KR102057667B1 - Digital io board for detecting a railway signal lamp - Google Patents

Abstract

Disclosed is a digital IO board for detecting a railway signal lamp. According to the present invention, the digital IO board for detecting a railway signal lamp comprises: a filter unit filtering out noise from input direct current (DC) power; a DC/DC conversion unit converting voltage from which the noise is filtered out by the filter unit to generate DC voltages: a signal input unit receiving DC voltage applied to a railway signal lamp side and DC output voltage from the DC/DC conversion unit; a comparison unit comparing an output signal from the signal input unit depending on the DC voltage applied to the railway signal lamp side with a preset reference voltage; a first insulation output unit generating a first digital result signal of a high or low level depending on a comparison result signal of the comparison unit; a voltage monitoring unit monitoring the DC output voltage from the DC/DC conversion unit; and a second insulation output unit generating a second digital result signal of a high or low level depending on an output signal of the voltage monitoring unit. Accordingly, a railway signal lamp is detected in a voltage detection method, not a current detection method, with respect to a railway signal lamp made of an LED, thereby increasing reliability in detection of the railway signal lamp.

Description

Digital IO board for railroad traffic light detection {DIGITAL IO BOARD FOR DETECTING A RAILWAY SIGNAL LAMP}

The present invention relates to a digital IO board for detecting a railroad traffic light, and more specifically, to improve reliability by employing a voltage detection method instead of a current detection method for an LED (Light Emitting Diode) -based railroad traffic light. A digital IO board used in a track side control unit (LEU) for detecting traffic lights.

Various control devices are installed and operated for fast and safe operation of trains, and as the demand for railway traffic increases, the number of trains running on railroads increases rapidly, which is very accurate and accurate to guarantee safety in high-density operation of trains. Control technology is required. Control systems for high-density operation include, for example, automatic occlusion control device (ABS), track circuit control device, track switching device, interlock control device, railroad crossing security device, train automatic control device (ATC, ATO, ATS, ATP, MBS). Many control devices such as) are being applied.

Among them, an automatic train protection (ATP) system transmits various digital information necessary for the operation of a train to a vehicle through a device called a balise, so that control devices including various processing devices installed in the vehicle are trained. It is a train control related facility that automatically detects the speed of the vehicle and stops it automatically when it exceeds a certain speed. Ballise is a device used to transmit information from the ground equipment to the onboard equipment through the RF antenna.

The line side electronic unit (LEU), as shown in FIG. 1, is a component of the onboard signal system (ATP) and is installed at the line side to detect a failure of a balise. It refers to a device that participates in or detects a traffic light (LAMP) installed on a track.

Although not shown in detail in FIG. 1, the line side control unit LEU generally includes a lamp detection board LDB, a ballless drive board BDB, and the like. In the track side control unit LEU, in particular, the lamp detection board LDB detects signals applied to the lamp LAMP, i.e., a signal lamp (for example, a signal lamp lighting red, green, yellow, etc.) installed on the line. It is a component that serves to provide the detection result to the on-vehicle control system on the train side.

Conventional lamp detection board (LDB) has been detected by detecting the current applied to the side of the traffic light, such that the conventional traffic light is mainly filament-based lamps, and using it. However, as LED-based railroad traffic lights, which are eco-friendly light emitting devices, are dominant, when a small amount of current applied to the LED-based train traffic lights is detected on the lamp detection board, detection errors are frequent and the risk of accidents increases. There is a situation. Accordingly, there is a need for a solution capable of overcoming a problem of deterioration in detecting railroad traffic lights by detecting a current applied to the LED-based train traffic lights.

The problem to be solved by the present invention is to detect the railroad traffic lights that can detect the railroad traffic lights by detecting the voltage provided to the LED-based train traffic lights in order to detect the LED-based railway traffic lights in the lamp detection board in the track control unit. To provide a digital IO board.

