JPH10271145A - Communication network terminal equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication network terminal equipment with which high-reliability data transmission is performed and a communication network, is attained by preventing the entire network from being affected by a fault even when that fault occurs at partial terminal equipment connected to the communication network. SOLUTION: Separately from a software control part 70, a transmission permission discrimination circuit 36 is provided with a hardware circuit, and a transmission line use permit signal corresponding to a present station is detected by this circuit 36. On the other hand, the software control part 70 detects the relevant signal as well. Both the detected results are inputted to an output control circuit 74 and when both the signals are satisfied together, the output control circuit 74 opens the gate of output circuit 34 and enables to transmit transmission signal from the software control part 70 to a transmission line 22. Besides, when any abnormality at the software control part 70 is detected by a main processing part monitoring circuit 72, the gate of the output circuit 34 is closed and the sending of the transmission signal is inhibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication network terminal connected to a communication network for transmitting and receiving data, and more particularly to improvement in reliability related to channel assignment.

[0002]

2. Description of the Related Art Conventionally, in a communication network system, a plurality of nodes (terminals) connected to a transmission line alternately send data to the transmission line under a certain control, thereby transmitting data on the transmission line. To prevent data collision and realize reliable data transmission. The control for allocating the use of the transmission path to each node is called channel allocation, and there are several methods.

One of the simple ones is a polling method. In a network system adopting the polling method, one control node is provided, which controls the use of a transmission line for many other general nodes. For example, the control node gives a transmission path use permission by designating general nodes in order. In other words, a certain order is defined between the general nodes, and the control node asks each general node according to the order to determine whether or not there is a transmission request. And data can be transmitted to the transmission path.

Another well-known system is the token system. In this method, one token is generated in the network system, and this token is sequentially circulated between nodes. This token gives the transmission path use permission, and the node that has obtained this token transmits data to the transmission path and then transfers the token to the next node.

FIG. 5 is a schematic configuration diagram of a conventional bus-connected network using a polling method. Transmission line 2
Is composed of two electric signal lines 2a and 2b. In the figure, a master station 4 as a control node and one slave station 6 are shown. Each of the master station 4 and the slave station 6 has a hardware control unit 8 and a software control unit (main processing unit) 10. The hardware control unit 8 includes an input circuit 12 and an output circuit 14. .

[0006] The input circuit 12 is connected to the transmission path 2 and receives an electrical transmission signal on the transmission path 2. Then, the input circuit 12 processes the transmission signal based on a communication protocol adopted in the communication network. The processed received signal is input to the software control unit 10. On the other hand, the data output from the software control unit 10 is converted into a transmission signal based on a communication protocol in the output circuit 14 and transmitted to the transmission path 2.

For example, in the polling system, the master station 4
Asks each slave station in turn for the presence or absence of a transmission request. Specifically, a transmission line use permission signal designating a specific slave station is transmitted from the master station 4 to the transmission line 2. This signal can be received by each slave station. Software control unit 10 of slave station 6
Monitors a received signal output from the input circuit 12 and, when detecting a transmission path use permission signal therein, determines whether or not the signal is for the own station. Generally, the transmission path use permission signal stores the address of the slave station to which permission is given, and the determination can be made based on this address.

When the transmission path use permission signal is for the own station, the software control unit 10 starts the transmission process if there is data requested to be transmitted from an application or the like, and outputs the data to the output circuit 14. To send to. The output circuit 14 converts the received data into a transmission signal as described above and sends the signal to the transmission line 2.

[0009]

In a conventional communication network system, control is performed on a communication node that permits the use of a transmission path as described above, but control is performed on a communication node that is not permitted to use the transmission path. In other words, control to prohibit the use of the transmission path has not been performed. Therefore, for example, when an error occurs in processing in the software control unit 10 of a node not specified in the permission signal, the software control unit 10 may transmit data ignoring polling or a token. In that case, the data is transmitted through the transmission line 2 in the conventional communication node.
And a transmission signal such as a packet transmitted from a communication node that has obtained a proper permission causes a collision on the transmission path 2. That is, in a conventional node (terminal device) connected to a communication network, there is a problem that channel assignment is not correctly performed in response to a node failure, and the entire network may be down.

