JPH0646074A - Signal distributing device having automatic terminating function - Google Patents

Abstract

PURPOSE:To prevent deterioration of a transmission characteristic caused by forgetting to terminate at the time of constituting an information communication system of a start type by a distributor by using a precedent information wiring system as a transmission medium. CONSTITUTION:The device is provided with a distributor B for distributing a signal on one port PO to plural distribution ports Pi (i=1,..., N), a terminal detecting means Ki for detecting whether a terminal Ti is connected to each distribution port Pi in this distributor B or not by utilizing other unused line than a signal transmission line of a transmission medium 4i, and a terminating means Ri for connecting a terminal resistance to the distribution port Pi in which the connection of the terminal Ti is not detected by the terminal detecting means Ki. Accordingly, there is no fear that deterioration of a transmission characteristic caused by forgetting to terminate, and transmission reliability can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a signal distribution device having an automatic termination function, and is used for an information communication system using a star type information wiring.

[0002]

2. Description of the Related Art FIG. 9 is a schematic block diagram of an information communication system using conventional bus type wiring. In the figure, C is a control unit, and Ta, Tb, and Tc are terminals.
The control unit C and the terminals Ta, Tb, Tc are connected by a bus type wiring using the coaxial cable 1.
In the middle of the coaxial cable 1, cable connectors 2a, 2
b and 2c are provided, and a terminator 3 is provided at the end of the coaxial cable 1. As described above, wiring such as a coaxial cable is used for communication between computers and terminals. Among these, there is an example in which signals are bidirectionally transmitted in baseband. Among these transmission methods, in addition to the transmission method corresponding to the standard LAN, there are transmission methods dedicated to each company.

By the way, if a star type leading information wiring system of unshielded twisted pair wire which is generally used in a building is used to perform signal transmission between devices using the above-mentioned dedicated system for each company, It is thought that the wiring system can be constructed at low cost. However, in many dedicated transmission methods, as shown in FIG. 9, a bus type topology is used logically or physically, and these are of a star type (physically) using standard twisted pair wires. When transmitting on the integrated information wiring, it is necessary to fold the wiring back to the cross-connect (exchange board) X as a concentrator to form a pseudo star wiring (logically, bus type) as shown in FIG. there were.

In FIG. 9, 4a, 4b, 4c, ... Are twisted pair wires, and Ja, Jb, Jc are information outlets. Further, Ta, Tb and Tc are terminals, and 3 is a terminator. The twisted pair wire 4a connected to the control unit C is connected to the twisted pair wire 4b via the exchange board X. The twisted pair wire 4b is connected to the terminal Ta via the information outlet Ja. The signal transmitted from the control unit C is transmitted to the terminal Ta via the twisted pair line 4a, the exchange board X, the twisted pair line 4b, and the information outlet Ja. Further, it is transmitted to the terminal Tb via the information outlet Ja, the twisted pair wire 4c, the exchange board X, the twisted pair wire 4d, and the information outlet Jb. Further, it is transmitted to the terminal Tb via the information outlet Jb, the twisted pair wire 4e, the exchange board X, and the twisted pair wire 4f, and is terminated by the terminator 3. Each terminal T
The signals transmitted from a, Tb, and Tc are transmitted to another terminal or control unit C through the same wiring. As described above, in order to form the wiring which is logically a bus type and is physically a star type, inside the exchange board X as a concentrator, the twisted pair wires 4a and 4b are connected to the internal wiring X.
a, the twisted pair wires 4c and 4d are connected by the internal wiring Xb, and the twisted pair wires 4e and 4f are connected by the internal wiring Xc. In addition, information outlet Jc
Is not used, and the twisted pair wires 4g and 4h are opened inside the exchange board X.

In the signal folding method shown in FIG. 10, a bus type is logically formed and a star type wiring is physically formed, so that the line length becomes long and the attenuation becomes large. In some cases, the number of operable terminals that could be realized by using the original dedicated wiring could not be secured in some cases.

