JPS6133419B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention transmits power and control signals from a central control panel to a large number of terminal devices by baseband transmission via a dedicated two-core transmission line, and sends back signals in current mode. Regarding repeaters for time-division leased line multiplex transmission equipment that send back signals and process them at a central control board, the purpose of this is to prevent the transmission waveform from being distorted due to line resistance, stray capacitance, etc. of the transmission line, and to significantly increase the possible transmission distance. The purpose is to make it possible to extend the range so that a large number of terminals can be controlled by a single system central control panel even in large-scale building monitoring, etc. Another purpose is to prevent the signal level at each repeater from changing. An object of the present invention is to provide a repeater that can reliably detect a returned signal even if the signal is returned.

FIG. 1 is a block circuit diagram of a dedicated line multiplex transmission device according to the present invention, in which 1 is a central control panel, 2 is a repeater,
3 is a terminal device, 4 is a commercial power supply, and the central control panel 1 sends out signals as shown in FIG. 2a. That is,
As shown in FIG. 2a, each terminal transmits a signal consisting of a start signal S ₁ , a terminal address signal S ₂ , a control data signal S ₃ and a return data standby signal S ₄ to the central control panel 1.
Send from Figure 2b output from the terminal 3
The return data signal _S5 is superimposed on the return data standby signal _S4 and is sent back to the central control board 1 as a return signal as shown in FIG. 2c or 2d.
FIG. 2c is a voltage mode waveform, and FIG. 2d is a current mode waveform. This signal per terminal device is serially and cyclically carried on the transmission line 5 by the number of terminal devices, and is processed by the central control panel 1 and the terminal device 3, respectively.

The present invention, which relates to a repeater for this leased line multiplex transmission equipment, will be explained in detail with reference to embodiments below.

In FIG. 3, 6 is a signal detection section, and the transmission line 5
This is to extract the signal sent from the central control panel 1.
A voltage shaping drive output section 7 shapes the voltage, drives it up, and outputs it. The direction from this input 8 to the output 9 is assumed to be a voltage shaping system. Reference numeral 10 denotes a resistor connected in series to the transmission line 5, and the voltage across this resistor 10 causes a return signal detecting section 11 to extract the return signal. 12 is a return gate signal generation part, 13 is a line short circuit part,
The return signal is set to current mode and sent back to the central control panel 1. Voltage shaping drive output section 7 and return signal detection section 1
1 is the same as that in the central control panel 1, and the signal detecting section 6 and line shorting section 13 are of the same configuration as those in the terminal device 3.

As shown in FIG. 4, the return signal detection unit 11 is composed of OP amplifiers 14, 15, a comparator 16, etc., and distinguishes between a return signal period and a control signal period in a steady state, and detects a control signal in a steady state. is integrated by a resistor _R7 and a capacitor C to generate a reference voltage _VR , and a comparator 16 compares this reference voltage with the voltage level obtained by converting the current mode return signal into a voltage by a transmission line series resistor 10. Compare and detect the returned signal. Here, the return gate signal generating section 12 generates a gate signal so that the signal avoids the integrating circuit during the return period in order to prevent the reference voltage from increasing due to integration of the return signal during the return period T shown in FIG. is generated. In addition, Fig. 5a is a transmission signal waveform diagram, and Fig. 5b is a diagram of the transmission signal waveform.
is a return gate signal waveform diagram.

The return gate signal generating section 12 includes a start signal determining section 17 and a control signal number counting section 1 as shown in FIG.
8, flip-flop 19, basic pulse generator 2
0 and a return data waiting signal end determination unit 21. 22 is a signal input, and 23 is a return gate signal output. Conventionally, the return gate signal was sent to the second gate in the process of creating the transmission signal in the central control panel 1.
Although the gate signal is generated from the signal that provides the return data waiting signal _S4 shown in the figure, in the present invention, the gate signal is extracted within the repeater 2 from the completed transmission signal.

