JPS62203441A - Abnormality processing circuit for repeater - Google Patents

Abstract

PURPOSE:To ensure the communication in a normal segment by adopting the constitution that the state of a main control section is restored forcibly into the idle state by a reset signal outputted from a reset generating section when a signal exceeding a maximum packet length is inputted from any segment. CONSTITUTION:When the inputted signal exceeds the maximum packetlength and a state signal from a main control section 18 is consecutive for a prescribed time or more, the state detection of a state detection section 19 continues for a long time and a timer section 20 outputs a timeup signal. The main control section 18 to which a reset signal generated by a reset generation section 21 is supplied is restored to the idle state Id to interrupt the relay of both segments 2, 3. If one of the station of one segment 2(3) is faulty, the segment 2(3) of the faulty station is separated from other segment 3(2). Thus, no effect of the faulty station is given to the other segment 3(2), and the communication is ensured.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is applicable to a common bus type local area network (LAN) such as the C8MA/CD type, in which data and conflict status are relayed between segments. This invention relates to an abnormality processing circuit for an i-device.

<Prior art> Since CSMA/CD type LAN communicates using baseband on one common bus, bidirectional transmission is originally impossible, but the middle U unit used in this type of LAN ,
Bidirectional relaying is achieved by switching the relaying direction of signals on the common bus on a first-come, first-served basis without collisions.

In this type of LAN, signals sent from multiple stations collide on a common bus. Therefore, medium aV
In S, a collision situation that occurs on both sides or one side is
It is relayed in the same way as normal data packets.

<Problems to be Solved by the Invention> By the way, in the CS MA/CD type LAN, the operation sequence and processing method of each station are strictly determined, so the situations that can occur on the common bus are as follows. It can be fully predicted. Therefore, the repeater may be designed to handle situations that are expected to occur.

However, not all devices connected to a LAN always operate normally according to the required specifications.
Malfunctions may cause abnormal operation. In addition, external noise may cause abnormal situations that could not be predicted at the repeater design stage.

If such an abnormal situation is transmitted to other normal segments by the repeater, communication in the other normal segments will be inhibited, and the reliability of the entire LAN will be significantly impaired.

The present invention has been made in view of the above-mentioned problems, and when an abnormal situation occurs in any segment, the relay operation from the segment where the abnormality has occurred to other segments is stopped, and the abnormal situation is resolved. By temporarily separating the abnormal segment from the normal segment until the problem is resolved, the purpose is to ensure communication within the normal segment and improve the reliability of the entire LAN.

Means for Solving Problems> In order to achieve the above object, the present invention provides an idle state in a main control section that transitions from an idle state to a required operating state in response to signal input from each segment. a state detection section that introduces a state signal indicating each operating state other than that and detects the continuation of that operating state; a timer section that operates a timer for a certain period of time in response to the state detection by the state detection section; and the timer section. and a reset generating section which gives a reset signal to the main control section in response to the time-up signal of the main control section to return the main control section to an idle state, thereby configuring an abnormality processing circuit for the repeater.

According to the above configuration, when a signal is input from any segment through the transceiver, the main control section in the repeater shifts from an idle state to an operating state according to the signal input, and transmits the data signal to another. However, if an abnormal situation occurs such as a station in one of the segments transmitting a data signal that exceeds the maximum packet length due to a failure or other cause, the main control unit A signal with a length greater than 100 kHz will result in a longer stay in the same operating state.

The state detection section detects that the main control section remains in the same operating state. When the time for which the device remains in the same operating state exceeds a certain period of time, a time-up signal is output from the timer section, and in response to this time-up signal, the reset generation section outputs a reset signal. This reset signal causes the main controller to return to an idle state, and whatever operating state the repeater itself is in is interrupted. This separates the segment in which the abnormality has occurred from the normal segment.

<Example> Hereinafter, the present invention will be described in detail based on an example shown in the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG. 2 is a state diagram showing the operation of its main control circuit.

In FIG. 1, the repeater l of this embodiment is provided between a first segment 2 and a second segment 3. In FIG. First coaxial cable 4 forming first segment 2
is attached with a first transceiver 5, and a second coaxial cable 6 constituting the second segment 3 is attached with a second transceiver 5.
A transceiver 7 is attached.

The repeater 1 includes a main circuit 8 that relays data signals and collision signals, and an abnormality processing circuit 9.

