JPH05260059A - Circuit for inserting node to duplexed local area network - Google Patents

Abstract

PURPOSE:To normally maintain one local area network at any time zone without fail by performing connection to the duplexed local area networks while adding time difference. CONSTITUTION:When connecting a node 60 to local area networks 1 and 2, a contact drive circuit 71 is driven and controlled by a command signal 81 from a central control unit 5, first of all, a contact 8 is turned off, the node 60 is connected to the local area network 1, next a contact 9 is turned off after the local area network 1 is recovered normally after the lapse of line use disable time for a communication sequence with the participation of a transmission/reception circuit 3, and the node 60 is connected to the local area network 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a node insertion circuit applied to a system in which a local area network (LAN) is duplicated.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional node connecting means to a duplicated local area network.

In FIG. 2, reference numerals 1 and 2 denote duplicated local area networks (LANs).
Reference numeral 1 is an A-system local area network, and 2 is a B-system local area network.

Reference numerals 6 and 6 are nodes connected to the duplicated local area networks 1 and 2, respectively. Each node 6 has a central controller 5,
And transmission / reception circuits 3 and 4 for performing transmission / reception processing of each of the local area networks 1 and 2.

In serial communication from the local area network 1, serial data on the local area network 1 is received by the transmission / reception circuit 3 via the lobe 31 and serial-parallel converted into parallel data.
Is supplied to the central control unit 5 via. On the other hand, in the transmission from the central control unit 5, contrary to the above route, the parallel data on the bus 32 is parallel-serial converted by the transmission / reception circuit 3 and sent out to the local area network 1.

Here, the reason for providing the two local area networks 1 and 2 is that even if one local area network fails and becomes unusable, communication can be continued on the remaining local area networks. To do so. That is, for example, when the A-system local area network 1 becomes unusable, the transmission / reception circuit 3 cannot transmit / receive, so that communication is continued using the B-system local area network 2 and the transmission / reception circuit 4.

By the way, when the node 6 is connected to the local area networks 1 and 2, the node 6 newly joins the local area networks 1 and 2. Therefore, the communication procedure at the time of entry is from the node 6 to the transmitting / receiving circuit 3 , 4, commanded by local area networks 1, 2
At the same time, there will be a time zone when they cannot be used. For this reason,
A problem occurs in which communication between the nodes 6 is disturbed during that time period.

[0008]

As described above, conventionally, when a node is connected to a duplicated local area network, that node newly joins the local area networks 1 and 2, so the communication procedure at the time of entry Is instructed from the node 6 to the transmission / reception circuits 3 and 4, and a time zone in which the local area networks 1 and 2 are temporarily unavailable at the same time occurs, and communication between the nodes 6 is disturbed during that time zone. was there.

[0009]

According to the present invention, when a node is newly connected to a duplicated local area network, a switching contact is inserted in series at a connection point to each local area network, and the contact is A contact drive circuit for driving and a command signal generating means for giving a command by giving a time difference in each local area network to this contact drive circuit are provided, and the time given by the command signal is provided between the duplicated local area networks. It is characterized by having it.

[0010]

According to the present invention, the contact drive circuits (D) 71, 72 are provided to the node 6 as shown in FIG. 1 in order to prevent the node from becoming incommunicable during the time period connected to the local area network. , And contacts 8 and 9 were added. The contact drive circuits (D) 71 and 72 are respectively the central controller 5
It operates by receiving the command signals 81 and 82 from. Here, the contacts 8 and 9 and the contact drive circuits (D) 71 and 72
And the command signals 81 and 82 realize a node insertion circuit.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention.

In FIG. 1, reference numerals 1 and 2 denote duplicated local area networks (LAN).
Reference numeral 1 is an A-system local area network, and 2 is a B-system local area network.

Reference numerals 60 and 60 are nodes connected to the duplicated local area networks 1 and 2, respectively. Each of the nodes 60 is provided with a central control device 5 and transmission / reception circuits 3 and 4 for performing transmission / reception processing of the local area networks 1 and 2, respectively, as well as contacts 8, 9 and a contact drive circuit (D) 71, 72,
A node insertion circuit constituted by command signals 81, 82 and the like is provided. The contact drive circuits (D) 71 and 72 operate by receiving command signals 81 and 82 from the central controller 5, respectively. When the central control unit 5 connects the node 60 to the duplicated local area networks 1 and 2 (enters the networks 1 and 2), command signals 81 and 82
Is output with a predetermined time difference. Here, the operation of the node insertion circuit shown in FIG. 1 will be described.

When connecting the node 60 to the duplicated local area networks 1 and 2, the central controller 5 first outputs a command signal 81 to output the contact drive circuit (D).
71 to close contact 8. By this command, the node 60 is connected to the local area network 1. With this connection, the local area network 1 cannot be used during a certain time zone (usually several seconds) due to the communication procedure when the transceiver circuit 3 enters. However, at this time, the system of the local area network 2 can still normally communicate.

After the local area network 1 normally returns from the unusable state at the time of joining the node, the connection with the local area network 2 is made in the same procedure as the local area network 1.

That is, after closing the contact 8, the central control unit 5 outputs the command signal 82 after a time zone of the communication procedure accompanying the entry of the transmission / reception circuit 3 and then outputs the contact drive circuit (D). ) 72, instructing the contact point 9 to be closed and connecting the node 60 to the B-system local area network 2.

By connecting to the duplicated local area network with a time lag, one local area network can always be maintained normally in any time zone, so that the problem of communication interruption can be prevented.

According to the configuration of FIG. 1 described above, the communication disabled state does not occur at the same time in both local area networks 1 and 2 due to the communication procedure of entry when connecting a node to a duplicated local area network. , Because there is a time lag in the procedure for connection,
At any one time, either one of the duplicated local area networks can be kept communicable.
Therefore, communication between nodes can be continued.

[0019]

As described in detail above, according to the node insertion circuit of the present invention, when a node is connected to a duplicated local area network, both nodes of the local area network are incapable of communication due to a communication procedure of entry. By providing a time lag in the connection procedure so that they do not occur at the same time, at least one of the duplicated local area networks can be maintained in a communicable state at any time.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an exemplary embodiment of the present invention.

FIG. 2 is a block diagram showing a conventional configuration.

[Explanation of symbols]

1, 2 ... Local area network, 3, 4 ... Transceiver circuit, 5 ... Central control unit, 60 ... Node, 8, 9 ... Contact, 31, 41 ... Lobe, 32, 42 ... Bus, 71, 7
2 ... Contact drive circuit (D), 81, 82 ... Command signal.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location 8948-5K H04L 11/02 Z

Claims (1)

[Claims] 1. A switching contact connected in series to each node connected to the duplicated local area network and a series of switching contacts connected to each of the duplicated local area networks, and each of the switching contacts is drive-controlled with a time difference. A circuit for inserting a node into a duplicated local area network, comprising: