JPH0233417Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Field of the Invention> The present invention relates to data transmission using a DC power line as a transmission path, and particularly relates to a device for determining the cause of abnormality in data transmission.

<Prior Art and its Problems> Conventionally, there is a so-called DC power superimposition data transmission system in which a DC power supply path is used as a transmission path and signals are sent out cyclically. In this method, the voltage of the DC power supply path is not checked at either the primary station or the secondary station, so whether or not data transmission is being carried out normally is determined by the polling from the primary station at the secondary station. This is done by checking at the primary station whether or not the station has responded. For this reason,
The circuit for checking responses to polling becomes more complex, and when an abnormality occurs in data transmission, it is difficult for the primary station to accurately determine whether the cause of the abnormality is in the transmission line itself or in the secondary station. It was not always easy to distinguish.

<Purpose of the invention> The present invention has been made in view of the above points, and the purpose of this invention is to determine whether an abnormality in data transmission is caused by the transmission path or not.
The purpose is to make it simple and easy to determine whether the information is from a secondary station.

<Structure and effects of the invention> In order to achieve the above purpose, the invention has the following features:
A first detection means for detecting fluctuations in the voltage of the communication line, and a first display for indicating that the voltage drop value exceeds a predetermined value based on the output from the first detection means, on the terminal side of the DC power supply path. means for extracting the signal superimposed on the communication line; second detection means for detecting the signal extracted by the extraction means; and a second display means for displaying whether or not a signal is input. Therefore, according to the present invention, the first,
If the first and second display means perform a display operation by the second detection means, it can be determined that the communication line is abnormal, and if the second display means performs a display operation by the second detection means. It is now possible to determine that the secondary station is abnormal, and it has become possible to accurately and easily determine the cause of data transmission abnormalities.

<Description of Embodiments> Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a simplified configuration diagram of data transmission using the DC power superimposition method. In the figure, numeral 1 is a primary station, and 2a to 2e are secondary stations. The DC power supply path is a transmission path 3 looped from the signal sending end A of the primary station 1 to the signal receiving end B of the secondary station 1 via each of the secondary stations 2a to 2e.
Generally, if data transmission is normal, signal sending end A
A voltage of 24V is applied to, and at the signal receiving end B,
Normally, a voltage of 20V is detected due to voltage drop due to cables, etc.

FIG. 2 is a block diagram of one embodiment of the present invention. The data transmission abnormality determination device 4 of the present invention is a DC
It is provided on the signal receiving end B side of the power supply path, that is, the transmission path 3.

This abnormality determination device 4 includes a first detection means 5 for detecting fluctuations in voltage of a communication line constituting the transmission line 3.
Based on the output from the first detection means 5,
A first display means 6 is provided for displaying when the voltage drop in the transmission line exceeds a predetermined value.

This abnormality determination device 4 also includes an extraction means 7 for extracting a signal superimposed on the communication line, a second detection means 8 for detecting the signal extracted by the extraction means 7, and a second detection means for detecting the signal extracted by the extraction means 7. and a second display means 9 for displaying whether or not the superimposed signal is input based on the output of the superimposed signal.

The first detection means 5 for detecting fluctuations in the voltage of the communication line includes a Zener diode 10 and a transistor.
Tr1 and resistors R1 and R2, the Zener voltage of this Zener diode 10 is
The voltage is set to be lower than the normal voltage at the signal receiving end B of , that is, 20V. The first display means 6 that displays when the voltage drop value of the communication line exceeds a predetermined value includes a light emitting diode 11 for displaying the display.
and a transistor Tr2 that provides a drive current to the light emitting diode 11.

The extraction means 7 for extracting the superimposed signal is composed of a capacitor C1 as a high-pass filter, a diode 12, and a resistor R3, and the second detection means 8 for detecting the extracted signal is a retrigger timer 1.
3, capacitor C2, and resistors R4, R5, R6
It consists of The second display means 9, which displays the presence or absence of input of the extracted signal based on the output from the second detection means 8, displays a light emitting diode 14 that lights up when the superimposed signal is not applied, and a light emitting diode 14 that lights up when no superimposed signal is applied. Transistor Tr that supplies drive current
It consists of 3.

Next, the operation of the data transmission abnormality determining device 4 configured as described above will be explained.

When an abnormality occurs in the transmission line 3 and the voltage of the communication line drops beyond a predetermined value, and as a result, the voltage of the communication line becomes lower than the Zener voltage of the Zener diode 10 of the first detection means 5, the Zener diode 10 Turn off. Then the transistor
When Tr1 turns off, the transistor of the first display means 6
Tr2 turns on. This makes the transistor Tr
A light emitting diode 11 serving as a first display means is lit by the collector current of 2. This lighting of the light emitting diode 11 indicates that the voltage of the communication line has dropped beyond a predetermined value.

The extraction means 7 extracts the signal superimposed on the communication line using a high-pass filter and supplies the extracted signal to the input terminal (IN) of the retrigger timer 13 of the second detection means 8. This retrigger timer 13, while the signal 15 (shown in FIG. 3A) extracted from the extraction means 7 shown in FIG. 3B is input to its input terminal IN at intervals shorter than the predetermined time t, The potential of the output terminal Q (shown in FIG. 3B) remains at a low level, and at this time, the transistor Tr of the second display means 9
3 is off, and the light emitting diode 14 does not light up. It can be seen that when the light emitting diode 14 does not light up in this way, the signal is cyclically superimposed every period t and is being sent normally. If an abnormality occurs in the communication line or the secondary stations 2a to 2e, the signal 15 will not be input to the input terminal IN of the retrigger timer 13 during the period t, so the potential of the output terminal Q of the retrigger timer 13 will be high. As a result, the transistor Tr3 of the second display means 9 is turned on and the light emitting diode 14 is turned on.
lights up, indicating that the signal is not being given correctly. Note that this period t is set by the resistor R4 and capacitor C2 of the second detection means 8.

Therefore, according to this embodiment, if the communication line is abnormal, the voltage drops beyond a predetermined value and the superimposed signal is no longer provided.
The light emitting diode 11 of the first display means 6 and the second
The light emitting diodes 14 of the display means 9 are both lit. On the other hand, in the case of an abnormality in the secondary stations 2a to 2e,
Since the superimposed signal is no longer applied, only the light emitting diode 14 of the second display means 9 lights up.
This determines whether the abnormality in data transmission is in the transmission path, that is, the communication line, or whether the
It becomes possible to easily and accurately determine whether the image is in e.

[Brief explanation of the drawing]

Figure 1 is a simplified configuration diagram of data transmission using the DC power superimposition method, Figure 2 is a block diagram of an embodiment of the present invention, and Figure 3 is a time diagram to explain the operation timing of the retrigger timer in Figure 2. It's a chat. 1...Primary station, 2a-2e...Secondary station, 3...
Transmission line, 4... Data transmission abnormality determination device, 5...
First detection means, 6...first display means, 7...extraction means, 8...second detection means, 9...second display means.

Claims (1)

[Scope of utility model registration request] An abnormality determination device for data transmission using a DC power supply line connected in a loop as a transmission line, the first detection means being provided at the terminal end of the DC power supply line and detecting fluctuations in voltage of a communication line; a first display means for displaying that the voltage drop value exceeds a predetermined value based on the output from the first detection means; an extraction means for extracting the signal superimposed on the communication line; and a second display means for displaying whether or not the superimposed signal is input based on the output of the second detection means. Abnormality determination device.