JPH07325980A - Control circuit and control system for display unit for train operation board - Google Patents

Abstract

PURPOSE:To double display units even on the operation board whose space is limited. CONSTITUTION:This system is equipped with control circuits 2a and 2b which are enabled to send signals for display to all instruments, and the control circuit 2b which is normally given with priority displays all instruments of the display units. If the control circuit 2b gets out of order, a watchdog timer 23 detects that and then a tri-state buffer 22 is switched; and the tri-state buffer 22 of the control circuit 2b which is ON so far is turned OFF and the tri-state buffer 22 of the control circuit 2a which is OFF so far is tuned ON instead.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control circuit for a train cab display, which controls various displays such as a speedometer provided in a train cab.

[0002]

2. Description of the Related Art Trains have various indicators such as speedometers, overhead line voltmeters and pressure gauges. In each of these, the signals generated from the respective sensors are taken in through an interface circuit, and then a predetermined process is performed by the control circuit before being displayed on the display. Among these instruments, for example, the speedometer is particularly important, so the control circuit is duplicated to provide redundancy. In recent years, due to traffic conditions, train density has become more and more crowded, and if one train fails, the trains that follow it will be affected. However, it is important to ensure that the content of the failure does not hinder driving. Therefore, by duplicating not only the speedometer but also other indicators, even if one indicator is abnormal,
It is desirable to ensure normal operation by the display contents of the other display.

[0003]

However, in order to perform the duplication, a special device is required to switch them, which deteriorates the economical efficiency and hinders the compatibility of the devices.

[0004]

In order to solve such a problem, the invention according to claim 1 processes a signal according to an input train operating condition to display a display signal corresponding to all display contents of a display. And a processing unit for outputting an abnormal signal when there is an abnormality in the processing, and a second terminal when the abnormal signal is not supplied to the first terminal (23c) having first to third terminals When a signal having a first level (“0”) is transmitted from (23b) and an abnormal signal is supplied to the first terminal (23c), a second level (“1” is output from the second terminal (23b). , ”) And sends a signal to the third terminal (23
When a signal of the first level (“0”) is supplied to a), the second terminal (2) is supplied regardless of the signal supplied to the first terminal.
3b) sends a signal of a second level (“1”) from the failure detection circuit, and the failure detection circuit outputs the first signal from the second terminal.
And a buffer that sends the output signal of the processing unit to the display when the signal of the level ("0") is being sent. The invention of claim 2 includes the first and second control circuits having the function of claim 1, and the second terminal of the first control circuit is connected to the first terminal of the second control circuit. In addition, the same signal is input to the input of the processing unit, and the buffer output is connected in common to the display unit. That is, a control circuit that outputs signals corresponding to all display functions
Duplication, its input is commonly supplied, output is output through a tri-state buffer, and that tri-state buffer is always given priority by setting the side to which priority is given to the on state. When the processing section of the control circuit on the side becomes abnormal, the tristate buffer on the side to which priority is given is turned off, and the tristate buffer on the side to which priority is not given is turned on Is.

[0005]

According to the invention of claim 1, a failure signal is supplied to the failure detection circuit when the processing section fails. Therefore, the failure detection circuit sends a signal to the "0" level, so that the tri-state buffer is turned off and the input signal is not output.
The invention according to claim 2 uses the two control circuits according to claim 1, and when one of the failure detection circuits outputs a "0" level output signal in a normal state, the other control circuit has the tri-state buffer turned off. When the "1" level signal is being sent from one of the failure detection circuits, the tri-state buffer of one control circuit stops operating, and the tri-state buffer of the other control circuit starts operating. To do. That is, since the two control circuits are supplied with a common input signal, the tri-state buffer of the control circuit to which the priority is given is normally turned on, and the output signal is transmitted from there. If the control circuit becomes abnormal, the tristate buffer on the side that was given priority turns off, and the tristate buffer on the side that was not given priority turns on. Is sent.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an embodiment in which control circuits for all indicators are duplicated. For example, when signals for detecting speed, pressure and current are supplied from various sensors as a representative, It is supplied in parallel to the control circuits 2a and 2b via the interface circuit 1. Control circuit 2a
2 and 2b take in the supplied signals and process them in a time-division manner so as to obtain a signal suitable for a display for each signal.

