JPS62247647A - Local area network - Google Patents

Abstract

PURPOSE:To facilitate the multi-address communication by starting a collision generating circuit of a transceiver connected to a controller for a fixed period of time to suppress the new transmission when the multi-address communication is detected out of a program by a decoding circuit set to an LAN controller. CONSTITUTION:The LAN controllers 5, 8, 11 and 20 are connected to a coaxial cable 2 terminated by terminal resistances 1 and 3 at its both ends via transceivers 6, 9, 16 and 21 respectively. The controllers 5-20 contain external connection devices 4, 7, 10 and 19 respectively. Each LAN controller consists of a decording circuit 12 and a transmission/reception control circuit 14. When the circuit 12 of the controller 11 detects a program of multi-address communication out of data, the collision generating circuit of the transceiver 16 is started for a fixed period of time by a collision generating signal line 13. Thus the new transmission is suppressed and the multi-address communication is carried out. In such a way, the multi-address communication and the emergency communication can be performed simply and assuredly.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to local area networks.
15-- Go; Jl st -r /
/'---; --O----Multiple A
ccess with Co11ision Dete
This invention relates to a transmission control system for C8MA/C0 network.

(Prior art) COMA/CD type local area networks (for example, IE standard for local area networks)
:Carrier 8ense Multiple A
ccessWi th Co11 1sion Det
ection Access Method andP
physical layer 5 specific
ons) Published by IEEE.

1985), each device located at a node can start full transmission at any time if the transmission path is free. However, if multiple devices start transmitting at the same time, signal collisions occur on the transmission path, making normal signal transmission impossible. For this reason, each device detects a collision on the transmission path, avoids the collision, and resumes transmission again. When such a collision will occur is a matter of probability. Therefore 0 8
MA/CD access right acquisition is equal for each device, and the time required for acquisition is stochastic. Broadcast communication is used to distribute the same data to all devices connected to a local area network. COM of the above I BEE standard
A/CD In a local area network, a broadcast address (Broadcast address) is used for this purpose.
cast Address) is a setting error (see the above document).

[Problems to be Solved by the Invention] However, in the conventional C8MA/CD local area network, even when performing broadcast communication, the access right to start this communication is the same as for other communication, and if a collision occurs, the retransmission procedure is canceled. After that, access rights will be secured again.

Therefore, urgent broadcast communication is not possible with the conventional 08MA/CD type local area network.
The problem is that real-time communication is difficult because the time required to obtain the access right is not constant but stochastic.

[Means for solving problems]

The uninvented network includes a decoding circuit that decodes a broadcast request or a real-time communication request and generates a collision occurrence signal in response to the supply of a broadcast request or a real-time communication request, and a decoder circuit that generates a collision occurrence signal by decoding the same in response to the supply of a broadcast request or a real-time communication request; a transceiver that forms a signal collision condition, and configures each node of the network to suppress new transmissions when it detects a signal collision condition on the line.

[Example] Next, examples of the present invention will be explained with reference to the oral side.

FIG. 1 is a block diagram showing one embodiment of the present invention. A coaxial cable 2 terminated with a terminating resistor 1 and a terminating resistor 3, and a transceiver 6.9 connected to this coaxial cable.
16.21 and LA connected to our transceiver
N control device [5, 8° 11, 20 TcsMA/CD
1 type (7) o-power kx IJ network is constructed, and this network has 4 external connection devices. 7.
10. 19 are connected.

The LAN control device 11 includes an external connection ink face for connecting the external control device 10, a transmission/reception control circuit 14,
A collision occurrence signal line 13 is provided for a collision occurrence signal 17 for a certain period of time by detecting the occurrence of a request for emergency relay communication or real-time communication, and a signal collision state can be created. FIG. 2 shows its detailed block diagram.

The trunk cooper 16 has reception data terminals 17-2, collision detection signal terminals 17-3, . . . as signal terminals of the transceiver interface. A transmission data terminal 17-1 and a collision occurrence signal terminal 13 are provided.

The coaxial cable 2 is terminated at both ends with a terminating resistor 1 and a terminating resistor 3, and its signal line and signal ground are connected to a transceiver 16.

The signal on the coaxial cable 2 is received by the receiving circuit 34 and sent by the driver 25 to the transceiver ink face.

The collision detection circuit 35 connected to the signal line of the coaxial cable 2 detects the signal collision occurring in the coaxial cable 2. Detected by an increase in the signal amplitude or an increase in the average voltage of the signal.

The output of the collision detection circuit 35 and the output of the collision indication signal generation circuit 29 are ANDed by an AND circuit 30, and when a collision is detected, a collision indication signal is sent to the collision detection signal terminal 17 of the transceiver interface via the driver 26. -3 is output.

The transmission data applied to the transmission data terminal 7-1 is input to the multiplexer 31 via the receiver 27.

The collision occurrence signal applied to the collision occurrence signal terminal 13 is supplied to the multiplexer 31 and the driver 33 via the receiver 28.

The driver 33, which receives this collision occurrence signal and the output signal of the multiplexer 31 as input, is activated by supplying the collision occurrence signal, and fully drives the base of the output transistor 370 connected to the output terminal of this transceiver.

Similarly, the output transistor 36 is connected to the driver 32 which inputs all the output signals of the multiplexer 31.

