JPH0294940A - Communication control equipment - Google Patents

Abstract

PURPOSE:To continue communication in other control station even when any one out of plural control stations is made into a stopped state by temporarily storing messages collected by the polling selecting of one control station in each memory provided for each of other control stations. CONSTITUTION:A communication control equipment 1 selects, for example, the polling signal of a control station 2a and causes to flow the polling signal to a low-order port 5, and return messages from a group 3 of stations to be controlled are once stored in transmission buffers 12a-12n of respective high- order ports 4a-4n. When polling from the control station 2a to be the subject of polling for the stations to be controlled is discontinued for a fixed period, the discontinuity is detected by a polling supervising timer 11a, and switching is executed so that the polling of the control station 2b can be caused to flow to the low-order port 5 by driving a switching means 13. Thus, even when any control station is stopped, or even when plural control stations are stopped, the polling for the stations to be controlled can be executed by the polling signals of the remaining control stations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention is applied to a polling/selecting method. In particular, the present invention relates to a communication control device that connects a controlled station to a plurality of control stations.

〔overview〕

The present invention provides a means for controlling the collection of messages by polling/selecting controlled stations by a plurality of control stations, in which messages collected by polling/selecting of one control station are sent to each of the other control stations. By temporarily storing messages in memory and collecting these messages through polling from other control stations, it is possible to freely configure multiple control stations with the same architecture.

[Conventional technology]

In the conventional example, the number of ports through which the controlled station is accessed from the perspective of the control station is one, and it is possible to perform pointing and selection from multiple control stations to one controlled station at any timing. could not.

[Problem that the invention seeks to solve]

In such conventional devices, one control station corresponds to one controlled station, and this control station calls and communicates with multiple controlled stations one by one using a procedure based on the polling/selecting method. Since this method avoids access conflicts between controlled stations, it has the disadvantage that multiple control stations cannot exchange messages with one controlled station.

SUMMARY OF THE INVENTION The present invention aims to eliminate such drawbacks and provides a communication control device having a means for continuing communication with other control stations even if any of a plurality of control stations is stopped. .

[Means for solving problems]

The present invention comprises a numbered upper port connected to a control station that sends polling and selecting signals, and a lower port connected to a group of controlled stations that sends out return messages in response to polling signals and selecting signals. A communication control device comprising: cycle detection means for detecting the cycle of a polling signal that passes through each of the upper ports, which is provided corresponding to each upper port; A storage means for temporarily storing a return message in response to a polling signal passing through the host port, and transmitting the contents read in response to a polling signal passing through an upper port to which the mountain means is connected to the upper port; When the cycle detection means connected to a certain upper-level port detects an abnormal cycle, the upper-level port with the next number in the cyclic structure is output modulo the number of upper-level ports, and the upper-level port with the next number is selected as the route for the polling signal. The present invention is characterized in that it includes a switching means that sequentially selects an upper port as a route for the selecting signals when the selecting signals via the ports arrive at the same time.

[Effect]

One control station is associated with n control stations, n upper ports are provided corresponding to the control station, and polling information from one selected upper port is always sent to the controlled station via the lower port. The return message obtained thereby is stored in the transmission buffer memory attached to the first to n-th upper port, and then stored in the memory and simultaneously transmitted to the control station of the upper port that is the subject of polling. A return message is sent, but it is sent to other upper ports in accordance with the polling timing of the upper ports. By the way, when the polling of the selected upper port stops, if the timer that monitors the periodic polling of the upper port times out and the main upper port stops operating, the remaining upper ports are prioritized in numerical order. selects the upper port that should become the next subject, sends the polling signal of this upper port to the lower port, and obtains a return message. This switching is 1.2
, , n, 1.2, in particular to eliminate the need for failback operations to the recovery port, eliminate the need for failback operations to multiple upper-level ports, and eliminate the need for failback operations to multiple upper-level ports, as well as when multiple upper-level ports stop operating. also allows the remaining upper ports to continue polling.

On the other hand, the selection from the control station is accepted at one of the first to n-th upper ports, and the selection from this communication control device is accepted at each of the remaining n-1 upper ports. negative response (N
AK) to avoid temporary selection conflicts from each control station. Furthermore, a pseudo end response (EOT) is sent back to a polling operation of another station performed during the selection process of a specific station to avoid a temporary conflict between polling and selecting.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings. The figure is a block configuration diagram showing the configuration of this embodiment.

