JPH06301876A - Disaster prevention monitoring device - Google Patents

Abstract

(57) [Abstract] [Purpose] Performs waveform transmission that can accurately restore voltage pulses on the terminal side without being affected by waveform distortion due to reflection even if impedance matching is not achieved. [Construction] A receiver 1 is provided with a transmission drive circuit 12 for inputting a transmission pulse having an abrupt rise and fall and blunting the rise and fall of the pulse according to a predetermined time constant and transmitting the pulse. The time constant of the transmission drive circuit 12 is set in the range of 5 μs to 100 μs.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disaster prevention monitor for collecting and monitoring terminal information and controlling terminals by connecting one or a plurality of terminal devices between signal lines drawn from a receiver.

[0002]

2. Description of the Related Art Conventionally, in a disaster prevention monitoring device for monitoring abnormality such as fire and gas leakage, a plurality of terminals 20 are connected to a transmission signal line 2 drawn from a receiver as shown in FIG. The fire information detected by the sensor of the terminal 20 is collected and monitored by polling by specifying the terminal address from the receiver 1. If the receiver 1 determines a fire, specify the terminal address equipped with the disaster prevention device and specify the terminal 2
You can send a control command to 0 to control the disaster prevention device.

In such a disaster prevention monitoring apparatus, the transmission pulse source 17 of the receiver 1 outputs a transmission pulse according to the terminal address and the bit state of various commands, and the transmission drive circuit 19 transmits the transmission signal line 2 Have been sent to. still,
The function of the transmission pulse source 17 is the control CP provided in the receiver 1.
Realized by U. Usually, the transmission pulse from the transmission pulse source 17 is superimposed on the power supply voltage supplied to the terminal 20, and is sent in the voltage mode. On the other hand, the response from the terminal 20 is performed in the current mode in which the current flowing through the transmission signal line 2 is changed.

[0004]

However, in the transmission of the transmission pulse in the voltage mode from the receiver in such a conventional disaster prevention monitoring device, there are the following problems. As shown in FIG. 4, a different number of terminals 20 are connected to the transmission signal line 2 drawn from the receiver depending on the scale of the equipment, and the signal line is appropriately branched depending on the situation of the caution area. There is. The number of terminals that can be connected here corresponds to the maximum current value that can be supplied to the load according to the capacity of the receiver power supply. Therefore, the load impedance on the side of the terminal seen from the receiver 1 is not uniquely determined, and takes various values depending on the number of terminals and the branching state, and the transmission drive circuit 19 of the receiver 1
It is not possible to match the load impedance with respect to.

Therefore, even if the transmission pulse source 17 transmits a transmission pulse having a sharp rise and a fall to the transmission drive circuit 19 and sends it to the transmission signal line 2, the impedance on the load side cannot be matched. , Reflection occurs on the transmission line. Due to the reflection on this transmission line, the transmission pulse is shown in FIG.
As shown in (a), waveform distortion (ringing) due to reflection occurs following the rising and falling edges. If the terminal 20 captures the edge of the transmission pulse and restores the transmission pulse, the edge of the waveform distortion portion due to reflection is also erroneously detected and erroneous information is restored, as shown in FIG. 5B. Will end up.

Further, as shown in FIG. 6, for example, the power supply voltage 3
When a transmission pulse having a peak value of 8.5 V is superimposed on 1.0 V and transmitted, the linking waveform due to reflection fluctuates in the range of 31.0 V to 48.0 V at the rising edge portion, and Up to 22.5 on the falling edge
It varies in the range of V to 31.0V. For this reason, a peak voltage of 48 V at maximum is applied to the terminal circuit due to waveform fluctuation due to reflection, which may damage elements such as a Zener diode used in the terminal circuit or deteriorate durability. Further, if the power supply voltage of the terminal drops to at least 22.5 V due to the waveform fluctuation due to reflection, for example, a voltage drop detection circuit provided in the terminal may operate and erroneously determine a power failure.

The present invention has been made in view of such conventional problems, and a waveform capable of accurately restoring a voltage pulse on the terminal side without being affected by waveform distortion due to reflection even if impedance matching is not achieved. It is an object to provide a disaster prevention monitoring device that performs transmission.

