JPS6359144A - Line supervisory system for local area network - Google Patents

Abstract

PURPOSE:To detect a line fault even at non-communication state by providing a power supply applying a prescribed DC voltage to a transmission line of a local area network and a means detecting a change in a line voltage and using the detection means to detect a line fault of the network as a line voltage change. CONSTITUTION:A voltage 5V is applied to each one end of transmission lines 1,1 at both sides of a repeater 2. Then line voltage detectors 5A-5g detect the voltage change in the line 1 at nodes 3A-3E and the repeater 2 and the line fault is detected as the change in the line voltage VN. For example, if an open line 1 takes place somewhere in the line 1, it is detected by any of the detectors 5A-5G as the line voltage change from 5V to 0V. In this case, depending which of the line voltage detectors 5A-5G detects the voltage change and which of the, do not detect, the open line position of the line 1 is specified among the nodes 5A-5G or between the nodes and the repeater 2 and detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a line monitoring system for a local area network that monitors the status of a line in a local area network and detects abnormalities such as disconnection of the line.

[Prior Art] A local area network (hereinafter referred to as an abbreviation of LA) is a communication network that performs communication between multiple information processing devices such as computers within a unified area such as within the same building or the same factory. It has developed and become popular with the progress of office automation in recent years.

[Problem to be solved by the invention 1] However, the conventional LAm system does not have a line monitoring unit that constantly monitors the line status and detects abnormalities in the line. This is a situation in which a line abnormality is known, and no line abnormality was detected during non-communication. Another problem is that as networks become more complex, it becomes difficult to detect faults that are causing line abnormalities.

[Means for Solving the Problems] In order to solve the above-mentioned problems, according to the present invention, as a line monitoring system for a local area network, a power supply that applies a predetermined DC voltage to a transmission line of a local area network, A configuration is adopted in which a means for detecting a change in line voltage is provided, and the detecting means detects an abnormality in the line of the network as a change in the line voltage.

[Function] According to such a configuration, line abnormalities can be detected even during non-communication. Furthermore, by using a suitable plurality of the above-mentioned detection means and arranging them appropriately to detect voltage changes in the transmission line, it is possible to easily detect the failure point that causes the abnormality in the line. can.

[Embodiments] Hereinafter, details of embodiments of the present invention will be described with reference to the attached drawings.

FIG. 1 explains one embodiment of the present invention, in which the network type is a bus-type LA! 9t schematically shows a configuration for performing line monitoring.

Those indicated by reference numerals 1.1 are LAN transmission lines, and are connected by a repeater 2.

It's being relayed. In addition, nodes 3A to 3E are nodes for connecting information processing devices and peripheral devices such as computers to the transmission line l (connection and always supplying a predetermined direct current to the transmission line l in order to detect abnormalities in this line). a line voltage supply device (line bias device) 4 that applies voltage;
Line voltage detectors (disconnection detectors) 5A to 5G are provided to detect changes in the line voltage of the transmission line l. The line voltage supply 4 is connected in parallel with the repeater 2 and the two transmission lines are connected in parallel with the repeater 2 to each of the two transmission lines. Also, each of the line voltage detectors 5A to 5G is connected to the node 3.
Transmission line l at the front stage of each of A to 3E and repeater 2
connected to.

The line voltage supply device 4 is composed of a known stabilized DC constant voltage power supply circuit, and voltage is applied to the transmission line 1 as shown in FIG. 2(A).

That is, as shown in FIG. 2(A), the transmission line 1 is composed of a set of two lines, which are connected as a loop through bonded end resistors Ro, Ro having the same resistance value at both ends, and are grounded. Here, a predetermined direct voltage Vc generated by a line voltage supply device 4 (not shown) is connected in parallel to the transmission line 1 at a feed point A on one side via a voltage dividing resistor R1.

