JPH05308358A - Data communication network system - Google Patents

Abstract

PURPOSE:To simplify the constitution of a node station and the whole system. CONSTITUTION:A token passing system LAN 14 is constituted by cascading seven node stations 10a-10g by a cable 13. Then a carrier generator 15 which sends an up carrier is connected to the node station 10a of the lowest-order stage through a cable 17 and a frequency converting repeater 18 which converts the up carrier into a down carrier of different frequency and sends it back is connected to the node station 10a of the highest-order stage through a cable 20. Then the respective node stations 10a-10g are each provided with a function which amplifies the up carrier and a modulating wave for the up carrier and also amplifies the down carrier and a modulating wave for the down carrier and a function which imposes two-phase modulation on the up carrier with a digital signal when a token is acquired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication network system adopting a token passing system.

[0002]

2. Description of the Related Art A LAN (abbreviation of local area network), which is a data communication network for high-speed transmission of data between a large number of computers used in general factories and business establishments, adopts a token passing system. Is often provided.

As an example of a conventional LAN of this type, as shown in FIG. 4, the input / output terminals of a plurality of node stations 1 to which computers are respectively connected are connected via a cable 2 to respective downlinks of a distributor 3. There is a configuration in which the upstream side input / output terminals of the distributor 3 are connected to the side input / output terminals, respectively, and are connected to the input / output terminals of the frequency conversion repeater 5 via the cable 4.

As shown in FIG. 5, each node station 1 has a data processing unit 1a connected to a computer via an interface, an input / output terminal 1b connected to a cable 2, and the data processing unit. The modulator 1c and the high-pass filter 1d connected between the output port of 1a and the input / output terminal 1b, the carrier wave generator 1e connected to the modulator 1c, the input / output terminal 1b and the input of the data processing unit 1a. Low-pass filter 1f and demodulator 1 connected between ports
and g.

Thus, the cable 2 is circulated with tokens indicating the transmission right in a predetermined order, and when each node station 1 receives the token, if there is no transmission request, the node station 1 transmits the token next. To the node station 1, and if there is a transmission request, the token is captured and data is transmitted.

The data transmission / reception operation at this time is as follows. That is, the data processing unit 1a of the node station 1 on the data transmitting side outputs the address of the partner node station 1 to be transmitted and the data to be transmitted as a digital signal, and the modulator 1c is the carrier wave generator 1e. The upstream carrier of, for example, 58.75 MHz is phase-modulated by the digital signal and output to the input / output terminal 1b via the high-pass filter 1d.

The upstream modulated wave output to the input / output terminal 1b in this manner is the cable 2, the distributor 3 and the cable 4.
Is given to the frequency conversion repeater 5 via the above, where the above-mentioned uplink carrier is converted into a downlink carrier of, for example, 38.9 MHz, and downlink modulation is performed on each cable 2 via the cable 4 and the distributor 3. Returned as a wave.

Then, the node station 1 addressed as described above demodulates the digital signal from the downlink modulation wave by the demodulator 1g and the data processing unit 1a.
To give to.

[0009]

In the conventional configuration, each node station 1 needs to be provided with a carrier generator 1e for generating an upstream carrier, and the phase shift of the carrier from each carrier generator 1e is required. Therefore, the configuration of each node station 1 becomes complicated.

In addition, when installing the LAN system, it is necessary to consider the loss compensation of the cable 2, the loss compensation of the distributor 3, the impedance matching, etc., and the configuration of the entire system becomes complicated.

The present invention has been made in view of the above circumstances, and an object thereof is to adopt a token passing system and to simplify the configuration of a node / station and to simplify the configuration of the entire system. It is to provide a data communication network system capable of doing.

[0012]

According to the data communication network system of the present invention, a plurality of node stations are arranged such that the upstream input / output terminals of the lower node station are connected to the downstream input / output terminals of the upper node station. A token-passing data communication network is formed by connecting in series by connecting cables in sequence, and the carrier wave is generated to transmit the upstream carrier wave to the downstream input / output terminal of the node station at the bottom of this data communication network. And a frequency for converting the upstream carrier wave from the upstream side input / output terminal of the uppermost node station of the data communication network into a downstream carrier wave having a frequency different from that of the upstream carrier wave and returning it to the upstream side input / output terminal. A conversion repeater is provided so that each node / station is input to the downstream side input / output terminal. Amplify the signal and output it to the upstream input / output terminal, amplify the signal input to the upstream input / output terminal and output it to the downstream input / output terminal, and when the token is captured, the data for the desired node / station. Is characterized in that it is configured to perform the transmission of.

