JPS6229246A - Transceiver - Google Patents

Abstract

PURPOSE:To use many kinds of power supplies and to improve the reliability by providing the N-set of multi-output switching power supplies generating the M-kind of power supplies isolated electrically from a power supply from stations corresponding one by one to the N-set of stations while using the station power supply. CONSTITUTION:DC voltage V1 of equi-potential from smoothing circuits 8a-8c are combined by diodes 12a-12c for the purpose of multi-kind usage. Simiarly, DC voltages V2 of equi-potential from smoothing circuits 9a-9c are combined by diodes 13a-13c, DC voltages V3 of equi-potential from smoothing circuits 11a-11c are combined by diodes 14a-14c for the purpose of multiplexing usage. Thus, even if switching power supplies 40b, 40c corresponding to stations STN 10b, 10c are failed, when the switching supply 40a is normal, three kinds of power supplies V1-V3 are supplied from the power supply 40a. The voltage drop at the output terminal of the voltages V1, V2, V3 due to the fault of the switching power supplies 40b, 40c is prevented by the reverse current block ing operation by the diodes 12b, 12c, 13b, 13c, 14b, 14c.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transceiver suitable for a CSMA/Go type local area network.

[Technical Background of the Invention] As a local area network, media access using the CSMA/CD method (completely distributed peer-to-peer protocol with stochastic contention avoidance means), typified by Xerox Corporation's Ethernet, is known. This type of local area network achieves high transmission speed (for example, 10 Mbit/sec) using a single coaxial cable as a broadcast communication medium, and data is transmitted and received between stations using transceivers provided at each station.

This type of transceiver has two transmissions performed simultaneously on the coaxial cable: a transmitter that receives data transmitted from the station and sends the signal to the coaxial cable, and a receiver that receives the signal on the coaxial cable. In other words, the station has a collision detector for detecting transmission collisions, and is configured so that only one station exclusively uses the coaxial cable for transmission.

[Problems of the Background Art] In the above-mentioned local area network, the connection between the transceiver and the coaxial cable is generally made by a T-connector or a tap. However, since this connector is expensive, it poses a cost problem for networks with a large number of stations.

Now, in the above network, there is always one transmitting station at a time. At this time, all other stations are in the state of receiving transmission data from the transmitting station. That is, in a CSMA/CD type local area network, each transceiver handles the same signal except when transmitting. However, even though the signal handled by the conventional transceiver is the same as that of the conventional transceiver, the conventional transceiver must have circuitry for handling the signal, ie, a receiver and a collision detector, along with the transmitter. Therefore, in a network with a large number of stations, there is a problem in that the system price becomes high.

[Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to enable common use by a plurality of stations arranged in close proximity, thereby reducing the number of receivers and collision detectors;
Moreover, the object is to provide a highly reliable transceiver.

[Summary of the Invention] In this invention, N stations are shared by N stations in a CSMA/CD local area network.
A transmitter/receiver section driven by M types of power sources that are electrically isolated from the N sources of the two stations, and a power source section that supplies M types of power sources to the transmitter/receiver section are provided.

The transmitter/receiver section includes N transmitters that are provided in one-to-one correspondence with N stations and that receive transmission signals from the corresponding stations and send the signals to the broadcast channel, and and a collision detector for detecting transmission collisions on the broadcast channel. The output of each of the N transmitters and the input of the receiver and input of the collision detector are commonly connected to a broadcast channel. The received signal from the receiver is distributed to the first distribution means, and the detection signal from the collision detector is distributed to the N stations in common by the second distribution means.

In addition, the power supply section is provided in one-to-one correspondence with N stations, and has N multi-output switching devices that generate M types of N sources electrically isolated from the power source by the power source from the corresponding station. It has a power source and a group of diodes. The diode group is used to combine M types of power supplies respectively generated by N switching power supplies with the same type of power supplies to generate M types of multiplexed power supplies for driving the transmitter/receiver unit.

The transceiver configured as described above can be shared by N stations, and therefore only one receiver and one collision detector are required for transmission and reception by the N stations. Furthermore, by simply adding a group of diodes, power supplies can be multiplexed, improving the reliability of the power supply section.

