JPH02301345A - Alarm detection system in loop transmission line - Google Patents

Abstract

PURPOSE:To retrieve a faulty communication slave station immediately by collating the content of an address bit with a node address and replacing the identification bit to 1 in the case of dissidence and checking whether or not the content of the identification bit is a prescribed value thereby detecting alarm. CONSTITUTION:N+1 is preset to a master station A as a node address and 1 to N are set respectively to N-set of slave stations #1-#N as respective node addresses. Suppose that a communication fault takes place in the slave station #N, the content of the U/D bit is replaced into '1'. The master station A checks the content of the U/D bit and when the content is '0', all modes are regarded as normal communication, while the U/D bit is '1', it is regarded that one slave station or over among N sets of slave stations #1-#N is in communication fault to raise an alarm. In this case, the values (x) stored in the slave station is collected to the master station A with simultaneous polling to the N sets of the slave stations from the station A. Thus, the node address of all slave stations showing communication fault is recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an abnormality (alarm) detection method for a plurality of data communication devices connected in a loop.

[Conventional technology]

Generally, in a data communication system in which one master station (main data communication device) and N (N is a positive integer) slave stations (slave data communication devices) are connected in a loop, so-called 1:N communication is performed. At this time, the master station sends U/
The D bit is set to 0, and the slave station transmits the U/
The D bit is set to 1 and transmitted to the lower slave station.

At the master station, if the U/D bit in the transmitted data from the own station that has returned after one round of loop-shaped transmission is 1, it is considered normal and excessive, and if it is O, it is regarded as abnormal communication and an alarm is detected. Go and have fun.

[Problem to be solved by the invention]

As mentioned above, in conventional alarm detection, the N slave stations set the received U/D bit to 1 and transmit it to the lower slave station, and the R station receives the transmission that has gone around the loop transmission path and returned. If the U/D bit in the data is 1, it is assumed that communication is normal.

Therefore, as long as normal communication can be performed with one of the N slave stations, even if communication with the other N-1 slave stations is abnormal.

The master station always considers the communication to be normal and cannot detect any abnormalities.

Furthermore, there is the problem that it is not possible to immediately determine which slave station is abnormal.

An object of the present invention is to provide an alarm detection method that can accurately detect abnormalities in a slave station.

[Means to solve the problem]

According to the present invention, one master station and N (N is a positive integer) slave stations are connected in a loop through a transmission path.

In a data communication system that transmits and receives data having an identification bit and an address bit for detecting an abnormal communication node, the slave station is sequentially set with 1 to N as a node address, and the master station is set with a node address as a node address. N
+1 is set.

Each of the slave stations is provided with first replacement means for replacing the contents of the address bits with the node address of each slave station +1, and each of the slave stations and the master station is provided with a collating means for collating the node address; and, as a result of the collation, if the address bit is smaller than the node address, storing a positive number determined by the contents of the address bit and a value subtracted by 1 from the node address; A storage means, and a second replacement means for performing IK replacement on the identification bit in the case of the mismatch.

Furthermore, the master station includes a third replacement means for replacing the content of the address bit with 1, a detection means for detecting an alarm by checking whether the content of the identification bit is a predetermined value, and the and collecting means for collecting abnormal node addresses by collecting positive values stored in the storage means by simultaneous polling, and the master station sets the identification bit to 0 and transmits the data. An alarm detection method for a loop-shaped transmission path is obtained.

〔Example〕

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

Referring to FIG. 1, one master station A and N slave stations sl, ÷
2. 3. . . . and N are in a loop shape 1/ in the transmission line l.
c is connected. The master station A intensively corrects delays occurring in the loop data transmission network and monitors the entire transmission system. Each of the slave stations 1 to 1N receives and takes in the data from the transmission line I, then inputs regenerative relay, inserts additional information as necessary, and transmits the data to the lower station.

N+1 is preset as a node address in the master station A, and N slave stations φl, 2. +3°..., ΦN respectively have l as a node address.

2.3. ..., N is set and layered.

The master station A sets the contents of the identification bit (U/D bit) in the data format to 0. Initializes the contents of the address bit (AD-bit to 1) and transmits the data to the slave station via the transmission path l.The slave station that has successfully received data from the master station receives the AD bit contents M= 1 and own station node address NA1 = 1, replace the contents of the AD bit with M, = NA, + 1 = 1 + 1 = 2, do not manipulate the U/D bit, and send the data to the lower slave station +2. Send.

Here, the slave station ◆2. Assuming that a communication abnormality occurs in the ÷3 layer, the content of the AD-bit in the transmission data received by the slave station +4 becomes O. For slave station 4, its own node address NA4
:=4 is compared with the received AD-bit content M,=2. Because the result is a mismatch.

