JPH11298483A - Optical polling access system - Google Patents

Abstract

(57) [Summary] The present invention relates to an optical polling access system, and does not hinder ordinary polling access from a master station.
It is an object of the present invention to provide an optical polling access system capable of promptly issuing an interrupt notification such as an alarm or warning from a slave station. SOLUTION: In a system for transmitting information by connecting a master station and a plurality of slave stations with upstream and downstream optical fibers, an optical signal which reaches the master station from the slave station is converted into an electric signal in the master station. A detection unit that measures the level of the electric signal and determines that the value has reached a certain level or higher,
An attenuator that keeps the light level from the slave station to the master station constant is provided, and while the master station is communicating with the slave station, other slave stations that have not been requested to access transmit a certain amount of light and interrupt A request is made, and the master station is configured so that the detecting unit detects that the light receiving level has exceeded a certain value and recognizes an interrupt request from a station other than the accessing slave station.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical polling system, and more particularly, to a master station and a plurality of slave stations connected by an optical cable (a transmission line can be connected to a plurality of slave stations such as a bus type or a star type). In a polling access system in which a master station transmits data to all of a plurality of slave stations all at once and one slave station responds, the present invention relates to a method in which a slave station that is not accessing notifies an interrupt to the master station.

[0002]

2. Description of the Related Art Conventionally, in an optical polling system, the following three modes are considered as a method of controlling a system by a master station. The slave station waits for access to its own device even if there is information such as alarms and warnings. When the access is switched, the master station monitors the status of all slave stations for information such as alarms and warnings, and starts access to the next slave station. The communication of other slave stations is disturbed by the occurrence of alarms and warnings, etc., and notification is made by detecting data abnormality.

FIG. 20 is a diagram showing polling access timing showing the first method. Slave station is (a) ~
When the connection is made up to (n), the master station sets the access period T
Then poll all slave stations.

FIG. 21 is a diagram showing the timing of monitoring the switching of polling access according to the second method. If the slave station is connected to (a) to (n), the master station checks for information such as alarms and warnings when moving to the next slave station. Then, after checking, move to the next slave station.

[0005]

The first method described above has a problem in that abnormal processing such as alarms and warnings is delayed, and it takes a long time for the system to recover from an abnormality occurrence to a state. In the above-mentioned second method, there is a problem that a long time is spent for one access and the system operation capability is reduced. The third method described above has a problem that a trial process is required to cause a data abnormality, and it is difficult to construct a system that cannot perform the retry process.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and it is possible to promptly notify an interrupt such as an alarm / alarm from a slave station without interfering with ordinary polling access from the master station. It aims to provide an optical polling access system.

[0007]

(1) FIGS. 1 and 2 are block diagrams showing the principle of the present invention. FIG. 1 shows a case where the slave station is connected to the master station in a star shape, and FIG. 2 shows a case where the slave station and the master station are connected by a bus. In these figures, 1 is a master station, and 2 is a plurality of slave stations connected to the master station 1. 3 is a downstream optical fiber connecting the master station 1 and the slave station 2;
Is an upstream optical fiber connecting the master station and the slave station 2, and 5 is an optical coupler for branching an optical path.

In the master station 1, reference numeral 11 denotes a control unit for outputting a signal requesting access to the slave station 2, reference numeral 12 denotes an E / O converter for converting an electric signal from the control unit 11 into an optical signal, and reference numeral 13 denotes a slave station 2. This is an O / E converter for converting an optical signal from the optical signal into an electric signal.

In the slave station 2, the received signal 21 is the master station 1
A control unit for determining whether the signal is an access request signal from
An E / O converter 2 converts an output signal of the control unit 21 into an optical signal, and an O / O converter 23 converts a signal from the master station 1 into an electric signal.
/ E conversion unit.

