JPH04294653A - Ring line concentrator - Google Patents

Abstract

PURPOSE:To detect a fault of a transmission line due to a DC current by circulating the DC current to a ring transmission line independently of the presence of connection of a station to the ring transmission line via the ring line concentrator in a ring network system. CONSTITUTION:A DC bypass circuit 5 is added between In and OUT signal transformers 3,4 of a ring line concentrator 1. A transmission signal in the transmission signal and a DC current coming from a transmission line IN side 20-1 passes through a relay circuit 2-2 as it is and is sent to a station via the IN side signal transformer 3, and the DC current flows to a DC bypass circuit 5 and sent to a transmission line OUT side 20-2 via the OUT side signal transformer 4 and a relay circuit 2-1.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ring concentrator in a ring network system, and more particularly to a circuit configuration method suitable for confirming the normality of a transmission line in a ring network.

0002

2. Description of the Related Art In a ring network system, a plurality of line concentrators (ring line concentrators) connecting one or more stations are connected in a loop through a transmission line (ring transmission line). Each ring concentrator has the role of sending (receiving) signals on the transmission path to the station and sending (sending) signals from the station to the transmission path.

Conventionally, as a circuit configuration method of this type of ring concentrator, for example, "Token Ring Access
s Method and Physical Lay
er Specifications, IEEE SF
d 802.5-1985”,
A configuration using a signal transformer is known. In this conventional technology, when a station is connected to a transmission line via a ring concentrator, a transmission signal sent from an upstream station to the trunk cable in side of the concentrator is transmitted via a signal transformer to the transmission line. sent to the station's receiver. Furthermore, the transmission signal relayed at the station is sent from the trunk cable out side to the downstream station via a signal transformer. In this case, because of the signal transformer, the trunk cable in side and trunk cable out side are not directly connected. Note that when the station is not connected to the transmission path, the signal transformer is bypassed and the trunk cable in side and trunk cable out side are directly connected.

0004

[Problems to be Solved by the Invention] In the conventional ring concentrator described above, when a station is connected to a transmission line,
The transmission line in side and the transmission line out side are in isolation state. Therefore, confirmation of the normality of the transmission path and detection of transmission path failure are performed by monitoring the level and frequency of the transmission signal. Generally, in a ring network, shielded twisted pair wires are used as a transmission path, so if two of the twisted pair wires are disconnected, there will be no received signal and energy will be cut off, and a fault will be detected. If one of them is disconnected, the received signal will not be completely lost and the energy will not be cut off. However, since there is only one incomplete transmission, the reception level is low, the waveform is distorted, and there is a high possibility that data content abnormalities will occur intermittently.

One possible method for reliably detecting a transmission line fault in which one line is disconnected is to flow a direct current through the transmission line and monitor the current value, but in conventional ring concentrators, stations are This is not possible because direct current cannot pass through the concentrator.

SUMMARY OF THE INVENTION An object of the present invention is to provide a ring concentrator that can reliably detect a transmission line failure by passing a direct current through the transmission line in a ring network system.

[0007]

In order to achieve the above object, the present invention is characterized in that a DC bypass circuit is added between the signal transformers on the in-side and out-side of the transmission line of the ring concentrator.

[0008]

[Operation] The DC bypass circuit is constructed by inserting a DC cut capacitor between the signal transformers on the in and out sides of the transmission line of the ring concentrator to prevent DC current from passing between the lines. It is constructed by connecting both ends of the capacitor via an AC cutting inductance. As a result, even if the station is connected to the transmission line via the ring concentrator, the transmission signal (AC signal) sent from the upstream side is sent to the station receiver via the signal transformer as before. On the other hand, direct current can flow directly downstream.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a circuit diagram of an embodiment of a ring concentrator according to the present invention. This ring concentrator 1 is an example in which two stations can be connected, and in FIG. 1, the first station connection mechanism 10-1 has a station (
(not shown) is connected to the second station connection mechanism 1
0-2 indicates that no station is connected. Therefore, the second station connection mechanism 10-2
The inside and outside sides of are directly connected. The transmission line in side 20-1 is connected to the transmission line connection mechanism 9-1, and the transmission line out side 20-1 is connected to the transmission line connection mechanism 9-2. The same applies to the protection transmission line in side 30-1 and the protection transmission line out side 30-2.

