JPS60136448A - Communication system - Google Patents

Abstract

PURPOSE:To perform maintenance and inspection of a device efficiently by connecting a text returning device to the system where plural communication device which can communicate with one another are connected through a transmission line and returning the same text with a command from an optional communication device. CONSTITUTION:One text returning device 3 is connected to a transmission line 2 to which plural communication devices 1-1-1-N which can communicate with one another are connected. The text returning device 3 consists of a transceiver 4, a transmission/reception control part 5, and a text buffer 6. For example, if the communication device 1-1 cannot obtain the response from the other party, the device 1-1 transmits the command to the text returning device 3 together with the request source address (the address of the device 1-1 in this case) and the text. The device 3 monitors always the transmission line 2; and if it detects the command, the text is stored temporarily in the buffer 6, and the same text as the received text is returned to the request source. Thus, the communication device 1-1 detects easily the occurrence position of a trouble without interfering in the other normal devices in accordance with presence/absence of return.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a communication system in which communication devices capable of mutual communication are connected via a transmission path, and particularly to a maintenance method thereof.

(Background Art) Conventionally, in a communication system in which communication devices capable of mutual communication are connected via this type of transmission path, when a fault is detected on a certain device, this fault occurs within the device. In order to determine whether the device is present or on the transmission path, it is necessary for the device to communicate with any other device and check the status of the device.

At this time, there is a drawback in that the other device communicating with the other device must suspend normal operations and perform operations such as returning the message sent from the device detecting the failure as is.

(Problems to be solved by the invention) An object of the present invention is to provide a communication system that solves the above-mentioned drawbacks and allows equipment maintenance to be performed without interfering with normal system operation. The purpose is to install a communication device at any location on the road that has the function of receiving a telegram and sending it back to the device that sent it within a certain period of time.

(Structure and operation of the invention) Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a drawing showing an embodiment of the present invention, in which communication devices 1-1 to 1-N, which are composed of communication devices 1-1 to 1-N, a transmission line 2, and a message return device 3, are used for transmission. In this embodiment, a case will be considered in which each communication uses a frame synchronization method. FIG. 2 shows an example of a message return device, including a transceiver 4, a transmission/reception control unit 5, and a message buffer 6 that temporarily stores the received message until it is returned.
It consists of FIG. 3 is an example of a return instruction message issued from the communication device that detected the failure to the message return device 3, in which a flag 7, a source address (in this case, the address of the communication device that detected the failure) 8, Destination address (
In this case, the address of the message return device) 9, return command 10, return message information 11, and frame check sequence 12 are configured.

FIG. 4 is an example of a return response message from the message return device 3, which includes a flag 7, a source address (in this case, the address of the message return device) 8, and a destination address (the address of the communication device that issued the return instruction message). , Return response 13. It consists of return message information 11 and frame check sequence 12. Here, the contents of the return message information 1 in FIGS. 3 and 4 are the same.

Now, suppose that communication device 1-1 detects a failure such as no response from the other communication device °. Communication device 1-1 determines whether the cause of this failure is within the device. Therefore, normality can generally be checked by internally comparing the transmitted messages within the device. If this operation is normal, it can be seen that the devices before the transceiver section of the communication device are normal.

However, if there is a problem on the transmission path including the transceiver, it is necessary to communicate with other devices via the transmission path. A method of confirmation was taken.

In this case, in order to facilitate inspection, it is common for the other party's device to return the sent message as is, and the other party's device must suspend normal operations and return the received message. This was causing a problem in the operation of the device.

In the present invention, the communication device 1-1 that has detected a failure issues a return instruction message as shown in FIG. 3 to the message return device 3, and the message return device 3 constantly monitors the transmission path 2. When the communication control unit 5 recognizes that it is a return instruction message, it returns the received return instruction message to the issuing communication device in the format shown in FIG.

The communication device 1-1 that received the returned message can easily check the normality of the transmission path including the transceiver of its own device by comparing it with the contents of the message that it sent itself.

(Effects of the Invention) As detailed above, the present invention provides a message return device in addition to the original communication device on the transmission path, thereby preventing failures from occurring without affecting communication devices that are performing normal operations. There is an advantage that a return test can be performed via the transmission line of the communication device where the problem occurred.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram of a communication system that is an embodiment of the present invention, FIG. 2 is a block configuration diagram of a message return device,
FIG. 3 is a diagram showing an example of the frame structure of a return instruction message, and FIG. 4 is a diagram showing an example of the frame structure of the return message. 1-1 to 1-Nm-communication device, 2-m-transmission line, 3-m-telegram return device. 4-m-transceiver, 5-m-transmission/reception control section, 8-m
- Message buffer γ, 7 - Flag, 8 - M - Source address, 8 - Destination address, 10 - Eleven return command, 11 - Data, 1
2-11 frame check sequence, 13-11 return response. Patent applicant: Oki Electric Industry Co., Ltd. Patent application agent: Megumi Yamamoto

Claims (1)

[Claims] In a communication system in which a plurality of communication devices capable of mutual communication are connected via a transmission path, a message return device is connected to the transmission path, and the message return device is issued from any communication device and sends the message to the destination. A function that receives a message with an address and a return instruction command and recognizes that it is a return message, a message buffer that temporarily stores the message, and a message read from the message buffer to the issuing communication device via a transmission path. A communication system characterized by having a return function.