According to the present invention, an optical signal arriving at a master station from a slave station is converted into an electric signal, the level of the electric signal is measured, and it is determined that the value has reached a certain level or more. And an attenuator that keeps the light level reaching the master station from the slave station is constant, and other slave stations that have not been requested to access while the master station is communicating with the slave station are fixed. An interrupt request is made by transmitting light, and the detection unit detects that the light reception level has exceeded a predetermined value at the master station and recognizes an interrupt request from a slave station other than the accessing slave station. .

According to the configuration of the present invention, when another slave station that is not requested to access while the master station is communicating with the slave station sends out a certain amount of light and issues an interrupt request, it is detected. The interrupt request from another slave station can be determined by detecting that the light receiving level has exceeded a certain value by the unit.

(2) In the master station, a detecting section for converting an optical signal arriving from the slave station to the master station into an electric signal and measuring the level of the electric signal, and holding a value detected by the detecting section And a comparing unit for comparing the value of the holding unit with the value of the detecting unit, and when the control unit confirms that the master station has accessed the slave station and returned a response, the detecting unit at that time detects The measured light level is held by the holding unit, and the comparison unit determines whether the value held by the holding unit and the value measured by the detection unit match, and while the master station is accessing the slave station, When the slave station requests an interrupt by transmitting a certain level of light, the detection unit indicates a value in which the light level has increased from the state where the previous slave station is being accessed, and the comparison unit holds the value in the holding unit. If the value does not match the specified value, the control unit has generated an interrupt from another slave station. It is characterized by recognizing and.

[0013] According to the configuration of the present invention, the optical level from the slave station while the master station is accessing the slave station is held in the holding section, and the other slave stations are referenced based on the held light level. When there is an interrupt request from the slave station, it is possible to determine that there is an interrupt request from another slave station by increasing the light level.

(3) In the master station, a detector for converting an optical signal arriving from the slave station to the master station into an electric signal and measuring the level of the electric signal, an optical level value from each slave station, and An information memory that holds the light level value at the time of occurrence of the interrupt and a comparison unit that compares the value of the information memory with the value of the detector are provided. When a request occurs, the change in light level is measured by the detector,
The comparison unit compares the data in the information memory, and when the comparison results match, the control unit recognizes that an interrupt has occurred from another slave station.

According to the configuration of the present invention, the value obtained by changing the light level value from each slave station and the light level value at the time of interruption are stored in the information memory, so that other slave stations can be stored. By comparing the light level at the time of the interrupt request from with the light level value held in the information memory,
It is possible to determine that there has been an interrupt request from another slave station.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 3 is a block diagram showing the first embodiment of the present invention. 1 are denoted by the same reference numerals. In the master station 1, 11 is a control unit, 12 is an E / O converter, 13 is an O / E converter, 1
Reference numeral 4 denotes a detection unit that converts a received light signal into an electric signal and measures that the value rises above a certain level. Reference numeral 3 denotes a downstream optical fiber, 4 denotes an upstream optical fiber, and 5 denotes an optical coupler for branching an optical signal. Reference numeral 6 denotes an attenuator (ATT) for adjusting the optical signal level from the slave station 2 to the master station 1 to be constant. In the slave station 2, 21 is a control unit, 22 is an E / O conversion unit, and 23 is an O / E conversion unit.
In the embodiment shown in the figure, a case is shown where the master station 1 and three slave stations 2 # 1 to # 3 communicate. The operation of the circuit thus configured will be described as follows.

It is assumed that the master station 1 and the slave station # 1 are communicating via an optical fiber. At this time, after the signal from the master station 1 is converted into an optical signal by the E / O conversion unit 12,
The signal enters the O / E converter 23 of the slave station 2 via the optical coupler 5 and is converted into an electric signal. On the other hand, the signal from the slave station 2 is converted into an optical signal by the E / O converter 22, the optical level is adjusted by the attenuator 6, and the O / E conversion of the master station 1 is performed via the optical coupler 5. Enter the section 13. The signal detection level at this time is measured by the detection unit 14 and notified to the control unit 11.