[0010] The present invention has been made to solve the above problems, and has as its object to improve the reliability of channel assignment control. Provided is a communication network terminal device that realizes a communication network capable of performing data transmission with high reliability, even if a failure occurs in a main processing unit of the terminal device, the effect of which is prevented from spreading to the entire network. The purpose is to:

[0011]

A communication network terminal device according to the present invention comprises: an input circuit for receiving a transmission signal on a transmission line of a communication network and processing the transmission signal based on a communication protocol; A communication network terminal device comprising: a main processing unit for transmitting transmission data when a transmission path use permission signal is detected; and an output circuit for converting the transmission data into a transmission signal based on the communication protocol and transmitting the transmission signal to the transmission path. Detecting the transmission path use permission signal included in the output of the input circuit, determining that transmission from the device is permitted based on the transmission path use permission signal, and outputting a transmission permission determination signal. A transmission permission determination circuit, based on the transmission permission determination signal,
And an output control circuit for controlling whether or not the transmission signal can be transmitted from the output circuit to the transmission path.

Further, in the communication network terminal device according to the present invention, the main processing unit determines that transmission from the device is permitted based on the transmission path use permission signal, activates data transmission processing, and A transmission processing activation unit that outputs a transmission processing activation notification signal to the output control circuit, wherein the output control circuit is configured to output the transmission processing activation notification signal when both the transmission permission determination signal and the transmission processing activation notification signal are input. The output from the output circuit is controlled as possible.

Further, the communication network terminal device according to the present invention is a main processing unit monitoring circuit for monitoring whether or not the processing of the main processing unit is normal, and outputting a main processing unit abnormality detection signal when detecting an abnormality in the processing. Wherein the output control circuit performs control to prohibit output from the output circuit when the main processing unit abnormality detection signal is input.

[0014]

Next, embodiments of the present invention will be described with reference to the drawings.

Embodiment 1 FIG. 1 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to an embodiment of the present invention. Transmission line 22
Is composed of two electric signal lines 22a and 22b. In the figure, a master station 24 and one slave station 26, which are control nodes, are shown.

The master station 24 transmits a polling signal which has been well known as a transmission path use permission signal. In this polling signal, the address of each slave station 26 and other identifiers are specified in a predetermined order. Each slave station receives this polling signal, and is given the right to process a transmission request for a transmission line when the polling signal includes an address or the like designating its own station.

Each of the master station 24 and the slave station 26 includes a hardware control unit 28 and a software control unit (main processing unit) 30. The hardware control unit 28 includes an input circuit 32, an output circuit 34, A judgment circuit 36 and an output control circuit 38 are included.

Usually, these terminal devices are composed of a general-purpose computer and a circuit for connecting it to a network. The software control unit 30 includes a central processing unit (CPU) of the computer.
nit), and its functions are executed by program processing on the CPU. On the other hand, the function of the hardware control unit 28 is realized not by software processing executed by the CPU but by a hardware circuit.

The input circuit 32 is connected to the transmission line 22,
An electric transmission signal represented by a potential difference between the electric signal lines 22a and 22b is received. Then, the input circuit 32 performs a process on the transmission signal based on a communication protocol adopted in this communication network. Specifically, the processing performed by the input circuit 32 is a lower level of the processing of the communication protocol, for example, a hardware control level or a physical layer level in a general hierarchical protocol. Processing is targeted. The received signal processed by the input circuit 32 is input to the software control unit 30, and the remaining high-level processing is performed by software in the software control unit 30.

On the other hand, the software control section 30 performs higher-level processing of a communication protocol on transmission data by software. Then, the transmission data processed to an intermediate level of the protocol is input to the output circuit 34,
Here, the processing based on the communication protocol is completed. The transmission signal generated by the output circuit 34 is connected to the electric signal line 22a,
The signal is transmitted to the transmission line 22 as a potential difference signal between the terminals 22b.

In the present embodiment, the master station 24 and the slave station 26
The major feature of the terminal device is that the transmission permission determination circuit 3
6. It has an output control circuit 38. When detecting the polling signal from the master station 24 in the output signal of the input circuit 32, the transmission permission determining circuit 36 determines whether or not the polling is for the own station based on the address or the like specified in the signal. If it is determined that the own station has been designated, the transmission permission determination circuit 36 outputs a transmission permission determination signal.

The output control circuit 38 outputs a signal based on the transmission permission determination signal output from the transmission permission determination circuit 36.
It controls whether a transmission signal can be transmitted from the output circuit 34 to the transmission line 22. For example, when the output control circuit 38 obtains the transmission permission determination signal, it opens the gate in the output circuit 34,
Conversely, when the transmission permission determination signal cannot be obtained, an output gate opening / closing signal for closing the gate in the output circuit 34 is output to the output circuit 34.

