JPS62175044A - Duplexing loop-shaped transmission line - Google Patents

Abstract

PURPOSE:To early take the trouble countermeasure by time-supervising a token frame circulating a loop in respective nodes, informing a node master and displaying the time supervising condition of the token frame of respective nodes at the external part. CONSTITUTION:A transmission line is composed of one duplexed node master 3 to supervise and control the transmission line, plural duplexed nodes 1, 2 and 4 and a duplexed line to link in a loop shape between the nodes. Respective nodes have token detecting parts 6 and 10 to supervise always a token frame, token supervising timers 7 and 11 to be reset, start at the time of receiving the token frame, and output a setting signal when a certain time or above expires, node control parts 9 and 13 to execute the communication between nodes by the flip-flop set by a setting signal output and a token passing control and read the output value of the flip flop by the request from the node master and communicate the value to the node master. The node master 3 displays the output value of the flip-flop in respective nodes at the external part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a duplex loop-shaped transmission line, and more particularly to a detection circuit for a fault in the transmission line.

[Conventional technology]

Conventionally, in this type of loop-shaped transmission line with a duplex transmission line, one duplex node master that controls the entire transmission line and a plurality of duplex nodes are connected in a loop with a duplex line. It has a connected configuration, with one node and line (active system) used for normal communication, and the other node and line (standby system) on standby as a backup in case of a failure. Faults detected at each node include a drop in the signal level on the transmission path, inability to extract a clock from the transmission path signal, when the logic of the signal on the transmission path is clamped to the same logic for a long time, and a framing check sequence error. This fault information is detected by the standby node control unit in the node and transmitted to the synode master through the standby transmission path. The node master knows the status of each node and performs control such as displaying abnormalities to the outside and changing transmission level crossings. In addition to the above-mentioned detectable failures, all transferred frames may be replaced by an idle pattern, and the transmission path may be identified as idle to lower nodes. In this case, it is not possible to determine that a failure has occurred simply by checking the transmission line signal. One way to detect this failure is when a particular node
A method of monitoring 7 frames and recognizing that a failure has occurred if a token frame cannot be detected within a certain period of time;
A method in which the node that made the transmission request monitors the token frame and recognizes that a failure has occurred if the token frame cannot be received within a certain period of time, and the nine nodes that transmit the frame circulate on the loop. There is a method for recognizing that a failure has occurred when a frame returned from a receiver or a response frame from a receiving node cannot be received within a certain period of time.

[Problem that the invention seeks to solve]

In the conventional method described above in which a specific node detects that a transfer frame has changed to an idle pattern by monitoring token frames, it is possible to detect that a failure has occurred, but it is not possible to detect the location where the failure has occurred. In addition, in the method in which the node that issued the transmission request monitors the token frame and the transmission path by the returned transmission frame or response frame, the node master also monitors the failure detection status of each node and It is possible to isolate the location of the fault by examining the nodes that are detecting the error and the nodes that are detecting the abnormality, but the time from when the fault occurs until the location is recognized is It has the disadvantage that it may become large because it depends on the generation status of transmission requests at each node.

[Failure to solve the problem]

The duplex loop-shaped transmission line of the present invention monitors the transmission line, ft.
It consists of one duplicated node master for JIJ control, multiple duplicated nodes, and duplicated lines connecting these nodes in a loop, and each node constantly monitors token frames. A token detection unit that is reset when a token frame is received, a token monitoring timer that is activated and outputs a sect signal after a certain period of time, and a token monitoring timer that is reset when a token frame is received and set by the token monitoring timer's set signal output. A node control unit that performs communication between nodes through token passing control, reads the output value of the above-mentioned 7 lip-flops in response to a request from the node master, and communicates this value to the node master. has a function of externally displaying the output value of the flip-flop at each node.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. A plurality of nodes 1, 2, 3.4 are connected in a "C loop" by a duplex loop transmission path. The transmission lines and nodes are duplexed and are called the O system and the 1 system to distinguish them. The system that is in operation is called the active system, and the system that is on standby is called the standby system. In FIG. 1, the explanation will be made assuming that the θ system is the active system and the 1st system is the standby system. Node 3 monitors the entire transmission path.
A node master for control monitors the status of each node using a standby transmission line, and can change the transmission line by sending commands such as system switching, bypass, and loopback to each node. Since the configuration of each node is the same, node 1 will be explained.

