JP3373759B2 - Optical communication method, optical repeater, and optical communication system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical communication system, and more particularly to a bus state matching system for connecting two electric buses in a network with an optical fiber.

[0002]

2. Description of the Related Art Since an industrial field LAN is installed in a field environment, it is easily affected by electromagnetic noise from power cables and lightning strikes. Therefore, replace it with an electric cable,
By using an optical fiber as a noise resistant transmission medium, the power cable and the control LAN can be embedded in the same side groove. However, since optical transmission equipment is generally more expensive than electrical transmission equipment, if the whole is connected by an optical fiber, the system cost will increase. On the other hand, the places where optical transmission equipment must be used often have a limited environment within the system, so if the locations where expensive optical transmission equipment is used can be limited, it is possible to suppress system cost increases. it can.

In response to this demand, a part of the electric bus is replaced with an optical fiber, and both ends of the optical fiber are connected to the electric bus via a photoelectric conversion device. For example, a program controller (Hitachi, Ltd.) S10 / 2α)
The optical link device (LWZ440) has been put to practical use.

Controller S10 / 2α and LWZ440
In the system using, the control LAN master is limited to one controller, and therefore the signal flowing to the control LAN is either master → slave or slave → master. Therefore, the LWZ 440 implements data transfer between the master and slave of data by switching the transmission direction in units of one packet transfer.

A conventional control system in which a part of an electric bus is replaced with an optical fiber is composed of one master which gives an instruction to a control LAN and a plurality of slaves which operate in response to the instruction. The reason for this is that if there are multiple masters, control data (instruction) is output to the control LAN at the same time, so that the control LAN itself needs an arbitration function, and it becomes difficult to guarantee real-time property of exchanging data in a fixed cycle. Because.

However, when the master is one controller,
If the controller fails, manual operation from the operation panel becomes impossible. Therefore, it is necessary to have a separate instruction system for stopping the entire system in an emergency.

To solve this problem, the control LAN
A multi-master system is required in which multiple nodes connected to can become masters. One of the transfer methods compatible with this multi-master is the ISO11898 standard.

According to the transmission method of the ISO11898 standard, as disclosed in Japanese Patent Laid-Open No. 6-236333, a plurality of nodes are connected by a bus-like serial line and at the same time data is output from a plurality of nodes to a LAN. It is possible. Further, according to this standard, data is transferred by each node repeating data output to the serial line and detection of the bus state bit by bit. Also, each node drives the bus when outputting a logical 0 to the serial line, and outputs a logical 1
When data is output, data is transferred bit by bit by a method in which the bus is not driven, and even if one node outputs a logic 0, the bus becomes a logic 0 state.

Therefore, each node detects the bus state after outputting the data. At this time, the value output to the bus is compared with the state of the bus, and if a mismatch occurs, the node stops outputting data, and the nodes continue to interrupt packet transmission, and arbitration Done.

[0010]

Unlike the conventional single master system, a system using the ISO11898 standard needs to match all bus states during transfer of one bit. Therefore, the above optical link device (LW
In the method of switching the transmission direction by the optical fiber in units of one packet like Z440), the states of the electric buses at both ends of the optical fiber cannot be matched.

Therefore, let us consider transmitting the state of one electric bus to the drive state of the other electric bus via an optical fiber. The optical bus bridge device attached to both ends of the optical fiber observes the state of the electric bus connected to itself and outputs light when confirming that it is being driven, and the other optical bus via the optical fiber. Tell the bridge device. The other optical bus bridge device drives the electrical bus upon detecting the optical input from the optical fiber. As a result, the drive state of one electric bus can be transmitted to the other electric bus via the optical fiber.

However, in order to enable multi-master, if the optical link device uses two optical fibers to bidirectionally transmit and respond to the bus state, an optical loop is formed by the two optical link devices and the optical fibers. There is a possibility that it will be carried out, and as described below, a “deadlock state” or a “stabbed condition” will occur, making correct matching impossible.

FIG. 17 shows a problem caused by the bidirectional optical link device. This system drives the electric buses a and b to which the node 1 and the node 2 are connected, respectively.
Further, the optical link devices a and b are connected to both ends of the optical fiber, the optical link device a is connected to the bus a, and the optical link device b is connected to the bus b. The optical link devices a and b output light to the optical fiber when the electric bus to which they are connected are in a drive state, and conversely, when the light is input from the optical fiber, the electric bus to which they are connected. drive.

(1) As an initial state, it is assumed that the two electric buses a and b are not driven. At this time,
Since the optical link devices a and b are not driven by the buses a and b, there is no optical output to the optical fiber, which is a stable state.

(2) In this state, the node 1 connected to the bus a drives the bus a.

(3) When detecting that the bus a has been driven, the optical link device a outputs light to the optical fiber.
In response to this, the optical link device b starts driving to the bus b.

(4) The optical link device b puts the bus b in the drive state, the node 2 detects that the bus b is in the drive state, and the bus b is in the drive state. Provides optical output to the fiber. As a result, the optical link device a starts driving to the bus a.

(5) Next, the node 1 stops driving to the bus a. However, since the optical link device a drives the bus a, the bus a remains in the drive state, and both the buses a and b are stabilized in the drive state.
In this way, since a large one latch loop is formed by the two optical fibers and the optical link device, the bus a,
b remains stable in the drive state and falls into the so-called "deadlock state".

When the two electric buses a and b are both driven to the ON state during one transfer cycle, the optical link devices a and b respectively have their own buses turned on. Each other trying to turn on the side bus,
It is in a "stabbed condition" where light is output to the optical fiber. In this "stabbed condition", the bus drive signals from the optical link devices a and b move back and forth between the buses, so that the bus a and the bus b enter an oscillating state in which the ON / OFF state is repeated.

An object of the present invention is to overcome the problems of the prior art described above, to correctly match the drive states of two electric buses connected by an optical fiber, and to enable a plurality of nodes to drive the bus at the same time. An object is to provide a communication method, an optical repeater, and an optical communication system.

[0021]

SUMMARY OF THE INVENTION The present invention is a bus system for relaying two electric buses with an optical fiber, and by separating the state of optical output to an optical fiber and the state of electric output to an electric bus, This prevents the formation of the above-mentioned optical loop.

The above object is to provide an optical communication method in which the bus states of two electric buses relayed by an optical fiber are made to coincide with each other, and the electric buses are not driven (OFF state).
At the time of, the bus state and the state of the optical fiber are observed, and while one or both of the electric buses are bus-driven (ON state) from the node connected to each of them and continue the bus drive, The optical output is continuously output to the optical fiber from the input side, and while the optical input from the optical fiber is continued, the bus state is not observed, and the electrical output is output to the electrical bus on the input side. Then, when the bus drive from the node is stopped,
This is accomplished by turning off the light output and the electrical output and leaving the electrical bus non-driven. This allows
The deadlock state described above can be reliably avoided.