In accordance with an aspect of the present invention for solving the above problems, a digital IO board for detecting a railroad traffic light includes a filter unit 101 for filtering noise from an input DC power supply Vin, and noise filtering by the filter unit. A DC / DC converter 102 for converting the converted voltage to generate a DC output voltage Vout1, a DC voltage Sin1 applied to the train signal light side, and a DC output voltage Vout1 from the DC / DC converter. Comparator 104a for comparing the output signal Sout1 from the signal input unit 103a, which is dependent on the signal input unit 103a and the DC voltage Sin1 applied to the train traffic light side, to receive a preset reference voltage. ), A first insulation output unit 105a for generating a high level or low level first digital result signal Sd1 depending on the comparison result signal C1 from the comparison unit, and the DC / DC converter. Collect the DC voltage (Vout1) from (102). And a second insulation output unit 107a for generating a high level or low level second digital result signal Sd3 depending on the output signal Sv1 of the voltage monitoring unit. Characterized in that.

According to an embodiment, the DC / DC converter 102 may include a transformer for converting the voltage filtered by the filter into a predetermined DC voltage, and a pulse width modulation (PWM) in real time by monitoring the transformer. PWM control unit for controlling and a rectifying unit for rectifying the voltage transformed by the transformer.

In example embodiments, the first insulation output unit 105a may include a photo coupler that generates a first digital result signal Sd1 having a high level or a low level depending on the comparison result signal C1.

According to an embodiment, the second insulation output unit 107a may include a photo coupler for generating a high level or low level second digital result signal Sd3 depending on the output signal Sv1 of the voltage monitoring unit. do.

According to an embodiment, the comparator 104a includes a plurality of comparators 104a1 to 104a4, each of the plurality of comparators outputted from the signal input part 103a based on a respective reference voltage. After comparison with the signal Sout1, the respective comparison result signals C1-1 to C1-4 are generated, and the first insulation output unit 105a includes a plurality of photos corresponding to each of the plurality of comparators. And a plurality of photo couplers, each of which generates the first digital result signals Sd1-1 to Sd1-4 having a high level or a low level depending on the comparison result signals.

According to one embodiment, the reference voltage of each of the plurality of comparators is set to have a different voltage magnitude.

In accordance with another aspect of the present invention for solving the above problems, a digital IO board for detecting a railroad traffic light includes: a filter unit 101 for filtering noise from an input DC power source Vin; A DC / DC converter 102 for converting a voltage from which noise is filtered by the filter unit to generate first DC output voltages Vout1; A first signal input unit 103a for receiving a DC voltage Sin1 applied to a first train signal light side and a first DC output voltage Vout1 from the DC / DC converter; A second signal input unit 103b for receiving a DC voltage Sin2 applied to a second train signal light side and a second DC output voltage Vout2 from the DC / DC converter; A first comparing unit 104a for comparing an output signal Sout1 from the first signal input unit 103a depending on the DC voltage Sin1 applied to the first train traffic light side with a preset reference voltage; A second comparing unit 104b for comparing an output signal Sout2 from the second signal input unit 103b depending on the DC voltage Sin2 applied to the second train traffic light side with a preset reference voltage; A 1-1 insulated output unit 105a for generating a high level or low level 1-1 digital result signal Sd1 depending on the comparison result signal C1 from the first comparator; A 1-2 isolation output unit 105b for generating a high level or low level 1-2 digital result signal Sd2 depending on the comparison result signal C2 from the second comparison unit; A first voltage monitoring unit 106a for monitoring a first DC output voltage Vout1 from the DC / DC conversion unit 102; A second voltage monitoring unit 106b for monitoring a second DC output voltage Vout2 from the DC / DC conversion unit 102; A 2-1 insulated output unit 107a for generating a high level or low level 2-1 digital result signal Sd3 depending on the first output signal Sv1 of the voltage monitoring unit; And a second-2 isolated output unit 107b for generating a high level or low level second-2 digital result signal Sd4 depending on the second output signal Sv2 of the voltage monitoring unit. It is done.

The present invention provides a digital IO board for detecting railroad traffic lights of a new concept capable of detecting railroad traffic lights by detecting the voltage provided to the LED-based train traffic lights, thereby increasing the reliability of railroad traffic light detection, Accidents also have an effect that can be prevented.

1 is a view schematically showing a general ATP system,
2 is a block diagram of a track side control unit (LEU) 1 to which a digital IO board for detecting a railroad traffic light according to an embodiment of the present invention is applied,
3 is a block diagram of a digital IO board for railroad traffic light detection according to an embodiment of the present invention,
FIG. 4 is a block diagram illustrating an example of the configuration of the comparison units 104a and 104b in FIG. 3.
FIG. 5 is a block diagram illustrating a configuration example of the first insulation output units 105a and 105b in FIG. 3.
FIG. 6 is a block diagram illustrating a configuration example of the second insulation output units 107a and 107b in FIG. 3.
FIG. 7 is a diagram illustrating a detailed configuration example of the first insulation output units 105a and 105b or the second insulation output units 107a and 107b in FIG. 3.
FIG. 8 is a diagram illustrating a configuration example of the DC / DC converter 102 in FIG. 3.

