JPH01180127A - Data transmission equipment - Google Patents

Abstract

PURPOSE:To discriminate power failure of an opposite station by its own station being a reception side by comparing an input terminal voltage of a line receiver of its own station with a voltage comparison band decided by a forward voltage of a diode of the opposite station. CONSTITUTION:When a positive power supply V1 of a power supply of an opposite station is stopped, even if anoutput resistance of a line driver 1 is infinite, a forward current from the positive power supply V3 flows to a diode (D) 4 and a forward voltage drop is generated in the D4. The forward voltage drop is inputted to a window comparator 9 as the input terminal voltage EIN of the line receiver 7 through a cable 2. The comparator 9 compares the voltage EIN with the preset forward voltage drop Vr1 and with the reverse voltage drop Vr2 and a fault signal is outputted as power fault detection of an opposite station 6. If the negative power supply V2 of the opposite station is failed, a fault signal is outputted as the detection of power failure of the opposite station similarly.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a data transmission device that allows a receiving station to monitor the power status of a partner station.

(Prior Art) Conventionally, in an Elm Base device, etc., EIA R32 is used as a data transmission/reception interface to serially transmit an elevator operating status signal as a digital signal to the receiving side.
When applying the 32C standard, if it is only for signal transmission, a minimum of three wires such as a signal transmission/reception line and a ground wire are sufficient, but in general, in order to control transmission, several control lines in addition to the above lines are installed. is normal.

However, the increase in the number of control lines in addition to signal transmission lines means that the signal receiving partner station is located far away, and as the signal transmission and reception distance increases, cable installation work becomes complicated and costs increase. Therefore, in recent years, a method has often been used in which only the above-mentioned transmission, reception, and grounding wires are provided between signal transmitters and receivers, and signal transmission control is performed by software processing using a computer.

[Problem to be solved by the invention]

Conventional data transmission equipment performs signal transmission control using software processing as described above, so if a signal response is not returned normally from the other station to the own station, is it an abnormality in the control system, or is it simply a problem with the other station? If software were to be used to determine whether there is a power outage, the software would become even more complex and would not be able to easily carry out the determination function.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a data transmission device that allows the own station, which is the signal receiving side, to easily determine a power outage of the other station.

(Means for Solving the Problems) A data transmission device according to the present invention provides a data transmission device that transmits signals in the forward direction between the output terminal of a line driver provided in a transmitting/receiving partner station and a positive power supply terminal and a negative power supply terminal provided in the partner station. Resistors connected between the connected diode, the input terminal of the line receiver in the local station connected to the data transmission cable from the other station, the positive power terminal of the local station, and the negative power terminal, respectively. and a window comparator that compares the input terminal voltage of the line receiver with the voltage comparison band determined by the forward voltage drop value of each of the diodes and detects whether the input terminal voltage falls within the voltage comparison band. be.

(Function) According to the present invention, when the positive power supply of the other station is out of power, the current loop consisting of the positive power supply of the own station - the resistor - the data transmission cable - the diode of the other station - the positive power supply of the other station which has become zero potential - is activated. As a result, the forward voltage drop of the diode of the other station appears at the input terminal of the line receiver via the resistor of the own station, and the input terminal voltage is input to the window comparator, where the positive voltage drop of the diode set in advance appears at the input terminal of the line receiver. Comparing it with the forward voltage drop value, if the input end voltage falls within the set value, it can be determined that the other station's positive power supply has failed. In addition, when the negative power supply of the other station is out of power, a current loop is formed that includes the negative power supply of the other station, which is at zero potential, the diode, the data transmission cable, the resistor of the own station, and the negative power supply, and the connection to the negative power supply is established. Input the voltage drop of the resistor (forward voltage drop of the diode connected to the negative power supply of the other station) to the window comparator, and compare it with the preset negative forward voltage drop of the diode. If the input terminal voltage falls within the set value, it can be determined that the negative power supply of the other station has failed. This makes it possible to accurately detect only a power outage at the other station without affecting data transmission.