Further, when stopping the electric output and shifting to the non-drive, a state is set in which the electric bus is not observed for a preset fixed period. As a result, even if the optical bus bridge device stops driving to the electric bus, the state of the electric bus changes from ON to OF.
It is possible to prevent a transitional change to F, mistaking the transitional ON state as a bus drive, and prevent malfunction. The certain period is a transitional period or more.

Further, when both of the electric buses are bus-driven from the respective nodes and optical output is simultaneously made from the both sides to the optical fiber, one side stops the optical output and performs only the electric output. It is characterized by As a result, the above-mentioned “stabbed condition” can be resolved.

An optical repeater (optical bus bridge device) for realizing the optical communication method of the present invention is provided between an optical fiber connecting the two electric buses and the electric bus, and sets the bus states of both electric buses. A device for matching, a standby mode for observing a bus state and a state of an optical fiber when the electric bus is not driven (OFF state), and a bus drive (ON state) from a node connected to the electric bus. The optical output mode in which the standby mode is changed to output light to the optical fiber, the bus drive mode in which electric power is output to the electric bus on its own side when light is input from the optical fiber, and the node Non-observation mode in which the bus state is not observed for a certain period when the bus drive mode is changed to the standby mode when the bus drive is stopped. Means for performing is provided, and switches the modes according to the bus state.

Further, both electric buses are bus-driven from the respective nodes, and when two optical bus bridge devices provided on both sides of the optical fiber are simultaneously switched to the optical output mode, one of them is driven by the bus drive. A mode transition signal setting means for making a transition to a mode is provided.

Further, an optical communication system to which the optical repeater of the present invention is applied, has an electric bus having an electrically binary state, a plurality of nodes for outputting binary data to the electric bus, and an electric signal. A system comprising: an optical repeater having means for converting an optical signal and means for converting an optical signal into an electric signal; and an optical fiber for connecting the two electric buses via the optical repeater, the system comprising: The optical fiber has two optical fibers for the optical repeater to separately perform optical output and optical input for bidirectionally transmitting the bus state of the electric bus, and the optical repeater includes the electric bus. The ON / OFF state of and the presence / absence of the optical input from the optical fiber, and when the electric bus is in the ON state, the optical output is performed to the optical fiber, and when the optical input from the optical fiber is present. Electricity output to your own electric bus And a mode switching function of stopping one optical output and performing only the electric output when two optical fibers simultaneously output the optical output to generate an optical loop state, and In addition, when the electric bus is driven according to ON / OFF of each 1-bit data from the node, the drive state of both electric buses is passed through the optical fiber and the optical repeaters on both sides thereof. Are matched, and each node samples the electric bus after the matching.

Further, when the data is simultaneously output to the electric bus from a plurality of the nodes, the state of the bus is always decided to one state of priority, and each node outputs the data to the electric bus by itself. It is characterized in that the state is compared with the state of the electric bus to decide whether or not to continue the data output to the electric bus thereafter.

FIG. 18 illustrates a process of matching the drive states of the electric buses according to the present invention.

(1) As an initial state, two electric buses a,
Assume that b is not driven together. At this time, the optical bus bridge devices a and b are both in the standby mode.

(2) Next, the node 1 connected to the bus a drives the bus a.

(3) The optical bus bridge device a detects that the bus a has been driven, makes a transition from the standby mode to the optical output mode, and outputs light to the optical fiber. In response to this, the optical bus bridge device b transits from the standby mode to the bus drive mode and starts driving to the bus b. Bus observation is not performed in bus drive mode.

(4) As a result, the bus b is brought into the drive state, and the states of both buses a and b are made coincident. Node 2
Takes in the drive state of the bus b and completes the transmission of 1 bit from the node 1 to the node 2.

(5) Next, the node 1 stops driving to the bus a. As a result, the optical bus bridge device a transits from the optical output mode to the standby mode and stops the optical output to the optical fiber. In response to this, the optical bus bridge device b
Transits from the bus drive mode to the standby mode.

As described above, one of the optical bus bridge devices transits to the optical output state and the other transits to the bus drive state, whereby the "deadlock state" due to the formation of the optical loop can be avoided.

Further, in the above (5), when the optical bus bridge device b transits from the bus drive mode to the standby mode, it goes through the non-observation mode for a certain period. As a result, malfunction of the optical bus bridge device can be prevented.

Further, when two optical bus bridge devices simultaneously enter the optical output mode, the device side to which the mode transition signal (MODE) is set in advance switches the mode from the optical output mode to the bus drive mode. I do.

Actually, since the bus drive performed by each node in accordance with the ISO11898 standard is every 1-bit transfer period, it is not necessary for both of the two optical bus bridge devices to be in the optical output mode, and only one is in the optical output mode. Is enough.

[0039]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the configuration of an optical communication system according to an embodiment of the present invention. The two electric buses A and B connecting the nodes 30 are respectively the optical bus bridge device 1
Optical fibers 50 are connected via 0a and 10b to form a network. As will be described later, the optical bus bridge device 10 is the core part of the present invention.

The bus A system 1a is composed of an optical bus bridge device 10a and nodes 30a and 30b electrically connected by an electric bus A20a (hereinafter referred to as bus 20a). Similarly for the bus B system 1b, the electric bus B20
The optical bus bridge device 10b and the nodes 30c and 30d are electrically connected to b (hereinafter referred to as the bus 20b). The optical fiber 50 is the optical bus bridge device 10.
It is composed of two optical fibers that transmit the optical output of a to the optical bus bridge device 10b and an optical fiber that transmits the optical output of the optical bus bridge device 10b to the optical bus bridge device 10a.

Each of the nodes 30 repeatedly performs a 1-bit data transfer to the bus and a bus state detection called a transfer cycle, in accordance with the ISO 11898 standard protocol. Therefore, the output of a node 30 is
It has to reach all the nodes 30 before the sampling point SP that detects the bus state at the end of the transfer cycle.

In order to realize this, the optical bus bridge device 10 responds to the standby mode for detecting the bus state during the transfer cycle, the optical output mode for transmitting the drive state of the own bus to the other side, and the optical input. While switching the non-observation mode in which the bus state is not observed only for a certain period of time, passing through the bus drive mode that drives the bus on your side, the transition from the bus drive mode to the standby mode,
Correctly match the states of the buses 10a and 10b.

Here, the description will be made in accordance with the operation of the system in which the bus 20a is driven from the standby mode in which neither the bus 20a nor the bus 20b is driven, the drive is stopped in the next transfer cycle, and the mode is returned to the standby mode again. To do.

The node 30a or the node 30b is the bus 2
When 0a is driven, the optical bus bridge device 10a switches to an optical output mode in which the drive state of the bus 20a is transmitted to the B system on the other side, and optical output is performed to the optical fiber 50 as a drive request. On the other hand, B-type optical bus bridge device 1
0b receives the drive request from the A system via the optical fiber 50, and changes the state of the bus 20a to that of the own bus 20a.
Switch to the bus drive mode that tells b
Start driving to b. As a result, the bus 20a and the bus 20b are brought into the same drive state, and the node 30
c and 30d can detect that the bus 20b is in a drive state. That is, 1-bit data (ON) is transferred from the A system to the B system.