According to the present invention, when the railroad traffic light is gradually changed to an LED-based traffic light, when detecting a train traffic light by detecting a current supplied to the traffic light side as in the prior art, unlike a conventional filament-based train traffic light, In this case, since the current supplied is relatively weak, in order to solve an error problem that frequently occurs in detecting a traffic light, it is basically a voltage-based detection method, not a detection method based on a current supplied to a railroad traffic light side.

To this end, according to the present invention, the railroad signal detecting digital IO board is a high level or low level depending on the comparison result signal from the filter unit, DC / DC converter, signal input unit, comparison unit, the comparison unit A first insulation output unit for generating a first digital result signal, a voltage monitoring unit for monitoring the DC output voltage from the DC / DC converter, and a second insulation output unit.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. It is to be noted that the accompanying drawings and embodiments are simplified and illustrated for the purpose of helping those skilled in the art to understand the present invention.

FIG. 2 is a block diagram of a track side control unit (LEU) 1 to which a digital IO board for railroad traffic light detection according to an embodiment of the present invention is applied. Referring to FIG. 2, the line side control unit (LEU) 1 basically includes a lamp detection board (LDB) 10, a ballless drive board (BDB) 20, and a power board 30. The present invention relates to the lamp detection board 10, the lamp detection board 10 is referred to as a digital IO board 10 for railroad traffic light detection.

3 is a block diagram of a digital IO board for railroad traffic light detection according to an embodiment of the present invention. Referring to FIG. 3, the digital IO board 10 for railroad traffic light detection according to the present invention includes a filter unit 101 and a filter unit 101 that filter out noise from an input DC power supply Vin. The DC / DC converter 102 generating the DC voltages Vout1 by converting the voltage Vf, the DC voltage Sin1 applied to the train signal light side, and the DC output voltage from the DC / DC converter 102. A comparison unit for comparing the output signal Sout1 from the signal input unit 103a, which receives the Vout1, and the signal input unit 103a depending on the DC voltage Sin1 applied to the train traffic light side, with a preset reference voltage ( 104a, a first isolation output section 105a for generating a high level or low level first digital result signal Sd1 depending on the comparison result signal C1 from the comparison section 104a, and DC / DC. A voltage monitoring unit 106a for monitoring the DC output voltage Vout1 from the conversion unit 102; And a second insulation output unit 107a for generating a high level or low level second digital result signal Sd3 depending on the output signal Sv1 of the voltage monitoring unit 106a. First, as described above, it is assumed that only one signal input unit, a comparison unit, a first insulation output unit, a voltage monitoring unit, and a second insulation output unit are provided. Each case provided with two will be described later, it is not shown in the drawings, it is also possible that the configuration provided with three or more each.

First, the filter unit 101 receives a DC power supply (Vin) for operating the digital IO board for detecting a railway traffic light, removes noise included in the DC power supply (Vin), and then removes the DC voltage (Vf) from which the noise is removed. Output The voltage level of the DC power supply Vin is generally 16V to 50V.

The DC / DC converter 102 receives the DC voltage Vf from which the noise is removed by the filter 101 and converts the DC voltage to generate the DC output voltage Vout1. Since a specific example of the DC / DC converter 102 is illustrated in FIG. 8, it will be described later with reference to FIG. 8.

The signal input unit 103a receives a DC voltage Sin1 (hereinafter also referred to as a “lamp signal”) applied to the side of a traffic light along with a DC output voltage Vout1 from the DC / DC converter 102. The ramp signal Sin1 is generally a DC 12V to 40V. The signal input unit 103a further includes a surge protection circuit so as to protect the LED from lightning and the like. In addition, as illustrated, a plurality of lamps may be configured to correspond to each other so as to receive different lamp signals Sin1 and Sin2. In this example, it consists of two signal input parts 103a and 103b.

The comparison unit 104a compares the output signal Sout1 from the signal input unit 103a depending on the ramp signal Sin1 with a preset reference voltage, and generates a comparison result signal C1 accordingly. An example of the configuration of the comparing unit 104a is shown in FIG. 4 and will be described later.