Here, another slave station to which no access is requested, for example, the slave station 2 of # 2 issues an interrupt request by transmitting a certain amount of light. Then, the detection unit 14 of the master station 1 detects that the light level to be received rises above a certain value.
The detection result is notified to the control unit 11. Therefore, master station 1
Detects that an interrupt has occurred from a station other than the currently accessed slave station, accesses all the slave stations 2, and determines that an interrupt has occurred from the slave station # 2.

According to this embodiment, the slave station 2 can receive the access request signal from the master station 1 and determine whether or not the access request signal is for the own station. The slave station 2 that has made the access request responds to the master station 1 so that the master station 1 can determine that it is a response signal from a specific slave station 2.

Further, according to this embodiment, the master station 1
If the other station 2 that has not been requested to access during communication with the slave station 2 sends out a certain amount of light and makes an interrupt request, the light receiving level becomes higher than a certain value by the detector 14. By detecting this, it is possible to determine an interrupt request from another slave station.

FIG. 4 is a block diagram showing a second embodiment of the present invention. The same components as those in FIG. 3 are denoted by the same reference numerals. In the master station 1 shown in the figure, 14 is a detection unit for measuring the level of a received signal, 15 is a holding unit for holding the measured signal level, and 16 is the output of the detection unit 14 and the holding unit 1
5 and compares the comparison result with the control unit 11.
Is a comparing unit for notifying the user. Other configurations are the same as those in FIG. The operation of the circuit thus configured will be described as follows.

When the master station 1 accesses the slave station 2 of # 1 and confirms that the response from the slave station 2 has been returned, the controller 11 checks the light level measured by the detector 14 at that time.
5. Then, the comparison unit 16 notifies the control unit 11 that the value held by the holding unit 15 and the value measured by the detection unit 14 match.

Now, while the master station 1 is accessing the slave station 2 of # 1, another slave station, for example, the slave station 2 of # 2 emits light of a certain level and requests an interrupt. Then, master station 1
The detector 14 measures that the light level has increased from the state where the slave station 2 of # 1 is being accessed. Comparison section 16
Compares the value held by the holding unit 15 with the value detected by the detection unit 14. As a result of the comparison,
This is notified to the control unit 11. Therefore, the master station 1 monitors the signal from the comparison section 16 to detect that an interrupt has occurred from the slave stations 2 other than the slave station 2 of # 1 currently being accessed. To determine the interrupt from the slave station 2 of # 2.

According to this embodiment, the light level from the slave station while the master station is accessing the slave station is held in the holding section, and the other slaves are referenced based on the held light level. When there is an interrupt request from the station, it is possible to determine that there is an interrupt request from another slave station by increasing the light level.

FIG. 5 is a block diagram showing a third embodiment of the present invention. 3 and 4 are designated by the same reference numerals. In the master station 1, reference numeral 17 denotes an information memory for holding a light level value from each slave station 2 and a light level value when an interrupt occurs. The comparison unit 16 is a detection unit 14
Is compared with the value held in the information memory 17, and the result is notified to the control unit 11. In this circuit, the light level reaching the master station 1 from the slave station 2 is adjusted by the attenuator 6. The operation of the circuit thus configured will be described as follows.

If another slave station, for example, the slave station 2 of # 2 generates an interrupt while the master station 1 is accessing the slave station 2 of # 1,
The light level changes. The light level is measured by the detection unit 14 of the master station 1 and compared with the data of the information memory 17 by the comparison unit 16.
To compare. The control unit 11 switches the data in the information memory 17 and receives the coincidence notification from the comparison unit 16 so as to determine the occurrence of an interrupt from the slave station 2 of # 2. Therefore, the master station 1 determines from which slave station 2 the interrupt is issued, and the interrupt processing functions immediately.

According to this embodiment, the light level value from each slave station is made different, and the light level value at the time of interruption is stored in the information memory.
By comparing the light level at the time of an interrupt request from another slave station with the light level value held in the information memory, it is possible to determine that there is an interrupt request from another slave station. it can.