[0008]

To achieve this object, the present invention is constructed as follows. First, according to the present invention, one or a plurality of terminal devices are connected between the signal lines drawn from the receiving means, and various command signals using voltage pulses are transmitted from the receiving means to collect terminal information and control terminals. For disaster prevention monitoring equipment.

According to the present invention for such a disaster prevention monitoring apparatus, a transmission pulse having an abrupt rise and fall is input to the receiving means, and the rise and fall of the pulse are damped in accordance with a predetermined time constant. A transmission drive circuit for transmitting is provided. Here, the time constant of the transmission drive circuit is 5 in consideration that the transmission line used for the disaster prevention monitoring device has a line length of about several tens of meters to several kilometers.
It may be set in the range of μs to 100 μs.

As the command signal transmitted from the receiving means to the terminal, at least a command field for storing a terminal address and a command field for storing various commands are provided, and a voltage pulse corresponding to the bit state of each field is transmitted to the transmission drive. Send to the terminal through the circuit. Furthermore, when the receiving means of the present invention is composed of only a receiver,
When it is composed of a receiver and one or a plurality of relay boards as a local receiver connected to a transmission path from the receiver,
Alternatively, it includes a case where only a relay board as a plurality of local receivers connected to each other by a transmission path is included.

[0011]

According to the disaster prevention monitoring apparatus of the present invention having such a configuration, since the impedance is not matched with the terminal side, waveform distortion due to reflection occurs in the transmission waveform,
The transmission drive circuit blunts the rising edge and falling edge of the transmission pulse according to a predetermined time constant and transmits.

For this reason, the linking due to the waveform distortion due to the reflection occurs at the gently rising portion and only causes the stepwise waveform change at the rising portion. Even if the transmission pulse is restored by the edge detection on the terminal side, the waveform due to the reflection is generated. No change in distortion is detected. Similarly, since the falling edge of the transmission pulse also changes gently, the waveform distortion due to reflection causes only a stepwise waveform change at the rising edge.
Even if the transmission pulse is restored by edge detection on the terminal side, the change in waveform distortion due to reflection is not detected.

[0013]

1 is an explanatory view showing an example of a disaster prevention monitoring device to which the present invention is applied. In FIG. 1, a pair of transmission signal lines 2a and 2b are drawn out from a receiver 1, and in this embodiment, a detector repeater 3, an analog fire detector 6 and a control repeater 7 are connected as terminals. The transmission signal lines 2a and 2b for transmission supply power from the receiver 1 to the terminal side at the same time as information transmission between the receiver 1 and the terminal.

From the repeater 3 for the detector, signal lines 4a and 4b also serving as a power source are drawn out as a detector line, and a plurality of on / off fire detectors 5 are connected. The on / off fire detector detects smoke, heat, etc. associated with the fire and detects the signal lines 4a, 4 which also serve as power sources.
A short circuit between b and a low impedance is made to flow an alarming current, and this alarming current is received by the sensor repeater 3 and judged to be a fire.

The analog fire detector 6 detects heat and smoke density associated with a fire with an analog sensor, and sends back the detected analog signal as terminal information to the call from the receiver 1 in which a terminal address is designated. Also, analog fire detector 6
May have a function of judging a fire by comparing with the same threshold value as the on / off fire detector 5. Control repeater 7
The control signal lines 8a and 8b are drawn out from, and a plurality of control loads 9 are connected. As the control load 9, there are a district bell, a smoke prevention device, a fire door and the like.

The receiver 1 is provided with a control CPU 10, a transmission circuit section 11, a power supply section 13, an operation section 14 and a display section 15. The transmission circuit section 11 is provided with a transmission drive circuit 12 according to the present invention. The transmission drive circuit 12 inputs from the control CPU 10 a transmission pulse having a sharp rise and fall according to transmission data to the terminal, and makes the rise and fall of the transmission pulse dull according to a predetermined time constant to transmit a signal line. It outputs to 2a and 2b.

In the steady monitoring state, the control CPU 10 sequentially designates terminal addresses and sends a call command. In response to this calling command, the terminal detection information is returned from the repeater on the terminal side which has determined that the address matches the self-address. There is no particular limitation on the content of transmission and the form of transmission performed with the repeater on the terminal side under the control of the control CPU 10, and the transmission data from the control CPU 10 is transmitted by the transmission circuit unit 1.
Anything that is converted into a voltage pulse by 1 and sent out is applicable.