When the drive to the bus 20a is stopped in the next transfer cycle, the optical bus bridge device 10a switches to the standby mode and stops the optical output to the optical fiber 50. The optical bus bridge device 10b stops the drive to the bus 20b because there is no bus drive request from the A system. At this time, the optical bus bridge device 10b immediately switches from the bus drive mode to the standby mode and the bus 2
When the observation of 0b is started, since the bus 20b is still in an electrical transition period driven by the optical bus bridge device 10b, the optical bus bridge device 10b misunderstands that the bus 20b has been driven, and the optical output malfunctions. Will do.

Therefore, the optical bus bridge device 10b shifts to the non-observation mode in which the observation of the bus 20b is stopped for a certain period of time before shifting to the standby mode, and after a certain period of time, the bus 20b stabilizes from the ON state to the OFF state. Then, it shifts to the standby mode and restarts the observation of the bus 20b. As a result, both buses 20a and 20b are in the non-drive state.

If the bus 20b is in the drive state when the observation is restarted after a certain time has passed, the node 30c or the node 3 connected to the bus 20b is connected.
It is recognized that 0d is the result of driving, and the optical bus bridge device 10b transitions to the optical output mode and starts optical output to the optical fiber 50. In response to this, the optical bus bridge device 10a drives the bus 20a.

FIG. 2 shows the configuration of the optical bus bridge device. The optical bus bridge device 10 has the same configuration for the A system and the B system, and therefore will be described below without distinction between the systems. Also,
If necessary, the reference numeral of the corresponding signal line is added in parentheses after the signal name.

The optical bus bridge device 10 has a bus driver circuit 11 for driving the bus 20 and detecting the state, and converts an electric signal into light and outputs the light to the optical fiber 50.
The operation mode conversion device 12 includes a photoelectric converter 13 that converts an optical input from the optical fiber 50 into an electric signal.

The bus driver circuit 11 and the operation mode converter 12 have the signal line 131 for the signal RxD_N and the signal Tx.
In the signal line 134 of D_N, the operation mode converter 1
2 and the photoelectric converter 13 are connected to the DOUT signal line 132 and DI.
N signal lines 133 are connected to each other.

FIG. 3 shows a schematic diagram of the bus driver circuit. The bus driver circuit 11 includes a receiver 1101 that detects the state of the bus 20 and a transmitter 1102 that drives the bus 20. The bus 20 is composed of two signal lines 31 and 32 for transmitting the signals BUSH and BUSL. Both BUSH (31) and BUSL (32) are the output of the transmitter 1102 and the input of the receiver 1101.

FIG. 4 shows the operation of the transmitter and the receiver and the packet structure. The same figure (a)
Is the operation of the transmitter 1102, and the input signal Tx
If the value of D_N (134) is ON (0), BUSH (31),
BUSL (32) is a predetermined voltage Vonh, Vo, respectively.
It changes to nl and the bus 20 is turned on. On the other hand, Tx
If the value of D_N is OFF (1), the transmitter 11
02 does not drive the bus 20, BUSH and BUSL both become the predetermined voltage Voff, and the bus 20 is OF
It becomes the F state.

FIG. 4B shows the operation of the receiver 1101. If the potential difference Vdf between BUSH (31) and BUSL (32) is larger than the threshold value Vth, the receiver 1101 determines that the bus 20 is in the ON state, and RxD_N of the signal line 131 is determined.
Is turned on (0). On the contrary, if the potential difference Vdf is smaller than the threshold value Vth, the receiver 1101 determines that the bus 20 is in the OFF state, and sets RxD_N (131) to OFF (1).
Let

In the bus driver circuit 11, inputs of the transmitter 1102 and the receiver 1101 are BUSH.
Since it is connected to (31) via BUSL (32), when the input TxD_N (134) of the transmitter 1102 is turned on, the potential difference Vdf between BUSH (31) and BUSL (32) becomes larger than the threshold value Vth. The output RxD_N (131) of the receiver 1101 is turned on.

For example, Vonh = 3.5 (v), Vonl
= 1.5 (v), Voff = 2.5 (v), Vth = 0.
8 (v). When the transmitter 1102 drives the bus to the ON state, the potential difference V between BUSH and BUSL
df becomes Vonh-Vonl = 2.0 (v). Vof
Since f ≧ Vth, the receiver 1101 detects the ON state of the bus 20. If the transmitter 1102 does not drive and the bus 20 is off, the BUS
The potential difference Vdf between H and BUSL is 0 (v), Voff <Vt
Therefore, the receiver 1101 detects the OFF state of the bus 20.

A plurality of nodes 3 connected to the bus 20
0 includes a bus driver circuit (not shown) similar to the bus driver circuit 11. The bus driver circuit of each node 30 can drive the bus 20 at the same time. If there is at least one node 30 that drives the bus 20 (ON state), a potential difference occurs between BUSH (31) and BUSL (32), and the bus is turned on. At this time, the other nodes 30 that did not drive in an attempt to turn off the bus 20 also detect that the bus 20 is on.

Due to this characteristic, the packet in the ISO11898 standard has a header 70 as shown in FIG.
01, a data body 7002, and a tail 7003. The node 30 compares its output with the bus state bit by bit during the transfer of the header 7001 and performs an arbitration process of stopping the packet transfer if different. Therefore, at the stage of starting the transfer of the data body 7002, only one node is transferring data to the bus.

FIG. 5 shows a schematic diagram of the photoelectric converter. The photoelectric converter 13 is an optical / electrical converter O / that converts light into electricity.
E1301 and electric / optical converter E for converting electricity into light
/ O1302. In the figure, DIN (1
33) is an electrical control signal for turning on / off the optical output, D
OUT (132) is the input TxD_ of the transmitter 1102.
It is an electrical control signal for turning ON / OFF the N (134).

FIG. 6 shows an explanatory diagram of the operation of the photoelectric converter. The optical / electrical converter O / E 1301 has an electrical output DOUT (1) when there is no optical input through the optical fiber 50, that is, when the OIN (1311) is OFF, as shown in FIG.
32) is OFF (0), and when OIN (1311) is ON, DOUT (132) is ON (1).

The electric / optical converter E / O 1302 has the electric input DIN (133) turned off as shown in FIG.
When (0), the optical output OOUT (1312) is turned off and optical output is not performed, and when DIN (133) is ON (1), OOUT is output.
(1312) is turned on (1) to output light to the optical fiber 50.

FIG. 7 shows a schematic diagram of the operation mode conversion device. The operation mode conversion device 12 includes the operation mode conversion circuit 1
21 and the condition setting device 122. The operation mode conversion circuit 121 includes a mode switching circuit 200, a synchronization circuit 300, and a timer device 400.

