JPH02270036A - Redundant switch protecting circuit - Google Patents

Abstract

PURPOSE:To prevent the occurrence of undesired redundant switch by preparing a circuit which inspects the validity of the redundant switch control signal when the switch control signal has an error with each unit of a redundant system. CONSTITUTION:A 3-stage shift register 2 stores the control signal received from a switch control circuit 1. The AND gates 2 and 3 secure the ANDs of the forward phase output and the inverted output among the stages of the register 2. Then an RS-flip-flop 4 fetches the outputs of both gates 2 and 3 into the S and R inputs respectively and outputs a redundant switch signal. The output of the redundant switch signal is controlled based on the data equivalent to plural past clocks equal to the continuous stages of the register 2. Thus the influence of the control signal error is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to stabilization of a redundancy switching function in devices constituting a redundant system.

[Conventional technology]

Conventionally, the switching method for devices that make up this type of redundant system uses control signals and latch signals output from a switching control circuit that controls the switching state of each unit that makes up the redundant system of the device, as shown in Figure 2. is taken into a one-stage D-flip-flop provided in the receiving section of each unit, and a redundancy switching signal is output from the D-flip-flop.

[Problem that the invention aims to solve]

In each unit that constitutes the conventional redundant system mentioned above,
Since the receiving section of the control signal from the switching control circuit uses a single-stage flip-flop, unnecessary redundancy is generated when an error occurs in the control signal input to the control signal receiving section of each unit. There was a drawback that switching was easy to occur. Such control signal errors are caused, for example, by hot insertion and removal of the switching control circuit.

[Means to solve the problem]

In the redundant switching protection method of the present invention, in each unit constituting the redundant system, a shift register is provided in a receiving section that receives a control signal output from a switching control circuit of the device, and a positive phase output of each stage of the shift register is provided. An AND gate circuit that performs AND logic, and an AND gate circuit that performs AND logic of the inverted output of each stage.
It has a gate circuit and an R3 flip-flop which takes in the outputs of the two AND gate circuits, the positive phase output being taken into the S input, and the inverted input being taken into the R input.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 is a circuit diagram of a conventional circuit configuration, and FIG. 1 is an embodiment of the present invention, which is a circuit diagram of a redundant switching protection circuit when the shift register has three stages. In FIG. 1, a three-stage shift register 2 stores a control signal output from a switching control circuit 1.

AND gate 2 and AND gate 3 take the AND of the positive phase output and inverted output of each stage of the shift register, respectively, and the RS-flip-flop 4 takes in the outputs of AND gate 2 and AND gate 3 into S and R inputs, respectively. outputs a redundant switching signal.

4 shows the conventional redundant switching circuit shown in FIG. 1, and FIG. 3 shows an example of the effect when disturbance of the switching control signal occurs in the conventional redundant switching circuit shown in FIG. 2, using a time chart for comparison. In the conventional method, an error in the control signal is output as is as a redundancy switching signal, but in the present invention, the output of the redundancy switching signal is controlled using data for multiple past clocks corresponding to the number of consecutive shift register stages. Less susceptible to error.

〔Effect of the invention〕

As explained above, the present invention provides a device that constitutes a redundant system, by providing a circuit that verifies the validity of the redundant switching control signal when an error occurs in the switching control signal in each unit of the redundant system. This has the effect of preventing unnecessary redundant switching from occurring.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a redundant switching protection circuit of the present invention, FIG. 2 is a circuit diagram of a conventional redundant switching circuit, and FIG. 3 is a time chart showing an example of the execution of a switching function in the event of a control signal error according to the conventional method. FIG. 4 is a time chart showing the execution of the switching function of the system of the present invention when the same control signal error as in FIG. 3 occurs. 1...Switching control circuit, 2...Shift register, 3...AND gate circuit, 4...
...AND gate circuit, 5...RS-flip-flop. Agent Patent Attorney Uchihara Oto 1 Anonymous Pi J ゝ Figure 2 Ring 3 Figure 4

Claims (1)

[Claims] a switching control circuit that controls switching of each unit in a device that configures a redundant system with a plurality of units; a shift register that receives a switching control signal and a latch signal output from the switching control circuit; and each of the shift registers. An AND gate circuit performs AND logic of the positive phase output of the stage, an AND gate circuit performs AND logic of the inverted output of the shift register, and of the respective outputs of the two AND gate circuits, the positive phase output is connected to the S input. A redundant switching protection system characterized in that it has an RS-flip-flop whose inverted output is taken into the R input.