JPH04170236A - Data transmission fault detector in communication equipment - Google Patents

Abstract

PURPOSE:To prevent transmission of a fault data to a communication line by informing it as a fault when a pulse signal sent at data transmission is returned cyclicly earlier than a prescribed delay time. CONSTITUTION:When each terminal interface section 32 sends a data to a transmission bus, a selector 9 is selected to send a pulse signal P. When the pulse signal P is returned cyclicly through other terminal interface section, a pulse input monitor circuit 7 measures the time when the pulse signal P is sent till it is received again. When the signal is received earlier than a specified delay time, it is discriminated that other terminal interface section sends a data simultaneously so as to be recognized as 'fault'. Thus, when the fault is detected., the transmission is stopped to prevent a fault data from being transmitted to a transmission line.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a transmission frame in which two or more communication devices to which a plurality of terminals can be connected are connected, and the transmission between the communication devices is composed of a plurality of channels. The present invention relates to a communication system carried out by a communication system, and particularly to a device for detecting an abnormality in data transmission from a plurality of terminals to a device channel consisting of one basic section for transmitting frames and a plurality of terminal interface sections.

[Prior art] In recent years, due to the diversification of communications, one
Increasingly, users are connecting multiple different devices instead of just one terminal device.

As a typical example, Fig. 5 shows an example of the configuration of a circuit-switched LAN system. (A or B) is connected.

FIG. 6 shows an example of the configuration of the transmission frame 21 of the circuit-switched LAN. The transmission frame 21 is composed of a plurality of channels, and transmission between terminals is performed by occupying a part of the transmission frame according to channel assignment. For example, terminal A and terminal B have channel "'1"
'', and telephone A and telephone B decide to use channel "2" and perform mutual transmission.

FIG. 7 shows an example of the internal configuration of a circuit-switched LAN node. The inside of the node is comprised of a basic unit 31 that performs frame transmission, channel multiplexing, etc., and a plurality of terminal interface units 32a and 32b that manage the interface between the basic unit and the terminals. There are various methods for connecting the basic part and the terminal interface part, but here, we will consider a configuration as described below.

First, in reception, a signal from the channel receiving section 33 in the basic section is sent to all the terminal interface sections 3 via the receiving bus 34.
2, and each terminal interface section 32, when receiving pre-assigned channel data, takes it in and controls it to send it to the terminal. Transmission is first performed by each terminal interface section 32 and the channel transmitting section 3 within the basic section.
6 is connected by one transmission bus 35. Each terminal interface unit 32 is connected to the transmission bus through a 3-state gate to prevent signals from colliding, and gates 1 to 3 are opened only when transmitting to a pre-assigned channel. Then, the data from the terminal is sent to the channel transmitter 36. The channel transmitting unit 36 basically only performs the operation of writing data from the transmitting bus 35 into the channel.

In the case of this method, there is no need to separately provide signals between the node basic section 31 and the terminal interface section 32 for each terminal interface section, so there is an advantage that the number of signals can be reduced and the amount of hardware can also be reduced.

[Problems to be Solved by the Invention] However, in FIG. 7, the transmission bus 35 has the outputs from the respective terminal interface sections 32a and 32b connected in a wired-OR manner, so that a plurality of terminal interface sections are gated at the same time. When I turn on and output to bus 35, a problem occurs.

If simultaneous output from a plurality of terminal interface units can occur, it is possible that there is a mistake in the channel allocation settings for the terminal interface units.

In this case, since the node basic unit 31 does not have a means to detect this, the abnormal data is written as is into the channel and transmitted from the node. This abnormality detection basically has to be carried out on the receiving terminal side, but if the receiving terminal does not perform a data error check (CRC check, etc.), the abnormal data will be received as is, which may cause problems depending on the system. There are cases where this happens.

