or reception timeout for node # 01 at node # 00. , And the case where there is no state change in the output data in the node # 01, the node # 01 transmits only the header part to the node # 00 in response to the polling command.

Next, in collecting data from the node # 02, there is a previous reception error or reception timeout for the node # 02 in the node # 00, or the node # 02.
02 shows the case where the output data has no state change, and the response data (132 words) is sent from node # 02 to node # 0.
Send to 0.

Similarly, the node # 03 shows the case of the same response as the node # 01, and the node # 04 shows the case of the same response as the node # 02.

In this communication example, 128 words of data can be reduced in the responses from the node # 01 and the node # 03, respectively.

[0041]

## EQU00001 ## Transmission / reception of (4 + 4) .times.2 + (4 + 132) .times.2 + 644 = 932 words is sufficient, and the cycle of 256 words can be shortened. This time reduction becomes more effective as the number of nodes in which the state change has not occurred increases and the data size of each node increases.

Furthermore, when the node that has become the polling master has previously received a reception error or reception time-out, response data is transmitted and received even if there is no state change on the polled node side. Be seen.

(Second Embodiment) FIG. 4 shows a procedure in which a node which has become a polling master receives data from another node. Further, FIG. 5 shows a procedure in which a node other than the polling master transmits response data to the polling command.

In FIG. 4, the polling master transmits a polling command (step S21) and, after the transmission is completed, activates a first timer for checking the presence of response data (step S22).

When the first timer times out (step S23), it is checked whether or not the response data is being received (step S24), and when the response data is being received, the reception completion is checked. The timer is activated (step S25).

If the response data is not being received, the time-up counter for the node is incremented by 1 (step S31), and when the result is a predetermined β times or more, the unconnection of the node is recognized. (Steps S32 and S33), and the process for that node ends.

When the second timer is started, if the response data is completely received before the time is up (step S2
6), the polling master fetches the received data into the output data area of the node (step S27), clears the time-up counter to 0 (step S28), recognizes the connection of the node (step S29), and recognizes the node. Finish the process.

When the second timer times out (step S30), the time-up counter is incremented by 1 (step S31), and if the result is a predetermined β times or more, the unconnection of the node is recognized. By doing so (steps S32 and S33), the process for the node ends.

On the other hand, the node receiving the polling command, as shown in FIG. 5, after receiving the polling command (step S41), checks whether or not the output data this time has a state change (step S42). , If there is a state change, the response of output data is transmitted (step S
43), the transmission check counter 0 is cleared (step S44).

If there is no change in the status, this transmission check counter is sent several times (β / 2) in response to the polling command.
Once) is a check counter for transmitting response data, and clearing it to 0 stores in memory what was transmitted this time.

When the output data has no state change, the transmission check counter is incremented by 1 (step S45), and it is checked whether or not the result is β / 2 times or more (step S46), and β / 2 times or more. If this happens, the output data is sent to the polling master to notify it that its own node is operating, and as a recovery when the polling master misses the previously sent output data (step S43). The counter is cleared to 0 and the processing is finished.

When the transmission check counter is checked, β /
In the case of two times or less, the processing is terminated without transmitting the output data.

FIG. 6 shows a broadcast communication procedure of this embodiment. When the polling command is transmitted from the node # 00 that has become the polling master to the nodes # 01 to # 04 and the response data thereof is collected, the transmission check counter is set to β / The case is less than twice, and the node # 1 does not transmit the response data to the polling command.

Next, in the case of collecting data from the node # 02, the case where there is a state change in the output data at the node # 02 is shown, and the response data (132 words) is sent from the node # 02.
To node # 00.

Similarly, the node # 03 shows the case where no response data is transmitted like the node # 01, and the node # 04 shows the case where the response is the same as the node # 02.

In this communication example, data of 132 words can be reduced in each of the responses in the node # 01 and the node # 03 (however, 1 out of β / 2 times of simultaneous broadcast communication).
(The times are the same as in Figure 6.)

[0057]

## EQU00002 ## 4 × 2 + (4 + 132) × 2 + 644 = 924 words can be transmitted / received, and the cycle of 264 words can be shortened. This time reduction becomes more effective as the number of nodes in which the state change has not occurred increases and the data size of each node increases.

Moreover, since the response data is transmitted once or several times (β / 2 times) even if there is no state change on the polled node side, the node that has become the polling command has an instantaneous transmission protocol. Even if the received data is missed due to an error, the data update is guaranteed.

According to this embodiment, the polling master is
After transmitting the polling command, instead of waiting for the completion of reception of the response data, it is determined whether there is response data, and if it is recognized that there is no response data, the process immediately shifts to the transmission of a polling command to the next node.

