JPH03187528A - Redundant switching control system - Google Patents

Abstract

PURPOSE:To prevent a malfunction caused by input data when a power source is applied and communication is interrupted by holding selective information with a controller to be switched when the communication with a switching controller is interrupted and the power source is applied. CONSTITUTION:In a control circuit 1 to be switched, a selective information signal 108 from a switching control circuit 2 and a signal inverting a power ON reset pulse 109 are received and based on these two signals, a selective information signal 110 is prepared by a latch circuit 16 and transmitted to a selective circuit 17. In the latch circuit 16, the selective information signal 108 from the switching control circuit 2 is outputted as a selective information signal 110 as it is and when the power source of the control circuit 1 to be switched is turned on and the connection with the device 1 is interrupted, the former state (the selective information signal output 108) is held. Thus, when the power source is turned on or when the signal between the respective devices is interrupted, the selective information are not missed and the malfunction can be prevented from being generated in the controller 1 to be switched.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a redundant switching control method for a plurality of information signals, and particularly to a redundant switching control method when a control device and a controlled device are separated.

[Conventional technology]

Conventionally, this type of redundant switching control method simply sends the alarm detection results of each input signal from the controlled device to the control device as is, and the control device generates a selection signal to be sent to the controlled device based on the alarm detection results. The controlled device was configured to use the selection signal as is for selecting the input signal.

[Problem to be solved by the invention]

In the conventional redundant switching control method described above, alarm detection result information for each input information signal is directly sent from the controlled device to the control device, and only selection information is sent from the control device to the controlled device. Since it is configured not to send
There is a drawback that when the power is turned on or when signals between devices are cut off for maintenance or the like, selection information is incorrect in the controlled device, resulting in malfunction.

[Means to solve the problem]

The redundant switching control system of the present invention includes a switched control device and a control device that controls the switched control device, and the switched control device selects a normal signal from among a plurality of input signals. a selection signal sending circuit that receives a selection signal and power-on reset information from the switching control device and outputs a selection signal to the selection circuit; and a selection signal sending circuit that monitors each of the plurality of input signals and issues an alarm if an abnormality is detected. and an alarm issuance prohibition circuit that forcibly prohibits the issuance of an alarm at the time of power-on reset in the switched controlled device, and the switched controlled device receives the alarm from the switched controlled device. and a power-on reset circuit that generates the power-on reset information.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In FIG. 1, this embodiment has one system of input data 101.
, the switched control device 1 selects one from two systems of input data 102, and the selection information signal 108 to the switched control device 1.
．． The switched control device 1 includes an alarm detection circuit 11.12 that detects an alarm from one system of input data 101 and two systems of input data 102. , a power-on reset pulse generation circuit 13 that outputs a power-on reset pulse 105 after the power (not shown) in the switched control device 1 is turned on, and an alarm detection circuit 11 that outputs a power-on reset pulse 105 to the switching control device 2 by outputting the power-on reset pulse 105. NAND gate 14.15 that outputs alarm detection result output 106.107 from .12, and selection information signal 1 from switching control device 2.
08° A latch circuit 16 that receives the power-on reset signal 109 and outputs the selection information signal 110, and a selection circuit that selects one input data from the 1-system and 2-system input data 101, 102 using the selection information signal 110. 17, the switching control device 2 has a switching control circuit 21 which receives the alarm detection result outputs 103, 104 from the switched control device 1 and outputs the selection information signal 108, and the switching control device 2 A power-on reset pulse generation circuit 22 outputs a power-on reset pulse 109 after the power supply (not shown) is turned on.

Next, the operation of this embodiment will be explained.

One system of input data 101.2 input from the input terminal
The system input data 102 are input to the first alarm detection circuit 11 . The second alarm detection circuit 12 detects an alarm, and outputs the alarm detection result outputs 103 and 104 (here, the level is "low" when normal and the level is "high" when an alarm is detected).

The power-on reset pulse generation circuit 13 generates a power-on reset pulse 105 that is at a "low" level immediately after the power is turned on and becomes a "high" level after a while.
and NAND the alarm detection result outputs 103 and 104.
By way of the gate 14.15, the switching control device 2
The alarm detection results are output as alarm detection result outputs 106 and 107.

In the switching control device 2, the switching control circuit 21 receives the alarm detection result outputs 106, 107 from the switched controlled device 1, and outputs the selection information signal 108 to the switched controlled device 1 based on this information. Also, a power-on reset pulse 109 (polarity is 1) from the power-on reset pulse generation circuit 22
05) is output to the switched control device 1.

Next, the switched control circuit 1 receives the selection information signal 108 from the switching control circuit 2 and the power-on reset pulse 109.
Based on these two signals, the latch circuit 16 creates a selection information signal 110 and transmits it to the selection circuit 17. The latch circuit 16 normally outputs the selection information signal 108 from the switching control device 2 as it is as the selection information signal 110, and outputs the selection information signal 108 as it is as the selection information signal 110 when the switching control device 1 is powered on or when the connection with the switching control device 1 is disconnected. The previous state jffl (selection information signal output 108) is retained.

The selection circuit 17 receives the selection information signal 1 from the latch circuit 16.
Input data of 1 system and 2 systems based on 101.102
Choose one.

〔Effect of the invention〕

As explained above, the present invention forcibly sets the alarm detection result in the switched control device to the normal side when the power is turned on, and also maintains the selection information when the communication with the switching control device is cut off and the power is turned on. This has the effect of preventing malfunctions due to input data when communication is interrupted, such as during power-on or maintenance.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1...Switched control device, 2...Switching control device, 11
... Alarm detection circuit, 12... Alarm detection circuit, 13.
22... Power-on reset pulse generation circuit, 14° 15... NAND gate, 16... Latch circuit, 1
7... Selection circuit, 21... Switching control circuit, 101.
...Input data of one system, 102...Input data of two systems, 103.106...Output of alarm detection result, 104
, 107... Alarm detection result output, 105, 109...
- Power-on reset pulse, 108, 110... selection information signal, 111... selection data.

Claims (1)

[Claims] It consists of a switched control device and a switching control device that controls the switched control device, and the switched control device includes a selection circuit for selecting a normal signal from among a plurality of input signals, and the switching control device. a selection signal sending circuit that receives selection information and power-on reset information from the circuit and outputs a selection signal to the selection circuit; an alarm detection circuit that monitors each of the plurality of signals and issues an alarm in case of an abnormality; and an alarm generation prohibition circuit that forcibly prohibits the generation of an alarm at the time of power-on reset in the switched control device, and the switching control device receives the alarm from the switched control device and creates the selection signal. A redundant switching control system comprising a switching control circuit and a power-on reset circuit that generates the power-on reset information.