The synchronization circuit 300 includes the bus driver circuit 1
The output RxD_N (131) of the receiver 1101 and the output DOUT (132) of the optical / electrical converter 1301 are input and synchronized with the clock of the mode switching circuit 200, RxD_N is SRxD (141), and DOUT is SDOUT (142). And output to the mode switching circuit 200, respectively.

The mode switching circuit 200 has SRxD (14
1), SDOUT (142), time-up signal CNT_UP (144) from timer device 400, and condition setting device 122
Input the mode transition setting signal MODE (151) from
Input DIN (133) of the electro-optical converter 1302, input TxD_N (134) of the transmitter 1102, timer device 4
The timer operation request CNT_ENB (143) to 00 is output.

The timer device 400 uses the timer operation request CN.
When T_ENB is received and the timer count number CNT (152) set from the condition setting device 122 is counted,
A time-up signal CNT_UP is sent to the mode switching circuit 200.
Outputs (144).

FIG. 8 shows the structure of the synchronizing circuit. The synchronization circuit 300 includes a NOT circuit 3011 and a mode switching circuit 2
It is composed of four latches 3001 to 3004 which take in data in synchronization with the clock 00.

RxD_N which is the input of the synchronization circuit 300
(131) and DOUT (132) change asynchronously with the clock of the mode switching circuit 200. So RxD_N and DOU
T is a latch 3001, 3002 and a latch 3003, 3
Signals SRxD (141) and SDOUT (142) synchronized with the clock of the mode switching circuit 200 through the two-stage latch 004.
Is converted to. Since RxD_N is a negative logic signal, after being converted into a positive logic signal by the NOT circuit 3011,
It is input to the latch 3001.

FIG. 9 shows the configuration of the timer device. The timer device 400 is composed of a selector 4012, a 4-bit decrementer 4001, and a latch 4011. The selector 4012 selects the output of the latch 4011 when the input of the timer operation request CNT_ENB (144) is ON (1), selects the input of the timer count number (152) when CNT_ENB is OFF (0), and selects 4 bits. Decrementer 40
Output to 01. The 4-bit decrementer 4001 outputs a value obtained by subtracting 1 from the output (4021) of the selector 4012 (4
022) is output to the latch 4011. When the input (4021) of the 4-bit decrementer 4001 is 0, CN
It outputs 1 to T_UP (143) and outputs 0 to CNT_UP (143) when the input (4021) is not 0.

FIG. 10 shows a truth table of the 4-bit decrementer. The timer device 500 includes the mode switching circuit 200.
When the operation request CNT_ENB (144) from is OFF,
Since the selector 4021 selects the timer count number,
A value obtained by subtracting 1 from the timer count number CNT is latched in the latch 4011. Next, when CNT_ENB (144) is turned on, the selector 4021 selects the output of the latch 4011, so that the value held in the latch 4011 is decreased by 1 each time the clock rises. When this hold value, that is, the output (4021) of the latch 4011 becomes 0,
Output 1 to CNT_UP (143).

As described above, the timer device 500 outputs the time-up signal CNT_UP when counting the clocks by the timer count number CNT after the operation request signal CNT_ENB is turned on. The count period of the count number CNT becomes a period of a non-observation mode described later.

FIG. 11 is a schematic diagram of the condition setting device.
The condition setting device 122 is a 5-bit setting switch 122.
It is composed of 1 and pull-up resistor 1222, and outputs 0 to the signal line whose contact is closed and 1 to the signal line which is opened for each bit. Of the 5 bit output, 1 bit by one signal line 151 is the mode transition setting signal MO.
DE, 4 bits by four signal lines 152 output the timer count number CNT. MODE = 0, as described below
The optical bus bridge device 10 in which is set changes its mode to the bus drive mode when the optical output mode competes with others.

Next, the operation mode conversion circuit 121 will be described. As described above, the bus 20 connected by the optical fiber 50
In order to correctly match the bus states of a and the bus 20b in both directions, the operation mode conversion circuit 121 determines the bus state on its own side, the optical input state from the optical fiber, etc., and the mode switching circuit 200 switches the mode. Each unit of the optical bus bridge device 10 performs a corresponding operation according to the mode.

12 and 13 are explanatory views showing the mode switching operation of the operation mode converter. Both figures
(A) shows the state transition diagram by mode switching, optical output,
Standby mode Q0 that does not perform both bus drives, bus drive mode Q1 that only drives the bus, optical output mode Q2 that only performs optical output, and non-passing when transiting from the bus drive mode Q1 to the standby mode Q0. Observation mode Q3.

FIG. 12 shows the mode transition setting signal MODE (1
Under the condition of 51) = 1, the transition from the optical output mode Q2 to the bus drive mode Q1 is not performed. The output of the mode switching circuit 200 is shown in FIG.

First, the operation state of the standby mode Q0 will be described. In mode Q0, the bus 20 that is the input of the optical bus ridge device 10 is in the OFF state, and the optical input OIN (1311) to the photoelectric converter 13 is OFF, so the synchronization circuit 3
The outputs SRxD (141) and SDOUT (142) of 00 become logic 0. Therefore, in the output of the mode switching circuit 200, DIN (133) is OFF, TxD_N (134) is OFF, C
NT_ENB (144) is turned off. Therefore, the optical output OOUT (1312) to the optical fiber 50 and the drive to the bus 20 (BUSH (31) ON) are not performed, and the timer device 4
00 is also not working.

When the bus 20 is driven and turned on in the standby mode Q0, the output RxD_N (131) of the bus driver circuit 11 is turned on, so the synchronization circuit 3
The output SRxD (141) of 00 changes from logic 0 to 1.
In response to this, the mode switching circuit 200 transits from the mode Q0 to the optical output mode Q2.

When light enters the photoelectric converter 13 through the optical fiber 50 in the standby mode Q0, DO
UT (132) turns on. Therefore, the output SDOT (142) of the synchronization circuit 300 changes from logic 0 to 1. In response to this, the mode switching circuit 200 transits from the mode Q0 to the bus drive mode Q1.

In this way, the operation mode conversion device 12 set to MODE = 1 transits from the standby mode Q0 to the optical output mode Q2 when the bus 20 on its own side observes the drive, and the mode Q2 is set. From the mode to the mode Q1 is not performed. On the other hand, when the light input from the optical fiber 50 is observed, the state transits from the mode Q0 to the mode Q1. This avoids the formation of the optical loop described above.

Next, the operating state of the bus drive mode Q1 will be described. In mode Q1, the output of the mode switching circuit 200 is that DIN (133) is OFF and TxD_N (134) is ON,
CNT_ENB (144) is turned off. Therefore, the transmitter 1102 of the bus driver circuit 11 is turned on,
The bus 20a is driven. On the other hand, DIN (133) is O
Since it is FF, the output to the optical fiber 50 is not performed, and the timer device 400 is not operating.