FIG. 2 is a block diagram of an embodiment showing an embodiment of the transmission drive circuit 12 provided in the transmission circuit section 11 of FIG. In FIG. 2, the transmission drive circuit 12 provided in the receiver 1 has an operational amplifier 16 as a driver. The transmission pulse from the transmission pulse source 17 is input to the positive input terminal of the operational amplifier 16 via the input resistor R1. The transmission pulse source 17 is a control CPU for the receiver 1 shown in FIG.
It is realized as a function of 10 and is abstractly shown as a transmission pulse source 17.

A capacitor C1 and a resistor R3 are connected in parallel to the feedback circuit between the output of the operational amplifier 16 and the negative input terminal. A resistor R2 is connected between the negative input terminal and ground. In the present invention, the abrupt rise and fall of the transmission pulse from the transmission pulse source 17 is positively activated according to the time constant determined by the resistor R3 and the capacitor C1 provided in the feedback circuit of the operational amplifier 16 of the transmission drive circuit 12. I'm blunting.

The time constant τ for blunting the edges of the rising and falling portions of the transmission pulse is several tens of meters when the transmission signal lines 2a and 2b of the disaster prevention monitoring device have the shortest line length, and even the longest. Considering this line length, the time constant τ = 5 μsec to 100 μsec because it is several km.
The range should be set to. That is, the attenuation rate (constant) in the line is the same regardless of the line length, but when the line length is short, the reflection period at which the linking-like waveform distortion occurs is short and the reflection frequency at the beginning and end becomes large, so that the linking Will end soon. Therefore, the transmission drive circuit 12
The time constant τ may be set to the smaller range within the above range. On the contrary, when the line length becomes long, the reflection period which causes the linking waveform distortion becomes long. Therefore, the time constant τ of the transmission drive circuit 12 may be set to a large time constant within the above range. Although the transmission drive circuit using the operational amplifier is used in this embodiment, other appropriate means can be used.

The terminal 18 connected to the transmission drive circuit 12 of FIG. 2 via the transmission signal lines 2a and 2b has the transmission signal lines 2a and 2b appropriately branched as shown in FIG. Since the number of repeaters and sensors to be connected as is not uniquely determined, impedance matching between the impedance Z seen from the receiver 1 and the transmission drive circuit 12 is usually not obtained.

Next, the transmission operation by the transmission drive circuit 12 provided in the receiver 1 of FIG. 2 will be described with reference to the signal waveform diagram of FIG. The transmission pulse source 17 outputs a transmission pulse having an abrupt rising edge and a falling edge as shown in FIG. 3A to the transmission drive circuit 12 according to the terminal address and the bit state of the command. Here, the modulation rate by the transmission pulse source 17 is 1200 baud, for example,
Therefore, the pulse width T _w of the transmission pulse shown in FIG. 3A is T _w = 0.83 msec.

The transmission pulse from the transmission pulse source 17 having such abrupt rising and falling edges is input to the operational amplifier 16 of the transmission drive circuit 12 via the input resistor R1 and the capacitor provided in the feedback circuit. C
1 is converted into a pulse waveform obtained by integrating the rising edge and the falling edge according to the time constant τ determined by the resistor R3,
It is sent between the transmission signal lines 2a and 2b.

FIG. 3B shows a transmission pulse when the impedance is matched with the terminal side impedance Z as seen from the transmission drive circuit 12, and in this case, there is no reflection on the transmission line, The transmission drive circuit 12 outputs a transmission pulse obtained by integrating the rising edge and the falling edge according to the time constant τ. FIG. 3C shows a transmission pulse when impedance matching is not achieved, and reflection occurs at a cycle according to the line length, so that the transmission drive circuit 12
The stepwise waveform distortion due to reflection occurs in the gently changing portions of the rising edge and the falling edge integrated by. However, since the waveform distortion due to reflection is not due to the abrupt rising and falling of the edge, the waveform distortion does not become so large, and it is larger than the conventional large waveform distortion like linking as shown in FIGS. 5 and 6. Then, it will be within a very small fluctuation.