Therefore, in order to solve the problem of attenuation, depending on the protocol such as when the transmission is a polling method, conversion to a star type is performed using a passive type signal distributor used in a TV co-listening system or the like. There was also an example.
An example thereof is shown in FIG. In the figure, X is a cross connect (exchange board) as a concentrator, and B is an N distributor. Further, J is an information outlet, and A is a balun adapter. The balun adapter A performs signal conversion between an unbalanced signal transmission system using a coaxial cable such as the control unit C and the terminal T and a balanced signal transmission system using a balanced cable such as the twisted pair wire 4. With such a configuration, it is not necessary to return the signal, so that the line length is shortened and the problem of attenuation is solved.
However, in the integrated information wiring system using the twisted pair wire 4, since telephones and various information transmission signals coexist in the same wiring system, it is difficult to take termination of each port like a TV co-listening device, and passive type. The distribution method has a problem that performance is degraded due to forgetting the end. Further, there is a problem that it is difficult for the distributor to grasp the termination condition of the cable connected to the tip of the distributor.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to use a prior information wiring system as a transmission medium and to use a star-type distributor by a distributor. The purpose of this is to prevent deterioration of transmission characteristics due to forgetting the termination when configuring an information communication system.

[0008]

In order to solve the above-mentioned problems, the signal distributor having the automatic termination function of the present invention uses a plurality of signals on one port P0 as shown in FIG. , PN of the distribution ports P1, P2, P3, ..., PN, and terminals T1, ..., TN to the distribution ports P1, P2, P3 ,.
Detecting means K1, ..., KN for detecting the presence or absence of connection of
And the terminal T by means of the terminal detection means Ki (i = 1, ..., N).
A terminal means Ri for connecting a terminating resistor to the distribution port Pi in which the connection of i is not detected is provided, and the terminal detection means Ki
Is a signal transmission line of the transmission medium 4i, as shown in FIG.
It is characterized in that the presence or absence of the connection of the terminal Ti is detected by detecting the current, voltage or impedance on the wiring other than the above.
In addition, it is preferable to include a display unit 8 for displaying the presence / absence of connection of the terminal Ti detected by the terminal detection unit Ki.

[0009]

According to the present invention, the current or voltage or impedance on the wiring other than the signal transmission line of the transmission medium 4i connected to each distribution port Pi (i = 1, ..., N) of the distributor B, By detecting the presence or absence of the connection of the terminal Ti to each distribution port Pi, the distribution port Pi to which the terminal Ti is not connected is connected to a terminating resistor. There is no fear of deterioration, and transmission reliability can be improved.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic configuration diagram of an embodiment of the present invention. The twisted pair wire 40 connected to the control unit installed in the control center is the N distributor B.
It is connected to the. The first to Nth distribution ports P1, P2, P3, ..., PN of the N distributor B are connected to the first to Nth exchange input terminals of the exchange board X. Exchange board X first ~
The Nth exchange output terminal is a twisted pair wire 41, 42, 4
Information outlets J1, J2, J through 3, ..., 4N
3, ..., JN. Terminals T1 and TN are connected to some information outlets J1 and JN.
First to Nth distribution ports P1, P2, P of the N distributor B
Terminals R1, ..., RN and terminal detectors K1, ..., KN are provided on the respective distribution signal lines connected to 3 ,.

Information outlets J1, J2, J
3, ..., JN are, for example, standard R's as shown in FIG.
It is composed of a modular jack such as a J-45 connector, and its pins 1, 2 or 3, 6 are used as signal transmission lines. The 7th and 8th pins are not used as signal transmission lines. Each twisted pair wire 4
, 42, 43, ..., 4N are unshielded twisted pair cables, and use four pairs of twisted pair wires bundled in one cable. In this embodiment,
Eight signal lines in this one cable ...
Among them, the signal line is used as a signal transmission line, and the signal line is used as a wire for detecting a terminal connection. A twisted pair wire derived from a balun adapter on the terminal side is connected to the modular jack via a modular plug. In this modular plug or the balun adapter on the terminal side, the signal line used as the wiring for detecting the terminal connection is short-circuited via an appropriate dummy resistor.