In this mode Q1, the output DOUT (132) of the photoelectric converter 13 is ON while the optical input from the optical fiber 50 is present (that is, while the drive request is made from the other system).
Then, the output SDOUT (142) of the synchronization circuit 300 is logic 1
The drive state to the bus 20 is maintained as it is.

Further, due to the structure of the bus driver circuit 11, the output of the transmitter 1102 is directly input to the receiver 1101. Therefore, TxD_N
Bus (2) with (134) ON and transmitter 1102 ON
When 0a is driven, the receiver 1101 turns on and R
xD_N (131) turns on. As a result, the synchronization circuit 3
The output SRxD (141) of 00 becomes logic 1, but the mode switching circuit 200 is in the bus drive mode Q1 and SRxD (1
Since 41) is not observed, it is not affected by the change.

In the bus drive mode Q1, the optical fiber 5
When the light input from 0 is cut off, the output D of the photoelectric converter 13
OUT (132) is turned off, and the output SDOUT (142) of the synchronization circuit 300 becomes logic 0. In response to this, the mode switching circuit 200 changes the mode Q1 to the non-observation mode Q3.
Transition the state to.

As described above, the bus drive mode Q1
At that time, after turning off TxD_N (134) for a while,
Keep on. This transitional period is the unobserved state,
The optical bus bridge device 10 is prevented from being mistaken for a bus drive.

Next, the operation state of the light output mode Q2 will be described. In mode Q2, the output of the mode switching circuit 200 is DIN (133) ON, TxD_N (134) OFF, and CNT.
_ENB (144) is turned off. Therefore, the OOUT (1312) of the photoelectric converter 13 is turned on, and the optical output is performed to the optical fiber 50. On the other hand, since TxD_N (134) is OFF, the bus 20 is not driven and the timer device 40
0 does not work either.

In the optical output mode Q2, while the bus 20 is in the drive state, the output RxD_N (131) of the receiver 1101 of the bus driver circuit 11 is ON, so SRx
D (141) remains at logic 1, and the mode switching circuit 200 maintains the mode Q2.

The optical bus bridge device 10 has the optical output mode Q.
When there is an optical input from another system via the optical fiber 50 at the time of 2, DOUT (132) is ON and SDOUT (142) is O.
It becomes N and becomes the above-mentioned “stabbed condition”. However, when MODE (151) = 1 is set by the condition setting device 122, the mode switching circuit 200 operates in the mode Q2 in the SDO mode.
Since the UT (142) is not observed, the optical output mode Q2 is stably maintained without falling into a "stabbed condition".

When the bus 20 is turned off in the light output mode Q2, the output RxD_N (1
31) is turned off, and the output SRxD of the synchronization circuit 300
(141) changes from logic 1 to 0. In response to this, the mode switching circuit 200 shifts the operating state from the mode Q2 to the standby state mode Q0. Unlike the case of the mode Q1, the mode Q2 is changed to the mode Q0 after the state of the bus 20 is settled, so that the input SRxD of the mode switching circuit 200 is changed.
There is no fear that (141) will be mistaken for ON, and no malfunction will occur even if the mode immediately shifts to the standby mode Q1.

Next, the operating state of the non-observation mode Q3 will be described. In mode Q3, the output of the mode switching circuit 200 is DIN (133) OFF, TxD_N (134) OFF, CN
T_ENB (144) is turned on. Therefore, the timer device 400 is activated and counts every clock, and when the set count number CNT (152) is reached, the time-up signal C
It outputs NT_UP (143).

In the mode Q3, the mode switching circuit 200 does not observe the SRxD (141) and SDOUT (142) but only the output CNT_UP (143) of the timer device 400, and the CN
The mode Q3 is maintained while T_UP = 0. Mode Q3
During the non-observation period, the optical bus bridge device 10
This is the period until the drive to 0 is stopped and the bus 20 stabilizes in the OFF state. When CNT_UP = 1, the mode switching circuit 200 changes the operating state from mode 3 to mode 0.
Then, the observation of SRxD (141) and SDOUT (142) is restarted. As a result, the malfunction of the optical bus bridge device 10 due to the transient change of the bus state can be prevented.

FIG. 13 shows the mode transition setting signal MODE (1
Under the condition of 51) = 0, the transition from the optical output mode Q2 to the bus drive mode Q1 is performed. The state transition diagram of FIG. 12A is different from that of FIG. 12A only in the operation in the “pricking situation” in the light output mode Q2. The differences will be described below.

In the optical output mode Q2, since the mode switching circuit 200 has MODE = 0, the output D of the photoelectric converter 13 is
Observe the change of OUT (132). Therefore, when there is an optical input from the optical fiber 50, the DOUT (132) turns on and S
DOUT (142) changes from logic 0 to 1. In response to this, the mode switching circuit 200 determines that the “stabbed condition” has occurred, and transits from the mode Q2 to the bus drive mode Q1. As a result, DIN (133) is OFF, TxD_N (13
Since 4) is turned on, the optical output of the photoelectric converter 13a is turned off.
Then, the “stabbed condition” is resolved.

As a result, during the same transfer cycle, the bus 2
Even if 0a and 20b are driven to the ON state, it is possible to avoid the vibration of the bus due to the "stabbed condition",
0b can be correctly matched.

FIG. 14 is a timing chart showing the operation of the optical communication system according to this embodiment. In a situation where the node 30a (or 30b) connected to the bus 20a drives the bus 20a to an ON state in a certain transfer cycle and turns OFF without driving in the next transfer cycle, the operation of each part of the system in FIG. Shows.

First, the A-system and B-system optical bus bridge devices 1
Both 0a and 0b are in the standby mode Q0. When the A-system bus 20a is turned on, the bus driver circuit 11a
Output RxD_N (131) of the logic switching from logic 1 to 0, and the input of the mode switching circuit 200 (output of the synchronization circuit 300) S
RxD (141) changes from logic 0 to 1. The mode switching circuit 200 transitions from the standby mode Q0 to the optical output mode Q2 according to the transition diagram of FIG.
(133) changes from logic 0 to 1.

In response to the change of DIN (133), the optical output OOUT (1312) of the photoelectric converter 13a is turned on, and the optical fiber 5
It is transmitted to the B-system optical bus bridge device 10b via 0. The optical input OIN (1311) of the photoelectric converter 13b is turned on,
Its output DOUT (132) changes from logic 0 to 1. A
A delay due to the optical transmission time occurs from the change of the DIN (133) of the system to the DOUT (132) of the B system.

In response to DOUT (132), the B-system mode switching circuit 200 receives the standby mode Q0 as shown in FIG.
From bus drive mode Q1 to output Tx
D_N (134) changes from logic 1 to 0. TxD_N (13
In response to the change in 4), the bus driver circuit 11b changes the bus B2
Drive 0b to ON state.

In this way, the ON state of the bus 20a is transferred to the bus 20b via the optical bus bridge devices 10a and 10b.
To the node 30b (or 30a) at the sampling point SP1 which is the end of the 1-bit transfer time.
Is from the bus 20a, and the nodes 30c and 30d are from the bus B20.
Recognize that the bus is in the ON state by fetching the state from b. That is, 1-bit data transfer is performed by the node 30a turning on the bus 20.