FIG. 6 is a block diagram showing a fourth embodiment of the present invention. The same components as those in FIG. 5 are denoted by the same reference numerals. In the master station 1, reference numeral 17 denotes an information memory for holding the output of the detection unit. The comparing unit 16 compares the value held in the information memory 17 with the output of the detecting unit 14 and notifies the control unit 11 of the result. The operation of the circuit thus configured will be described as follows.

The master station 1 outputs an interrupt to the other slave stations 2 while accessing one slave station 2, and stores the value measured by the detector 14 at that time in the information memory 1.
Hold at 7. This control is performed by the control unit 11.

Thereafter, when the master station 1 is accessing the slave station # 1 and the other slave station # 2 generates an interrupt, the light level changes. The detecting unit 14 measures the change in the light level and supplies it to the comparing unit 16. The comparison unit 16
Compares the output of the detection unit 14 with the output of the information memory 17. If the comparison results match, the control unit 11 can determine that there has been an interrupt from another slave station 2. Therefore, the master station 1 determines from which slave station 2 the interrupt is issued, and the interrupt processing can be immediately performed.

According to this embodiment, the light levels at the time of all the interrupt patterns reaching the master station from the slave station at the time of the interrupt are stored in the information memory, so that an interrupt request from another slave station can be obtained. By comparing the light level at the time of the occurrence with the light level value held in the information memory, it is possible to determine that there has been an interrupt request from another slave station.

FIG. 7 is a block diagram showing a fifth embodiment of the present invention. The same components as those in FIG. 3 are denoted by the same reference numerals. In the master station 1, a timer 18 receives the output of the detection unit 14, measures the time during which the light level is increasing, and notifies the control unit 11 of the time. In this circuit, the light level reaching the master station 1 from the slave station 2 is adjusted by the attenuator 6. The operation of the circuit thus configured will be described as follows.

While the master station 1 is communicating with the slave station 2 of # 1, another slave station that has not been requested to access, for example, the slave station 2 of # 2 transmits an optical pulse for a predetermined time. Then, the detection unit 14 of the master station 1 detects that the light level to be received rises above a certain value for a certain time, measures the time detected by the detection unit 14 with the timer 18, and notifies the control unit 11. Therefore, based on the monitoring time of the timer 18, the master station 1 determines an interrupt from a slave station other than the currently accessed slave station # 1 and can immediately execute the interrupt processing.

According to this embodiment, an optical pulse for a fixed time is transmitted from another slave station, and the master station detects that the light receiving level increases for a certain time, and this fixed time is used for each slave station. Thus, it is possible to determine that there has been an interrupt request from another slave station.

FIG. 8 is a block diagram showing a sixth embodiment of the present invention. The same components as those in FIG. 3 are denoted by the same reference numerals. In this embodiment, the master station 1 and the slave station 2 communicate with each other using FM-modulated signals. In the master station 1, 19 receives a signal from the control unit 11 and
Reference numeral 20 denotes an FM demodulation unit for notifying the O conversion unit 12, and an FM demodulation unit 20 for receiving the output of the O / E conversion unit 13 and notifying the control unit 11.

In the slave station 2, reference numeral 24 denotes an O / E converter 23.
Is an FM demodulation unit that demodulates a modulation signal in response to the output of the control unit 21 and notifies the control unit 21 of the demodulated signal. Reference numeral 26 denotes a relay for receiving the output of the FM modulator 25, and the output is supplied to the E / O converter 22. ON / OFF control of the relay 26 is given from the control unit 21. The operation of the device configured as described above will be described below.

The master station 1 and the slave station 2 are connected to the FM modems 19 and 2
Communication is performed using the signals modulated and demodulated by 0, 24, and 25 so that the signal level is constant on average. Now, while the slave station # 1 is performing polling access from the master station 1, the signal from the FM modulator 25 is disconnected by the relay 25 so that the slave station # 2 # 2 notifies an interrupt. Is controlled by the control unit 21 so as to output only light.