As shown in the figure, this embodiment includes numbered upper ports 4a to 4n connected to control stations 2a to 2n that send out polling and selecting signals, and A polling monitoring timer is provided corresponding to the lower port 5 connected to the controlled station group 3 that sends messages and each upper port, and is a cycle detection means for detecting the cycle of the polling signal passing through each of the upper ports 4a to 4n. lla
to lln, and the return message in response to a polling signal via an upper port other than the upper port to which the own school level is connected is temporarily stored, and the content read out in response to a polling signal via the upper port to which the own school level is connected. A transmission buffer 12a is a storage means for transmitting the data to this upper port.
to 12n, and when the cycle detecting means connected to the upper port, which is the route of the polling signal, detects an abnormal cycle, the polling signal is routed to the upper port with the next number in a cyclic structure modulo the number of upper ports. Selected as road,
Furthermore, when selecting signals via a plurality of higher-level ports arrive at the same time, a switching means 13 is provided that sequentially selects the higher-level ports as the route of the selecting signal.

Next, the operation of this embodiment will be explained.

The communication control device 1 always receives polling signals from the control stations 2a to 2n, and selects one of them, for example, the polling signal of the control station 2a, and sends it to the lower port 5. Return messages from the controlled station group 3 in response to this polling signal are distributed and sent to the respective upper ports 4a to 4n. Return messages are sent to each upper port 4a to 4n.
However, the return message corresponding to the control station 2a is immediately sent to the control station 2a, and the return message corresponding to the control station 2a is sent to the upper port 4b other than the control station 2a.
to 40 transmit the contents accumulated in the transmission buffers 12b to 12n at the time of receiving polling. Furthermore, when polling from the control station 2a, which is the subject of controlled station polling, ceases for a certain period of time, the polling monitoring timer lla detects this and drives the switching means 13 to switch the polling from the control station 2b to the lower port 5. Switch to flow to This switching means 13 has a logic means that prioritizes and processes the outputs of the polling monitoring timers lla to lln of each upper port. For example, even if the control station 2b subsequently stops polling, the next control The station 2C operates so as to become the subject of controlled station polling. As a result, even if any control station stops, or even if a plurality of control stations stop, the controlled stations can be polled using the Bo+IJ song numbers of the remaining control stations.

Only one selection on the upper port 4a to 4n can be accepted by the switching operation of the switching means 13. At this time, the communication control device 1 returns a negative selection response (NAK) to the non-accepting side. Furthermore, in response to polling from a non-receiving side, a pseudo signal indicating the end of transmission (EOT) indicating that there is no returned data is transmitted. In this way, the same message can be returned to any polling from a plurality of control stations. Also,
It is possible to process selections from multiple upper ports without causing protocol errors.

〔Effect of the invention〕

As explained above, the present invention enables multiple control stations using the polling/selecting method, and has the advantage that the control station can have a redundant configuration and data can be transferred to another higher-level system based on the same architecture. There is.

In addition, since the same architecture can handle an increase in the number of control stations, the same hardware and software can be used when duplicating control station equipment (for example, computers), and the distribution of processing can be reduced. This has the effect of eliminating the need to consider the influence on other computers even when multiple computers are connected to achieve the desired goal.

[Brief explanation of drawings]

The figure is a block configuration diagram showing the configuration of an embodiment of the present invention. 1... Communication control device, 2a-2n... Control station, 3.
...Controlled station group, 4a to 4n...Upper port, 5...
- Lower port, 10a~ton...Upper port transmitting/receiving means, lla~lln...Polling monitoring timer, 1
2a-12n... Transmission buffer, 13... Switching means, 14... Lower port transmitting/receiving means.

Claims (1)

[Claims] 1. A numbered upper port connected to a control station that sends polling and selecting signals and a group of controlled stations that sends out return messages in response to polling signals and selecting signals. In the communication control device, the communication control device is equipped with a lower port and a lower port, which is provided corresponding to each upper port and detects the cycle of a polling signal passing through each of the upper ports; storage means for temporarily storing a return message in response to a polling signal via an upper port other than the upper port to which the own means is connected, and transmitting the content read in response to a polling signal via an upper port to which the own means is connected to the upper port; and a polling signal. When the cycle detecting means connected to the upper port which is the route of the polling signal detects an abnormal cycle, it selects the higher port with the next number in the cyclic structure modulo the number of upper ports as the route of the polling signal, and 1. A communication control device comprising: switching means for sequentially selecting an upper port as a route for a selecting signal when selecting signals via a plurality of upper ports arrive at the same time.