The control circuits 2a and 2b include a processing unit 21,
It has a tri-state buffer 22 and a failure detection circuit 23. The failure detection circuit 23 monitors the operation of the processing unit 21, and when the signal indicating that the processing unit 21 is normal is supplied to the terminal 23c, the signal of "0" level is transmitted from the terminal 23b. However, when a signal indicating an abnormality is supplied from the processing unit 21, the terminal 2
A signal of "1" level is transmitted from 3b.

The tri-state buffer 22 outputs an input signal when a signal of "0" level is supplied from the terminal 23b of the failure detection circuit 23, and when the signal supplied from the terminal 23c is "1" level. Does not send an input signal. Further, when the signal supplied to the terminal 23a is at "1" level, the signal level output from the terminal 23b is governed by the signal supplied to the terminal 23c as described above. When is at "0" level, the signal of "1" level is transmitted from the terminal 23b regardless of the signal supplied to the terminal 23c.

The control circuits 2a and 2b thus configured
As shown in FIG. 1, a common signal is supplied to the input side and the output signal of the buffer 22 is commonly supplied to the display device 3. On the other hand, the terminal 23a of the control circuit 2a is connected to the terminal 23b of the control circuit 2b, and the terminal 2a of the control circuit 2b is connected.
Leave 3a open.

The operation of the device configured as described above is as follows. When both the control circuits 2a and 2b are normal, the processing units 21 in both control circuits output a signal indicating that they are normal, and the terminal 23c of the failure detection circuit 23.
Is being supplied to. On the other hand, since the terminal 23a of the control circuit 2b is open, the failure detection circuit 23 has the terminal 23a.
The signal of level "0" is transmitted from b. For this reason,
The tri-state buffer 22 is on,
The signal output from the processing unit 21 is supplied to the display device 3.

The "0" level signal output from the terminal 23b of the failure detection circuit 23 in the control circuit 2b is supplied to the terminal 23a of the failure detection circuit 23 in the control circuit 2a. When a "0" level signal is supplied, it is unconditionally "1" from the terminal 23b.
Send level signal. Therefore, the tri-state buffer 22 is turned off and the input signal is not sent to the output side. That is, the output sides of the control circuits 2a and 2b are commonly connected, but only the signal output from the control circuit 2b is supplied to the display device 3.

If the processing section 21 of the control circuit 2b fails and the failure signal is supplied to the terminal 23c of the failure detection circuit 23, the failure detection circuit 23 outputs a "1" level signal from the terminal 23b. become. As a result, the control circuit 2
The tristate buffer 22 of b is turned off and does not output any output signal. On the other hand, since the failure detection circuit 23 of the control circuit 2a is supplied with the signal of "1" level at the terminal 23a, the signal level output from the terminal 23b is controlled by the signal level supplied to the terminal 23c. Will be done.

In the operation at this time, as described above, since the signal of "0" level is output from the terminal 23b when the processing unit 21 is normal, the tri-state buffer 22 is turned on and the output of the processing unit 21 is output. The signal is supplied to the display 3. Therefore, priority is given to the control circuit 2b by connecting the output terminal of the failure detection circuit 23 to the daisy chain, and when the control circuit to which the priority is given fails, the control circuit with lower priority operates. Become.
In FIG. 1, two normal control circuits are used to form a double system, but if three daisy chains are connected in the same manner to form a triple system, a more reliable system can be constructed. . Further, although the present invention only discusses switching of operating control circuits, as an actual product, a failure signal output from the processing unit 21 is monitored, and when a failure signal is transmitted, a failure display is displayed. However, the description thereof is omitted because it is not related to the gist of the present invention.