The terminating means Ri (i = 1, ..., N) is shown in FIG.
, A relay contact Si having two interlocking contacts
The terminating resistor R is connected to the normally open contact. In the figure,
, Are signal transmission lines and are connected to the normally closed contacts of the relay. The common contact of the relay is connected to the distribution port Pi of the N distributor B. In the initial state, the distribution port Pi of the N distributor B is connected to the signal transmission line on the terminal side. In this state, whether or not the terminal Ti is connected is detected by the terminal detection means Ki, and if the terminal Ti is not connected, the common contact of the relay is connected to the normally open contact, and the terminating resistor R is distributed by the N distributor B. It is connected to the port Pi. As a result, the distribution port Pi to which the terminal Ti is not connected can be automatically terminated.

Each of the terminal detecting means K1, ..., KN is composed of, for example, a voltage level determining device, and is used as a transmission medium 4i.
By determining the voltage levels on the wirings other than the signal transmission line, the terminals T1, ..., TN as loads are individually detected by the terminal detection unit 6. When the voltage level on wirings other than the signal transmission line of the transmission medium 4i is lower than a predetermined level, it is determined that the terminal is connected, and when the voltage level is higher than the predetermined level, it is determined that the terminal is not connected. The control unit 7 controls the termination control unit 5 according to the presence / absence of a terminal connection detected by the terminal detection unit 6, and among the distribution signal lines of the N distributor B, the terminal Ti (i =
, ..., N) corresponding to the connected end means Ri
The relay contact Si is switched to connect the terminating resistor R. The relay contact Si of each terminating means Ri is individually controlled to be opened / closed by the termination control unit 5. As the terminal detection means Ki connected to the output port on the terminal side, in addition to the means for detecting the current or voltage on the wiring, the terminal Ti of the terminal Ti is measured by measuring the change in the impedance on the wiring. A means for detecting the presence or absence may be used.

Further, the first to Nth display lamps L1, L2, L3, ..., LN of the display means 8 cause the terminals T1 ,.
Displays whether TN is connected or not. In this embodiment, by connecting the indicator lamp Li to the wiring other than the signal transmission line of the transmission medium 4i via the DC power source Ei and the resistor r,
It is configured to be able to display whether or not the terminal is connected.

FIG. 4 shows a usage state of this embodiment.
The box of the signal distribution device 9 has a display lamp of the display means 8 on the front panel, and the twisted pair wire 40 connected to the control unit C is connected to the rear side thereof and connected to the exchange board X. The first to Nth distribution signal lines are connected. The exchange board X has first to Nth inputs and first to Nth outputs, and is configured so that any input can be connected to any output. Terminals T1, ..., TN are connected to all or part of the first to Nth outputs of the exchange board X. In addition, the twisted pair wire 40 on the control unit C side
Is connected to the control unit C via an information outlet J and a balun adapter A.

Although the circuit configuration of the N divider B used in this embodiment is not particularly limited, for example, a divider using a transformer Tf as shown in FIG. 5 or as shown in FIG. A distributor having an arbitrary circuit configuration such as a distributor using the resistors Ra to Rc can be used.

The operation of this embodiment will be described below.
In the present embodiment, as shown in FIG. 1, the terminal detecting means K1, ..., KN provided on each distribution signal line of the N distributor B detect whether or not the terminals T1 ,. .
When the terminal Ti (i = 1, ..., N) is connected, the wiring on the terminal side other than the signal transmission line of the transmission medium 4i is short-circuited via an appropriate resistance, so that this wiring is connected. An electric current flows through. When this current flows through the resistor r, a voltage drop occurs across the resistor r, the voltage level between the wirings decreases, and the terminal detecting means Ki detects the presence of the terminal. As a result, under the control of the termination control unit 5, the termination means Ri shown in FIG.
The relay contact Si of is switched, the terminating resistor R is disconnected from the distribution signal line, and the terminal Ti is directly connected to the distribution port Pi of the N distributor B. When the terminal Ti as a load is not connected, no current flows in the wiring other than the signal transmission line of the transmission medium 4i, so that no voltage drop occurs across the resistor r, and the voltage level between the wiring and Since it becomes higher, the absence of the terminal is detected by the terminal detection means Ki. At this time, under the control of the termination control unit 5, the relay contact Si of the termination means Ri shown in FIG.
Are connected, and the distribution port Pi of the N distributor B is automatically terminated. Therefore, it is possible to prevent the characteristic of the N distributor B from being deteriorated by forgetting the termination.
Further, when a current flows through wirings other than the signal transmission line of the transmission medium 4i, the display lamp L of the display means 8 is simultaneously displayed.
When i is turned on, the connection state of the terminal Ti can be confirmed from outside the box of the signal distribution device 9.