The multiplexer 31 normally selects the register -/<270 output (collision occurrence signal logic "0"), but in response to the supply of the collision occurrence signal (collision occurrence signal logic @1") the collision display signal generation circuit 29 Select the output of

Figure 3 shows the operation of the transceiver fli? This is a timing chart in which each signal corresponds to transmission data 100. Collision occurrence signal 110. Multiplexer output 140, output signal 130 of driver 33. The transmission waveform 120 shows the envelope of all signals other than the V collision occurrence signal. Also, logic is indicated by negative logic.

When creating a collision state using a transceiver, the collision occurrence signal 110 of the transceiver interface is set to logic @1''.At this time, in FIG. The driver 32 and driver 33 appear and are fully driven.

Collision occurrence signal 1 is input to the other input terminal of the driver 33.
10 is supplied, the output signal 1 of the driver 33
30 is the same as the output signal of the driver 32. Transistors 36 and 37, whose collectors are commonly connected to the output terminal of the transceiver, are driven by drivers 32 and 33, and the same collector current can flow through each transistor. Therefore, collision occurrence signal 1
When 10 becomes logic 11'', the driver 32 and driver 33 operate simultaneously. As a result, as shown in FIG.
0''), the transceiver that receives this detects this as a collision.
When m, the transmitted data 10 supplied to the transceiver is
0 is applied to driver 33 via multiplexer 31 (see multiplexer output 140e). The output of the driver 33 is maintained at logic @0# because the collision occurrence signal 110 is logic 10" at this time. As a result, only the transistor 36 is used to drive the coaxial cable 2, and the output of the coaxial cable 2 The upper signal amplitude is at the normal level.

Next, using FIG. 1 and FIG.
t, that is, the operation of performing broadcast communication to the external connection devices 4, 7, and 19 will be described.

External connection device! 110 is an external connection interface 18
When a request signal for broadcast communication is output to LAN control 1 device 1
The decoding circuit 12 of 1 decodes all of this and sends the collision occurrence signal 110 to the transceiver face 1 over a certain period of time.
It is sent to the transceiver 16 via the collision occurrence signal line 13 of No. 7. This allows the transceiver 16 to connect to the coaxial cable 2.
The collision occurrence waveform at- is transmitted. As mentioned above, this collision generation waveform a has an amplitude more than twice that of the normal transmission waveform, and its average voltage is also usually larger than that when one transceiver transmits, so collisions with other transceivers 6.9.21 A signal @crash is detected by the detection path, collision display signal generation circuit, etc.

LAN control device5. 8. 20 detects a collision and suspends transmission for a certain period of time or longer to avoid the collision. This results in L A N itt control device! After the signal collision condition in which No. 11 occurs, a certain no-signal condition occurs.

In this manner, the LAN control device 11 is only able to transmit data for broadcast communication (data waveform b in FIG. 2) in this no-signal state.

In this way, in the local area network of this embodiment, the L A N % control device creates a signal collision state by itself to ensure a transmittable state, so that urgent broadcast communication or real-time transmission is possible. All time communication can be realized.

[Effects of the Invention] A decoding circuit is installed in a local area network control device to detect a broadcast communication command or a real-time superstition command in a program, and when the above command is detected, the control device decodes the decoding circuit. The collision generation circuit of the connected transceiver is activated for a certain period of time. As a result, a signal collision occurs on the coaxial cable i to which the transceiver is connected for a certain period of time, and the other V::wi connected to the same cable simultaneously detect the signal collision and suppress new transmission. By using the blank time M1 caused by the collision condition forcibly caused in this way, it is possible to realize broadcast communication and real-time song transmission, which has the effect of completely improving the utilization efficiency of the local area network.

[Brief explanation of drawings]

Figure 1 is a block diagram of one embodiment of a misfire, and Figure 2 is a block diagram of an example of a misfire.
The third factor in the detailed block diagram of the transceiver shown in FIG. 1 is a timing chart showing an example of the operation of the LAN control device and transceiver shown in FIG. 1.3...Terminal resistor, 2...Bloc axis cable, 4゜7.10,19...External connection device,
5. 8. 11゜20...LAN control device,
6. 9. 16. 21...transceiver,
18... External connection interface, 12...
...Decoding circuit, 13...Collision occurrence signal line,
14... Transmission/reception control circuit, 17... Transceiver interface, 25. 26. 32
．． 33... Driver, 27, 28...
・Receiver, 29... Collision indication signal generation circuit,
30...AND circuit, 31010. ...Multiplexer, 34...Reception circuit, 35...
・fiT collision detection trout 1 path, 36.37...transistor, 100...transmission data, 110...
... Collision occurrence signal, 120 ... Transmission waveform, 1
30... Output signal of driver 33, 140...
...Multiplexer output, a... Surgical waveform, b... Data waveform. Mine 1st time Minesa Harudenta Z times

Claims (1)

[Scope of Claims] A decoding circuit that decodes a broadcast communication request or a real-time communication request and generates a collision occurrence signal in response to the supply of a broadcast communication request or a real-time communication request, and a signal collision on a railway line in response to the supply of the collision occurrence signal. a transceiver for forming a condition, each node of the network suppressing new transmissions when detecting a signal collision condition on said line.