The light level reaching the master station 1 from one slave station 2 is adjusted by the attenuator 6, and the light level reaching the master station 1 is set to -10 dBm. Here, when the # 2 slave station 2 emits light, the light level is doubled as shown in FIG. 9 and changes to -7 dBm. The level when this is converted from an optical signal to an electric signal by the O / E converter 13 is changed from -20 dBm to -14 dBm. The O / E converter 13 includes a photodiode 13b, a resistor R0, and an amplifier 13a. The photodiode 13b generates an electric signal according to incident light. This is amplified by the amplifier 13a.

Therefore, if a circuit for detecting a level of -17 dBm or more is used in the detection unit 14, it is possible to detect that an interrupt has occurred due to amplification of light. That is, the detecting unit 1 shown in FIG.
4, the divided voltage of the resistors R1 and R2 is set to be equivalent to -17 dBm. As a result, if the output of the amplifier 13a is received and is −14 dBm, the level detector 14a becomes “1” level and can notify the control unit 11 that an interrupt has occurred. The control unit 11
When an interrupt is detected, all slave stations 2 are accessed, and it is possible to determine that an interrupt has occurred from the slave station # 2.

FIG. 10 is a block diagram showing a seventh embodiment of the present invention. 8 are denoted by the same reference numerals. In the master station 1, a holding unit 15 holds the signal level measured by the detection unit 14. A comparison unit 16 compares the output of the detection unit 14 with the value stored in the storage unit 15 and notifies the control unit 11 of the result. Other configurations are the same as those in FIG. 8 except that there is no attenuator.
The operation of the circuit thus configured will be described as follows.

In this embodiment, while the master station 1 is communicating with the slave station 2 of # 1 by polling access, the slave station 2 of # 2 notifies the interrupt of the slave station # 2. The slave station 2 disconnects the signal from the FM modulator 25 with the relay 26 and controls the controller 21 so as to output only light.

The master station 1 converts a response from polling access from the slave station # 1 into an electric signal by the O / E converter 13, demodulates the FM signal by the FM demodulator 20, and converts the response signal by the controller 11. To detect. FIG. 11 is an operation explanatory view of the seventh embodiment of the present invention. Now, in the O / E conversion unit 13, # 1
It is assumed that the optical signal of the slave station 2 is −10 dBm, and the analog signal of −20 dBm converted into an electric signal is converted from an analog level to a digital level by an A / D converter constituting the detection unit 14. The control unit 11 receives the response signal from the FM demodulation unit 20 and stores the value converted by the A / D converter 14 in the memory 15 constituting the holding unit 15.

The signal demodulated by the FM demodulation unit 20 is sent to the control unit 11. Then # 2
When the slave station 2 sends out the light, the light level is temporarily -10 dB.
It is assumed that the value has changed from m to −8 dBm. This is O /
The signal is converted into an electric signal by the E converter 13, and is converted into a digital level by the detector 14. The level at this time is -16
dBm.

The comparing section 16 determines the level (−16 dB)
m) held by the holding unit 15 (−20 dB)
As compared with m), an interrupt notification due to the rise in level is sent to the control unit 11. In this way, by monitoring the level amplification based on the held light level,
It is possible to determine an interrupt from another slave station.

FIG. 12 is a block diagram showing an eighth embodiment of the present invention. 5, 8, and 10 are denoted by the same reference numerals. This system is a master station 1
The mobile station 2 and the mobile station 2 communicate with each other by using the signal subjected to the FM modulation and demodulation, and adjust the optical response level from each mobile station 2 to the terminal light level shown in FIG. In the figure,
Reference numeral 17 denotes an information memory which holds (stores) the light level value from each slave station 2 and the light level value when an interrupt occurs.
This holds the data shown in FIG. The operation of the circuit thus configured will be described as follows.

In FIG. 14, the reason why the input level of the slave station being accessed is different is that the control unit 11 of the master station 1 can determine which slave station is responding. In the figure, the optical amplification level is set in advance by the combination of the accessing slave station and the interrupt slave station.

While the slave station 2 of # 1 is performing polling access from the master station 1, the slave station 2 of # 2 notifies an interrupt. The signal is cut by the relay 26 and the control unit 21 controls so that only light is output.