(Example) Below, an embodiment of the present invention will be explained with reference to the figures. In Figure 0, (1) is a line driver, the power supply is Vl, Vl (for example, Vl = 12V, v2 = -12V) is supplied, and the output amplitude is The width is approximately V1%v2. The output terminal of the line driver (1) is connected to the input terminal of the line receiver (3) via the cable (2) and at the same time to V, , V, respectively via the diodes (4) and (5). has been done. The polarities of the diodes (4) and (5) are as shown. Line driver (1), diode (4)
), (5) are implemented in the partner station (6). On the other hand, the input terminal of the line receiver (3) is connected to the power supply V3. V4 (e.g. Vs” 12V, V4--12V) and resistor (7)
, (8). The resistance values of resistors (7) and (8) are chosen to be equal. Window comparator (
The input terminal of line receiver (3) is connected to the input terminal of line receiver (3), and while the voltage is above L1 and below 2 (for example, Vrl
= 2V, V, ”-2V) signal □ is output. (10) is a filter that outputs a short-time signal (for example, when the input signal changes to V, -V, or Vl-V) of the window comparator (9). When the line receiver (
3), resistors (7), (8), window comparator (
9), the filter (10) is installed in the local station (11).

Further, a grounding wire (12) is installed between the other station (6) and the own station (11).

Other transmission or serial conversion circuits are required, but will be omitted.

Next, the operation of this embodiment will be explained based on the above configuration. When the power supply v1 or v2 of the partner station (6) is normal, the output voltage of the line driver (1) is the same <vi or v2. The voltage input to the window comparator (9) from the input terminal of the line receiver (3) built into the own station (11) is set by the window comparator (9), and since it is higher than or lower than Vr2, the voltage input to the other station is An abnormality signal indicating a power supply abnormality is not output.

Now, if the positive power supply V of the other station's power supply fails and becomes zero potential, the positive power supply V3 of the own station - resistor (7) - cable (2)
A current loop is formed: - the diode (4) of the other station - the positive power supply V of the other station which has become zero potential. As a result, even if the output resistance of the line driver (1) becomes infinite, a forward current from the positive power supply V flows through the diode (4), and a forward voltage drop occurs in the diode (4). . This forward voltage drop is passed through the cable (2) and inputted to the window comparator (9) as the input terminal voltage Eln of the line receiver (7). The window comparator (9) has a positive forward voltage drop vr+ and a negative forward voltage drop Vr2, which are preset to the input terminal voltage Eln.
If the relationship vrl≧Eln≧2 holds, an abnormality signal is output as detection of a power outage in the partner station (6). This abnormal signal is output as a power-off signal to the partner station (6) through the filter (10).

Next, when the negative power supply v2 of the other station loses power and becomes zero potential,
Zero potential negative power supply v2 - diode (5) - cable (2
) - Resistor (8) - Local station negative power supply Va (V2> V4
) A current loop is formed.

As a result, the negative forward voltage drop generated in the diode (5) appears at the input terminal of the line receiver (3) of the local station (11) as a voltage Eln. This input terminal voltage E
ln is compared with preset positive and negative forward voltage drops Vrl and vr2 by a window comparator (9), and V
If there is a relationship of rl≧Eln≧Vr2, an abnormal signal is output as detection of a power outage in the partner station (6). This abnormal signal is output as a power-off signal to the other station (6) through the filter (1O).

〔Effect of the invention〕

As described above, according to the present invention, it is possible for the own station to monitor the power outage status of the other station via the data transmission cable that connects the other station and the own station. There is no longer a need to install cables. Therefore,
This has the effect of providing a highly reliable data transmission device that can reliably identify a data transmission abnormality due to a power outage at a partner station with a simple configuration.

BRIEF DESCRIPTION OF THE DRAWINGS The figure is a block diagram showing the configuration of a data transmission device according to an embodiment of the present invention. In the figure, (1) is a line driver, (3) is a line receiver, (4) and (5) are diodes, (6) is a partner station, (7) and (8) are resistors, (
9) is the wind comparator, and (11) is the own station.

Claims (1)

[Claims] In a data transmission device in which the output terminal of a line driver provided at a partner station and the input terminal of a line receiver provided at the own station are connected by a cable for data transmission, the output terminal of the line driver and the positive power supply provided at the partner station are connected. The first and second terminals are connected in the forward direction between the terminals and between the negative power supply terminals, respectively.
a diode, first and second resistors connected between the input terminal of the line receiver and the positive power terminal of the own station, and between the negative power terminal, respectively, and the input terminal voltage of the line receiver and the forward direction of each of the diodes. A data transmission device comprising: a window comparator that compares an input terminal voltage with a voltage comparison band value determined by a voltage drop value and detects whether or not an input terminal voltage falls within the voltage comparison band value.