JPH0897840A - Duplex switching device for link unit - Google Patents

Abstract

PURPOSE: To duplex link units by opening and closing the power source of the unit capable of transmitting and receiving low level signals. CONSTITUTION: In the case of units for linking the data highway 10Mbps line of an EX-5000 system and the data highways 10Mbps and 1.5Mbps lines of an EX-1000A system, by defining one of them as a system '1' and the other as the system '2' and inputting self diagnostic signals 2 from both systems, the self diagnosis of a link unit is monitored, the link unit provided with abnormality is cut off by switching signals 4 by a changeover logic circuit 1 constituted of a relay and a normal unit is linked. Output status signals 6 for indicating the unit of which system, the system '1' or '2,' is connected and whether or not the link unit is normal or abnormal are recognized from a software. In such a manner, the unit for linking the two communication channels of the different systems is duplexed, a continuous operation is made possible even when one of the link units breaks down due to a fault and the fault unit is exchanged even during the operation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer of a unit for linking two systems of communication circuits, and when the other becomes abnormal, the circuit is switched by hardware so that continuous operation can be executed. .

[0002]

2. Description of the Related Art It is desirable that a control system for various plants be continuously operated for 24 hours. For this reason, each unit uses a dual configuration as standard to improve reliability, but the conventional 1.5 Mbps
The unit that links the s line system and the new system's 10 Mbps line had a single configuration. When the unit went down, each line was disconnected and access from both sides was impossible.

Further, when a conventional switching device is used for a 10 Mbps line and the line is switched by a relay, the reception level of the line may be as low as 10 mV depending on the cable length. For 10 mV, the receiving operation may not operate normally.

[0004]

In the above-mentioned prior art, the reception level of communication is low and the circuits cannot be switched, so that a unit in which the units for linking the two lines are switched by hardware cannot be realized.

The present invention has made it possible to duplicate the unit in a highly reliable manner.

[0006]

The above object is to provide a signal extension unit capable of transmitting and receiving a low level signal in order to achieve duplication of a unit for linking two lines, and turn on / off the power of the unit. By providing a switch that switches the line, it is possible to duplicate the link unit.

[0007]

The present invention has a low level signal of 10 Mbps line and 1.
When the unit that links the 5Mbps line is duplicated,
When there is a hardware abnormality, the switch for switching the execution right to the other can disconnect and switch the line by providing a signal extension unit capable of transmitting and receiving a low level signal of 10 mV. As a result, the unit that links the two lines can be configured in a duplicated manner, and high reliability can be obtained.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of a switch when the link unit is duplicated.

When a unit for linking the data highway 10 Mbps line of the EX-5000 system and the data highway 10 Mbps, 1.5 Mbps line of the EX-1000A system is duplicated, one of them is set as 1 system and the other is set as 2 system. By inputting the self-diagnosis signal 2, the self-diagnosis of the link unit is monitored, and the link unit having an abnormality from the switching logic circuit 1 composed of a relay is separated from the switching signal 4 and linked with the normal unit. It is a system that does.

Further, the switching of the 1-system and the 2-system is configured so as to be software controlled by the control signal 5.
The output status signal 6 indicating whether the system or the system 2 is connected, whether the link unit is normal or abnormal can be known from the software.

The switching device receives the switching signal 4 from the EX-1000.
Low-level signal 1 of EX-5000 system by switching the 1-system and 2-system systems with relay contacts on the A system's 1.5 Mbps line.
The 0Mbps line switches between the 1-system and 2-system by turning off the power of the signal extension unit.

This system is a system which is continuously operated for 24 hours, and it is desirable that the system is duplicated in order to improve reliability. The conventional system is a single system as shown in Fig. 2. When the link unit 7 goes down, 10Mb
The ps line 8 and the 1.5Mbps line 9 were disconnected, and the communication conversation between the two systems became impossible.

FIGS. 3 and 4 show the system configuration when the link unit 7 is duplicated. Both link units 7 are supplied with power, but the line is 10 Mbps 8,1.5 Mb.
It is connected only to either the 1-system or the 2-system of ps9.

Further, in order to configure the duplication without the intervention of software, it is necessary to disconnect the abnormal line in terms of hardware and provide the switch 10 for switching to the normal line.

FIG. 3 shows a conventional system in which the switch 10 is used. When a line of a low level signal of 10 mV is switched by a relay contact having a minimum applicable load of 10 mV,
There is no possibility that the signal received by the link unit 7 can be received normally. Even if the link unit 7 itself is normal, an error of communication error is issued. Therefore,
Signal extension unit 3 for low-level signal transmission and reception as shown in Fig. 4.
As the switch 12 that can control the signal extension unit 3
The low-level signal is switched by turning the power on and off.

[0017]

According to the present invention, a unit for linking two communication lines of another system is duplicated, and even if one of the link units fails and goes down, continuous operation is possible and while the unit is in operation. It became a system that can replace a failed unit.

[Brief description of drawings]

FIG. 1 is a block diagram of the inside of a switch.

FIG. 2 is an explanatory diagram of a conventional single link unit.

FIG. 3 is a block diagram of link unit duplication in which an error can occur.

FIG. 4 is a block diagram of link unit duplication.

[Explanation of symbols]

1 ... Switching logic circuit, 2 ... Self-diagnosis signal, 3 ... Signal extension unit, 4 ... Switching signal, 5 ... Input control signal,
6 ... Output status signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsutomu Sakamaki 882 Ichige, Katsuta City, Ibaraki Prefecture Hitachi Ltd. Measuring Instruments Division

Claims (2)

[Claims] 1. A control system for an industrial plant, comprising:
In order to duplicate the unit that links the two communication lines, if both abnormal signals are monitored and it is judged as abnormal, the execution right is switched by hardware without affecting the software.
Duplex switch for link unit, which enables continuous operation for 4 hours. 2. A communication circuit of 10 Mbps of the two communication lines has a low level signal, and neither a relay contact nor a transistor can support it. Therefore, a signal extension unit is used and the unit is turned on and off. By doing so, the line unit is switched, and the duplexer of the link unit is characterized.