JPS6229244A - Transceiver - Google Patents

Abstract

PURPOSE:To obtain a transceiver used in common and to which the number of receivers and collision detectors is saved by connecting in common each output of N-set of transmitters, the inputs of receivers and collision detectors to a multiple address communication line and using a distribution means to distribute in common the reception and detection signals to N-set of stations. CONSTITUTION:A receiver 23, in receiving a signal on a coaxial cable 30, outputs the corresponding 1st reception signal and the 2nd reception signal generated in secondary windings 1a-1c of a transformer 1 is outputted to a reception signal input terminal of STN 10a-10c. Further, the STNs 10a-10c output the desired 1st transmission signal from a transmission signal output terminal as required and transmitters 22a-22c send a signal to the coaxial able 30. In this case, the collision of the transmission signal takes place on the coaxial cable 30. The 1st coolision detection signal form the collision detector 24 is led to the primary winding of a transformer 3 and the 2nd collision detection signal generated in the secondary windings 3a-3c is outputted to the collision detection signal input terminals of the STN 10a-10c.

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to a transceiver suitable for a CSMA/CD 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's Ethernet in the United States, is known. There is. This type of local area network achieves high-speed transmission speeds (for example, IOM bits/second) 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 using 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, conventional transceivers, even if their handling signals are the same as those of other transceivers, must have circuitry for handling the signals, ie, a receiver and a collision detector, along with the transmitter. For this reason, networks with a large number of stations have the problem of high system costs.

[Objective of the Invention 1] This invention has been made in view of the above circumstances, and its purpose is to provide a transceiver that can be shared by a plurality of stations arranged in close proximity, thereby reducing the number of receivers and collision detectors. There is a particular thing.

[Summary of the Invention] In this invention, a system is provided in a one-to-one correspondence with N stations in a CSMA/CD type local area network, and receives a transmission signal from the corresponding station and sends the signal to a broadcast channel. There are provided N transmitters for transmitting data, a receiver for receiving signals on the broadcast channel, 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.

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.

[Embodiment of the invention] FIG. 1(a) shows a C8M A according to an embodiment of the invention.
/ Shows the system configuration of a CD-based local area network. In the figure, 118 to 11c are stations (hereinafter referred to as STN).

In this example R, S T N 10a to 10C are arranged close to each other. The S T N 108 to IOC 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). Note that in FIG. 1, transceivers other than the transceiver 20 and STNs (stations) connected to the transceiver are omitted.

FIG. 1(1)) shows the transceiver 20 shown in FIG. 1(a).
The configuration of the transmitter/receiver section is shown below. In the same figure, 21a to 21
b is a transformer. The primary windings of the transformers 21a-2IC are connected to the transmission signal output terminals (not shown) of the S T N 10a-100, and the secondary windings are connected to the transmitter (T) 22a-22.
Connected to the input of C. Each output of the transmitters 22a to 22C is connected to S T N 10a to 10c I, in one place by a T-connector (not shown), with both the receiver (R) 23 and collision detector 24 being shared. It is connected to a coaxial cable 30.

The output of the receiver 23 is connected to the primary winding of the transformer 1. The transformer 1 has secondary windings 18-1C. The secondary winding 18-1C of the transformer 1 is connected to the input of the driver 28-2G, and the output of the driver 28-2C is ST N
10a to the received signal input terminals (not shown) of the IOC.

The output of the collision detector 24 is connected to the primary winding of the transformer 3. The transformer 3 has secondary windings 3a to 3C. The secondary windings 38 to 3C of the transformer 3 are the drivers 48 to 4C.
The outputs of the drivers 48 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-22c, receiver 2
3 and a collision detector 24, the transmitter/receiver circuit 25 includes:
A voltage 1li (insulated voltage R) rc156V1 (positive 1f pressure) and V2 (negative voltage) which are electrically insulated from the power source of S T N 10a to 10c is applied. Also driver 28~
2c and drivers 48 to 4C, V3 (negative voltage) is a power supply (insulated power supply) electrically isolated from N1IN of S T N lOa to 10c.
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 winding generated in the secondary windings 131a to 1G of the transformer 1
The received signal is S T N 1 by the drivers 2a to 2C.
It is output to the received signal input terminals 0a 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).

S T N 10a to 10c are connected to other S when transmission is necessary.
It is detected whether a transmission signal from the TN exists on the coaxial cable 30. The presence or absence of a transmission signal on the coaxial cable 30 can be detected by checking the output signals from the drivers 2a to 2c guided to the reception signal input terminals of the 8TNs 10a to 10C. When the S T N 10a to 10C detect that no transmission signal is present 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 218-21c, thereby causing their secondary windings to be electrically isolated from the first transmitted signals. A second transmission signal is generated. Transmitter 2
28 to 22c receive the second transmission signals generated in the secondary windings of the transformers 218 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 has a waveform amplitude centered around -1,025V, but 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 -2V). 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.
is led to the secondary winding, which causes the first! A second collision detection signal electrically isolated from the i collision detection signal is generated. The second collision detection signals generated in the two large turns J13a to 3C of the transformer 3 are outputted to the collision detection signal input terminals of S T N 10a to 10G by the drivers 4a to 4C. As a result, the STNs 10a to 10c can perform collision processing without any problems, similar to the conventional example in which a collision detector is prepared for each STN (station).

The S T Ns 10a to 10c determine whether transmission from their own STN collides with transmission from another STN, based on output signals from the drivers 48 to 4C guided to their collision detection signal input terminals. When a collision occurs as in this example, STNs 10a to 10C (furthermore, if there is a simultaneous transmission STN among other STNs (not shown), that 5T
N) stops transmission, waits for an appropriate time, and then retransmits. The time until this retransmission is set, for example, by a random number for each STN.
is set independently.

