JPS62205442A - Alarm detecting system - Google Patents

Abstract

PURPOSE:To save the number of a signal line by connecting serially both circuits of the transmitting and receiving an alarm, forming a single loop, controlling the output and non-output of alarm information and deciding the alarm. CONSTITUTION:A terminal control device 1 and terminal devices 2 and 3 are connected by signal lines 18-21, and an electric current loop is formed through lines 18-21 by an electric current supplying source 17. When an alarm is generated at the device 1 and the devices 2 and 3, an electric current switching circuit 6 and electric current switching circuits 13 and 16 are operated, the electric current loop is turned off and electric current detecting circuits 7, 10, 11 and 14 detect that an electric current is off. In such a case, when the circuits 7 and 10 detect that the electric current is off, a changing-over circuit 4 and a selecting circuit 5 are operated and the output to the circuit 6 of alarm information cannot be executed. Thus, the influence of the circuit 6 to an alarm circuit is eliminated, and therefore, the alarm of the devices 2 and 3 can be decided. Thus, by connecting serially both transmitting and receiving circuits, forming a single loop and deciding the alarm, the number of the signal line can be saved.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an alarm detection method between a terminal control device and a terminal device.

BACKGROUND ART Conventionally, as shown in FIG. 3, an alarm circuit of this type of alarm detection method has a current switch circuit 6 of a terminal control device 41 and a current detection circuit 11.14 of a terminal bag Wi42.43.
to the current detection circuit 7.10 of the terminal control bag @41. Connect the current switch circuits 13 and 16 of 42 and 43, respectively, and connect the alarm transmission and reception signal lines 25 to 32.
were connected to each separately. In the figure, two terminal devices 42.43 are connected to the terminal control device 41, but the same holds true even if a larger number of terminal devices a42.43 are connected. This alarm circuit is connected to the terminal control device 41
The alarm transmission from the terminal device 42, 43 to the terminal device 42, 43 and in the opposite direction are also equivalent. A current loop is formed by current supply sources 22 to 24 via signal lines 25 to 32 in the alarm circuit in a normal state without an alarm.

Now, when an alarm occurs in the terminal control device 41, the current switch circuit 6 operates to turn off the current loop. Next, the current detection circuit 11.14 of the terminal device 42.43 detects the current off and detects an alarm. In addition, the terminal device 4
2, when an alarm occurs, the current switch circuit 13 turns off the current loop, and the current detection circuit 7 of the terminal control circuit 41 detects the current off and detects an alarm.

In this way, alarms are transmitted using four signal wires for each terminal device, two for transmitting and two for receiving, so as the number of terminal devices increases, the number of signal wires increases. There were drawbacks. Furthermore, even if the number of terminal devices is small, it is desirable to have a small number of signal lines from the viewpoint of ease of construction and economy.

OBJECTS OF THE INVENTION The present invention has been made to eliminate the above-mentioned drawbacks of the conventional method, and an object of the present invention is to provide an alarm detection method that can save the number of signal lines.

Structure of the Invention The alarm detection method according to the present invention is an alarm detection method in which alarms are transmitted and received between a terminal control device and a terminal device, and the means for transmitting and receiving the alarms are connected in series with each other. a single loop; and a control means for controlling the output of the alarm to change, the control means controlling the output of one of the alarms, and the changed alarm from the control means and each of the alarms. The present invention is characterized in that the source of the alarm is detected in response to the alarm from the device.

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

FIG. 1 is a block diagram showing an alarm circuit according to an embodiment of the present invention. In the figure, on the terminal control device 1 side, there is a switching circuit 4 that switches alarm output on and off, a selection circuit 5 that controls whether or not to output an alarm together with the switching circuit 4, a current switch circuit 6, and a current switching circuit 4. Detection circuit 7.
10, a determination circuit 8.9 that determines an alarm according to the switching timing of the switching circuit 4 based on the detection result of the current detection circuit 7.10, and a current supply source 17. 7.10 is connected in series.

On the terminal device 2.3 side, a current detection circuit 11.14, a determination circuit 12.15 that determines an alarm from the detection result of the current detection circuit 11.14, and a current switch circuit 13.16.
A current detection circuit 11 and a current switch circuit 13 are connected in series, and a current detection circuit 14 and a current switch circuit 16 are respectively connected in series.