Therefore, even if the terminal side detects the rising edge of the transmission pulse and restores the transmission pulse,
FIG. 3 having waveform distortion due to reflection as shown in FIG.
The edge detection is performed only for the first rising edge of the transmission pulse in (c), and the edge detection is performed only for the next first falling edge, so that the same pulse as the original transmission pulse can be accurately restored.

Further, since the fluctuation of the waveform distortion included in the gentle rising edge and the falling edge due to the reflection is small in terms of energy, even if the transmission pulse is superposed on the power supply voltage and sent to the terminal side, the power supply by the reflection is generated. The voltage hardly changes. Therefore, even if the transmission distortion due to reflection is received, the power supply voltage does not rise and the element is not destroyed,
Further, it is possible to prevent the power supply voltage from being extremely reduced due to the waveform distortion and causing the voltage drop detection circuit to malfunction.

In the above embodiment, the transmission pulse is sent by superimposing it on the power supply voltage supplied to the terminal. However, the same is applied to the case where the transmission pulse is sent in the voltage mode without superimposing the power supply voltage. can do. In addition, although the above-mentioned embodiment has exemplified the case where the receiving means is configured by only the receiver 1, other than that, the receiver and the local receiver connected to the transmission path from the receiver may be the one or It includes a case where it is composed of a plurality of relay boards, or a case where it is composed of only a relay board as a plurality of local receivers connected to each other by a transmission path.

[0028]

As described above, according to the present invention, even if the transmission waveform of the receiver is not matched with the impedance of the terminal as seen from the transmission drive circuit on the receiver side and the waveform is distorted due to reflection, the transmission is performed. Since the rising and falling edges of the pulse are blunted during transmission, fluctuations in waveform distortion due to reflection can be minimized, and the original transmitted pulse can be accurately restored by detecting the edge of the received pulse on the terminal side. it can.

Further, since the waveform distortion due to the reflection is suppressed, the element breakdown due to the voltage rise when the transmission pulse is superposed on the power supply voltage and transmitted is surely prevented, and the voltage drop detection circuit due to the extreme voltage drop is provided. Malfunctions can be prevented.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an example of a disaster prevention monitoring device to which the present invention is applied.

FIG. 2 is a configuration diagram of an embodiment of a transmission drive circuit of the present invention.

FIG. 3 is an explanatory diagram showing a transmission waveform of the transmission drive circuit of FIG.

FIG. 4 is a schematic explanatory view of a conventional device.

FIG. 5 is an explanatory diagram showing waveform distortion due to reflection on a transmission line and terminal restoration pulse.

FIG. 6 is an explanatory diagram showing maximum waveform distortion when a transmission pulse is superimposed on a power supply voltage.

[Explanation of symbols]

 1: Receiver 2: Transmission path 2a, 2b: Transmission signal line 3: Repeater for detector 4a, 4b: Signal line for power supply 5: On / off fire detector 6: Analog fire detector 7: Repeater for control 8a, 8b : Control signal line 9: control load 10: control CPU 11: transmission circuit section 12: transmission drive circuit 13: power supply section 14: operation section 15: display section 16: operational amplifier 17: transmission pulse source 18, 20: terminal

Claims (4)

[Claims] 1. One or a plurality of terminal devices are connected between the signal lines drawn from the receiving means, and various command signals using voltage pulses are transmitted from the receiving means to collect terminal information and control terminals. In the disaster prevention monitoring device, the receiving means is provided with a transmission drive circuit for inputting a transmission pulse having an abrupt rise and fall and blunting the rise and fall of the pulse according to a predetermined time constant to transmit. Disaster prevention monitoring device. 2. The disaster prevention monitoring device according to claim 1, wherein the time constant of the transmission drive circuit is set in a range of 5 μs to 100 μs. 3. The disaster prevention monitoring apparatus according to claim 1, wherein the command signal transmitted from the receiving means to the terminal has at least a command field for storing a terminal address and a command field for storing various commands, A disaster prevention monitoring device, which transmits a voltage pulse according to a bit state of each field to a terminal through the transmission circuit. 4. The disaster prevention monitoring device according to claim 1, wherein the receiving means is composed of only a receiver, or as a local receiver connected to the receiver and a transmission path from the receiver. A disaster prevention monitoring device comprising one or a plurality of relay boards, or only a relay board as a plurality of local receivers mutually connected by a transmission path.