The first insulation output unit 105a generates the high or low level first digital result signal Sd1 depending on the comparison result signal C1 output from the comparator 104a. An example of the configuration of the first insulation output section 105a is shown in Figs. 5 and 7, and will be described later.

The voltage monitoring unit 106a is a component for monitoring the DC voltage output Vout1 from the DC / DC converter 102 and checks whether the DC voltage output Vout1 from the DC / DC converter 102 is normal. To monitor if it is not. The monitoring result is also finally output as a digital signal, and the part for this is the second insulation output unit 107a.

That is, the second insulation output unit 107a generates the second digital result signal Sd3 having the high level or the low level depending on the output signal Sv1 of the voltage monitoring unit 106a. An example of the configuration of the second insulation output unit 107a is shown in Figs. 6 and 7 and will be described later.

4 is a block diagram illustrating an example of the configuration of the comparison units 104a and 104b in FIG. 3. Referring to FIG. 4, the comparison unit 104a may include four blocks 104a1 to 104a4. In addition, as described above, when the comparison unit is provided with a plurality of 104a and 104b, each of the comparator may be composed of four blocks. Each block is represented by a comparator for convenience of description. Referring to one comparator (eg, 104a), the comparator 104a includes a plurality of comparators 104a1 to 104a4, and each of the comparators 104a1 to 104a4 includes a respective reference voltage REF1. After comparison with the output signal Sout1 from the signal input unit 103a on the basis of -1 to REF1-4, the respective comparison result signals C1-1 to C1-4 are generated. The reference voltages REF1-1 to REF1-4 may all be set identically or differently. Referring to the case in which the reference voltages REF1-1 to REF1-4 are set to be the same, if all comparators or components or wires in front of the comparators are in a normal state, the same comparison result signals will be generated.

FIG. 5 is a block diagram illustrating a configuration example of the first insulation output units 105a and 105b in FIG. 3. Referring to FIG. 5, the first insulation output unit (eg, 105a) may be configured with a plurality of 105a1 ˜ 105a4 corresponding to each of the plurality of comparators 104a1 ˜ 104a4. In addition, the first insulation output unit 105a includes a plurality of photo couplers (see FIG. 7) corresponding to each of the plurality of comparators 104a1 to 104a4, and each of the plurality of photo couplers is a result of the comparison. Depending on the signals C1-1 to C1-4, the first digital result signals Sd1-1 to Sd1-4 of high level or low level are generated.

As such, by configuring a plurality of comparators and a plurality of photo couplers corresponding to each, even if damage or malfunction of some comparators or some photo coupler (s) occurs, the normal operation of a plurality of normal comparators and photo couplers The first digital result signals can be provided to the next stage, for example, the Bally drive board (BDB) side, so that accurate information can be finally sent to the train side, thereby ensuring reliability and stability. For example, when three or more of the four digital signals constituting the first digital result signals are at a low level, it may be confirmed that the corresponding ramp signal (eg, Sin1) is normally input. Although not shown, a logic gate circuit (eg, an AND gate, an OR gate, or a combination thereof) may be further provided at a rear end thereof so as to process the plurality of first digital result signals.

FIG. 6 is a block diagram illustrating a configuration example of the second insulation output units 107a and 107b in FIG. 3. Like the first insulation output unit, the second insulation output unit may include a plurality of photo couplers (see FIG. 7), and each of the plurality of photo couplers may respectively output an output signal Sv1 of the voltage monitoring unit 106a. The second digital result signal Sd3 having a high level or a low level may be generated depending on -1 to Sv1-4). Similarly, by configuring the second insulation output unit with a plurality of photo couplers, even if damage or malfunction of some photo coupler (s) occurs, the second digital result signals due to the normal operation of the plurality of normal comparators and photo couplers are corrected. It can be provided to the drive board (BDB) side to finally send accurate information to the train side, thereby ensuring the reliability and stability. Again, like this, for example, when three or more of the second digital result signals are at the low level, it can be confirmed that the operation state is normal.

FIG. 7 illustrates a detailed configuration example of the first insulation output units 105a and 105b or the second insulation output units 107a and 107b in FIG. 3, wherein a plurality of first insulation output units or second insulation output units are provided. It is composed of photo couplers.