Now, since the optical level reaching the master station 1 from the slave station # 1 of # 1 is adjusted by the attenuator 6, when the optical level entering the master station 1 is -30 dBm, the operation explanatory diagram of FIG. As shown in (1), the level when the optical signal is converted into the electric signal by the O / E converter 13 is -60 dBm.

The detection unit 14 converts the analog level into a digital level by the A / D converter 14 and
Enter 6 At this time, the control unit 11 outputs the data switching address to the address [0000] of the slave station 2 of # 1 that is accessing the data, switches the data in the information memory 17 and inputs it to the comparing unit 16.

The comparator 16 compares the output of the A / D converter 14 with the output of the information memory 17. Here, if the comparison results match, the comparison unit 16 notifies the control unit 11 that the response is the response of the slave station 2 of # 1.

Thereafter, when the slave station 2 of # 2 emits light,
The light level rises by 4.8 dBm (see FIG. 14), and the light level becomes −25.2 dBm. This is the O / E converter 1
The level when converted to an electric signal in 3 is -50.4 dB
Therefore, the comparison unit 16 does not agree when comparing the data from the detection unit 14 with the data from the information memory 17.

Upon receiving this mismatch result, the control unit 11
Can recognize that access is being made from a slave station 2 other than the slave station 2 of # 1. When the control unit 11 confirms the interruption from the slave station 2, the address in the information memory 17 is switched until the address is matched by the comparison unit 16, and # 2
When switching to the slave station 2, the data from the detection unit 14 and the data read from the information memory 17 match, and it is possible to determine from which slave station an interrupt has occurred. As a result, # 2 can be accessed without accessing all slave stations.
Interrupt from the slave station 2 can be determined.

FIG. 15 is a block diagram showing a ninth embodiment of the present invention. The same thing as FIG. 10 and FIG.
The same reference numerals are given. In the above embodiment, the attenuator 6 adjusts the optical level input from each of the slave stations 2 to the master station 1 so that the master station 1 detects the interrupt of # 2. In this embodiment, the light level input to the master station 1 is not adjusted.

In this embodiment, since the contents of the information memory 17 of the above-described embodiment (FIGS. 12 to 14) cannot be written in advance, as shown in FIG.
Is such that information from the detection unit 14 is held by a write control signal from the control unit 11. The operation of the circuit thus configured will be described as follows.

In this embodiment, the master station 1 performs the following at the start-up of the system or at regular time intervals, and creates an information table in the information memory 17 so that the light level due to dirt on the optical unit or the like is obtained. I am trying to correct the changes.

The master station 1 accesses the slave station 2 of # 1, and the controller 11 causes the information memory 17 to hold (latch) the light level detected by the detector 14 at that time in response to the slave station 2. The master station 1 causes the slave station 2 of # 2 to perform an interrupt notification while accessing the slave station 2 of # 1. # 2 slave station 2 is FM
The signal from the modulating unit 25 is cut by the relay 26, and the control unit 21 controls so as to output only light.

In the master station 1, the data in the information memory 17 does not match the data in the detector 14 because the slave station 2 of # 2 outputs light. The control unit 11 switches the address to the information memory 17 to the address of the level table when the # 2 slave station 2 issues an interrupt when the # 1 slave station 2 is accessed, and holds the data from the detection unit 14.

Next, the slave station of # 2 is changed to # 3 and # 4, and the light level at the time of each interruption is stored in the information memory 17.
To hold. In the same way as above, the access destination is
The light level at the time of changing from 2 to # 4 is held in the information memory 17.

As described above, by holding the light levels at the time of all the interrupt patterns, the same interrupt detection as in the above-described embodiment can be performed. FIG. 17 is a block diagram showing a tenth embodiment of the present invention. 7, 8, and 9 are denoted by the same reference numerals. The data in the information memory 17 in the above-described eighth embodiment is
As the number of devices increases, the amount of data also increases, and there is a limit to the difference in light level detectable level. Therefore, in this embodiment, the light level entering the master station 1 is made constant by the attenuator 6 for all the slave stations 2, and a timer 18 for monitoring the interrupt level detection time of the light level is provided. The operation of the circuit thus configured will be described as follows.