[Embodiment of the invention] FIG. 1(a) shows a CSMA/C according to an embodiment of the invention.
The system configuration of a D-type local area network is shown. In the figure, 11a to 11c are stations (
(hereinafter referred to as STN). In this example,
S T N 10a to 10c are arranged close to each other. S
T N 10a to 10c are connected to one transceiver 20, and the transceiver 20 is connected to a coaxial cable 30 as a broadcast communication path, for example, by a T connector (not shown). In addition, in FIG. 1, the transceiver 20
Transceivers other than the above and STNs (stations) connected to the transceivers are omitted.

FIG. 1(b) shows the configuration of the transmitting/receiving section of the transceiver 20 shown in FIG. 1(a). In the same figure, 21a to 21b
is a transformer. The primary winding of transformers 21a to 2IC is S
It is connected to the transmission signal output terminal (not shown) of T N 10a to 10C, and the secondary winding is
is connected to the input of Each output of the transmitters 22a to 22C is transmitted to a receiver (R) shared by the 5TNs 10a to 10C.
23 and the flesh input of the collision detector 24 are connected to the coaxial cable 30 at one point by a T-connector (not shown).

The output of the receiver 23 is connected to the primary winding of the transformer 1. The transformer 1 has a secondary winding 18 to IC. The secondary windings 111a to 1C of the transformer 1 are connected to the inputs of the drivers 28 to 2C, and the outputs of the drivers 28 to 2C are S T
It is connected to the received signal input terminals (not shown) of N 10a to 10c.

The output of the collision detector 24 is connected to the primary winding of the transformer 3. The transformer 3 has two windings*3a to 3C. Secondary winding of transformer 3 @3a~3C is driver 48~4C
The outputs of drivers 4a to 4C are connected to the inputs of S T
N 10a to 10c are connected to collision detection signal input terminals (not shown).

In this embodiment, transmitters 22a to 22G, receiver 2
3 and a collision detector 24, the transmitter/receiver circuit 25 includes:
5TN10a~10C ms and electrically isolated voltage '
fIA (insulated power supply) Vl (positive voltage), V2 (
negative voltage) is applied. Further, the input circuit 26 consisting of the drivers 2a to 2C and the drivers 48 to 4C has an S T
V3 (negative voltage), which is a power supply (insulated power supply) electrically insulated from the power supply of N10a to 100, is applied.

Now, the signal (transmission signal) on the coaxial cable 30 is guided to the input of the receiver 23. Receiver 23 receives the signal on coaxial cable 30 and outputs a corresponding first received signal. The first received signal from the receiver 23 is guided to the primary winding of the transformer 1, which causes the secondary windings 18 to 1C to receive a second received signal electrically isolated from the first received signal. Occur. The second received signal generated in the secondary windings 18 to 1C of the transformer 1 is S T N 10 by the drivers 2a to 2C.
It is output to the received signal input terminals of a to 10c. As a result,
The STNs 10a to 10C can perform reception processing without any problems, similar to the conventional example in which a receiver is prepared for each STN (station).

When the 5TNs 10a to 10C need to transmit, they detect whether a transmission signal from another STN is present on the coaxial cable 30. Detection of the presence or absence of a transmission signal on the coaxial cable 30 is performed by S
This is possible by checking the output signals from the drivers 28 to 2C led to the received signal input terminals of the T N 10a to 10c. When the S T N 10a to 10c detect that no transmission signal exists on the coaxial cable 30 when transmission is required, they output a desired first transmission signal from their transmission signal output ends. The independent first transmitted signals from S T N 10a-10C are directed to the primary windings of transformers 21a-21c, thereby causing their secondary windings to be electrically isolated from the first transmitted signals. A second transmission signal is generated. Transmitter 22
a to 22C receive the second transmission signals generated in the secondary windings of the transformers 21a to 21c, and transmit the signals to the coaxial cable 30.

In this case, a collision of transmitted signals occurs on the coaxial cable 30.