In the case of one photo coupler constituting the first insulation output unit 105a, the high level is dependent on the comparison result signal (any one of C1-1 to C1-4 or any one of C2-1 to C2-4). Alternatively, a low level first digital result signal (any one of Sd1-1 to Sd1-4 or one of Sd2-1 to Sd2-4) is generated. For example, when a DC voltage of a predetermined magnitude or more is input as the comparison result signal (eg, C1-1), the light emitting diode D1 emits light, and the transistor Q1 is turned on, and the transistor Q1 is turned on. When turned on, the first digital result signal (eg, Sd1-1) is viewed as being connected to the ground side, and thus becomes a low level signal. On the contrary, when the comparison result signal C1-1 is input at a voltage lower than the turn-on voltage of the light emitting diode D1, since the transistor Q1 is in the off state, the first digital result signal Sd1-1 is 5V, That is, it becomes a high level signal. In the drawing, the ground voltage (0V) is configured to be a low level and 5V to a high level, but the magnitude of the voltage may be designed to be different.

When the photo coupler of FIG. 7 is one photo coupler constituting the second insulation output unit 107a, the input of the photo coupler is the output signal Sv1 of the voltage monitoring unit 106a, and the digital output of the photo coupler is The same description may be applied as it is except for the second digital result signal Sd3 or Sd4.

FIG. 8 is a diagram illustrating a configuration example of the DC / DC converter 102 in FIG. 3. Referring to FIG. 8, the DC / DC converter 102 includes transformers T1 and T2 for converting the voltage Vf from which noise is filtered by the filter unit 101 into a predetermined DC voltage, and the transformer ( PWM control unit for monitoring the pulse width modulation (PWM) in real time by monitoring the T1, T2, and rectifier (RECT1, RECT2) for rectifying the voltage transformed by the transformer (T1, T2). Thus, finally, the voltages Vout1 and Vout2 rectified by the rectifiers RECT1 and RECT2 are provided to the signal input units 103a and 103b. In addition, the voltage monitoring units 106a and 106b also monitor the voltages Vout1 and Vout2.

In addition, as shown in FIG. 3, the signal input units 103a and 103b, the comparison units 104a and 104b, the first insulation output units 105a and 105b, the voltage monitoring units 106a and 106b and the second insulation outputs. The digital IO board for railroad traffic signal detection of this invention comprised by the some part 107a, 107b is summarized as follows.

The digital IO board for detecting a railroad traffic light according to the present invention includes a filter unit 101 for filtering noise from an input DC power source Vin, and converting a voltage from which noise is filtered by the filter unit 101 to output a first DC output. The DC / DC converter 102 generating the voltages Vout1, the DC voltage Sin1 applied to the first train signal light side, and the first DC output voltage Vout1 from the DC / DC converter are input. A second signal input unit (receiving the first signal input unit 103a), a DC voltage Sin2 applied to the second train traffic light side, and a second DC output voltage Vout2 from the DC / DC converter; 103b) and a first comparison section 104a for comparing the output signal Sout1 from the first signal input section 103a, which depends on the DC voltage Sin1 applied to the first train traffic light side, with a preset reference voltage; , The second signal input unit dependent on the DC voltage Sin2 applied to the second train traffic light side High or low level depending on the second comparison unit 104b for comparing the output signal Sout2 from 103b with a preset reference voltage and the comparison result signal C1 from the first comparison unit 104a. A high level or low level depending on the first-first isolation output section 105a for generating the first-first digital result signal Sd1 and the comparison result signal C2 from the second comparison section 104b. 1-2 insulation output unit 105b for generating 1-2 digital result signal Sd2 and first voltage for monitoring first DC output voltage Vout1 from DC / DC converter 102. The first monitoring unit 106a, the second voltage monitoring unit 106b for monitoring the second DC output voltage Vout2 from the DC / DC converter 102, and the first of the first voltage monitoring unit 106a. A 2-1 insulated output unit 107a for generating a high level or low level 2-1 digital result signal Sd3 depending on the output signal Sv1, and a second voltage monitor In dependence on the second output signal (Sv2) of the ring (106b) and a second-second isolated output section (107b) for generating a second-second digital result signal (Sd4) of high level or low level.