The output pulses of the basic pulse generator 20 have a frequency several times higher than the frequency of the transmission signal, which is necessary for distinguishing various signals so as not to confuse them with noise. First, the start signal S ₁ is determined by the basic pulse in the start signal discriminator 17, and the number of the next control signals (in this case refers to the terminal device address signal S ₂ and the control data signal S ₃ ) is determined by the control signal number counter 18. After all the control signals have been output, the flip-flop 19 is triggered, and on the other hand, the end of the return data wait signal is determined by the return data wait signal end determination section 21 using the basic pulse, and the flip-flop 19 is reset. . The output of this flip-flop 19 becomes the return gate signal.

FIG. 7 is a specific circuit diagram of the return gate signal generating section 12, where 24 is a first counter, and its set value A is the narrowest pulse in the transmission signal and is the value that can be counted as a basic pulse. B is the value for basic pulse counting with start signal S ₁ , and setting value C is B+2 ~
The value 3 distinguishes the start signal _S1 from the return data waiting signal _S4 . However, it is assumed that the width of the start signal _S1 is narrower than the width of the return data waiting signal _S4 . 25 is a second counter, and the set value N is set to the number of pulses of the control signal. 26 is a flip-flop, and 27, 28, and 29 are AND gates. FIG. 8 is a signal waveform diagram of each part of FIG. 7.

As described above, the present invention outputs a signal taken out from a transmission line by a signal detection section, voltage-shapes it by a voltage-shaping drive output section, drives it up, and detects a return signal via a resistor connected in series with the transmission line. Since the return signal is taken out by the section and a return gate signal generator is provided, and the return signal is returned in current mode by the line short circuit section, the transmission waveform is affected by the line resistance, stray capacitance, etc. of the transmission line. It can prevent distortion and significantly extend the transmission distance.
Even in large-scale building monitoring, it is possible to control a large number of terminals with one central control panel, and it also detects the peak voltage across the current detection resistor and adjusts the reference voltage of the voltage comparator for return signal detection. In addition to changing the peak voltage according to the peak voltage, the number of pulses of the transmission signal is counted to detect the interval from the end of the control data signal to the next start signal, and the detection of the peak voltage is stopped during the interval. Therefore, even if the signal level received by the repeater varies greatly depending on the length of the transmission line or the number of terminals installed, the reference level for detecting the returned signal will follow it, and the returned signal will be reliably detected and relayed. This has the effect of making it possible to substantially relay the return signal in current mode.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a dedicated line multiplex transmission device according to the present invention, FIGS. 2 a to d are signal waveform diagrams of the same as above, FIG. The figure is a circuit diagram of the return signal detection section same as above, Figures 5a and b are main part signal waveform diagrams same as above, and Figure 6
This figure is a block circuit diagram of the return gate signal generating section same as above, FIG. 7 is a specific circuit diagram same as above, and FIGS. 8 a to 8 j are main part signal waveform diagrams same as above. 5... Transmission line, 6... Signal detection section, 7... Voltage shaping drive output section, 10... Resistor, 11... Return signal detection section,
12...Return gate signal generation section, 13...Line short circuit section, 17...Start signal discrimination section, 18...Control signal number counting section, 19...Flip-flop, 20...Basic pulse generator, 21...Return data waiting signal end discrimination section .

Claims (1)

[Claims] 1 Transmit a fixed number of transmission signals including a start signal, a terminal address signal, a control data signal, and a return data waiting signal to multiple terminal devices from the central control panel via a dedicated transmission line, and A signal detection section is inserted in the transmission line of a time division multiplex transmission device that returns the return signal by short-circuiting the transmission line during the pulse interval of the return data waiting signal, and detects the transmission signal; A voltage shaping drive output section that amplifies and shapes the signal and retransmits it; a return signal detection section that detects the return signal using a current detection resistor connected in series with the transmission line; and a return signal detection section that retransmits the return signal in current mode. In the repeater consisting of a line short-circuit section, means for detecting the peak voltage between both ends of the current detection resistor and changing the reference voltage of the voltage comparator for detecting the return signal in accordance with the peak voltage, and a pulse of the transmission signal. A leased line multiplex transmission device characterized by comprising means for counting the number of signals and detecting an interval from the end point of the control data signal to the next start signal, and stopping detection of the peak voltage during the interval. relay.