[0010] Here, regarding the circuit configuration on the side to which the stations in the present ring concentrator 1 are connected, the following are as follows.
-1 is a relay circuit, 3 is an in-side (for reception) signal transformer, 4 is an out-side (for transmission) signal transformer, and 5 is a DC bypass circuit. The DC bypass circuit 5 includes DC cut capacitors 6a and 6b inserted between the in-side and out-side signal transformers 3 and 4 to prevent DC current from passing between the lines (transformer two Next side capacitors 8a, 8
b), both ends of these capacitors 6a, 6b are connected via AC cut inductances 7a, 7b. The circuit configuration on the side to which no stations are connected is exactly the same.

The operation of the ring concentrator 1 will be explained as follows.
When a transmission signal (AC signal) and DC current are sent from the transmission line in side 20-1, the relay circuit 2-2 is in a bypass state, so they pass through the relay circuit 2-1.
Since the station is in a connected state, it flows into the signal transformer 3, the transmission signal of which passes through the signal transformer 3 and is sent to the receiver of the station, and the DC current flows into the DC bypass circuit 5. . Here, the capacitors 6a and 6b are direct current cutting capacitors, and function to prevent direct current from crossing between transmission paths. The DC current flowing into the DC bypass circuit 5 passes through the AC cut inductances 7a and 7b and the signal transformer 4, and then passes through the relay circuit 2.
-1 and is sent to the transmission line outside side 20-2.

[0012] In this manner, the present ring concentrator 1 allows direct current coming from upstream to flow downstream as it is, regardless of whether or not a station is connected to the ring transmission line.

FIG. 2 shows a conceptual diagram of a ring network system constructed using this ring concentrator. In the figure, numerals 1-1 to 1-n are ring concentrators having the circuit configuration shown in FIG. 1, and are connected, for example, to a shielded twisted pair transmission line 20 in a loop shape. Each ring concentrator has one
One or more stations 11 are connected, and data is transmitted and received between any of the stations.

On the other hand, the DC current sending circuit 100 always
Direct current is sent to the ring transmission line 20. This DC current passes through each ring concentrator 1-1, 1-2, 1-n, surrounds the ring transmission line 20, and returns to the DC current sending circuit 100 again. Here, as shown at 21 in FIG. 3, if a ring transmission path failure such as one disconnection occurs, the DC current will not circulate through the transmission path and will not return to the DC current sending circuit 100. This makes it possible to monitor ring transmission path failures using direct current.

[0015]

Effects of the Invention As explained above, according to the ring concentrator of the present invention, one-cycle monitoring of the ring transmission line can be realized using direct current regardless of the insertion and removal of stations from the transmission line, and one line disconnection can be realized. It is possible to reliably detect transmission path failures that are not detected by conventional devices such as the above.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of an embodiment of a ring concentrator according to the present invention.

FIG. 2 is a conceptual diagram of a ring network system using the ring concentrator of the present invention.

FIG. 3 is a diagram showing an example of a transmission path failure in FIG. 2;

[Explanation of symbols]

1 Ring concentrator 2-1, 2-2 Relay circuit 3,4 Signal transformer 5 DC bypass circuit 20-1 Transmission line in side (upstream side)

Claims (1)

[Claims] Claim 1: In a ring concentrator that is installed in a ring transmission line and sends signals from the transmission line to a station and signals from the station to the transmission line, among the signals and DC signals arriving from the upstream side, A ring concentrator characterized by a circuit configuration in which only the components are sent to the station, and the DC component is directly passed downstream without passing through the station.