Then, in the next transfer cycle, the node 30a
(Or 30b) does not drive the bus 20a, the output RxD_N (131) of the bus driver circuit 11a changes from logic 0 to 1. Due to this change, the mode switching circuit 200 transits from mode Q2 to mode Q0, the output DIN (133) changes from logic 0 to 1, and the optical output OOUT (132) of the photoelectric converter 13a turns off.

As a result, the B-system optical bus bridge device 2
At 0b, the optical input OIN (1311) from the optical fiber 50 becomes O.
It becomes FF, and the output DOUT (132) changes from logic 1 to 0. Here again, a delay occurs due to the optical transmission time. When the output DOUT (132) changes to 0, the mode switching circuit 2
00 changes the state from the mode Q1 to the mode Q3 according to FIG.

In the non-observation mode Q3, the mode switching circuit 200 changes CNT_ENB (144) from logic 0 to 1 to activate the timer device 400, and at the same time, observes the value R
Input SRxD (141) by xD_N (131) is ignored. Further, in the non-observation mode Q3, the nodes 30c, 30
Since d has already entered the next bit transfer cycle, there is a possibility that the nodes 30c and 30d are driving the bus 20b to the ON state (in the example of FIG. 14, since the bus 20b is not driven). , The bus 20b is changing from the ON state to the OFF state).

Therefore, by the non-observation mode Q3,
By having the state in which the bus 20b is not observed, it is possible to prevent the transition period of the bus 20b from the ON state to the OFF state from being erroneously recognized as a bus drive from a B-system node.
Further, when the nodes 30c and 30d drive the bus 20b to the ON state, when the non-observation mode Q3 transits to the standby mode Q0, the SRxD (141) observation is restarted, so that the optical output mode Q2 And the state of the bus 20b can be correctly recognized.

CNT_U which is the output of the timer device 400
When P (143) changes from logic 0 to 1, the mode switching circuit 200 transits from mode Q3 to mode Q0, restarts observation of the bus 20b, and outputs TxD_N (1
34) is changed from logic 0 to 1 and the bus driver circuit 11b
Stops driving the bus 20b. As a result,
When the B system nodes 30c and 30d are not driven as in the example of 4, the bus 20b is turned off, and the nodes 30b to 30d are turned off at the sampling point SP2.
Capture the FF state.

FIG. 15 shows a timing chart in a situation different from that of FIG. In this example, the bus 20a and the bus 20b are driven in the ON state in a certain transfer cycle, and the bus 20a is not driven in the next transfer cycle.
MODE (151) = in the A mode operation mode conversion device 12a
MODE (151) = 0 is set for the 1st and Bth systems.

When the buses 20a and 20b are driven to the ON state in the same transfer cycle, the bus driver circuit 1
The input RxD_N (131) from 1a and 11b changes from logic 1 to 0. In response to this change, both the operation mode converters 12a and 12b transit from the mode Q0 to the mode Q2, the output DIN (133) changes from logic 0 to 1, and the photoelectric converters 13a and 13b both output light. OOUT
(1312) is turned on.

Therefore, the ON state is transmitted bidirectionally through the two optical fibers 50, and the photoelectric converters 13a and 13b are transmitted.
In both cases, the electric output DOUT (132) changes from logic 0 to 1. At this time, the operation mode conversion device 12b is set to MODE.
Since (151) = 0, as shown in FIG. 13A, the state changes from the mode Q2 to the mode Q1 and the output DIN (13
3), TxD_N (134) both change from logic 1 to 0,
The optical output OOUT (1312) of the photoelectric converter 13b is turned off,
The bus driver circuit 11b drives the bus 20b to the ON state.

At the sampling point SP1, the node 3
0a to 30d capture the states of the buses 20a and 20b, respectively, and capture one bit in the ON state.

Then, in the next transfer cycle, the node 30a
(Or 30b) stops the drive in the ON state of the bus 20a. Therefore, the operation mode conversion device 12a transits from the mode Q2 to the mode Q0 and outputs the output DIN (1
33) changes from logic 1 to 0. Therefore, the optical output OOUT (1312) of the photoelectric converter 13a is turned off.

In response to the change in the optical output OOUT (1312), the photoelectric converter 13b changes the electric output DOUT (132) from logic 1 to 0, and the operation mode converter 12b transits from the mode Q1 to the mode Q3. Then, CNT_ENB (144) is changed from logic 0 to 1 and the timer device 400 is started. After that, the output of the timer device 400, CNT_U
When P (143) changes from logic 0 to logic 1, the operation mode converter 12b transits from mode Q3 to mode Q0. However, since the node 30c (or 30d) is driving the bus 20b, the operation mode conversion device 1
The 2b input RxD_N1 (131) is still at logic zero.

Therefore, the operation mode converter 12b transits from the mode Q0 to the mode state Q2 and outputs the output DI.
N (133) is changed from logic 0 to logic 1, and the photoelectric converter 13
The optical output OOUT (1312) of b is turned on. Optical fiber 5
The photoelectric converter 13a receiving this change via 0 changes the electric output DOUT (132) from logic 0 to 1. D
Due to the change of OUT (132), the operation mode conversion device 12a
Transitions from mode Q0 to mode Q1 and TxD_
The N (134) is changed from logic 1 to logic 0, and the bus driver circuit 11a drives the bus 20a to the ON state. As a result, at the sampling point SP2, the node 30
a to 30d are turned on from the bus 20a and the bus 20b, respectively.
Capture state.

As described above, the bus 20a and the bus 20
It is possible to realize the coincidence of b and correctly perform data transfer.

Next, an application example of the present invention will be described. Figure 1
6 shows a water supply system to which the optical bus bridge device of the present invention is applied. Controller 8001 is pump 8012
Is controlled via the motor controller 8002 to keep the pressure of the water main 8110 constant and maintain an appropriate amount of water supply.

The controller 8001 is connected to the electric bus 20a.
The motor controller 8002 and the optical bus bridge device 10a are connected via. The operation panel 8011 is connected to the sensor 8013 attached to the water mains 8110 and the optical bus bridge device 10b via the electric bus 20b, and the optical bus bridge devices 10a and 10b are connected by the optical fiber 50. Motor controller 800
2 and a motor 8102 that drives the pump 8012 are connected by a power cable 8101. Sensor 801
Reference numeral 3 is a pressure gauge showing the pressure of the water main 8110 at the output of the pump.

Controller 800 that constitutes this system
1, the motor controller 8002, and the sensor 8013 are provided with a well-known function of performing communication according to the communication protocol of ISO11898.
001 and the operation panel 8011 together form a multi-master system that can be a master.