While the # 1 slave station 2 is performing polling from the master station 1, the # 2 slave station 2 disconnects the signal from the FM modulator 25 at the relay 26 in order to notify the interrupt. The control unit 21 controls so that only the light is output for a fixed time (the setting of the output time is changed for each slave station).

The detection of the interruption from the light level is the same as that of the sixth embodiment, but each of the slave stations 2 sends out a fixed time, as shown in FIG. When the level detector 14a detects an interrupt, the timer 18 counts the interrupt occurrence time, and the control unit 11 recognizes the counted value.

As shown in FIG. 19, the count value of the timer 18 is such that the count value before returning to “0” is the terminal number (terminal number × 1 clock) in which the interrupt has occurred. For example, in FIG. 19, the count value “2” before the counter returns to 0 becomes an interrupt from the slave station # 2, and the count value “3” before the counter returns to 0 becomes an interrupt from the slave station # 3. .

Therefore, by changing the function from the information memory 17 (see FIG. 12) to the timer 18, it is possible to determine the slave station that has generated the interrupt only by changing the counter capacity even if the slave station 2 increases. Will be able to

In the above-described embodiment, the case of the star connection shown in FIG. 1 is taken as an example, but the present invention is not limited to this, and is similarly applied to the case of the bus connection shown in FIG. be able to.

[0065]

As described above in detail, according to the present invention, (1) an optical signal reaching a master station from a slave station is converted into an electrical signal in the master station, and the level of the electrical signal is changed. Measuring, providing a detection unit that determines that the value has reached a certain level or more, providing an attenuator to keep the light level reaching the master station from the slave station, the master station communicates with the slave station While the access is being made, another slave station that has not been requested to access transmits a certain amount of light and issues an interrupt request, and at the master station, the detection unit detects that the light reception level has exceeded a certain value and accesses the base station. By recognizing an interrupt request from a slave station other than the slave station, another slave station that has not been requested to access while the master station is communicating with the slave station emits a certain amount of light and issues an interrupt request. If the light receiving level exceeds a certain Is detected, an interrupt request from another slave station can be determined.

(2) In the master station, a detecting section for converting an optical signal arriving from the slave station to the master station into an electric signal and measuring the level of the electric signal, and holding a value detected by the detecting section And a comparing unit for comparing the value of the holding unit with the value of the detecting unit, and when the control unit confirms that the master station has accessed the slave station and returned a response, the detecting unit at that time detects The measured light level is held by the holding unit, and the comparison unit determines whether the value held by the holding unit and the value measured by the detection unit match, and while the master station is accessing the slave station, When the slave station requests an interrupt by transmitting a certain level of light, the detection unit indicates a value in which the light level has increased from the state where the previous slave station is being accessed, and the comparison unit holds the value in the holding unit. If the value does not match the specified value, the control unit has generated an interrupt from another slave station. , The optical level from the slave station while the master station is accessing the slave station is held in the holding unit, and an interrupt request from another slave station is made based on the held light level. When there is, it is possible to determine that there has been an interrupt request from another slave station by increasing the light level.

(3) In the master station, a detector for converting an optical signal arriving from the slave station to the master station into an electric signal and measuring the level of the electric signal, and an optical level value from each slave station, An information memory that holds the light level value at the time of occurrence of the interrupt and a comparison unit that compares the value of the information memory with the value of the detector are provided. When a request occurs, the change in light level is measured by the detector,
The comparison unit compares the data with the data in the information memory, and when the comparison results match, the control unit recognizes that an interrupt has occurred from another slave station, so that the light level value from each slave station differs. And the light level at the time of interruption is held in the information memory, and the light level at the time of an interrupt request from another slave station is held at the information memory. By performing the comparison, it is possible to determine that there has been an interrupt request from another slave station.