Therefore, regarding such an abnormality within the communication devices 1a to 1d, a function is required to detect this within the communication device and prevent abnormal data from being sent to the terminal side.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to quickly detect when an abnormality in data transmission from a certain terminal interface section to the basic section occurs, and to stop the abnormal data communication. An object of the present invention is to provide a data transmission abnormality detection device in a communication device.

[Means for Solving the Problems] The data transmission abnormality detection device of the present invention is characterized in that two or more communication devices to which a plurality of terminals can be connected are connected to a transmission path, and transmission between the communication devices is composed of a plurality of channels. A communication system performed using a transmission frame in which a communication device
It has a basic part to which transmission frames are actually transmitted, and a plurality of terminal interface parts to which the terminal data transmission bus line to the basic part is connected by wired OR, and when transmitting data from a terminal, the terminal In a communication system configured such that the terminal interface section writes data from the terminal to the channel when the channel allocated for the communication device passes through the basic section, one In addition to connecting with the line, each terminal interface section has
A delay circuit that gives a certain delay to the signal flowing through the above line, a pulse generator that sends a pulse signal to the above line when transmitting data from the terminal to the channel, and a pulse signal that returns after completing one cycle. This configuration includes a pulse input monitoring circuit that notifies an abnormality if the signal returns earlier than a predetermined delay time.

[Function] The gist of the present invention is as follows: (1) One signal line is provided to sequentially connect each terminal interface section. In addition, in each terminal interface section,
It has a built-in circuit that delays the signal flowing on this line by a certain amount of time.

(2) Each terminal interface section transmits a pulse signal to the above line when transmitting data to the basic section. Then, the time required for the pulse signal to complete one cycle and return is monitored, and if the pulse signal returns earlier than a predetermined delay time (delay time equal to the number of terminal interface units), other terminal interface units also transmit data at the same time. Recognize the abnormality as something that is happening.

As a result, it becomes possible to quickly detect an abnormality in which multiple terminal interface units transmit data simultaneously to one channel, thereby improving communication systems using such devices. This greatly improves the reliability of the system.

[Example] The present invention will be described in detail with reference to FIG. 1, FIG. 2, and FIG.

FIG. 1 shows four terminal interface units 3 in one node.
2 is a connection diagram of transmission-related signals when 2a to 32d are connected. Each terminal interface section 32a~
The transmission output from 32d is wired-or connected by the transmission bus 35 to the node basic section (see 31 in Fig. 7).
However, in addition to that, each terminal interface section 3
One continuous in 4 is provided to sequentially connect between 2a to 32d. In the example of FIG. 1, terminal interface units 32a, 32cl, and 32c are connected on this connection line 4.

Data flows in the order of 32b, 32a, . . . .

FIG. 2 shows the configuration of each of the terminal interface sections 32a to 32d regarding the control of the terminal interface section connection line 4, and shows the terminal interface section 32 representing one of them.
This is shown in .

For reception from the front terminal interface section, a circuit 6.degree. for giving a certain delay time to the signal and a circuit 7 for monitoring the received pulse signal are provided. The amount of delay in the signal delay circuit 6 must be set to the same value for all terminal interface units.

For transmission to the next-stage terminal interface section, a selector 9 is provided for selecting whether to relay the signal from the previous stage as it is or to transmit the output from the internal pulse generator 8. When each terminal interface unit 32 sends data to the transmission bus 35, it switches the selector 9 and controls the pulse signal P to be transmitted. and,
When the pulse signal P passes through another terminal interface section and returns, the pulse input monitoring circuit 7 measures the time from when the pulse signal P is transmitted to when it is received. If that time is the specified delay time (determined by the delay time of the signal delay circuit x the number of terminal interface units), it is recognized as ``normal'' as the only person sending data to the transmission bus at that time is itself. do. However, if the pulse signal P is received earlier than the specified delay time, it is assumed that other terminal interface units are also transmitting data at the same time, and this is recognized as an "abnormality."

FIGS. 3 and 4 show how pulse signals are transmitted and received during normal and abnormal times. 3 and 4 illustrate the case where the terminal interface sections 32a and 32c transmit to the channel in the configuration in which the four terminal interface sections 32a to 32d shown in FIG. 1 are connected. .