The alarm circuit of this embodiment is configured by connecting a terminal control device 1 and terminal devices 2 and 3 through signal lines 18 to 21, and a current loop is connected by a current supply source 17 via signal lines 18 to 21. is formed.

When an alarm occurs in the terminal control device 1 or the terminal v4 position 2.3, the current switch circuit 6 or the current switch circuit 13.16 operates to turn off the current loop, and the current detection circuits 7.10 and 11.14 operate to turn off the current loop. Detect off.

When the current detection circuit 7.10 detects that the current is off, the switching circuit 4 and the selection circuit 5 are operated to disable the output of alarm information to the current switch circuit 6. This causes the current switch to the alarm circuit to be disabled. Since the influence of the circuit 6 is eliminated, alarms of the terminal devices 2 and 3 can be determined. however,
Even if the terminal device 2-3 is able to detect the occurrence of an alarm, it is not possible to determine from which device the alarm is coming from.

Next, other embodiments of the present invention will be described.

Since the alarm circuits of the other embodiments are the same as that of the first embodiment, description of the circuit configuration will be omitted.

In another embodiment, as shown in FIG. 2, the switching circuit 4 and the selection circuit 5 are operated at regular intervals, and the alarm information of the terminal control device 1 is either outputted to the current switch circuit 3 or not outputted. control to repeat the action. Second
In the figure, T1 indicates the time when the alarm information of the terminal control device 1 is output to the current switch circuit 6, and T2 indicates the time when the alarm information is not output.

First, the method for determining the alarm of the terminal device 2.3 in the terminal control device 1@ is that by verifying the detection result of the current detection circuit 7°10 during T2, the alarm of the terminal device 1 Since there is no influence of the above, it is possible to determine the alarm of the terminal devices 2 and 3.

Next, the alarm judgment method of the terminal control device a1 on the terminal devices 2 and 3 side is that the judgment circuit 12.15 scans the detection result of the current detection circuit 11.14 at T1. By performing the process at a period sufficiently shorter than T2, it is possible to detect the point of change from normal to alarm (or from alarm to normal), and it is possible to determine whether the terminal control device 1 is in alarm.

However, this is the case where no alarm has occurred on the terminal devices 2 and 3. When an alarm occurs on the terminal devices 2 and 3, the detection results of the current detection circuits 11 and 14 will change as shown in FIG. It becomes a constant alarm, and it is the terminal device 2.
．． It can be determined that it is an alarm on the 3rd side, but the terminal system at this time is tllll[! It is impossible to determine the alarm state of 1.

In both the embodiment and other embodiments of the present invention, if an alarm occurs simultaneously in the terminal control device 1 and the terminal devices 2 and 3, it is impossible to determine the source of the alarm. Occurring at the same time [This is rare, so there is no practical problem.]

In this way, both the transmitting and receiving circuits are connected in series to form a single loop, and by controlling the output and non-output of alarm information to determine alarms, the signal line can be connected without loss of functionality. You can cut the number in half. Further, if the number of signal lines per terminal device is reduced from four to two, and the signal lines can be shared with other signal lines, the number of signal lines can be further saved.

Incidentally, in both one embodiment and the other embodiments of the present invention, the switching circuit 4 and the selection circuit 5 are provided on the terminal control device 1 side, but these #AI! The 11 circuit may be provided on the terminal device 2.3 side or both devices, and in this case, control can be performed on either side.

Effects of the Invention As explained above, according to the present invention, both the alarm transmitting and receiving circuits are connected in series to form a single loop,
By controlling the output or non-output of alarm information to determine an alarm, it is possible to provide an alarm detection method that can save the number of signal lines.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an alarm circuit of one embodiment of the present invention and another embodiment, FIG. 2 is a timing chart of another embodiment, and FIG. 3 is a block diagram of a conventional example. Explanation of symbols of main parts 4...Switching circuit 5...Selection circuit

Claims (1)

[Claims] An alarm detection method for mutually transmitting and receiving alarms between a terminal control device and a terminal device, the method comprising a single loop in which the means for transmitting and receiving the alarms are connected in series with each other, and the output of the alarm changes. and control means for controlling the output of one of the alarms by the control means, and controlling the output of one of the alarms in response to the changed alarm from the control means and the alarm from each of the devices. An alarm detection method characterized by detecting the source of the alarm.