The signal on the coaxial cable 30 is directed to the input of the collision detector 24 as well as the receiver 23 described above. Collision detector 24 receives a signal on coaxial cable 30 and detects a collision using well-known means. The collision detection here is performed by detecting a change in the DC level of the coaxial cable 30. This detection principle is based on the coaxial cable 30 when only one STN (station) sends a signal.
The DC level of the DC level is centered around -1,025V, but the amplitude of the waveform is centered around -1,025V, whereas if multiple STNs send out signals at the same time, the center level decreases (for example, if two STNs send out signals at the same time) In some cases, the center drops to 12■). When the collision detector 24 performs collision detection according to the above principle, it outputs a first collision detection signal indicating the result.

The first collision detection signal from the collision detector 24 is transmitted to the first collision detection signal of the transformer 3.
This causes a second collision detection signal electrically isolated from the first vE collision detection signal to be generated in the secondary windings 38 to 3C. The second collision detection signals generated in the secondary windings 3a to 3c of the transformer 3 are outputted to the collision detection signal input terminals of the S T N 10a to 10c by the drivers 4a to 4C. As a result, S T N 10a to 10c are
As in the conventional example in which a collision detector is prepared for each STN (station), collision processing can be performed without any problems.

The S T N 10a to 10c determine whether or not the transmission from the own STN collides with the transmission from another STN, based on the output signals from the drivers 4a to 4c guided to their collision detection signal input terminals. When a collision occurs as in this example, STNs 10a to 100 (and if there is a simultaneous STN among other STNs not shown, those 5TNs) stop transmitting and take appropriate action. Wait a certain amount of time and resend. The time until this retransmission is set, for example, by a random number for each S
It is set independently in TN.

Now, if S T N 10a is the first to retransmit, no collision will occur on the coaxial cable 30, so S
T N 10a continues transmitting. S T N 10a
The transmitted signal on the coaxial cable 30 due to the transmission of
3 and sent to 5TN10b and IOC via transformer 1 and drivers 2b and 2c.

FIG. 1(C) shows the configuration of the power supply section of the transceiver 20 shown in FIG. 1(a). In the same figure, 40a to 40C are three kinds of 'l1mV1, V2, V3 which are electrically isolated from the N source of STN 10a to 10c.
This is a multi-output switching power supply that generates independently.

Switching power supply 408~40C is 5TN10a~1
It has switching circuits 41a to 41C that input electric current m from 0C<DC N source). switching circuit 41
The outputs of a to 41C are connected to the primary windings of transformers 42a to 42C. Transformers 42a-42c have three two-winding coils $15a-5C26a-6C27a-7C.

Secondary windings 5a to 5c, 6 of transformers 42a to 42c
a to 6c, 7a to 7C have smoothing circuits 8a to 8C19
a~9C118~41C of 111a~11c is 0N10
By being FFilJIO, transformers 428-42
C secondary windings 5a to 5c, 6a to 6c, 7a to
From S T N 10a to 10c (7
) Nm,! ：An isolated pulse waveform voltage is generated. These pulse waveform voltages are applied to the smoothing circuits 8a to 8.
c, 9a-9c.

Rectified and smoothed by 11a to 11c, stable DC voltages V1 (positive'! pressure), V2 (negative voltage), V3
(negative voltage).

A diode 12a is connected to the positive output terminal of the smoothing circuits 88 to 8C.
~120 anodes are connected and diodes 12a~1
The cathodes of 2c are commonly connected to form a V1 output terminal. On the other hand, the negative output terminals of the smoothing circuits 88 to 8c are commonly connected to form a G1 output terminal (tI ground terminal). Furthermore, diodes 13a to 1 are connected to the negative output terminals of the smoothing circuits 9a to 9c.
30 cathodes are connected, and diodes 13a to 13c
The anodes of are commonly connected to form the v2 output terminal.

On the other hand, the positive output terminals of the smoothing circuits 9a to 9C are connected to the smoothing circuits 88 to 88.
It is commonly connected with the negative output terminal of 8c to form the above-mentioned G1 output terminal (ground terminal). In addition, smoothing circuits 11a to 11
The cathodes of diodes 14a to 14c are connected to the negative output terminal of c, and the anodes of diodes t4a to 14c are commonly connected to form a 3 output terminal. On the other hand, the positive output ends of the smoothing circuits 11a to 11c are commonly connected to form a G3 output end (ground end).