The main circuit 8 includes first and second decoders 10.2 that respectively decode signals inputted through the first and second transceivers 5.7, and the first and second transceivers 5.2.
7 respectively encode the signals to be output through the first
and a second encoder 12.13, and first and second encoders 12.13 for detecting a collision condition on the first or second coaxial cable 4.6, respectively, through the first and second transceivers 5.7, respectively.
a collision detection unit 14, 15, and a FIFO circuit unit (first-in/first-out circuit unit) 16 that absorbs the error between the clock of the human input signal and the clock of the repeater l itself;
An output control section 17 that switches the direction of signal transmission to the FIFO circuit 16, decoders 10 and 11, and a collision detection section 1.
4.15 and a main control section 18 that controls the switching operation in the output control section 17 in response to the signal from the output control section 17. The main control unit 18 is configured to shift from an idle state, which is a state in which it waits for a signal input, to a required operating state in response to signal input from each segment 2.3.

Furthermore, the abnormality processing circuit 9 includes a state detection section! 9, a timer section 20, and a reset generation section 21. The state detection unit 19 introduces a state signal indicating each operating state other than the idle state in the main control unit 18 and detects the continuation of that operating state. The timer section 20 operates as a timer for a certain period of time in response to the state detection by the state detection section 19. The fixed time period during which the timer unit 20 operates is set in accordance with the maximum length of a normal data packet. Reset generation section 2
1 outputs a reset signal in response to the time-up signal of the timer section 20. The reset signal output from the reset generating section 21 is given to the main control section 18 of the main circuit 8, and the operating state of the main control section 18 is reset to an idle state in which no relay operation is performed.

Next, the operation of the above configuration will be explained.

All stations in each segment 2.3 are normal,
When transmitting a data packet of a predetermined length, the main body circuit 8 of repeater l relays the data packet to another segment 2.3. The operation in this case is as shown in the state diagram of FIG.

That is, when each transceiver 5.7 is not receiving any data packets, the main controller 18 is in the idle state Id.

Now, when a data packet is input to the first decoder lO through the first transceiver 5, the main control unit 18 detects the signal input from the first segment 2 by the signal from the first decoder lO, and to the second segment 3 enters the relay state R12. When this relay state R12 is reached, the switching in the output control unit 17 becomes a switching state corresponding to middle@R12. Therefore, the signal input to the first decoder 10 is decoded by the decoder 10, temporarily stored in the FIFO circuit section 16 through the output control section 17, and then sent to the second encoder 13 through the output control section 17 again. coded, second transceiver 1
7 onto the second segment 3.

When the signal input from the first segment 2 is completed, the main control unit 18 returns from the relay state Rt2 to the idle state Id, but it is not in the relay state! When a collision occurs in the first segment 2 at R12, the collision state is detected by the first collision detection unit 14.
Detected by Based on the detection signal from the collision detection unit 14, the main control unit 18 causes the collision relay state f! to relay the collision to the second segment 3. [Move to J2. As a result, the collision condition in the first segment 2 is relayed to the second segment 3.

Here, when the signal input from the first segment 2 ends, the main control section 18 shifts to the idle state ■d, but when a signal is input from the second segment 3 during this collision relay state J2, both segments A collision occurred at 2.3. In that case, the main control unit 18 shifts to a collision notification letter IJ12 that notifies both segments 2 and 3 of the collision state, and outputs a collision signal to both segments 2.3.

Furthermore, when a signal is input from the second segment 3 in the middle of the relay state an t 2 mentioned above, both segments 2.3
A conflict has occurred between them. In this case as well, the main control unit 18 sends a collision notification letter @J 12 to both segments 2.3.
The collision signal is output to both segments 2°3.

Each of the above operations is performed when a signal is first input to the first transceiver 5. However, when a signal is first input to the second transceiver 7, the main control unit 18 performs the following operations in each of the above cases. and relay in the opposite direction.

That is, when a signal is first input to the second transceiver 7, the main control unit 18 transmits the relay signal *nz to the first segment 2.
t, and if a collision occurs in the second segment 3 in the middle of the relay state @R21, the state shifts to the collision relay state Jl to the first segment 2, and in the middle of the collision relay state J1,
When a signal is input from the first segment 2, a collision notification state JI2 for both segments 2 and 3 is entered. Also, if a signal is input from the first segment 2 during the relay state R21, the state shifts to the collision notification state J12 for both segments 2.3.

