JPS63316955A - Multipoint communication control system - Google Patents

Abstract

PURPOSE:To shorten a polling time and to realize efficient polling even when faults are generated in plural slave stations, by performing the polling by a master station in case of recognizing the fault in the slave station, and sending a recovery signal by the slave station in which the fault is generated when it recovers from the fault. CONSTITUTION:The master station 1 monitors a response signal from all slave stations 6 by performing the polling at a prescribed cycle, and invites the transmission of data to the slave station individually. At this time, when the response signal representing the fault is received or no response signal is received from the slave station, the master station 1 recognizes the generation of the fault in the slave station, and interrupts ordinary polling to all of the slave stations in which the faults are generated, and removes an interruption period leaving one of the interruption periods when the polling is interrupted. Such operation is performed to shorten the polling time by eliminating wasteful polling. The master station 1 performs common polling to request the transmission of the recovery signal to inform the recovery from the fault when each station recovers from the fault according to a prescribed priority order preset at the slave station in advance for all slave stations where the faults are generated in a remaining interruption period.

Description

Detailed Description of the Invention (Summary) The present invention suspends normal polling when a failure occurs in any of the slave stations, and
The remaining suspension period will be omitted except for one, and the remaining suspension period will be omitted.
Since common polling is performed to prompt requests for transmission of recovery signals from slave stations that have recovered within one suspension period according to a predetermined priority order, the master station can efficiently and immediately detect the recovery status of slave stations. .

[Industrial application field]

The present invention relates to a multipoint communication control system, and more particularly to a multipoint communication control system in which data links are established by polling from a master station to a plurality of slave stations branch-connected to a master station, and transmission/reception is performed.

[Conventional technology]

Conventionally, a master station 81 as shown in FIG. 8 has slave stations 82, 83 .
There is a multi-point communication control system in which a data link is established and communication is performed by polling the terminal 84 and having the slave stations 82, 83, and 84 send response signals in response to the polling.

If a failure occurs in one or more of the slave stations 82, 83, 84, the master station 81 stops polling the slave station and eliminates all unnecessary suspension periods. I was trying to reduce the polling time.

That is, as shown in FIGS. 8 and 9, the master station transmits polling signals (polling sequences) to the slave stations 82, 83, and 84 at predetermined intervals, and recognizes that a failure has occurred in the slave station 83. In this case, the slave station 83 is removed from the polling list, and polling of the slave station 83 is subsequently discontinued.

[Problem that the invention seeks to solve]

By the way, in the conventional multipoint communication control system, when a failure occurs in a slave station as shown in FIG. 8 or 9, polling of the slave station is not performed and the We are trying to remove all suspension periods.

Therefore, the master station 81 cannot recognize that the failure of the slave station itself has been recovered, or that the slave station has recovered by switching to a pre-prepared backup device. This means that data cannot be sent or received.

On the other hand, if you constantly poll all the affected slave stations, if the recovery of the slave stations is delayed, polling will be wasted. Even if the priority level is lowered to reduce the number of times of polling, the master station will be delayed in recognizing the recovery of the slave station.

Therefore, the present invention has been made to solve the above problems, and provides multipoint communication that can efficiently communicate that a failed slave station has been restored or has been switched to another backup device. This was done for the purpose of providing a control method.

(Means for Solving the Problems) In order to solve the above problems, the present invention, as shown in FIG. In a multipoint communication control method that establishes a data link and sends and receives data,
When the master station recognizes that a failure has occurred in one or more of the slave stations (S1), it cancels further polling of the slave stations where the failure has occurred (S2), and also stops polling during the suspension period during which polling was stopped. All but one of the suspension periods are removed (S3), and common polling is performed for all the nodes during the remaining suspension period to request that a recovery signal indicating the recovery of the failed slave station be transmitted in accordance with a predetermined priority order. This is done for the station (S4).

[Effect]

In the present invention, in step S1, the master station monitors response signals from the slave stations by performing normal polling at a predetermined cycle, and invites the slave stations individually to transmit data. At this time, if a response signal indicating a failure is received from the slave station, or if there is no normal response signal, the master station recognizes that a failure has occurred in the slave station.

When the master station recognizes the occurrence of a failure, it stops normal polling of all the slave stations where the failure has occurred in step S2.