In this case, the power levels of the output signal and the input signal are compared in each node / station, and when the difference is less than a specified value, it is judged as a failure and the down side input / output terminal and the up side input / output terminal are judged. It is preferable that the two are short-circuited.

[0014]

According to the data communication network system of claim 1, when the token and the upstream carrier are given from the carrier generator to the lowest node station, the token and the upstream carrier are sequentially transmitted to the upper node station. To the frequency conversion repeater from the node station at the top stage.

The frequency conversion repeater converts the given upstream carrier into a downstream carrier having a frequency different from that of the carrier and returns the carrier together with the token to the uppermost node station.

After that, the token and the downlink carrier wave are transmitted from the node station at the uppermost stage toward the node station at the lowermost stage, but the node station having the transmission request receives the token and captures it. At that time, the transmission right is given, and the carrier wave for upstream is modulated with a digital signal indicating the address of the node station of the data transmission destination and the data to be transmitted and sent to the node station of the upper stage.

Therefore, as described above, the upstream modulated wave modulated by the digital signal is given to the frequency modulation repeater from the node station at the uppermost stage, is converted into the downlink modulated wave by the frequency conversion repeater, and is converted to the uppermost stage. Returned to the node station.

As a result, the downlink modulated wave is sequentially sent to the lower node station, and the addressed node station receives the address to demodulate the digital signal from the downlink modulated wave. You can read data.

The token and the upstream carrier wave transmitted from the carrier wave generator and the upstream modulated wave modulated by the digital signal at the node station are amplified each time they pass through each node station, and frequency conversion relay is performed. The token and downlink carrier wave returned from the device are amplified each time they pass through each node station.

According to another aspect of the data communication network system of the present invention, each node / station short-circuits the downstream side input / output terminal and the upstream side input / output terminal when a failure occurs in itself. Even with a configuration in which individual node stations are connected in cascade, there is no problem that the entire system does not function.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

First, the overall schematic structure will be described with reference to FIG.

A plurality of seven node stations 1
0a to 10g are connected in cascade by connecting each upstream input / output terminal 12 to the downstream input / output terminal 11 of the upper one by a cable 13, thereby configuring a LAN 14 as a data communication network. The downstream side input / output terminal 11 of the lowest node station 10a is connected to the input / output terminal 16 of the carrier wave generator 15 via a cable 17, and the upstream side input / output terminal 12 of the uppermost node station 10g is It is connected to the input / output terminal 19 of the frequency conversion repeater 18 via a cable 20.

In this case, the cables 13, 17 and 20
Consists of a 7C-2V or 5C-2V coaxial cable for general television, and each is set to a length of 300 m or less.

The carrier generator 15 is, for example, 58.75M.
A carrier wave for uplink of Hz is generated, and this carrier wave for uplink is transmitted via the input / output terminal 16 and the cable 17 to the downstream side input / output terminal 11 of the node station 10a at the lowest stage.
It is supposed to be transmitted to. The carrier wave generator 15 also has a function as a terminator.

The frequency conversion repeater 18 receives the upstream carrier from the node station 10g, for example, 38.9 MH.
It is adapted to be converted into a downlink carrier wave of z and returned to the upstream input / output terminal 12 of the uppermost node station 10g via the input / output terminal 19 and the cable 20.

Thus, the node stations 10a, 1
A personal computer 21, which is an information device, is connected to 0b, 10c, 10d, and 10g via an interface.

Now referring to FIGS. 2 and 3, the node stations 10a-10g will be described with the same construction.

That is, the data processing section 22 comprises a CPU 23 and a LAN control circuit 24, and the input / output port of the CPU 23 is connected to the personal computer 2 via an interface (eg RS232C or RS422) 25.
1 is connected to the input / output port. The input / output terminal of the LAN control circuit 24 is the high frequency modem circuit 2
6 are connected to the input / output terminals.

A DC power supply is supplied from a DC power supply circuit 27 to the data processing unit 22 and the high frequency modem circuit 26.

The high frequency modem circuit 26 is constructed as shown in FIG. That is, the high-pass filter 28, the amplifier 29, the modulator 30, the amplifier 31, and the high-pass filter 32 are connected in series between the down-side input / output terminal 11 and the up-side input / output terminal 12, and the modulation is performed. The signal input terminal of the container 30 is L
It is connected to the output terminal of the AN control circuit 24. Further, a low pass filter 33, an amplifier 34, an impedance converter 35 and a low pass filter 36 are connected in series between the upstream side input / output terminal 12 and the downstream side input / output terminal 11, and the amplifier 34 and the impedance are connected. An input terminal of the demodulator 37 is connected to a common connection point with the converter 35, and an output terminal of the demodulator 37 is connected to an input terminal of the LAN control circuit 24.