The operation of the water supply system will be described. The controller 8001 requests the sensor 8013 to output the pressure of the water main 8110.
3 outputs the pressure of the water main 8110. Next, the controller 8001 instructs the motor controller 8002 to increase the pressure if the pressure of the water mains 8110 is lower than the specified pressure, and decrease the pressure if the pressure of the water main 8110 is higher. In response to an instruction from the controller 8001, the motor controller 8002 changes the current voltage supplied to the motor 8102 that drives the pump 8012 to control the pump 8012 and changes the pressure of the water main 8110. By performing the above-described operation processing at regular intervals, it is possible to maintain the pressure of the water main 8110 at the specified pressure.

Next, the processing from the operation panel 8011 will be described. When the controller 8001 breaks down or an emergency occurs and the pump 8012 must be stopped, the operation panel 8011 sends an instruction by a manual operation by an operator. On the operation panel 8012, a manual / automatic changeover switch, an emergency stop switch for making an emergency stop of the pump 8012, a dial for setting the voltage / current applied to the motor 8102,
There is a meter or the like indicating the pressure of the water mains 8110, and the pressure of the water main 8110 is read from the sensor 8013 at a constant cycle and displayed on the meter, and when the automatic / manual switch is set to the manual side, The voltage / current value instructed by the operator is set to the motor controller 80.
Tell 02.

When controlling from the operation panel 8011, first, the automatic / manual changeover switch is set to the manual side.
As a result, a stop signal is output to the controller 8001 and all instructions from the controller 8001 are stopped. Next, the voltage / current to the motor 8102 that drives the pump 8012 is determined by looking at the pressure of the water mains 8110 displayed on the meter, and is set using the setting dial.
When the emergency stop switch is pressed, a stop signal is sent to the motor controller 8002 to stop the pump 8012. By doing this, the pump 8012 is manually operated.
Can be controlled.

Here, the multi-master operation when the controller 8001 and the operation panel 8011 output at the same time will be described. Arbitration is required when packets are simultaneously output from the controller 8001 and the operation panel 8011.

According to ISO11898, the bus is driven when a logic 0 is output to the bus, and the bus is not driven when a logic 1 is output. Therefore, even if one node outputs a logic 0, the entire bus is in a drive state and shows a logic 0. That is, the logic 0 is prioritized. In addition, since it is assumed that the drive state has propagated to all nodes in the 1-bit transfer time, by observing the bus state at the end of the 1-bit transfer time, The 1-bit data transfer is completed. Further, even if all the nodes do not transmit data, the end of the packet can be recognized because the bus value is observed. Therefore, when packet transmission is started from a plurality of nodes, the packet transmission start timing is known, so packet transmission is always started at the same time.

From the above, ISO11898 realizes the following arbitration. The packet has the structure shown in FIG. 4C, and the priority order of the packet is set in the header 7001, and packets having the same priority order are not simultaneously transmitted from different nodes. Therefore, at the time of transmitting the header 7001, when each node transmitting the packet observes the bus state at the time of 1-bit transfer, it compares the value output to itself with the bus state,
When a mismatch occurs (node: outputs logic 1, bus:
Drive status) suspends packet transmission and only observes bus status until the next packet can be transmitted.

When the transfer of the header 7001 is completed in this way, only the node that has transmitted the packet with the highest priority remains to win, and all the other nodes are in the mode of bus state observation. Arbitration is performed in this manner.

FIG. 19 shows a transition diagram for explaining art villation in this system. (A) The priority order of packets in the water supply and sewer system is based on a command from the controller 8001
Human orders from 11 have a high priority. Therefore, the first 2 bits of the header 7001 of the packet transmitted from the operation panel are set to 00, and the first 2 bits of the header 7001 of the packet transmitted from the controller are set to 01.

(B) Controller 8001 and operation panel 80
The packet transmission is started from 11 and the first bit is transmitted. Since the first bit of the header 7001 is 0, both the controller 8001 and the operation panel 8011 drive the electric buses 20a and 20b. Electric bus 20
Both a and 20b are in the drive state. For this reason, the controller 8001 and the operation panel 8011 are in the drive state as a result of monitoring the states of the electric buses 20a and 20b, respectively, so that the drive state to the bus and the drive state of the bus match.

(C) Then, the transfer of the second bit is started. Since the second bit of controller 8001 is 1,
Do not drive the electric bus 20a. Since the second bit of the operation panel 8011 is 0, it drives the electric bus 20b. As a result, the optical bus bridge device 10a enters the bus drive mode, the optical bus bridge device 10b enters the optical output mode, and both electric buses 20a and 20b enter the drive state. Therefore, in the controller 8001, the state of the drive to the bus and the state of the bus 20a do not match. On the other hand, the operation panel 8011 is a bus drive and a bus 2
The drive states of 0b match.

(D) Therefore, the controller 8001 stops the packet transmission and becomes the reception state, and the operation panel 80
11 continues packet transmission.

As described above, even if packets are transmitted from both the controller 8001 and the operation panel 8011 while complying with the ISO11898 standard, the operation panel 8011 must be
Can win the arbitration, the data 7002 can be transmitted, and the command from the operation panel 8011 has priority.
As a result, the controller 8001 is stopped, and switching from automatic to manual is promptly executed.

[0126]

According to the present invention, an optical bus bridge device having a mode conversion function is provided between an optical fiber and an electric bus when two electric buses each connecting a node are connected by an optical fiber. It is equipped with an optical output mode in which when both buses are not driven, it goes into a standby mode to observe the bus state on its own side, and when one or both buses are observed, it outputs light to the optical fiber. Since both optical bus bridge devices share the bus drive mode that outputs electric power to the electric bus, it is possible to avoid the "deadlock state" and "stabbed condition" that occur when both optical output states occur. The drive states of can be correctly matched.

Further, when transitioning from the bus drive mode to the standby mode, the bus state is not observed until the bus stabilizes from the ON state to the OFF state via the non-observation mode. A transient change is mistaken for a bus drive. Malfunctions can be prevented.

As a result, it becomes possible to construct a system in which a part of the network is replaced by an optical fiber, and a network system excellent in noise resistance can be provided at a low cost in the field. In addition, since bus states can be matched with each other for bus drives from a plurality of nodes while performing arbitration according to the ISO11898 standard, the configuration of the multi-master system becomes easy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an optical communication system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of an optical bus bridge device according to an embodiment.

FIG. 3 is a configuration diagram of a bus driver circuit according to an embodiment.

FIG. 4 is an explanatory diagram showing operation specifications of a transmitter and a receiver and a packet structure (ISO11898 standard).

FIG. 5 is a configuration diagram of a photoelectric converter according to an embodiment.

FIG. 6 is an explanatory diagram showing operation specifications of an optical / electrical converter and an electric / optical converter.

FIG. 7 is a configuration diagram of an operation mode conversion device according to an embodiment.

FIG. 8 is a configuration diagram of a synchronization circuit.

FIG. 9 is a block diagram of a timer device.

FIG. 10 is an explanatory diagram showing the operation of the decrementer.