In normal operating conditions, the system selector switch 5 in FIG.
is connected to terminal e, terminal f is connected to terminal C, terminal g is connected to terminal d, and terminal d is connected to terminal ri.The frame input from the 0-system transmission path passes from terminal a to terminal e and reaches θ of node 1. Input to the system side.

The output of the 0-system side of node 1 passes from terminal f to terminal
Output to the transmission line of the system. Further, frames inputted from the 1st system transmission path are inputted to the 1st system side of the node 1 via the terminal d. The output of the 1st system side of the node 1 passes from the terminal g to the terminal C and is input to the 1st system transmission path. In response to the control frame from the node master 3 via the transmission line of the standby system 1, the node control unit 13 issues a system switching control signal, switches the system changeover switch 5, and performs system switching bypass.
Change the transmission path such as loopback. 0, which is the current system
Token frames normally circulate on the transmission line of the system. When a redeemed frame passing through terminals a and e is input from the 0-system transmission line to the 0-system of node 1, the token detection unit 6
detects this and resets the token monitoring timer 7 and 7 lip-flop 8. The token frame is input to the node control unit 9 via the θ system input bus. If there is no communication request to the communication terminal connected to the node control unit 9, the token frame is output from the terminal f to the terminal f via the O non-output bus to the O system transmission path. When a communication terminal receives a communication request, it transmits a packet frame filled with communication information and destination node address information, and then outputs a token frame. Token monitoring timer 7 checks the transmitted token.
A value larger than the maximum time for a frame to go around the loop-shaped transmission line is set, and if the token frame does not return within this time, the flip-flop 8 is set to state 1.
Set to . Furthermore, if the token frame returns within this time, the token monitoring timers 7, 7 lip flow, and lubricant 8 are reset again and monitoring starts again. In order to investigate the status of each node master, the node master 3 periodically transmits a diagnostic frame to the transmission line of the standby system 1 system. A diagnostic frame is composed of a frame header indicating that it is a diagnostic frame, and an information section indicating the status of each node. Each node receives this, and its node control unit reads the output value of the active flip-flop, inserts it into the information field assigned to that node, and transmits it. For example, in the node 1, the 1st system 71 card control section 13 reads the output value of the 7 lip 70 tube 8, inserts it into the information section assigned to the node 1, and transmits it. node master 3
receives the diagnostic frame that has returned after one cycle and displays the status of each node to the outside.

〔Effect of the invention〕

As explained above, the present invention connects a plurality of duplexed nodes through a duplexed loop-shaped transmission path and uses a token padding control method as an access method to transmit and receive packetized data. In a loop-shaped transmission path, a node master has a function of collecting and externally displaying the status of each node; a token frame detector that constantly receives token frames in each node; A token frame that measures the time it takes to receive a token frame.
The mate side has the function of reading the state of the flip-flop and its 7 flip-flops and notifying the node master of the state depending on whether the frame monitoring timer and token/frame monitoring timer are below or above a certain value. A node control unit is provided to monitor the time of the token frame that is always circulating in the loop at each node, and notify the node master.The node master externally displays the time monitoring status of the token frame of each node. In particular, it has the effect of displaying externally the location of a fault where a frame that could not previously be detected changes into an idle pattern, allowing transmission line operation and maintenance personnel to see this and take early countermeasures against the fault. .

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention. 1...Node 1.2...Node 2.3
...Node master, 4...Node 4.
5... System changeover switch, 6... (O system) token detection unit, 7... (0 system) token monitoring timer, 8... (O system) series) 71j tube flop, 9... (0 series) node 1it 1 part, 1゜・
...(1 system) Token detection section, 11...
(1 series) Token monitoring timer, 12... (1 series) Flip □・'

Claims (1)

[Claims] In a duplex loop transmission path in which a plurality of duplex nodes are connected through a duplex loop transmission path and packetized data is sent and received using a token passing control method as an access method, each of the nodes A node master that has a function of collecting and externally displaying the status, a token frame detection unit that constantly receives token frames in each node, and after receiving the token frame until receiving the next token frame. A token frame monitoring timer that measures the time of A duplex loop transmission characterized in that a mate-side node control unit having a function of notifying the status is provided, and each node detects by the means described above that a token frame in the duplex loop is lost and communicates it to the node master. Road.