Further, the input terminal of the amplifier 29 and the amplifier 31
A level attenuation detection circuit 38 is connected between the input terminal of the amplifier 34 and the output terminal of the impedance converter 35.

The level attenuation detection circuit 38 is provided in the amplifier 3
The power level difference between the output signal of No. 1 and the input signal of the amplifier 29 is detected. When the detected power level difference is less than or equal to a specified value, it is determined that a failure has occurred and a failure detection signal is output from the output terminal. Output and relay switch 38a
Is turned on to short-circuit the downstream side input / output terminal 11 and the upstream side input / output terminal 12.

Further, the level attenuation detection circuit 38 is adapted to detect the power level difference between the output signal of the impedance converter 35 and the input signal of the amplifier 34, and when the detected power level difference is less than a specified value. Similarly, it is determined that a failure has occurred, a failure detection signal is output from the output terminal, and the relay switch 38a is turned on.

A failure detection signal generator 39 is connected to the upstream side input / output terminal 12, and the failure detection signal generator 39 has positive (+) and negative (-) as failure detection signals, as will be described later. ) Is output and transmitted to the upper node station (10b, 10c, 10d, 10e, 10f or 10g) via the upstream side input / output terminal 12 and the cable 13. The input terminal of the failure detection signal generator 39 is connected to the output terminal of the level attenuation detection circuit 38.

Thus, the failure detection signal generator 39 always outputs a negative (-) DC signal to the signal line (core wire) of the cable 13 connected to the upstream input / output terminal 12. When a failure detection signal is given from the level attenuation detection circuit 38 to which it belongs, a positive (+) DC signal is output to the signal line of the cable 13 via the upstream side input / output terminal 12.

The failure detector 4 is connected to the downstream side input / output terminal 11.
0 is connected to the failure detector 40, and the failure detector 40 includes node stations (10a, 10b, 10c, 10d,
The DC signal from 10e or 10f) is detected.

That is, when the failure detector 40 does not detect a negative (-) DC signal (when there is no voltage), the cable 13 connected to the downstream side input / output terminal 11 is disconnected. If the positive (+) DC signal is detected, it is determined that the node station in the lower stage than itself is in failure, and the disconnection alarm 40a is operated. The alarm 40b is operated.

Next, the operation of this embodiment will be described.

The carrier wave generator 15 is always 58.75M.
An uplink carrier wave of Hz is generated and transmitted to the downlink side input / output terminal 11 of the lowest node station 10a, and this uplink carrier wave is periodically phase-modulated by a token.

The upstream carrier including the token is transmitted from the lowest node station 10a to the highest node station 10g, and each node station 10a, 10b, 10c, 10d, 10e, 10f.
And amplifiers 28 and 31 respectively when passing 10 and 10 g
Will be amplified by. The amplifiers 28 and 31
Has an amplitude control high-gain amplification function capable of compensating for a transmission line loss of 900 m or more in total length of the cable 13.

In the example of FIG. 1, node station 10
Although the transmission line between d and 10g is about 900 m and can sufficiently compensate the transmission line loss, node stations 10e and 10f to which a personal computer as an information device is not connected between them. Are connected to the node stations 10e, 10
f acts as a relay amplifier having only an amplifying function for compensating the transmission line loss when the node station 10d or 10g fails.

Then, the node station 1 at the top level
The carrier for the uplink including the token from 0g is the cable 20.
To the frequency conversion repeater 18 where the upstream carrier is converted to a 38.9 MHz downstream carrier and returned to the uppermost node station 10g.

This downlink carrier wave is transmitted from the uppermost node station 10g to the lowermost node station 1.
0a, but each node station 1
0g, 10f, 10e, 10d, 10c, 10b and 1
It is amplified by each amplifier 34 as it passes through 0a. In this case, the amplifier 34 includes the amplifiers 28 and 31.
It is set to perform amplification similar to.

Thus, the node stations 10a to 10g are always in a reception standby state, and the demodulators 37 are in a state capable of receiving and demodulating the downlink carrier wave. As a result, when the node station having a transmission request, for example, the lowest node station 10a demodulates and receives and captures the token from the downlink carrier, the CPU 23 of the node station 10a sends the destination node station, for example, the middle stage. A packetized digital signal including the address of the node station 10d, data to be transmitted, etc. is applied to the signal input terminal of the modulator 30 via the LAN control circuit 24.