Thus, the data output from the software control unit 30 is transmitted to the transmission line 22 only when the transmission permission determination circuit 36 detects the polling signal for the own station.

The hardware control unit 28 including the transmission permission judgment circuit 36 and the output control circuit 38 is constituted by a hardware circuit in contrast to the software control unit 30, and executes a quicker and more reliable process. Can be.

The software control unit 30 can execute program processing of various applications and the like in addition to the communication processing program. In general, there should be no problem because they are managed by an operating system or the like so as not to interfere with each other. However, the fact that software processing is more flexible than hardware processing means that, conversely, errors such as interference between programs cannot be denied at all. Considering such a situation, it cannot be said that for some reason, the communication processing program abnormally operates and the data transmission processing is not started even though the channel is not allocated to the own station.

However, in the terminal device described in the present embodiment, the transmission permission determination circuit 36 and the output control circuit 38 determine polling of the own station separately from the software control unit 30 to control the opening and closing of the output circuit 34. Do. Therefore, even if the processing by the software control unit 30 becomes abnormal and data is transmitted, the data is not transmitted to the transmission line 22 because it is blocked by the output circuit 34. That is, a situation does not occur in which transmission signals from other nodes on the transmission path 22 are interfered with or the channel assignment control of the network system is disturbed to bring down the entire network system.

[Second Embodiment] FIG. 2 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to a second embodiment of the present invention. FIG.
The components having the same functions as those in FIG.
The same reference numerals are given and the description is omitted.

The terminal device shown in FIG. 2 is different from the terminal device shown in FIG.
0 is a point at which the transmission processing start notification signal 54 is input from the software control unit 52.

The software control unit 52 has basically the same function as the software control unit 30 and
2 is monitored, and when a polling signal for the own station is detected therein, the data transmission process is started. Here, what is characteristic of the software control unit 52 is that, when the data transmission processing is properly started based on the polling, the fact is notified to the transmission processing start notification signal 54.

On the other hand, the output control circuit 50 controls opening and closing of the output circuit 34 based on not only the transmission permission judgment signal from the transmission permission judgment circuit 36 but also the transmission processing start notification signal 54. That is, the output control circuit includes a transmission permission determination signal indicating that the transmission permission determination circuit 36 has detected the polling of the own station, and a transmission processing start notification signal 54 indicating that the software control unit 52 has detected the polling of the own station. When both are obtained, the transmission of the transmission signal from the output circuit 34 to the transmission line 22 is permitted.

As described above, since the double check is performed by the hardware polling check and the software polling check, the reliability of the terminal device in data transmission can be further improved.

[Third Embodiment] FIG. 3 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to a third embodiment of the present invention. FIG.
In FIG. 2, components having the same functions as those in FIGS. 1 and 2 are denoted by the same reference numerals as those drawings, and description thereof is omitted.

The terminal device shown in FIG. 3 is different from the terminal device of the above-described embodiment in that a hardware control unit 68 monitors an abnormality of a software control unit 70 as a main processing unit. That the main processing unit monitoring circuit 72 outputs a main processing unit abnormality detection signal to the output control circuit 74 when the abnormality of the software control unit 70 is detected, and that the output control circuit 74 outputs the main processing unit abnormality detection signal. The point is that transmission of a transmission signal from the output circuit 34 is prohibited when the signal is input.

The monitoring of the software control unit 70 by the main processing unit monitoring circuit 72 is performed, for example, as follows. The software control unit 70 executes a self-diagnosis program. The self-diagnosis program monitors another program executed by the software control unit 70. When the self-diagnosis program detects an abnormality, the self-diagnosis program issues a signal to notify the main processing unit monitoring circuit 72.

Further, the self-diagnosis program may be configured to notify the main processing unit monitoring circuit 72 of a predetermined signal even during normal operation. With this configuration, the main processing unit monitoring circuit 7
2 means that the self-diagnosis program itself became abnormal,
Judgment can be made from the fact that the normal signal is not sent.

It is also possible to adopt a configuration in which the main processing section monitoring circuit 72 makes an inquiry to the software control section 70 at any time and determines whether the software control section 70 is normal or abnormal based on the response. is there.