The equivalent circuit of this voltage application circuit is as shown in Figure 2 (B), which is determined by the equivalent resistance of the entire line as seen from the line voltage supply device 4 (Ro/2 if the resistance of the line itself is ignored) and the voltage dividing resistor R1. A constant voltage Vc is divided at a predetermined voltage division ratio, and a predetermined line voltage v~ is applied between feed points A and A' on the line. Note that if the voltage dividing resistor R1 is made equal to the equivalent resistor R2, that is, matched, high power feeding efficiency can be obtained and the circuit configuration can be simplified.

With such an application circuit, for example, the constant voltage ■c of the power supply can be changed to IOV.
, a voltage dividing resistor R1, and an equivalent resistor R2 of 50Ω, a line voltage vN of 5V is applied to the transmission line l. 1st
In the figure, 5V is applied to each side of the transmission line 1.1 on both sides of the repeater 2. - and the line voltage detectors 5A to 5G respectively detect the transmission line l at each of the nodes 3A to 3E and the repeater 2.
Detection of voltage changes is performed, and abnormalities in the line are detected when the line voltage V
is detected as a change in

For example, if a disconnection occurs somewhere on the transmission line 1, this is detected as a change in the line voltage VN from 5V to Ov by one of the line voltage detectors 5A to 5G.

In this case, the voltage change is detected by the line voltage detector 5A~
Depending on which 5G is detected and which is not detected, the disconnection location of the transmission line 1 is identified and detected at each node 5A to 5ann or the node and repeater 2L'1.

By monitoring the line as described above, it is possible to detect abnormalities in the line even when there is no communication, and also to detect the location of the abnormality.

Note that FIGS. 3(A) and 3(B) show configurations of line monitoring in different network configurations.

FIG. 3(A) shows a case where the network configuration is a loop type. In this case, each node 3A to 3E has a repeater function, connects and relays each transmission line l, and each node 3A to 3E has a repeater function. Line voltage detectors 5A to 5F are provided on each side of the connection portion with the transmission line of 3E. Further, as shown by symbols 4A to 4C, a plurality of line voltage suppliers are provided. This is to compensate for a large voltage drop in the line voltage V~ due to a long line length (see FIG. 2(A)) or a large number of nodes.

Note that when performing multi-point power feeding in this way, in order to prevent backflow of current to the line voltage supply device 4 and protect the line voltage supply device 4 in the voltage application circuit of FIG. A diode is inserted between the piezoresistor R1 and the transmission line 1 in the forward direction. Further, line voltage compensation may be performed by feeding power on both sides.

With the configuration shown in FIG. 3(A) as well, line abnormalities can be detected in the same way as in the case of FIG.
It is identified and detected between A and 3F.

Further, Fig. 3 CB) shows a configuration in which the network configuration is star-shaped, in which case the line voltage supply device 4 is provided at the center, and the line voltage V~ is distributed and supplied to each line l. There is. Further, line voltage detectors 5A to 5 are provided upstream of each node 3A to 3I and connected to each transmission line 1. With such a configuration, line monitoring can be performed in the same way.

[Effects] As is clear from the above description, according to the present invention, as a line monitoring method for a local area network, a power supply that applies a predetermined DC voltage to a transmission line of a local area network, and a change in the line voltage are used. The present invention employs a configuration in which a detection means is provided, and the detection means detects an abnormality in the line of the network as a change in the line voltage, so that the abnormality in the line of the local area network can be detected during non-communication with a simple and inexpensive configuration. It is possible to detect abnormalities as well as abnormalities, which has an excellent effect that is extremely useful for maintenance of local area networks.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the configuration of line monitoring according to an embodiment of the present invention, Figure 2 (A) is a circuit diagram of a voltage application circuit for the transmission line in Figure 1, and Figure 2 (B) is its equivalent. The circuit diagrams of FIGS. 3A and 3B are explanatory diagrams showing the configuration of line monitoring in different network configurations. 1... Transmission line 2... Repeater 3A to 3I
···node

Claims (1)

[Claims] A power source for applying a predetermined DC voltage to a transmission line of a local area network and means for detecting a change in the line voltage are provided, and the detecting means detects an abnormality in the line of the network as a change in the line voltage. A characteristic local area network line monitoring method.