When the token is captured by the node station 10a, the token disappears.

The modulator 30 two-phase phase-modulates the upstream carrier wave from the amplifier 29 given to the carrier wave input terminal with a digital signal, and transmits the modulated upstream carrier wave to the upper node station 10b. .. Hereafter, this upstream modulated wave is the same as the above-mentioned one.
It is transmitted to the station 10g and given to the frequency conversion repeater 18 from the node station 10g.

Since the frequency conversion repeater 18 converts the upstream carrier into the downstream carrier of 38.9 MHz, the above-mentioned upstream modulated wave is converted into the downstream modulated wave by the downstream carrier, and the uppermost node Returned to station 10g.

The downlink modulation wave returned to the uppermost node station 10g is the node station 10g.
Sequentially transmitted to f, 10e and 10d, the node station 10d operates as follows.

That is, when the demodulator 37 demodulates the address from the downlink modulation wave and receives it, the node station 10d receives the data from the downlink modulation wave because this address is its own. Then, the data thus received is transmitted to the personal computer 21 via the CPU 23 and the interface 25.

The node station 10 as described above
When the transmission / reception of data between a and 10b is completed, the carrier wave generator 15 again modulates the upstream carrier wave with the token.

Incidentally, the node stations 10a to 10
If a failure occurs in the amplifier 29, 31 or the modulator 30 in any of g, the amplifier 29, 3
Since the amplification function of No. 1 or the signal transmission function of the modulator 30 disappears, the power level difference between the output signal of the amplifier 31 and the input signal of the amplifier 29 becomes less than the specified value, and therefore the level attenuation detection circuit 38. Detects this, outputs a failure detection signal, and relay switch 38a.
Turn on.

As a result, when the relay switch 38a is turned on, the down side input / output terminal 11 and the up side input / output terminal 12 are
A signal will pass through the faulty node station as a result of a short circuit between.

Similarly, when a failure occurs in the amplifier 34 or the impedance converter 35 in any of the node stations 10a to 10g, the amplification function of the amplifier 34 or the impedance converter 35.
Since the signal transmission function of is lost, the power level difference between the output signal of the impedance converter 35 and the input signal of the amplifier 34 becomes a specified value or less, and the level attenuation detection circuit 38 detects this, The failure detection signal is output and the relay switch 38a is turned on.
Therefore, the signal will pass through the failed node station.

In any case, when the relay switch 38a is turned on by the level attenuation detection circuit 38, the failure detection signal from the level attenuation detection circuit 38 is given to the failure detection signal generator 39, so that the failure occurs. The detection signal generator 39 transmits a positive (+) DC signal to the upper node station via the upstream input / output terminal 12 and the cable 13. As a result, the failure detector 40 in the upper node station detects the positive (+) direct current signal and operates the node failure alarm 40b, so that the lower node station fails. The fact that this has been done is reported at the upper node station.

Further, each node station 10b to 1
At 0 g, the failure detector 40 detects the negative (-) DC signal from the lower node stations 10a to 10f, so that the node stations 10b to 10f are detected.
When the cable 13 connected to one of the downstream side input / output terminals 11 of g is disconnected, the failure detector 40 no longer detects the DC signal and operates the disconnection annunciator 40a.

As described above, according to this embodiment, the LAN 1
4, the token and the upstream carrier are transmitted from the carrier wave generator 15 to the lowest node station 10a, and the frequency conversion repeater 18 is transmitted to the highest node station 10g.
Therefore, the upstream carrier is converted into a downstream carrier having a frequency different from that of the upstream carrier and returned.

Therefore, unlike the prior art, it is not necessary to provide a carrier wave generator in each of the node stations 10a to 10g, and the phase shift of each carrier wave is considered in each of the node stations 10a to 10g as in the prior art. The need is eliminated and the construction of each node station 10a-10g can be simplified.

Further, since the LAN 14 can be constructed by simply connecting the node stations 10a to 10g in series, the construction is simple, the installation work cost is low, and the node
The addition of stations is extremely easy because it only has to be installed at a desired position on the LAN 14 using a cable.

Further, each of the node stations 10a to 1
Since 0 g is provided with upstream amplifiers 28 and 31 and downstream amplifier 34, respectively, the power level of the signal can be maintained within a predetermined range, reliable data communication can be performed, and the node The station can also be used as an amplification repeater.