The output control circuit 74 includes a transmission permission determination circuit 3
6 outputs the transmission permission determination signal and the software control unit 70 outputs the transmission processing start notification signal, the transmission from the output circuit 34 when the main processing unit monitoring circuit 72 outputs the main processing unit abnormality detection signal. Transmission of the transmission signal to the path 22 is prohibited. Only if all three conditions are met,
The output circuit 34 can output the transmission signal to the transmission line 22. By adopting such a fail-safe configuration, the reliability of the terminal device with respect to data transmission can be further improved.

[Fourth Embodiment] FIG. 4 is a schematic configuration diagram of a communication network system of a ring connection type using a polling method according to a fourth embodiment of the present invention. The configuration of the terminal device shown in FIG. 4 is the same as that described in the third embodiment.

The terminal device described above is also effective for such a ring connection type network. In addition, the terminal device according to the present invention is effective in various network connection forms such as a star connection type.

Further, in the above-described embodiment, the polling method has been described as an example of the channel allocation method. However, it is easy to understand that a terminal device having the same configuration is also effective for, for example, channel allocation in the token method. Will be understood.

[0041]

According to the communication network terminal device of the present invention, the transmission permission judgment circuit provided separately from the main processing section judges the transmission path use permission signal for itself, and the output control circuit determines the transmission path use permission signal based on the result. Controls whether a transmission signal can be transmitted from the output circuit to the transmission path. Therefore, even if the main processing unit starts transmitting data irrespective of the transmission path use permission signal due to some failure, the data is blocked by the output circuit and is not transmitted to the transmission path 22. In other words, there is an effect that a highly reliable communication network terminal device in which data is not erroneously transmitted is obtained, and thus a failure of one terminal device is prevented from adversely affecting a wide range of the communication network, The effect that the reliability of a network is ensured is obtained.

According to the communication network terminal device of the present invention, not only the detection result of the transmission path use permission signal for the self in the transmission permission determination circuit but also the transmission generated by the main processing unit based on the transmission path use permission signal. The processing start notification signal is also used, and transmission of the transmission signal from the output circuit to the transmission path is permitted only when both are satisfied. Therefore, the effect that the reliability of the communication network terminal device and the communication network can be further improved by the double check is obtained.

According to the communication network terminal device of the present invention, a main processing unit monitoring circuit for monitoring an abnormality of the main processing unit is provided, and when an abnormality of the main processing unit is detected, a signal is sent from the output circuit to the transmission line. Transmission of the transmission signal is prohibited. By using this control in combination with the control using the transmission permission determination signal by the transmission permission determination circuit and the transmission processing start notification signal by the main processing unit, the reliability of the communication network terminal device and the communication network is further improved. Is obtained.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a bus connection type communication network system using a polling method according to a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a ring-connected communication network system using a polling method according to a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a conventional bus connection type network using a polling method.

[Explanation of symbols]

22 transmission line, 24 master station, 26 slave station, 28, 48,
68 hardware control unit, 30, 52, 70 software control unit, 32 input circuit, 34 output circuit, 36
Transmission permission judgment circuit, 38, 50, 74 Output control circuit, 72 Main processing unit monitoring circuit.

Claims (3)

[Claims] 1. An input circuit for receiving a transmission signal on a transmission path of a communication network and processing the transmission signal based on a communication protocol, and transmitting transmission data when a transmission path use permission signal for itself is detected in an output signal of the input circuit. A communication network terminal device comprising: a main processing unit; and an output circuit that converts the transmission data into a transmission signal based on the communication protocol and sends the transmission signal to the transmission line, wherein the transmission line included in an output of the input circuit is used. A transmission permission determination circuit that detects a permission signal, determines that transmission from the device is permitted based on the transmission path use permission signal, and outputs a transmission permission determination signal, based on the transmission permission determination signal, An output control circuit for controlling whether or not the transmission signal can be transmitted from the output circuit to the transmission line. Terminal device. 2. The main processing unit determines that transmission from the device is permitted based on the transmission path use permission signal, activates data transmission processing, and transmits a transmission processing activation notification signal to the output control signal. A transmission processing activation unit for outputting to the circuit, wherein the output control circuit controls output from the output circuit when both the transmission permission determination signal and the transmission processing activation notification signal are input. The communication network terminal device according to claim 1, wherein: 3. A main processing unit monitoring circuit that monitors whether or not the processing of the main processing unit is normal and outputs a main processing unit abnormality detection signal when an abnormality of the processing is detected. 2. The communication network terminal device according to claim 1, wherein when the main processing unit abnormality detection signal is input, control is performed to inhibit output from the output circuit.