This is because polling is useless because a response signal cannot be obtained even if a failure occurs in the slave station.

In step S3, the master station removes all but one of the suspension periods during which polling of the failed slave station was suspended. This is to reduce polling time by eliminating unnecessary polling.

In step S4, the master station selects all slave stations in which a failure has occurred within the remaining suspension period according to a predetermined priority order set for the slave stations, and if each slave station recovers from the failure, A common poll is performed to request the transmission of a recovery signal indicating recovery from a failure.

Therefore, even if there are multiple failed slave stations,
Even if each slave station is not constantly polled, it is possible to notify recovery from a failure with one poll.

〔Example〕

Next, the present invention will be explained in detail.

FIG. 2 is a block diagram of the equipment configuration according to this embodiment.

The master station 1 monitors and controls the transmission status of various messages by polling all branch-connected slave stations 6. It has a receiving section 3 that receives messages such as response signals, a control section 4 that controls the transmitting section 2 and the receiving section 3, and a display output section 5 that displays or outputs the transmitted or received messages.

Each slave station 6 includes a receiving section 8 that receives messages such as polling signals transmitted from the master station 1 via a communication line, a transmitting section 7 that transmits a response signal to the polling signal, and a transmitting section 7 and a receiving section 8. It has a control section 9 such as a CPU that performs control, and a modulation/demodulation circuit 10 that is connected to a data terminal device 11 or a host CPU 12 via a communication line and provides various data to the control section 9 .

FIG. 3 shows the processing procedure in the master station 1 according to the multipoint control system of this embodiment.

Let n be the total number of all slave stations that are branch-connected to the master station 1 in step SMI. If there is no failure, no is equal to the number N for normal polling. The slave stations 6 are numbered according to the priority order, and the first slave station is set to n=1.

In step SM2, the master station 1 determines whether the number n of the slave station 6 is smaller than N, which is the total number of slave stations to be polled. Naturally, this is small in the case where no fault has occurred yet, so the master station polls the slave station 6 (n=1) in step SM3.

In step SM4, the master station 1 determines whether there is a response signal from the slave station 6(n;1), and if there is a response signal, it is determined that no failure has occurred, and the process proceeds to step SM5. Polling will be performed for slave station 6 (n=2).

On the other hand, if it is determined in step SM4 that there is no response signal from the slave station 6 (n=1), the master station 1 recognizes that a failure has occurred in the slave station 6 (n=1) in step SM6, and steps Proceeding to SM7, processing begins for the next slave station 6 (n=2). In step SM8, since the processing for the slave station 6 has not yet been completed, the process proceeds to step SM9.
Polling is performed to slave station 6 (n=2).

In step 5Ml0, it is determined whether or not there is a response signal to the polling of the slave station 6 (n=2), and if there is a response, the slave station 6 (n=2) is not in trouble. Therefore, the process proceeds to step SM7 and the next slave station 6
(n=3) is processed.

On the other hand, if it is determined in step 5M10 that there is no response signal, it is determined that a failure has occurred in the slave station 6 (n=2), and the process proceeds to step SM6, where the master station 1 recognizes the occurrence of the failure.

If the master station 1 has finished processing for all slave stations 6 in step SM8, the process advances to step 5M12, where the master station 1 stops polling the slave station 6 where the failure has occurred, and polls the slave stations to be polled. The number N is N−ν, excluding the number ν of slave stations where a failure has occurred.

In step 5M13, the polling suspension period for one slave station 6 in which a failure has occurred is left, and the other ν polling suspension periods are removed. This is to reduce polling time.

In step 5M14, common polling is performed for all slave stations in which a failure has occurred within the remaining suspension period. Here, common polling is a request for all slave stations where a failure has occurred to send a recovery signal that informs the master station whether or not the failure has been recovered from the slave station. It is. If restoration conflicts, for example, each slave station is requested to transmit a restoration signal in accordance with the above-mentioned priority order.

If there is a recovery signal from the failed slave station 6 in step 5M15, the process proceeds to step 5M16, and the master station 1 recognizes that the slave station 6 that received the recovery signal has recovered, and step 5M
The process proceeds to step S17, where the number N of slave stations 6 that perform normal polling is increased by 1, and as a result, in step S18, all the failed slave stations 6
If it is determined that the recovery has been completed, step SM is performed again.
Proceed to I and return to normal processing. If there is a slave station that has not been recovered yet, the process proceeds to step SM2 with one failed slave station remaining, and polling and the like for non-faulty slave stations are repeated.