FIG. 11 is a block diagram of a condition setting device.

FIG. 12 is an explanatory diagram showing a mode transition operation of the mode switching circuit.

FIG. 13 is an explanatory diagram showing another mode transition operation of the mode switching circuit.

FIG. 14 is a timing chart showing the operation of the optical communication system.

FIG. 15 is a timing chart showing another operation of the optical communication system.

FIG. 16 is a configuration diagram of a water and sewer system to which the present invention is applied.

FIG. 17 is an explanatory diagram showing a problem when an optical fiber is connected between electric buses.

FIG. 18 is an explanatory view schematically showing the process of bus matching operation of the optical bus bridge device of the present invention.

FIG. 19 is an explanatory diagram showing operations of arbitration and bus unification for simultaneous packet transmission from a plurality of nodes.

[Explanation of symbols]

1a, 1b ... Bus system, 10a, 10b ... Optical bus bridge device, 20a, 20b ... Bus, 30a-30d ... Node, 50 ... Optical fiber, 11a, 11b ... Bus driver circuit, 12a, 12b ... Operation mode conversion device, 13a,
13b ... Photoelectric converter, 121 ... Operation mode conversion circuit, 1
22 ... Condition setting device 1101 ... Receiver 1102 ...
Transmitter, 1301 ... Optical / electrical converter, 1302
... electric / optical converter, 200 ... mode switching circuit, 300 ...
Synchronization circuit, 400 ... Timer device, 3001-300
4, 4011 ... Latch, 3011 ... NOT circuit, 400
1 ... 4-bit decrementer, 4002 ... Selector, 12
21 ... Bit switch, 1222 ... Pull-up resistor, 8
001 ... Controller, 8002 ... Motor controller, 8011 ... Operation panel, 8012 ... Pump, 8013 ...
Sensor, 8101 ... Power cable, 8102 ... Motor,
8110 ... Water mains.

─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroaki Fukumaru Inventor Hiroaki Fukumaru 2-5-1, Omika-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Omika factory (72) Inventor Nao Ogawa 5-2, Omika-cho, Hitachi-shi, Ibaraki No. 1 Hitachi Ltd. Omika factory (56) Reference JP-A-6-291808 (JP, A) JP-A-9-233114 (JP, A) Special table 2000-505610 (JP, A) (58) Survey Areas (Int.Cl. ⁷ , DB name) H04L 12/28-12/46 H04B 10/20

Claims (8)

(57) [Claims] 1. At least one node and an optical repeater
There is a first electric bus and a second electric bus connected,
Bidirectional connection between optical repeaters with two optical fibers,
By matching the states of both electric buses,
In an optical communication method that enables communication between nodes connected to an electric bus, in each of the optical repeaters, the electric bus is a non-drive (O
When the FF state), observes the state of the optical fiber and the state of the electrical bus, the node connected to the first electrical bus, when Ru is the bus drive (ON state), is connected to the electric bus
In the first optical repeater, the bus drive continues.
Light is output while it is on the second electric bus via the optical fiber.
The second optical repeater connected to the second optical repeater is connected to the second optical repeater connected to the second optical repeater .
Bus the second electrical bus while optical input continues.
Along with the live performance, the observation of the electric bus is stopped and the bus drive from the node connected to the first electric bus
When Eve is stopped and the electric bus is turned off,
The first optical repeater stops the optical output and receives it.
Then, the second optical repeater stops the bus drive.
Then, the observation of the state of the electric bus is restarted . 2. The device according to claim 1, wherein the second optical repeater stops the bus drive and
2. The optical communication method, wherein when transitioning to the observation of the state of the electric bus, the state of the electric bus is not observed for a predetermined period. 3. The method according to claim 1 or 2, wherein both of the electric buses are bus-driven from the nodes connected to each of them, and optical output is simultaneously made from both sides to the optical fiber. An optical communication method, wherein an optical repeater stops the optical output and performs only the electrical output. Wherein between two electrical bus and said bus is provided between the two optical fibers to contact <br/> connection bidirectionally, optical repeater to match the both buses state of the electrical bus In the standby mode in which the bus state and the state of the optical fiber are observed when the electric bus is not driven (OFF state), and the node connected to the electric bus drives the bus drive (ON state).
State), an optical output mode of transitioning from the standby mode to perform optical output to the optical fiber, and an optical output from the optical fiber to electrically output to an electric bus of its own side and the bus state of A bus drive mode that stops observation and a non-observation mode that does not observe the bus state for a certain period when the bus drive mode from the node is changed to the standby mode when the bus drive from the node is stopped a means for performing the door, the bus-like
An optical repeater characterized in that each mode is switched according to the condition . 5. The electrical bus system of claim 4, wherein both electrical buses are bus driven from each node,
When two optical bus bridge devices provided on both sides of the optical fiber switch to the optical output mode at the same time, one of them is provided with a mode transition signal setting means for transitioning to one of the bus drive modes. apparatus. 6. An electric signal that is electrically connected to two electric buses that have an electrically binary state, a plurality of nodes that output binary data to the electric bus, and an electric signal that is connected to each of the two electric buses. optical communication system comprising two and optical repeater having means for converting into an electric signal means the optical signal into a signal, an optical fiber connecting the two said electric buses via the two optical repeater In the optical fiber, the optical fiber has two optical fibers that perform optical output and optical input separately for transmitting the bus state of the electric bus bidirectionally, and the optical fiber relay device, The ON / OFF state of the electric bus and the presence / absence of light input from the optical fiber are observed, and when the electric bus is in the ON state, light is output to the optical fiber,
Further, when there is an optical input from the optical fiber, it is electrically output to an electric bus on its own side, and ON / O of the electric bus
A function to stop the observation FF state, when the two optical fibers is the optical output at the same time, has one of the mode switching functions to stop the optical output performs only the electrical output, each transmission cycle In addition, when the electric bus is driven according to ON / OFF of each 1-bit data from the node, the drive state of both electric buses is passed through the optical fiber and the optical repeaters on both sides thereof. Match
The optical communication system, wherein each node samples the electric bus after the coincidence. 7. The state of the electric bus according to claim 6, wherein when the plurality of nodes simultaneously output the data to the electric bus, the state of the electric bus is determined to be one state having priority. An optical communication system, wherein a node compares the state output to the electric bus with the state of the electric bus to determine whether or not to continue the data output to the electric bus thereafter. 8. The first electric bus controls the equipment less.
Both are connected to a controller and a first optical repeater,
The second electric bus is a control panel for operating the device and a second light.
A repeater is connected to the first and second optical repeaters.
Two optical fibers for bi-directional transmission are connected
In the control system according to claim 1, the first and second optical repeaters are connected via the optical fiber.
The state of the first electric bus and the second electric bus.
By matching, it enables transmission and reception between buses,
Transmission from both the controller and the operation panel at the same time
When performed, the optical repeater is the controller
Transmission is stopped and priority is given to transmission on the operation panel.
A control system characterized by being made.