FIGS. 7 and 8 show another means for automatically terminating each distribution port Pi of the N distributor B. In this example, the terminating resistor R is built in the BNC connector used when connecting the coaxial cable to the balun adapter on the terminal side. As shown in FIG. 7, when the connector is in the connected state, the terminating resistor R is separated from the signal transmission line. However, as shown in FIG. 8, when the connector is in the unconnected state, the terminating resistor R is the signal. It is configured to be automatically connected to the transmission line. By using the BNC connector having such a built-in terminating resistor R for connecting the coaxial cable in the balun adapter on the terminal side, it is possible to reliably prevent forgetting the termination and prevent the performance deterioration of the N distributor B.

[0019]

According to the invention described in claim 1, the presence or absence of the connection of the terminal to each distribution port of the distributor is detected, and the terminating resistor is connected to the distribution port in which the connection of the terminal is not detected. Therefore, there is no fear that the transmission characteristics will be deteriorated due to forgetting the termination, and the transmission reliability can be improved, and the current, voltage or impedance on the wiring other than the signal transmission line of the transmission medium is detected. By detecting the presence / absence of connection of the terminal by this, there is an effect that a signal distribution device having an automatic termination function can be realized at a low cost with a simple configuration.

According to the second aspect of the present invention, the terminal connecting connector connected to the distribution port has a built-in terminating resistor, which is separated from the distribution port when the terminal is connected and is distributed when the terminal is not connected. Since it is configured to be connected to, it is possible to more reliably achieve the effect that transmission reliability can be improved without fear of deterioration of transmission characteristics due to forgetting termination.

According to the third aspect of the invention, since the presence or absence of the connection of the terminal to each distribution port of the distributor is displayed, it is possible to easily grasp the usage status of the signal distribution device. This has the effect of easily adding or relocating terminals.

[Brief description of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention.

FIG. 2 is a front view of an information outlet used in an embodiment of the present invention.

FIG. 3 is a circuit diagram of a termination means and a display means used in an embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a usage state of an embodiment of the present invention.

FIG. 5 is a circuit diagram showing an example of a distributor used in an embodiment of the present invention.

FIG. 6 is a circuit diagram showing another example of the distributor used in the embodiment of the present invention.

FIG. 7 is a schematic configuration diagram showing a connection state of another terminating means used in the present invention.

FIG. 8 is a schematic configuration diagram showing a non-connection state of another termination means used in the present invention.

FIG. 9 is a schematic configuration diagram of a first conventional example.

FIG. 10 is a schematic configuration diagram of a second conventional example.

FIG. 11 is a schematic configuration diagram of a third conventional example.

[Explanation of symbols]

 R1, ..., RN termination means K1, ..., KN terminal detection means BN distributor

Claims (3)

[Claims] 1. A distributor for distributing a signal on one port to a plurality of distribution ports, and a terminal detecting means for detecting whether or not a terminal is connected to each distribution port in the distributor.
The terminal detecting means comprises a terminating means for connecting a terminating resistor to the distribution port in which the terminal connection is not detected, and the terminal detecting means detects the current, voltage or impedance on the wiring other than the signal transmission line of the transmission medium. A signal distribution device having an automatic termination function, which is configured to detect whether or not a terminal is connected. 2. A dummy resistor is built in a connector for connecting a terminal connected to the distribution port, the dummy resistor is separated from the distribution port when the terminal is connected, and is connected to the distribution port when the terminal is not connected. The signal distribution device having the automatic termination function according to claim 1, wherein 3. A signal distribution apparatus having an automatic termination function according to claim 1, further comprising a display unit for displaying the presence / absence of connection of the terminal detected by the terminal detection unit.