If there is no recovery signal in step 5M15, the process goes to step SM2 again, with ν failed slave stations remaining, and polling and the like are repeated.

If it is determined in step SM2 that the processing for all slave stations has been completed, then in step SMII the original total number of all slave stations is n. and the total number N of slave stations currently polling are compared. If and N are equal, no failure has occurred at all, so step S is performed again.
The process proceeds to MI and the above steps are repeated. On the other hand, N is n. If it is smaller than , that is, if a failure has occurred, the process proceeds to step 5M12.

Note that the processing procedure from step SMI to step SMII corresponds to step S1, and step 5M
12 corresponds to step S2, and step 5
M13 corresponds to step S3, and the processing procedure from step 5M14 to step 5M16 corresponds to step S4.

Next, the processing procedure in the slave station of the multipoint communication control system according to this embodiment will be explained.

As shown in FIG. 4, when a slave station branch-connected to the master station receives polling from the master station in step SSI, it is determined in step SS2 whether or not the slave station is normal.

If the own station is normal in step SS2, step S
In S4, a response signal to the polling is transmitted to the master station.

On the other hand, if it is determined in step SS2 that a failure has occurred in the own station, no response signal is transmitted to the master station in step SS3.

It is assumed that the slave station is restored in step SS5 when the failed device in the slave station is restored or the failed device in the slave station is switched to a backup device.

Then, when the master station performs common polling in step SS6, in step SS7, in response to the common polling, the slave station transmits its own polling address and information indicating that it has been restored as a recovery signal to the master station.

Note that if another slave station also fails and recovers at the same time, it will compete with other recovery signals. In such a case, the recovery signal may be transmitted to the master station in accordance with a predetermined priority order for the master station.

The method according to this embodiment is particularly applicable to each slave station 6 as shown in FIG.
This is effective because the master station 1 can immediately know of the recovery if it has a standby station 16 and immediately switches over to restore the slave station 6 when a failure occurs in each slave station 6. .

FIG. 6 shows how when a failure occurs in one slave station B, polling for that slave station B is stopped and common polling is performed during the suspended period.

Note that, as described above, common polling does not necessarily have to be performed within the suspension period in which polling is actually halted, but common polling may be performed with a suspension period set aside from the suspension period.

(Effects of the Invention) In the present invention, by performing common polling, a recovery signal is sent when a failed slave station recovers from the failure, so even if there are multiple failed slave stations, each Even if slave stations are not constantly polled, recovery from failure can be notified through one common poll, so polling time can be shortened and polling can be carried out efficiently.

[Brief explanation of the drawing]

FIG. 1 is a flowchart of the principle of the present invention, FIG. 2 is a block diagram of the equipment configuration according to the embodiment, FIG. 3 is a flowchart in the master station according to the embodiment, FIG. 4 is a flowchart in the slave station according to the embodiment, and FIG. FIG. 5 is a diagram showing the line configuration according to the embodiment, FIG. 6 is a diagram showing the polling cycle according to the embodiment, FIG. 7 is a diagram showing the line configuration according to the conventional example, and FIGS. 8 and 9 are diagrams showing the line configuration according to the conventional example. FIG. 3 is a diagram showing a polling cycle according to a conventional example. 1...Main station 6...Slave station 16...Preliminary station misfire 80's psychological fallout No. 1 Kyotora ff'lI:l) 3m44P) pllg(3 Fig. 5 Real H9+l+:IS6ho 5° rub 1 (iljtR) $j
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Claims (1)

[Claims] In a multipoint communication control system in which a data link is established by polling a plurality of slave stations branch-connected to a master station in a predetermined order from the master station, and transmission/reception is performed, the master station has one or two slave stations. When it is recognized that a failure has occurred in the above-mentioned slave station (S1), it cancels further polling of the slave station where the failure has occurred (S2), and also cancels polling for all but one of the suspension periods during which polling was canceled. period (S3), and common polling is performed on all slave stations requesting them to transmit a recovery signal indicating the recovery of the failed slave station in accordance with a predetermined priority order during the remaining suspension period (S3).
S4) A multipoint communication control method characterized by the following.