In FIG. 3, regarding the channel transmission right, channel n
is used by the terminal interface unit 32a.

Channel n+1 is clearly divided to be used by the terminal interface unit 32c, and the pulse signal P transmitted by both terminal interface units 32a and 32c when they have channel transmission rights is delayed by a predetermined delay time (in this case is the delay time of four terminal interface sections), then
Self (This is received.

FIG. 4 shows a case where the terminal interface section 32c also attempts to use channel n, although channel n is originally supposed to be used by the terminal interface section 32a. In this case, the terminal interface sections 32a, 3
2c does not receive the pulse signal sent by itself, and the output signal of the terminal interface section 32c is first sent to the terminal interface section 32a.
2c receives the signal output from the terminal interface section 32a first. Therefore, the time from when the pulse signal is sent out until the pulse signal is received is the time for two terminal interface units, which is shorter than the predetermined delay time.

Therefore, from the comparison of the delay times, an abnormality of simultaneous transmission by multiple terminal interface sections is detected. There are various possible measures to take when an abnormality occurs; for example, when an abnormality is detected by the method described above, measures such as stopping transmission and preventing abnormal data from being sent to the transmission path may be taken.

In the above embodiment, a circuit-switched loop network was explained as an extension of the conventional technology. The method according to the present invention can be applied to a communication device configured as shown in FIG.

[Effects of the Invention] As explained above, according to the present invention, it is possible to quickly detect an abnormality in which a plurality of terminal interface units simultaneously transmit data to one channel, thereby preventing abnormal data from being transmitted onto a communication path. It becomes possible to prevent transmission,
As a result, a highly reliable system can be provided.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the connection between terminal interface sections in an embodiment of the present invention, FIG. 2 is a diagram showing the internal configuration of the terminal interface section, and FIG. 3 is a diagram showing the propagation of a pulse signal during normal operation. Figure 4 is a diagram showing the propagation of a pulse signal during an abnormality, and Figure 5 is a diagram showing a general line-switched type L.
FIG. 6 is a diagram showing an example of the system configuration of an AN, FIG. 6 is a diagram showing an example of the frame configuration of the circuit-switched LAN, and FIG. 7 is a diagram showing an example of the node configuration of the circuit-switched LAN. In the figure, 1a to 1d are circuit switched LAN nodes, 2 is a loop transmission path, 21 is a transmission frame, 31 is a node basic section, 32.32a to 32d are terminal interface sections, 3
3 is a channel reception section, 34 is a reception bus, 35 is a transmission bus, 36 is a channel transmission section, 4 is a connection line between terminal interface sections, 6 is a signal delay circuit, 7 is a pulse input monitoring circuit, and 8 is a pulse generator. , 9 indicate a selector. Patent applicant: Nobuo Kinutani, Patent Attorney, Hitachi Cable Co., Ltd.

Claims (1)

[Claims] 1. A communication system in which two or more communication devices to which a plurality of terminals can be connected are connected to a transmission path, and transmission between the communication devices is performed using a transmission frame composed of a plurality of channels, in which the communication device is It has a basic part to which transmission frames are actually transmitted, and a plurality of terminal interface parts to which the terminal data transmission bus line to the basic part is connected by wired OR, and when transmitting data from a terminal, the terminal In a communication system configured such that the terminal interface section writes data from the terminal to the channel when the channel allocated for the communication device passes through the basic section, one In addition, each terminal interface section includes a delay circuit that provides a certain delay to the signal flowing through the above line, and a pulse signal that is transmitted to the above line when transmitting data from the terminal to the channel. A data transmission abnormality detection device for a communication device, characterized in that it is provided with a pulse generator that performs one cycle, and a pulse input monitoring circuit that reports an abnormality when a pulse signal that has gone through one cycle and returns earlier than a predetermined delay time. .