On the other hand, each control circuit sends a signal for operating the display device 3 shown in FIG. 3 as an example. In the example of FIG. 3, each instrument is made up of an analog instrument and a digital instrument to form a double system configuration so that redundancy is increased, and even if one fails, the other can read the value. is there. The ammeter is composed of an analog ammeter 30 and a digital voltmeter 31, and the speed meter is composed of an analog speed meter 32 and a digital speed meter 33. There are two types of pressure system for measuring different systems, both of which are analog. It is composed of pressure gauges 34 and 37 and digital pressure gauges 35 and 36.

In order to supply a signal to such an indicator 3, both the control circuits 2a and 2b are constructed so as to be able to supply a signal to both an analog meter and a digital meter.
In this way, if a signal sent from one control circuit is used to supply a signal to each display device that has been made into a dual system, and if that control circuit is duplicated, then all instruments can be duplicated. In addition, the equipment can be made smaller than that in which the control circuit is duplicated for each instrument, and it can be installed even in the cab where the installation place is limited.

In the case of an analog instrument, for example, if the safe value range is displayed in green and the dangerous value range is displayed in red,
It is easy to intuitively understand whether or not the driving condition is safe. However, in the case of digital display, since the numbers are only displayed digitally, it is impossible to know whether or not the driving condition is safe unless the safe value is remembered. Figure 3
If it is displayed in combination with the analog display as in the above, it does not become a problem so long as the instrument of the analog display does not break down, for example, there are display items only for digital display,
If the analog display fails, it is not possible to intuitively grasp whether the operating state is in a safe state, which is a problem.

The indicator for digitally displaying such a state as a two-color indicator is provided with a comparator for discriminating the threshold value between the safe state and the dangerous state, and the comparator is in the safe state. If it is determined that the dangerous state is displayed, for example, the green state is displayed, and if the dangerous state is displayed in the red state, the dangerous state can be intuitively recognized.

[0018]

As described above, according to the first aspect of the invention, the control signal supplied to the tri-state buffer controls whether the input signal is output or not.
If a plurality of the same circuits are used and control is performed by giving priority to them, there is an effect that a multiple type can be easily configured with exactly the same circuit. The invention of claim 2 has an effect that it is not necessary to prepare a special circuit for multiplexing because the control terminals of the failure detection circuit are daisy-chain connected by using the plurality of control circuits of claim 1.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration when a control circuit is duplicated.

FIG. 2 is a view showing main instruments provided in a driver's cab.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Interface circuit 2a, 2b Control circuit 21 Processing unit 22 Tri-state buffer 23 Failure detection circuit 3 Indicator

Claims (2)

[Claims] 1. A control circuit for a train cab display, which displays operation information on the train cab, processes a signal corresponding to the train operation status that is input and responds to all display contents of the display. When a processing unit that outputs a display signal and sends an abnormal signal when there is an abnormality in the processing, and that has the first to third terminals and the abnormal signal is not supplied to the first terminal (23c) When a signal having a first level (“0”) is transmitted from the second terminal (23b) and the abnormal signal is supplied to the first terminal (23c), the second terminal (23b) Signal having a second level (“1”) is transmitted from the first terminal to the third terminal (23a) when the signal having the first level (“0”) is supplied to the first terminal. Signal from the second terminal (23b) regardless of the signal Le ( "1") and the failure detection circuit for sending a signal, the first from the second terminal of the fault detection circuit (23b)
And a buffer for sending the output signal of the processing unit to the display when the signal of the level ("0") is being sent. 2. A first and a second having the function of claim 1.
And a second terminal (23b) of the first control circuit is connected to the second control circuit.
Connected to the first terminal (23a) of the control circuit of
A control system for a train cab display, wherein the same signal is input to the input of the processing unit and the buffer output is commonly connected to the display.