This method is more polling than the method in which the node which receives the polling command responds only with the header portion (4 words) that the output data has no state change, as in the above embodiment. The polling command is transmitted to the next node faster because the master does not need to receive the response data.

Further, in the present embodiment, the reason why there is no response from the node is that there is no change in the state of the output data.
In order to determine if it is unconnected, the number of times there is no response is β times in a row so that the node is recognized as unconnected, and the node that receives the polling command is β / 2 even if there is no state change.
Since the output data is responded once at a time, it is possible to prevent the polling master from erroneously recognizing the node as unconnected.

Further, in the present embodiment, the node which receives the polling command transmits the output data once every β / 2, so that even if the polling master misses the data due to the transmission protocol error, it is permanently. The inconvenience that the data cannot be updated disappears.

[0063]

As described above, according to the present invention, a node that has become a polling master sends a polling command to another node, and another node responds to this polling command with response data to the polling master. In the broadcast communication method in which data is transmitted and the polling master broadcasts the data collected from each node to all the nodes as a batch data, the other nodes basically change the state in response to the reception of the polling command. If not, only the header part is sent as the response data, and the node that has become the polling master changes the unconditional reply bit provided in the polling command when a reception error or reception timeout occurs in the previous polling, and sends it. The node shall be a communication method that sends response data even when the response data has no state change. Therefore, there are the following effects.

(1) Basically, the response data is transmitted only when there is a state change, the amount of transmission data for data collection is reduced, and the broadcast communication cycle can be shortened.

(2) Even if there is no change in status when a reception error or reception time-out occurs in the previous polling, response data can be transmitted to eliminate missing data.

Further, according to the present invention, in response to the polling command, the other nodes basically do not transmit the response data when the state change does not occur, and transmit the response data once every several times, The node that has become the polling master checks if the response is being received after the polling command has been sent, and if it is not receiving it, it immediately shifts to sending the polling command to the next node, and only if it is not receiving β consecutive times. Since the communication method is to recognize the node as unconnected, the following effects are obtained.

(1) Basically, since the response data is transmitted only when there is a change in state, it is possible to reduce the amount of transmission data for data collection and shorten the broadcast communication cycle.

(2) The polling master always receives the response data once for β / 2 times of the polling command transmission, regardless of whether or not the state of the output data of the node on the polling side changes. It is possible to confirm the connection with other nodes and prevent the data from not being updated due to a momentary loss of data.

[Brief description of drawings]

FIG. 1 is a communication procedure diagram of a node serving as a polling master showing an embodiment of the present invention.

FIG. 2 is a communication procedure diagram of a node other than a polling master showing an embodiment of the present invention.

FIG. 3 is an example of simultaneous broadcast communication according to the embodiment.

FIG. 4 is a communication procedure diagram of a node which has become a polling master according to another embodiment of the present invention.

FIG. 5 is a communication procedure diagram of a node other than the polling master according to another embodiment of the present invention.

FIG. 6 shows an example of simultaneous broadcast communication of another embodiment.

FIG. 7 shows an example of conventional broadcast communication.

FIG. 8 is a shared data area diagram of each node.

Claims (2)

[Claims] 1. A node which has become a polling master sends a polling command to another node, and the other node sends response data to the polling master in response to this polling command, and the polling master collects from each node. In the broadcast communication method that broadcasts the collected data as batch data to each node, the polling master provides an unconditional response bit in the polling command, and the node that generated a reception error or reception timeout in the previous data collection. To the polling command for changing the unconditional response bit to "1", and the other node transmits the status data in response data to the received polling command or when the unconditional response bit is "1". Response data to the polling master, Broadcast communication method and transmits the polling master only header part of the response data when the absence of state change and said unconditional response bit is "0". 2. A node that has become a polling master sends a polling command to another node, and the other node sends response data to the polling master, and the polling master collects from each node. In the broadcast communication method that broadcasts the collected data as batch data to each node, the polling master communicates with other nodes according to the following procedure. (1) After the polling command has been transmitted, The first to confirm that the output data transmission operation has started
Start the timer of. (2) If the data from the other node is not being received when the first timer times out, the other node is judged to have no change in the output data and the polling command is transmitted to the next node. (3) When the data from the other node is not being received when the first timer times out, the time-up counter for the other node is incremented by 1, and when the number of times of the counter exceeds the set number, the time is counted. Recognize other nodes as unconnected. (4) A second timer is started while receiving the response data from the other node, and when the reception is completed before the time up of the second timer, the response data is fetched and the time-up counter is also provided. Is cleared to 0 and the connection is confirmed. (5) When the second timer times out, the time-up counter is incremented by +1. The other node is
When the status of the output data changes when the polling command is received, the response data is transmitted, and when the status of the output data does not change, the response data is not transmitted. A broadcast communication method characterized in that the response data is sometimes transmitted only once.