JP4990847B2 - Connection error detection circuit for railway security equipment - Google Patents

Description

  The present invention relates to a connection abnormality detection circuit for safely controlling field equipment in a railway security device.

  In railway security equipment that controls switches, signal lights, etc., equipment failures can lead to serious accidents. Therefore, a fail-safe configuration for controlling the entire apparatus to the safe side is indispensable in the railway security apparatus even when the apparatus fails. Here, “fail-safe” means that dangerous control that causes a serious accident due to a failure is not achieved. In order to realize fail-safe control, each device constituting the railway security device must be normally connected.

  For this reason, in the railway security device, connection abnormality detection is performed to confirm that each device is normally connected. A connection abnormality detection circuit for detecting a connection abnormality between the devices is required to have high reliability. This is because the risk of risky control cannot be excluded unless the connection state between the devices can be detected correctly.

  In general-purpose systems, a connection detection circuit as shown in FIG. 2 is often used in order to detect that devices are connected to each other. In the state where the device A1 and the device B2 are connected, the detection circuit 3 can confirm the ground voltage (L level) by being connected to the ground voltage 12.

  However, if the following event occurs in this general-purpose system, there is a possibility that the risk side control is performed directly or indirectly. For some reason, it is assumed that the ground voltage conducts 8 like a shaded portion. In this case, the detection circuit 3 of the device A1 detects the ground voltage (L level) because of the conduction 8 with the ground voltage. Although this detection can be normally detected, it is not possible to detect an abnormality such as conduction 8 with the ground voltage.

  Further, it is assumed that the wire break 9 occurs like a shaded portion. In this case, the detection circuit 3 of the device A1 is connected to the power supply 11 via the resistor 10 due to the disconnection 9, and detects the power supply voltage (H level). Originally, the ground voltage (L level) should be detected, but the power supply voltage (H level) is detected due to the disconnection 9 and erroneously detected, and an abnormality that the disconnection 9 has occurred cannot be detected.

  Since the abnormality cannot be detected in this way, there is a risk that the risk side control may be performed directly or indirectly. In order to solve this problem, it is necessary to detect an abnormality by adding a simple circuit.

  As in the background art, in a configuration in which connection detection is performed with a fixed voltage (DC signal), it is impossible to detect contact failure or abnormalities such as conduction at the connection between devices, so a simple circuit configuration Is added to provide an abnormality detection circuit.

The connection abnormality detection circuit according to the present invention is a connection abnormality detection circuit that monitors a connection state between the devices in a railway security system that requires connection between the first device and the second device in a double redundant configuration. there are, in a state in which the device are connected to each other, provided an oscillation circuit that oscillates start only when being properly connected to each device, the oscillation circuit, the first wiring of the first device When the second wiring of the second device is normally connected to the same potential, and the second wiring of the first device and the first wiring of the second device are normally connected to the same potential, Is routed from the second wiring of the first device to the second wiring of the second device via the inversion circuit, delay circuit of the first device, and first wiring of the first device. Connected to the inverting circuit, the delay circuit of the second device, and the first wiring of the second device. Each delay circuit receives a signal from the inverting circuit of the first device to the inverting circuit of the second device, or from the inverting circuit of the second device to the inverting circuit of the first device. It generates a delay when propagating to initiate self-oscillation is repeated to oscillate mutually detects abnormal connection between by Ri before Symbol device to monitor the oscillating signal of alternating the oscillation circuit outputs It is characterized by that.

  According to the present invention, instead of detecting with a fixed voltage (DC signal), an oscillation signal (AC signal) that starts oscillating by connecting devices is used, and the H level and L level change alternately. By detecting this, it becomes possible to prevent a contact failure at the connecting portion or an abnormality such as conduction.

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

  FIG. 1 shows an embodiment of a connection abnormality detection circuit. In FIG. 1, for the sake of simplification, the oscillation circuit 6 that starts oscillating with a normal connection with the device B and the oscillation circuit 7 that starts oscillating with a normal connection with the device A are used. An oscillation circuit that starts oscillation with a normal connection is shown.

  In FIG. 1, there are a device A1 and a device B2, and a double redundant configuration is used, so the devices A1 and B2 are exactly the same. When the device A1 and the device B2 are normally connected, the oscillation circuit 6 that starts oscillation when the device B2 is normally connected and the oscillation circuit 7 that starts oscillation when the device A1 is normally connected start oscillation. . The detection circuits 3 and 4 detect the oscillation signal (AC signal) output from the oscillation circuit 6 that starts oscillating with a normal connection with the device B2 and the oscillation circuit 7 that starts oscillating with a normal connection with the device A1. Detects a successful connection.