Moreover, in any of the node stations 10a to 10g, the amplifiers 29, 31, 34,
When the modulator 30 or the impedance converter 35 fails, the level attenuation detection circuit 38 detects it and short-circuits the down side input / output terminal 11 and the up side input / output terminal 12 by the relay switch 38a. Therefore, the signal passes through the faulty node station, so that the communication function is not hindered even in the system having the cascade connection configuration of the node stations 10a to 10g.

In this case, when a node station fails, a positive (+) DC signal is transmitted from the failure detection signal generator 39 of the node station to the upper node station. The failure detector 40 detects this, and the node failure alarm 40
b, so that no node
It is possible to identify whether the station has failed, and to quickly repair or replace the failed node station.

Since the amplifiers 29, 31 and 34 of the respective node stations 10a to 10g have an amplifying function of compensating for the transmission line loss of about 900m,
Even if two adjacent node stations fail, data communication will not be hindered.

Furthermore, when the cable 13 connecting between the node stations 10a to 10g is broken,
Since the failure detector 40 of the upper node station 10b to 10g detects this and operates the disconnection alarm 40a, it is possible to know which node station the disconnection alarm 40a is operating. It is possible to identify which cable is broken, and it is possible to quickly repair or replace the cable.

In the above embodiment, the carrier wave generator 1
5, the failure detection signal generator 39 is connected to the input / output terminal 16 and the failure detector 40 is connected to the input / output terminal 19 of the frequency conversion repeater 18, so that the carrier wave generator 15 and the node station at the lowermost stage are connected. Detection of disconnection of the cable 17 connecting between the cable 10 and 10a and the cable 20 connecting between the uppermost node station 10g and the frequency conversion repeater 18, and failure detection of the carrier generator 15 and the uppermost node station 10g. May be configured to perform.

In addition, the present invention is not limited to the above-mentioned embodiment, and for example, a sequencer may be used as the information device connected to the node station via the interface, etc. within the scope of the invention. Of course, it can be appropriately modified and implemented.

[0067]

Since the present invention is as described above, it has the following effects.

According to the data communication network system of the first aspect, a plurality of node stations are connected in cascade by a cable to form a token passing type data communication network, and the node station at the lowest stage is used for upstream communication. Since a carrier generator for transmitting a carrier wave is provided, and a frequency conversion repeater for converting an upstream carrier wave into a downstream carrier wave having a different frequency from the upstream carrier wave and returning the converted carrier wave, the node station The configuration can be simplified, and the configuration of the entire system can be simplified, so that the system can be inexpensively installed as a whole.

According to the data communication network system of the second aspect, each node / station is provided with a function of detecting its failure and short-circuiting between the upstream side input / output terminal and the downstream side input / output terminal. Even if one of the node stations fails, it does not hinder the communication function of the entire system.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing the configuration of a node station.

FIG. 3 is a block diagram showing a configuration of a high frequency modem circuit.

FIG. 4 is a block diagram showing an overall configuration of a conventional example.

FIG. 5 is a block diagram showing the configuration of a node station.

[Explanation of symbols]

In the drawing, 10a to 10g are node stations, 1
1 is a down side input / output terminal, 12 is an up side input / output terminal, 13
Is a cable, 14 is a LAN (data communication network), 15 is a carrier wave generator, 18 is a frequency conversion repeater,
Reference numeral 21 is a personal computer (information device), 22 is a data processing unit, 24 is a high frequency modem circuit, and 38 is a level attenuation detection circuit.

Claims (2)

[Claims] 1. A structure in which a plurality of node stations are connected in cascade by sequentially connecting the upstream input / output terminals of the lower node station to the downstream input / output terminals of the upper node station with a cable. A token passing data communication network, a carrier wave generator for transmitting an up carrier wave to a downstream side input / output terminal of a node station at the bottom of the data communication network, and a node at the top of the data communication network. A frequency conversion repeater for converting the upstream carrier from the upstream input / output terminal of the station into a downstream carrier having a different frequency from the upstream carrier and returning it to the upstream input / output terminal; , The signal input to the down side input / output terminal is amplified and output to the up side input / output terminal,
It is configured to amplify a signal input to the upstream side input / output terminal and output it to the downstream side input / output terminal, and to transmit data to a desired node station when a token is captured. Data communication network system. 2. Each node station compares the power levels of an output signal and an input signal, and when the difference is less than or equal to a specified value, it judges that there is a failure and between the down side input / output terminal and the up side input / output terminal. The data communication network system according to claim 1, wherein the data communication network system is configured to short-circuit.