Now, if S T N 10a is the first to retransmit, there will be no collision on the coaxial cable 30, so S
T N 10a continues transmitting. The transmitted signal on the coaxial cable 30 by the transmission of the 5TN10a is received by the receiver 23, and is transmitted through the transformer 1 and the drivers 2b and 2c to the 5TN10a.
Sent to TN10b, 100.

Figure 2 shows the power supply 11 of the transceiver 20 shown in Figure 1 <8).
The structure of part 1 is shown. In the same figure, 40a to 40C are S
This is a multi-output switching power supply that independently generates three illumination sources V1, V2, and V3 electrically isolated from the power supply of T N 10a to 10c. Switching! 1140a to 400 are S T N 10a
It has switching circuits 418 to 41C that input power (DC power) from 10c to 10c. Outputs of switching circuits 41a-41c are connected to primary windings of transformers 42a-42Q. The transformers 42a to 420 are three 2
Entourage II! 5a-5C96a-60.7a-7C. Secondary windings 5a to 5C2 of transformers 428 to 42c
6a to 6C27a to IC have smoothing circuits 8a to 8c,
Inputs 9a to 9c and 11a to 11c are connected.

In the power supply section of FIG. 2, the switching circuit 41a
~41c is 0N10FF, so that the secondary windings 5a ~5c, 6a ~6 of transformers 428~42C
c, 7a to 7C respectively S T N 108 to IO
A pulse waveform voltage isolated from the power supply from C is generated. These pulse waveform voltages are applied to the smoothing circuits 8a to 8C,
9a-9C.

11a to 110, the stable DC voltages Vl (positive voltage), V2 (negative '47 King), V3 (
negative voltage).

A diode 12a is connected to the positive output terminal of the smoothing circuits 88 to 8C.
The anode of ~12C is connected, and the diode 12a~1
The cathodes of 2C are commonly connected to form the 1 output terminal. On the other hand, the negative output ends of the smoothing circuits 8a to 8C are commonly connected to form a G1 output end (ground end). Furthermore, diodes 13a to 13 are connected to the negative output terminals of the smoothing circuits 98 to 9C.
The cathodes of diodes 13a to 13C are connected together, and the anodes of diodes 13a to 13C are commonly connected to form a V2 output terminal. On the other hand, the positive output terminal of the smoothing circuits 98 to 9C is connected to the smoothing circuits 88 to 8.
The above-mentioned G1 output terminal (
(grounded end). In addition, smoothing circuits 11a to 11C
The cathodes of diodes 14a to 14c are connected to the negative output terminal of , and the anodes of diodes 148 to 140 are commonly connected to form a third output terminal. On the other hand, the positive output terminals of the smoothing circuits 11a to Nc are commonly connected to the G3 output terminal (
(grounded end).

In the above power supply section, the DC voltages (1) of the same potential from the smoothing circuits 88-8C are coupled by diodes 128-12C. Similarly, the DC voltage V2 of the @ potential from the smoothing circuits 9a to 9C is coupled by the diodes 13a to 13C, and the DC voltage V2 of the same potential from the smoothing circuits 11a to 11C
3 are coupled by diodes 14a to 14C. Therefore, for example, switching circuits 41b, 41c, smoothing circuits 8b, 8c, switching circuits 140b, 40c corresponding to 5TN10b, 10C,
9b.

9c, 11b, 11c) fails,
If the switching power source M source 40a is normal, three types of power sources (1) to (3) can be supplied from the switching power source (M) source 40a. Moreover, the diodes 12b, 12c, 13
b, 13C, 14b.

Due to the reverse current blocking effect of 14C, Vl, V caused by a failure of the switching power supplies 40b, 40c
2.

A drop in the voltage (absolute m>) at the V3 output terminal 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, only one receiver and collision detector is required regardless of the number of stations N, but the number of transmitters required is equal to the number N of stations.

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 applied to a network using an optical fiber cable.

[Effects of the Invention] As described in detail above, according to the present invention, the required number of receivers and collision detectors can be reduced to N by providing a transceiver configuration that can be shared by N stations placed in particular proximity. can be reduced from 1 to 1.

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.

[Brief explanation of the drawing]

FIG. 1(a) shows a CSM according to an embodiment of the present invention.
A / CD system low power area network system configuration diagram; FIG. 1(b) is a block configuration diagram of the transmitter/receiver section of the transceiver 20 shown in FIG. 2(a), and FIG. FIG. 3 is a block configuration diagram of a power supply section. 1, 3, 21a-21c, 42a-42c...
・Transformer, 10a ~ 10cm...Station (ST
N), 12a to 12c, 13a to 13c, 1
4a to 14c...Diode, 2°...Transceiver, 22a to 22c...Transmitter, 23...Receiver, 24...Collision detector, 30...Coaxial cable,
40a to 40c...Switching power supply.

Claims (1)

[Claims] In a local area network that applies the CSMA/CD system, N transmitters are installed in one-to-one correspondence with N stations and receive transmission signals from the corresponding stations and send the signals to the broadcast channel. a receiver for receiving a signal on the broadcast channel; a first distribution means for commonly distributing the received signal from the receiver to the N stations; and a receiver for receiving a signal on the broadcast channel; a collision detector for detecting a collision; a second distribution means for commonly distributing a detection signal from the collision detector to the N stations; and connecting means for commonly connecting the input of the detector to the broadcast communication channel, the transceiver being shared by the N stations.