  An example in which an event similar to the event shown in the background art of FIG. For some reason, it is assumed that conduction 8 with the ground voltage occurs like a shaded portion. If it is not connected to the ground voltage 8, an oscillation signal (AC signal) should be generated if it is normally connected. However, if it is connected to the ground voltage 8, the oscillation signal (AC signal) ) Is not generated and becomes a fixed voltage (DC signal). Therefore, the detection circuits 3 and 4 determine that the connection is abnormal.

  Similarly, it is assumed that what has been wired, such as a shaded part, is broken 9 for some reason. If it is not disconnected 9, an oscillation signal (AC signal) should be generated if it is connected normally, but if it is disconnected 9, an oscillation signal (AC signal) is not generated, It becomes a fixed voltage (DC signal). Therefore, the detection circuits 3 and 4 determine that the connection is abnormal.

  In addition, since this embodiment has a dual redundant configuration, it is possible to perform the same connection abnormality detection between the device A1 and the device B2, and to match these connection abnormality detection results. Furthermore, highly reliable connection abnormality detection can be performed. In this way, by using an oscillation signal (AC signal) that starts oscillation upon normal connection as a connection abnormality detection signal, a highly reliable connection abnormality detection circuit can be configured with a simple circuit.

  Here, the operation of FIG. 3 will be described. The device A and the device B are in a connected state, the wiring 19 of the device A and the wiring 18 of the device B have the same potential, and similarly, the wiring 17 of the device A and the wiring 20 of the device B have the same potential. The wiring is connected from the wiring 17 of the device A to the wiring 18 of the device B via the inverting circuit 13, the delay circuit 15, and the wiring 19, and the signal passes through the inverting circuit 14, the delay circuit 16, and the wiring 20 of the device B. , And propagates to the wiring 17 of the device A.

  When a signal propagates from the inverter circuit 13 of the device A to the inverter circuit 14 of the device B, or from the inverter circuit 14 of the device B to the inverter circuit 13 of the device A, a delay is generated by each of the delay circuits 15 and 16, It becomes a mechanism to oscillate. Self-oscillation is started by repeating this loop. The oscillation signal (AC signal) generated by this operation is a connection abnormality detection circuit.

FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram showing the prior art. FIG. 3 is a diagram showing an oscillation circuit that starts oscillation with the normal connection of FIG.

Explanation of symbols

1 Device A
2 Device B
3 Device A Detection Circuit 4 Device B Detection Circuit 5 Self-Oscillation Loop Circuit 6 Oscillation Circuit that Starts Oscillation with Normal Connection with Device B 7 Oscillation Circuit that Starts Oscillation with Normal Connection with Device A 8 Ground Voltage and Conduction 9 Disconnection 10 resistor 11 power supply 12 ground voltage 13, 14 inversion circuit 15, 16 delay circuit 17-20 wiring

Claims (3)

In the connection abnormality detection circuit for monitoring the connection state between the devices in the railway security system that requires connection between the first device and the second device in the double redundant configuration ,
In a state in which the device are connected to each other, it provided an oscillation circuit that oscillates start only when being properly connected to the respective devices,
In the oscillation circuit, the first wiring of the first device and the second wiring of the second device are at the same potential,
When the second wiring of the first device and the first wiring of the second device are normally connected to the same potential,
The signal passes from the second wiring of the first device to the second wiring of the second device via the inverting circuit, the delay circuit of the first device, and the first wiring of the first device. Connected to
Propagating to the inverting circuit, the delay circuit, and the first wiring of the second device of the second device,
Each delay circuit has a signal from an inverting circuit of the first device to an inverting circuit of the second device,
Or, when a signal propagates from the inverting circuit of the second device to the inverting circuit of the first device, a delay is generated, and the self-oscillation is started by repeating the mutual oscillation.
Connection trouble detecting circuit and detects abnormal connection between said device by monitoring the oscillating signal of alternating the oscillation circuit outputs.   2. The connection abnormality detection circuit according to claim 1, wherein the connection state between each device can be monitored even when a plurality of devices are connected.   In the connection abnormality detection circuit according to claim 2, when connecting a plurality of devices, a connection abnormality detection circuit is provided for each device, and the connection abnormality detection results are compared with each other, thereby further increasing reliability. Connection abnormality detection circuit, characterized by enabling simple connection abnormality detection.

Images