In this way, when a signal is input from any segment 2.3, the main control unit 18 is in an operating state other than the idle state 11111d! r(l 2.R12, J 1.J 2゜J
12, and when there is no signal from any segment 2.3, the idle state 1d is returned. The length of the data signal input from each segment 2.3 is limited to a certain packet length, and the signal indicating a collision is also shorter than the certain packet length. Therefore, the time during which the main control unit 18 remains in a state other than the idle state Id is within the time corresponding to the maximum length of the data packet.

However, one of the stations connected to each segment 2.3 may transmit a data signal longer than a certain packet length due to a failure or other cause. Also,
A signal longer than a certain packet length may be input due to external noise.

In such a case, the main control unit 18 will remain in the same operating state for a time longer than the maximum packet length, but according to the present invention, the main control unit 18 will be Automatically returns to idle state Id.

That is, a signal indicating an operating state other than the idle state @Id in the main control section 18 is input to the state detection section 19. When the status signal is detected by the status detection unit 19, the timer unit 20 starts operating in response to this detection. This timer section 2
0 counts a time that is equal to or slightly longer than the maximum length of the data packet, and if the same status signal is continuously input to the status detection unit 19,
Continue timer operation.

If the signal input to relay a51 is a normal signal,
The operating state of the main control section 18 that operates in response to the signal is within a certain period of time. Therefore, the timer unit 20 stops its operation and returns to its initial state before the timer reaches its time-up. However, if the input signal exceeds the maximum packet length, the time during which the main control section 18 remains in one of the operating states exceeds a certain period of time.

In this manner, when the status signal from the main control unit 18 continues for a certain period of time or more, the status detection unit 19 continues detecting the status for a long time, and therefore the timer unit 20 outputs a time-up signal. In response to this time-up signal, the reset generating section 21 generates a reset signal. This reset signal is
Since the main control unit 18 is fed to the main control unit I8, the main control unit 18 is in the idle state
Return to d. As a result, the relay between both segments 2 and 3 is cut off. Therefore, one segment 2(3)
If one of the stations is faulty, the segment 2(3) with the faulty station is isolated from the other segments 3(2). Therefore, other segments 3(2) are not affected by the failed station, and communication within the other segments 3(2) is ensured.

If a signal exceeding the maximum packet length is input due to a temporary abnormality in the station or external noise, and relaying is interrupted, the abnormality will normally recover automatically within a short time and each transceiver will A normal signal will now be input to 5.7. When a normal signal is input, the main control unit 18 shifts from the idle state [d to a desired operating state and resumes the relay operation.

<Effects of the Invention> As described above, according to the present invention, when a signal exceeding the maximum packet length is input from any segment, the main control unit remains in the same operating state other than the idle state for a long time. Therefore, the state detection section and timer section that monitor the operating state of the main control section operate, and the reset signal is output from the reset generation section, and the reset signal forces the main control section into the idle state. be returned. Therefore, the middle U operation of the repeater is stopped and the abnormal segment is temporarily separated from the normal 7 segments until the abnormal situation is resolved. This ensures normal intra-segment communication and increases the reliability of the entire LAN.

Furthermore, since the abnormality processing circuit is provided separately from the main control section, the burden placed on the main control section to deal with abnormal situations is reduced, and the configuration of the main control section is simplified, making design easier.

Furthermore, even if the main body circuit including the main control section malfunctions, the relay will be interrupted, and it is possible to effectively deal with the occurrence of an abnormality in the repeater itself.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a state diagram showing the operation of the main control section. l...Repeater, 2...First segment, 3...Second segment, 8...Main circuit, 9...Abnormality processing circuit, 18...Main control unit, 19... state detection unit, 20
...Timer section, 21...Reset generation section.

Claims (1)

[Claims] (1) An abnormality processing circuit for a repeater having a main control section that transitions from an idle state to a required operating state in response to signal input from each segment, each operating state other than the idle state in the main control section a state detection unit that detects the continuation of the operating state by introducing a state signal indicating the state; a timer unit that operates a timer for a certain period of time in response to the state detection by the state detection unit; An abnormality processing circuit for a repeater, comprising: a reset generating section that responds by giving a reset signal to the main control section to return the main control section to an idle state.