JPS5827704B2 - Data transmission system using optical transmission line - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission system in which a master station and a plurality of slave stations are connected by an optical transmission line, and particularly to a signal bypass at a repeater thereof.

A data transmission system in which a plurality of master stations (master stations) M and slave stations (slave 7" stations) S are connected by optical transmission lines TL is being adopted for high-speed information transmission and processing between computer systems.

In the optical transmission line TL using optical fiber, etc., the attenuation is relatively large, so repeaters are used, and the MU and SU shown in the figure
This is a repeater for the master station and slave stations.

The optical transmission line T is connected between the master station M and the slave station S at these repeaters.
Connected to L.

As shown in Figure 2, the repeater SU includes a photoelectric converter 0/E that converts input light into electricity and amplifies it, gates G1 and G2 for waveform shaping, a timer TIM for clock extraction, and a delay circuit D.
L flip-flop FF, gate 0 for signal circuit switching
3~G5 and inverter In, convert electrical signal to optical signal 1
.

The slave station sends the amplified and shaped signal Sg to the flip-flop FF.
The data is taken in from the output end of the data terminal RD, and this is taken in as the received data RD.

The slave station transmission data SD is sent by setting the signal BPS to L (low) level.

That is, in this case, the Nant gate G3 is closed (fixed to the H level output state), and the Nant gate G5 is closed to the inverter I.
Since the inverted signal of BPS is input by n, it is opened and outputs of H and L levels according to H2L of the sending data SD are produced.

The same applies to the Nant gate G4, and the signal from the repeater input end is thus cut off, and the slave station transparent data SD is converted into electro-optical data by the converter E10 and sent to the transmission line TL.

Since the power required for amplification and shaping in the repeaters is relatively small, and since each repeater must be in operation at all times while the data transmission system is in operation, power is supplied from the master station.

In other words, this optical transmission line is equipped with an ordinary conductive cable for power supply in addition to the optical fiber for transmitting light;
The master station supplies power to each repeater using the cable.

However, some of the slave stations connected to each repeater have high power consumption, and usually draw power from the commercial power supply provided to the slave stations.

In this data transmission system, there is one master-slave method.
If the master station calls any slave station and communicates with it, then each slave station receives the signal from the transmission path and returns a response if the signal is addressed to its own station. , if the signal is not addressed to the local station, it is returned to the transmission path again.

However, in such a system, when the power of a slave station is cut off, signals passing to the slave station destined for other slave stations also disappear at the slave station.

Data transmission systems using optical transmission lines perform extremely high-speed data transmission, so even if a signal disappears, retransmission is impossible or difficult.

Furthermore, when the slave station power is cut off, noise and meaningless error signals are generated, which may cause trouble.

The present invention was made in order to deal with this problem.In a data transmission system in which a master station and a plurality of slave stations are connected via an optical transmission line, an opto-electrical converter on the input side and an opto-electric converter on the output side are used. An electro-optical converter, and a gate that switches the input of the electro-optical converter to the slave station transmitting circuit side when the slave station is transmitting, and to the output side of the opto-electric converter when the slave station is not transmitting and when the slave station power is cut off. A plurality of repeaters each having a group of switching circuits are inserted into the optical transmission line, the plurality of slave stations are connected to the optical transmission line via the repeater, and an opto-electrical converter of the repeater; The electro-optical converter, button, and switching circuit are characterized in that they are supplied with power from a master station through a conductive cable attached to an optical fiber of an optical transmission line.

In this way, it is possible to avoid troubles caused by power outages, and to ensure reliable data transmission.

Next, this will be explained with reference to the embodiment shown in FIG.

In FIG. 3, RV is an input circuit, which includes the opto-electrical converter 0/E of FIG. 2, gate G1. G2, timer TIM, delay circuit DIJ-, and flip-flop FF.

DV is an output circuit, which is the electrical-to-optical converter E10 in FIG.
corresponds to

The chain line frame is the switching circuit SWC, which is connected to gates 03 to 1 in Figure 1.
A Nant gate G6$- and an inverter ■n1 are added to G6 and inverter In.