As described above, according to the present invention, there is provided an optical polling access system capable of promptly issuing an interrupt notification such as an alarm / alarm from a slave station without interfering with ordinary polling access from a master station. be able to.

[Brief description of the drawings]

FIG. 1 is a principle block diagram of the present invention.

FIG. 2 is a principle block diagram of the present invention.

FIG. 3 is a block diagram showing a first embodiment of the present invention.

FIG. 4 is a block diagram showing a second embodiment of the present invention.

FIG. 5 is a block diagram showing a third embodiment of the present invention.

FIG. 6 is a block diagram showing a fourth embodiment of the present invention.

FIG. 7 is a block diagram showing a fifth embodiment of the present invention.

FIG. 8 is a block diagram showing a sixth embodiment of the present invention.

FIG. 9 is an operation explanatory diagram of the sixth embodiment of the present invention.

FIG. 10 is a block diagram showing a seventh embodiment of the present invention.

FIG. 11 is an operation explanatory view of a seventh embodiment of the present invention.

FIG. 12 is a block diagram showing an eighth embodiment of the present invention.

FIG. 13 is an operation explanatory diagram of the eighth embodiment of the present invention.

FIG. 14 is a diagram showing a terminal light level.

FIG. 15 is a block diagram showing a ninth embodiment of the present invention.

FIG. 16 is an operation explanatory diagram of the ninth embodiment of the present invention.

FIG. 17 is a block diagram showing a tenth embodiment of the present invention.

FIG. 18 is an operation explanatory diagram of the tenth embodiment of the present invention.

FIG. 19 is a time chart showing the operation of each unit.

FIG. 20 is a diagram showing polling access timing.

FIG. 21 is a diagram showing monitoring timing at the time of switching.

[Explanation of symbols]

 Reference Signs List 1 master station 2 slave station 3 downstream optical fiber 4 upstream optical fiber 5 optical coupler 11 control section 12 E / O conversion section 13 O / E conversion section 21 control section 22 E / O conversion section 23 O / E conversion section

Claims (3)

[Claims] In a system for transmitting information by connecting a master station and a plurality of slave stations with upstream and downstream optical fibers, an optical signal arriving from the slave station to the master station is converted into an electric signal in the master station. Converting, measuring the level of the electrical signal, providing a detection unit for determining that the value has exceeded a certain level, providing an attenuator for keeping the optical level reaching the master station from the slave station, While the station is communicating with the slave station, another slave station that has not been requested to access transmits a certain amount of light and issues an interrupt request, and at the master station, the detection unit detects that the light receiving level is higher than a certain value. An optical polling access system, characterized in that the optical polling access system detects an interruption request and recognizes an interrupt request from a slave station other than the accessing slave station. 2. A detecting unit for converting an optical signal arriving at a master station from a slave station into an electric signal and measuring a level of the electric signal, and a holding unit for holding a value detected by the detecting unit. And a comparing unit for comparing the value of the holding unit with the value of the detecting unit. When the control unit confirms that the master station has accessed the slave station and returned a response, the light measured by the detecting unit at that time is provided. The level is held in the holding unit, and the comparison unit determines whether the value held by the holding unit matches the value measured by the detection unit. When an interrupt is requested by transmitting light of a certain level, the detection unit indicates a value in which the light level is increased from the state where the previous slave station is being accessed, and the value held in the holding unit in the comparison unit is equal to the value held in the holding unit. If there is a mismatch, the control unit recognizes that an interrupt has occurred from another slave station. Light polling access system of claim 1, wherein Rukoto. 3. A detecting unit for converting an optical signal arriving from a slave station to the master station into an electric signal and measuring the level of the electric signal in the master station, and generating an optical level value and an interrupt from each slave station. An information memory that holds the optical level value at the time of the error and a comparison unit that compares the value of the information memory with the value of the detection unit are provided. Then, the change in the light level is measured by the detection unit, the comparison unit compares the data with the data in the information memory, and when the comparison results match, the control unit recognizes that an interrupt has occurred from another slave station. The optical polling access system according to claim 1, wherein: