JPS61245296A - Alarm - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a warning device for fire, gas leak, etc., and particularly to a warning device in which signals from a plurality of sensors are processed by a microcomputer or the like.

``Prior Art'' Conventionally, in an alarm device using a microcomputer, a processing program generally enters an infinite loop of a monitoring routine after passing through an initialization routine when the power is turned on. Therefore, if a status signal is output to a routine that always passes through in the monitoring routine, this status signal will be output at least once within the maximum processing time that can be considered from the program. A watchdog timer is often used to check whether a status signal is output by a circuit such as a mono-multivibrator within a predetermined period of time to determine if there is an abnormality in the computer. The watchdog timer detects a runaway in the computer, resets the computer at the node or returns it to its initial state through an interrupt, and also indicates that an abnormality has occurred in the computer.

``Problem to be solved by the invention'' The watchdog timer is easy and effective in restoring the computer to its original state when the computer goes out of control due to noise, etc., but it is easy and effective to restore the computer to its original state when the computer goes out of control due to noise, etc. It is not an effective means of dealing with damage. In an alarm system using a computer, once the computer goes out of control, there is a danger that it may display a false alarm or issue a control output.

"Means for Solving Problems" This invention is an alarm system using a computer, which detects abnormalities in the computer using a method similar to a watchdog timer, and when an abnormality occurs in the computer, the signal is input to the output device by a gate circuit or the like. This prevents erroneous control and alarm display by cutting off the signal that is being transmitted or by disabling the output device.

"Example" The alarm device of this invention will be explained based on the drawings.

The drawing is a system diagram showing an embodiment of the alarm device of the present invention, which includes a central processing unit MC such as a microprocessor,
A microcontroller consisting of a memory MR that stores processing programs or data, an input port (IP) that receives signals from sensors and operation units, and an output port OP that outputs alarm signals or status signals. The converter, the gate circuit ()T connected to the output capo () OP, and the output device P that displays alarms for environmental abnormalities, etc.
T, and a mono multivibrator which is triggered by a status signal outputted from an output port OP via a gate circuit GT.

When the power is turned on, the mono multivibrator is in a triggered state and the output Q is at a low level. The gate circuit GT is in an open state due to the signal of this output Q. When a computer is normally executing a processing program, a status signal is always outputted at least once within a predetermined period of time. Since the mono multi-vibrator gate performs a retrigger operation and the output pulse width is set slightly longer than a predetermined time, the mono multi-vibrator claw is usually always triggered and the output Q is maintained at a low level. In this state, the computer constantly receives signals from sensors from the IP (input port) using a processing program, and monitors environmental abnormalities such as fire outbreaks and gas leaks. When it is determined that there is an environmental abnormality, an alarm signal is output from OP, and the output device PT is driven via the gate circuit GT.
The abnormality occurrence status is displayed along with the abnormality occurrence area.

When a failure occurs in the computer memory MTt or the like and the status signal stops, the mono multivibrator MM is no longer triggered and the output Q becomes high level. The gate circuit GT remains closed, and once the computer enters an abnormal state, the mono-multivibrator MM maintains this state. Even if the computer goes out of control and outputs an erroneous alarm signal, the output device PT will not be driven, so no erroneous alarm will be displayed. Further, in the case of the output port OP with output prohibition, the gate circuit GT is not necessary because the output port OP can be directly controlled to cut off the output signal.

In addition, output signals other than the status signal are input directly to the output device PT without going through the gate circuit GT, and the output Q of the mono-multivibrator circuit is used to control the multi-output device PT, so that the output device PT is deactivated when the computer is abnormal. It is possible to prevent false alarm display even if the state is changed.

By the way, if the status signal from the output capacitor OP is used to directly trigger the mono multivibrator without going through the gate circuit GT, it is possible to return to the normal state at the same time as the computer returns to normal.

In this way, the mono multivibrator RO constitutes a lookout circuit that watches over the status signals output from the computer, and also has a gate circuit GT for the status signals.
is a lookout circuit with a holding function.

However, by providing an indicator light driven by the output of the mono multivibrator MM, the CPU (combi z-
It is possible to display the abnormal status of

"Effects of the Invention" As explained above, the alarm device of this invention usually has
This is extremely useful in the disaster prevention industry because it can prevent erroneous control or alarm display in the event that a computer processing signals and issuing various commands breaks down and goes out of control.

[Brief explanation of drawings]

The drawing is a system diagram showing one embodiment of the alarm device of the present invention. MC...Central processing unit, MR...Memo 1, 1-1I
P...Input port, OP...Output port, GT...
・Gate circuit, PT...output device, MM...mono multivibrator.

Claims (2)

[Claims] (1) In an alarm system in which a signal from a sensor is input to a computer, the computer determines whether the environment is normal or abnormal based on the input data, and when an abnormality occurs, the area where the abnormality has occurred and the state of the abnormality are displayed. a status signal that is always output once within a predetermined time when the processing program is normally executed; a watchdog circuit that detects that the status signal is not output even once within the predetermined time; and an alarm. The computer comprises an output device for displaying, etc., and means for cutting off an output signal from the computer that is controlled by the output of the lookout circuit and driving the output device, or for putting the output device in an inoperable state. An alarm device characterized in that it prevents false alarm output in the event of an abnormality. (2) The alarm device according to claim 1, wherein the lookout circuit includes a holding means for maintaining the state once the computer indicates an abnormality.