1: LEU
10: LDB
20: BDB
30: power board
101: filter unit
102: DC / DC converter
103a, 103b: signal input unit
104a, 104b: comparison unit
105a, 105b: first insulation output unit
106a, 106b: voltage monitoring unit
107a and 107b: second insulation output unit

Claims (7)

As a digital IO board for railroad traffic light detection,
A filter unit 101 for filtering noise from an input DC power source Vin;
A DC / DC converter 102 for converting a voltage from which noise is filtered by the filter unit to generate a DC output voltage Vout1;
A signal input unit 103a for receiving a DC voltage Sin1 applied to the train signal light side and a DC output voltage Vout1 from the DC / DC converter;
A comparison unit 104a for comparing an output signal Sout1 from the signal input unit 103a depending on the DC voltage Sin1 applied to the train signal light side with a preset reference voltage;
A first insulation output unit 105a for generating a high level or low level first digital result signal Sd1 depending on the comparison result signal C1 from the comparison unit;
A voltage monitoring unit 106a for monitoring a DC output voltage Vout1 from the DC / DC conversion unit 102; And
And a second insulation output unit 107a for generating a high level or low level second digital result signal Sd3 depending on the output signal Sv1 of the voltage monitoring unit. Digital IO board.
The method according to claim 1,
The DC / DC converter 102 may include a transformer for converting a voltage filtered by noise into the predetermined DC voltage, and a PWM controller for controlling the pulse width modulation (PWM) in real time by monitoring the transformer. And a rectifier for rectifying the voltage transformed by the transformer.
The method according to claim 1,
The first insulation output unit 105a may include a photo coupler for generating a high level or low level first digital result signal Sd1 depending on the comparison result signal C1. Digital IO board.
The method according to claim 1,
The second insulation output unit 107a may include a photo coupler for generating a high level or low level second digital result signal Sd3 depending on the output signal Sv1 of the voltage monitoring unit. Digital IO board for detecting railway traffic lights.
The method according to claim 3,
The comparator 104a includes a plurality of comparators 104a1 to 104a4, and each of the plurality of comparators is compared with an output signal Sout1 from the signal input unit 103a based on a respective reference voltage. After that, generate the respective comparison result signals (C1-1 ~ C1-4),
The first insulation output unit 105a includes a plurality of photo couplers corresponding to each of the plurality of comparators, each of the plurality of photo couplers each having a high level, depending on the comparison result signals. And generating low level first digital result signals (Sd1-1 to Sd1-4).
The method according to claim 5,
The reference voltage of each of the plurality of comparators is set to have a different voltage magnitude, characterized in that the digital IO board for railroad traffic light detection.
As a digital IO board for railroad traffic light detection,
A filter unit 101 for filtering noise from an input DC power source Vin;
A DC / DC converter 102 for converting a voltage from which noise is filtered by the filter unit to generate first DC output voltages Vout1;
A first signal input unit 103a for receiving a DC voltage Sin1 applied to a first train signal light side and a first DC output voltage Vout1 from the DC / DC converter;
A second signal input unit 103b for receiving a DC voltage Sin2 applied to a second train signal light side and a second DC output voltage Vout2 from the DC / DC converter;
A first comparing unit 104a for comparing an output signal Sout1 from the first signal input unit 103a depending on the DC voltage Sin1 applied to the first train traffic light side with a preset reference voltage;
A second comparing unit 104b for comparing an output signal Sout2 from the second signal input unit 103b depending on the DC voltage Sin2 applied to the second train traffic light side with a preset reference voltage;
A 1-1 insulated output unit 105a for generating a high level or low level 1-1 digital result signal Sd1 depending on the comparison result signal C1 from the first comparator;
A 1-2 insulation output unit 105b for generating a high level or low level 1-2 digital result signal Sd2 depending on the comparison result signal C2 from the second comparison unit;
A first voltage monitoring unit 106a for monitoring a first DC output voltage Vout1 from the DC / DC converter 102;
A second voltage monitoring unit 106b for monitoring a second DC output voltage Vout2 from the DC / DC converter 102;
A 2-1 insulated output unit 107a generating a 2-1 digital result signal Sd3 having a high level or a low level depending on the first output signal Sv1 of the first voltage monitoring unit; And
And a second-2 isolated output unit 107b for generating a high level or low level second-2 digital result signal Sd4 depending on the second output signal Sv2 of the second voltage monitoring unit. Digital IO board for railroad traffic light detection characterized by the above.

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