M, store all positive numbers x=2.3 where ≦X≦NA4. Furthermore, the contents of the received U/D bit are replaced with 1, and the contents of the AD bit are changed to M4= NA4 + 1 = 4+
1=5=N and transmits data to lower slave station +N.

Suppose that a communication error occurs in slave station +N.

The content of the AD bit in the data received by the master station is M4=N
, the content of the U/D bit is 1. The master station checks its own node address NAN, = N + 1, and the content of the received AD bit M4=N. In this case, since there is a mismatch, all positive numbers x of M4≦X≦NAN+, -1
= Remember N. Furthermore, the content of the received U/D bit is replaced with 1.

Next, master station A checks the contents of the U/D bit,
If it is 0, all nodes are considered to be communicating normally, while U
If the /D bit is 1, an alarm (
(abnormal alarm) is generated.

At this time, the value of X (2
, 3, N) are collected at the master station A by simultaneous polling from the master station A to N slave stations, and thereby the node addresses of all the slave stations with abnormal communication can be known.

Next, the configuration of each station will be explained with reference to FIG.

The optical transmission control unit l is electro-optical (E/I)), photoelectric (0/I)
E) Performs conversion and transmits and receives data from optical transmission line l. The loop synchronization control unit 2 is a circuit included in the master station A.

Intensive correction of delays occurring in the loop data transmission network and monitoring of the entire system. AD-bit check 5 is provided in the master station and slave stations, and checks the node address of the own station and the content of the AD bit in the received transmission data, and if there is a discrepancy, the The value is stored in the error node address storage section 6 and in the U/D bit replacement section 8.

Replace the contents of the U/D bit of the transmission data with 1.

The data control unit 3 includes a data reception unit and a data transmission unit (both not shown), and the data reception unit determines the presence or absence of frame synchronization and detects the seven levels in the wrinkled data frame to establish frame synchronization. One check sequence part is checked to detect whether it is good or bad, and the received data is taken in only when all checks are normal. On the other hand, the data transmitter creates frame synchronization, creates a frame check sequence part, inserts control data into the insertion control signal part of data sent from a terminal device (not shown), etc., and sends the transmission data to the sender. Ru. The terminal device interface section 4 is an interface section between the terminal device and the data control section 3.

In the AD bit insertion unit 7 when the data control unit 3 receives the received data normally.

Replace the contents of the AD bit with the value of the own node address + 1.

At master station A, the contents of the TJ/D bit in the transmission data via the U/D bit replacement section 8 are checked by the U/D bit alarm detection section 9, and the value of the U/D bit is 0.
When , it is considered normal communication.

When the U/D bit is 1, it is detected that one or more of the N slave stations is in abnormal communication, and an alarm is generated. Next, in the master station A, the U/D bit initializer 10
Then, the content of the U/D bit is set to 0 and the data is transmitted to the optical transmission control unit l.

〔Effect of the invention〕

As explained above, in the case of l:N communication on a loop type transmission path, if even one of the N slave stations is unable to perform normal communication, the present invention allows the master station to detect an alarm. °
Furthermore, the node address of the slave station with abnormal communication can be collected in the master station, and a search for the slave station with abnormal communication can be immediately performed, which has an additional effect.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram for explaining an embodiment of the alarm detection method in a loop-shaped transmission line according to the present invention, and FIG. 2 is a block diagram showing an embodiment of the configuration of a station used in the loop-shaped transmission line. be. l... Optical transmission control unit, 2... Loop synchronization control unit, 3
...Data control section, 4...Terminal device interface section. 5... AD bit check section, 6... Error node address storage section, 7... AD bit insertion section, 8...
- U/D bit replacement section, 9... U/D bit alarm detection section. 10...U/D bit initialization section.

Claims (1)

[Claims] 1. Data communication in which one master station and N (N is a positive integer) slave stations are connected in a loop through a transmission path and send and receive data having identification bits and address bits for detecting abnormal communication nodes. In the system, the slave station is sequentially set with node addresses from 1 to N, and the master station is set with a node address of N+1,
Each of the slave stations is provided with first replacement means for replacing the contents of the address bits with the node address of each slave station +1, and each of the slave stations and the master station is provided with collation means for collating the node address; and storage means for recording a positive value determined by the contents of the address bits and a value subtracted by one from the node address if the address bit is smaller than the node address as a result of the collation. and a second replacement means for replacing the identification bit with 1 in the case of the mismatch, and the master station further includes a third replacement means for replacing the content of the address bit with 1, and a third replacement means for replacing the content of the address bit with 1, and detection means for detecting an alarm by checking whether the contents of the bit are a predetermined value;
collecting means for collecting an abnormal node address by collecting the positive values stored in the storage means by simultaneous polling, and the master station sets the identification bit to 0 and transmits the data. An alarm detection method in a loop-shaped transmission line, characterized by the following.