In the above power supply section, the DC voltages 1 of the same potential from the smoothing circuits 8a to 8C are combined and multiplexed by the diodes 12a to 12c. Similarly, the DC voltage 2 of the same potential from the smoothing circuits 9a to 9C is applied to the diodes 13a to 13c.
are combined and multiplexed by smoothing circuits 11a to 11c.
The DC voltage ■3 with the same potential from the diodes 14a to 14
are combined and multiplexed by c.

Therefore, for example, switching circuits 41b, 41c, smoothing circuits 8b, 8 in switching tJI40b, 40c corresponding to 5TN10b, 10c
c, 9b, 9c, Nb.

11C) is out of order, the switching power supply 40a
If normal, three types of power supplies V1 to V3 are supplied from the same power supply 40a.
can be supplied. Moreover, the diode 12b
, 12c, 13b, 13c, 14b,
Due to the reverse current blocking action by 14c, Vl caused by a failure of switching power supplies 40b and 400,
A drop in voltage (absolute value) at the V2 and V3 output terminals is prevented.

In the above embodiment, a transceiver shared by three stations has been described, but the present invention can be applied to a transceiver shared by N stations. In this case, one receiver and one collision detector may be required regardless of the number of stations N, but the number of transmitters and switching power supplies required is equal to the number of stations N.

Further, in the above embodiment, a case has been described in which the present invention is applied to a transceiver applied to a local area network using a coaxial cable, but the present invention can also be applied to a transceiver used in a network using an optical fiber cable.

[Effect of the invention].

As detailed above, according to the present invention, the required number of receivers and collision detectors is reduced from N to 1 by creating a transceiver configuration that can be shared by N stations placed in close proximity. can do.

Further, according to the present invention, the required number of connectors for connecting to a broadcast communication channel such as a coaxial cable can be reduced from N to one.

Further, according to the present invention, power supplies can be multiplexed simply by adding a group of diodes, and a highly reliable transceiver power supply section can be realized with approximately the same number of components as the conventional transceiver power supply section.

[Brief explanation of drawings]

FIG. 1(a) shows a CSMA/C according to an embodiment of the present invention.
A system configuration diagram of a D-type local area network. FIG. 1(b) is a block diagram of the transmitter/receiver section of the transceiver 20 shown in FIG. 1(a), and FIG. 1(C) is a block diagram of the power supply section of the transceiver 20. FIG. 1, 3, 21a to 21c, 42a to 42c
...Transformer, 10a to 10cm...Station (STN), 12a to 12c, 13a to 13c
, 14a to 14cm...diode, 20...transceiver, 22a to 22C...transmitter, 23...
Receiver, 24... Collision detector, 30... Coaxial cable, 40a to 40c... Switching power supply. Applicant's agent Patent attorney Takehiko Suzue (a) STN STN STN STN STN
STN STN STN 5TN10az++
From 10b 10cJri To 10a To 10b 10
To c To 10a To 10b To 1oc (b) Figure 1

Claims (1)

[Scope of Claims] In a local area network applying the CSMA/CD system, a system is provided for N stations in one-to-one correspondence, and receives a transmission signal from the corresponding station and sends the signal to a broadcast channel. a receiver for receiving the signal on the broadcast channel; a first distribution means for commonly distributing the received signal from the receiver to the N stations; a collision detector for detecting a transmission collision of the collision detector; and a second distribution means for commonly distributing the detection signal from the collision detector to the N stations, and electrically isolated from the power supply of the N stations. a transmitting/receiving unit driven by M types of power sources, and a connecting means for commonly connecting the outputs of the N transmitters, the inputs of the receiver, and the inputs of the collision detector to the broadcast communication channel; N multi-output switching power supplies that are provided in one-to-one correspondence with N stations and generate M types of power supplies that are electrically isolated from the same power supply by the power supply from the corresponding station, and these N multi-output switching power supplies. a power supply unit including a group of diodes that combine M types of power supplies respectively generated by switching power supplies with the same type of power supplies to generate multiplexed M types of power supplies that drive the transmitting/receiving unit; A transceiver characterized in that it is shared by N stations.