On the slave station S side, RCV is the receiving circuit, SND is the transmitting circuit, and DE
T is a failure detection and power-off detection circuit.

The amplification and shaping operations in this repeater are as described above, and the transmission and reception are also similar, with the receiving circuit RCV taking in the signal RD from the master station from the output terminal of the input circuit RV, and the sending data SD being sent to the sending circuit. SND, gate G5. G4, and sends it to the transmission line TL via the output circuit DV path.

This data transmission system uses the HDLC procedure.

In this circuit, when the power of the slave station is turned off, the detection circuit DET generates the L level signal CBPS by a contact linked to the power switch, the output of the Nant gate G6 is at the H level, and the output of the inverter In is at the L level. become,
Nantes gate G3 opens, Nantes gate G5 closes, and Nantes gate G4 opens.

Therefore, the signal from the master station passes through this repeater SU and does not disappear towards the slave station SK.

When the slave station's power is cut off, the various gates and flip-flops in the slave station may have random output states in the process until the voltage drops to zero, and spikes may occur. Goo 1-G5 will be closed as soon as possible,
Since the slave station transmitting circuit is turned off, even if the power is turned off, the voltage does not immediately decrease to zero voltage, but gradually decreases due to delay elements such as capacitors.At voltage 1, various gates operate normally. Therefore, noise is not sent out to the optical transmission line through the gates G5 and G4.

The same applies when a failure occurs in the slave station, and the detection circuit DET generates an L level signal CBPS, closes the gate G, and opens the gate G3.

When the slave station sends data, the signal BPS becomes L level and the output of inverter In becomes H level. At this time, if all parts are normal, the signal CBPS is H level, so the output of Nantes gate G6 becomes L level and J Nantes Gate G
3 is closed, and the Nant gate G5 is opened by the H level output of the inverter In.

When transmitting slave station data, due to the characteristics of this master-slave system, there are no signals from other slave stations or the master station on the optical transmission line TL, so closing gate G3 has no meaning of signal interruption.

In this method, when there is no signal, a square wave with a duty of 50 is transmitted, and the signal is carried by removing a part of this square wave, and the slave station sending signal is also the same, but this It is necessary to avoid mixing the slave station signal with the square wave described above from the master station, and the gate G3 performs this function.

When the slave station is not transmitting, the signal BPS is at H level, so the gate G3 is open and the gate G4 is closed, and the repeater is in a through state.

Even if the slave station power is cut off in this state and the detection circuit DET generates the L level signal CBPS, this does not contribute to particular operation, but since it is in the through state to begin with, there is no particular problem.

As explained in detail above, according to the present invention, signal amplification and shaping are performed using a repeater supplied with power from the master station, so that the optical signal transmission capability is stabilized, and the optical signal is transmitted through the repeater. When power is cut off to a slave station connected to the transmission line, the repeater is put into a through state when the button is pressed and the slave station is not transmitting, so there is an advantage that no disturbance is caused to the trunk system.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing an overview of a data transmission system using an optical transmission line, FIG. 2 is a block diagram showing the configuration of a repeater, and FIG. 3 is a block diagram showing an embodiment of the present invention. In the drawing, M is a master station, S is a slave station, TL is an optical transmission line, SU is a repeater, and SWC is a switching circuit.

Claims (1)

[Scope of Claims] 1. A data transmission system in which a master station and a plurality of slave stations are connected via an optical transmission line, 4) an optical-electrical converter on the input side, an electro-optical converter on the output side, Equipped with a switching circuit having a group of gates that switches the power of the optical converter to the slave station sending circuit side when the slave station is transmitting, and to the output side of the optoelectric converter when the slave station is not transmitting and when the f-station power is cut off. A plurality of repeaters are inserted into the optical transmission line, the plurality of slave stations are connected to the optical transmission line via the repeater, and an opto-electrical converter, an electro-optic converter, a switch, and a switch of the repeater are inserted into the optical transmission line. A data transmission system using an optical transmission line, characterized in that the circuit is configured such that power is supplied from a master station through a conductive cable attached to an optical fiber of the optical transmission line.