JPH02301344A - Alarm detection system in loop transmission line - Google Patents

Abstract

PURPOSE:To retrieve a faulty communication slave station immediately by collating the content of a data identification bit with a node address and adding a value resulting from subtracting a content of the identification bit from a node address in the case of dissidence to an error count bit so as to check whether or not the content 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. The master station A collates the node address LN+1=N+1 in its own station with the content MN of a received U/D bit, stores the value (x) in the case of dissidence and adds Y to the content of the received U/D bit. The station checks the content of the E/C bit and raises an alarm as a communication fault in the case of ZN+1=1 to N. In this case, the (x) (2, 4, 5) stored in slave stations #3, #6 is collected by the master 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.

[Prior Art] Generally, in a data communication system in which one master station (main data communication device) and N.times. (N is a positive integer) slave stations (slave data communication devices) are connected in a loop, the so-called 1: N communications are performed. At this time, the master station sends U in the transmission data to N slave stations.
The /D bit is set to 0 and transmitted, 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 local station that has returned after one round of loop-shaped transmission is 1, it is regarded as normal communication, and if it is 0, it is regarded as abnormal communication, and an alarm is detected. I am doing it.

[Problems to be Solved by the Invention] As described above, in conventional alarm detection, N slave stations set the received U/D bit to 1 and transmit it to lower slave stations, and the master station performs loop transmission. If the U/D bit in the transmitted data returned after making one circuit around the road is 1, it is considered normal communication.

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

The master station always assumes normal communication and cannot detect any abnormality.

There is a problem in 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 slave stations.

[Means for Solving the Problems] 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 communication system that transmits and receives data having an identification bit and an error count bit, the slave station is sequentially set with a node address of 1 to N, the master station is set with a node address of N+1, and each of the slave stations is set with a node address of 1 to N. The station is equipped with a replacement means for replacing the contents of the information bits with the node address of each slave station + 1, and each slave station and the master station are provided with a means for replacing the contents of the information bits with the node address of each slave station, and each slave station and the master station are provided with a means for comparing the contents of the identification bits of the data with the node address. a storage means for storing a positive value determined by the content of the identification bit and a value subtracted by 1 from the node address when the result of the verification is a mismatch; addition means for adding a value obtained by subtracting the content of the bit to the error count bit, and the master station further includes a means for detecting an alarm by checking whether the content of the error count bit is a predetermined value. and the detection means to be carried out.

collecting means for collecting the positive values stored in the storage means, and the master station sets the identification bit to 1 and sets the error count bit to 0, and transmits the data. An alarm detection method in a loop-shaped transmission path is obtained.

[Example] Next, the present invention will be explained with reference to examples.

Referring to FIG. 1, one master station A and N slave stations #1. #
2. #3. . . , #N are connected in a loop through a transmission line I. The master station A intensively corrects delays occurring in the loop data transmission network and monitors the entire transmission system. Each slave station #1 to #N receives data from the transmission path p, takes it in, performs regenerative relay, inserts additional information as necessary, and transmits the data to the lower station.

N+1 is preset as a node address in master station A, and N slave stations #1. #2. #3゜..., #N each have a node address of 1゜'2, 3. ...
, N are set.

The master station A initializes the contents of the U/D bit in the data format to M-1 and the contents of the E/C bit to Z-0, and transmits the data to the slave station via the transmission path I. Slave station #1, which successfully received data from the master station, received the U/D
After comparing the bit content M-1 with the local node address L1-1, the content of the U/D bit is M+ -L+ +1=1
+1=2 and transmits data to lower slave station #2.

Assuming that a communication error has occurred in slave station #2, the content of the U/D bit in the transmission data received by slave station #3 is M+-2, and the content of the E/C bit is Zl-0. Become. Slave station #3 compares its own node □address 1-3 with the content M of the received U/D bit. Because the result is a mismatch.

All positive numbers x-2 with M1≦X≦L3-1 are stored.

Furthermore, the content of the received E/C bit ZI=OJ,:
Add Y −L s M r −3-2-1 to Z,
-1, and set the contents of the U/D bit to own node, door address +1. That is, it replaces M3-Ls +1-3+1-4 and transmits data to lower slave station #4.

Furthermore, slave station #4. If a communication abnormality occurs in #5, the content of the U/D bit in the data received by slave station #6 is M, -4, and the content of the E/C bit is Z, -1.

Slave station #6 compares its own node address L6-6 with the content M of the received U/D bit. In this case, since there is a mismatch, all positive numbers X-4 with M3≦X≦L6-1
, 5 are stored. Furthermore, Y=Lb Ml -64-2 is added to the received E/C bit content Z3 and Z6
-1+Y-1+2-3, and the contents of the U/D bit are M-
7-N and transmits data to lower slave station #N.

Assume that normal communication can be performed at slave station #N.

The content of the U/D bit in the data received by master station A is MN
-N+1. The contents of the E/C bit are 2. (3) At X, the master station A checks its own node address LN÷, -N+l and the content MN of the received U/D bit. If there is a mismatch, slave station #3. Same as #6, X
, and adds Y to the contents of the received U/D bit as described above.

Check the contents of the E/C bit, Z, +, +w Q
If so, it is assumed that all nodes are communicating normally, and Z□, −
1 to N, among N slave stations #1 to #N,
Z-1 to N slave stations generate an alarm (abnormality alarm) because of communication abnormality.

At this time, the values of It is possible to know the node addresses of all slave stations.

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

The optical transmission control unit 1 performs electro-optical (Elo) and opto-electric O/E conversion, and transmits and receives data from the optical transmission path g. The loop synchronization control unit 2 is a circuit included in the master station A, and performs intensive correction of delays occurring in the loop data transmission network and monitoring of the entire system. The U/D bit check unit 5 is provided in the master station and the slave station, and checks the node address of the own station and the content of the U/D bit in the received transmission data, and if there is a discrepancy, the above-mentioned The value of X is stored in the error node address storage unit 6, and the error count bit insertion unit 7 adds the value of Y to the E/C bit of the data transmitted from the local station.

The data control unit 3 includes a data receiving unit and a data transmitting unit (both not shown), and the data receiving unit determines the presence or absence of frame synchronization and establishes frame synchronization, and performs a frame check sequence in the data frame. The received data is taken in only when all the checks are normal. On the other hand, the data transmitter creates frame synchronization, creates frame check sequence part,
It inserts data from a terminal (not shown), inserts control data into a control signal section in a data frame, and sends out transmission data. The terminal device interface section 4 is an interface section between a terminal device (not shown) and the data control section 3.

When the received data is normally captured in the data control unit 3, the error count bit insertion unit 7 inputs E.
The value of Y mentioned above is added to the contents of the /C bit, and the U/D bit replacement section 8 replaces the contents of the U/D bit with the value of the node address of the local station +1.

In the master station A, the E/C in the transmission data via the error count bit insertion section 7 and the U/D bit replacement section 8 is
The contents of the bit are checked in the E/C bit alarm detection unit 9, and when the value Z of the E/C bit is 0, it is considered normal communication.When Z is any value from 1 to N, N
It is determined that two of the slave stations are in abnormal communication and an alarm is detected. Next, in the master station A, the U/D bit E/C bit initializing section 10 changes the contents of the U/D bit to 1. The contents of the E/C bit are set to 0 and the data is transmitted to the optical transmission control section 1.

[Effects of the Invention] As explained above, in the case of 1:N communication on a loop type transmission line, if even one of N slave stations is unable to communicate normally, the master station cannot detect an alarm. Furthermore, the node address of the slave station with abnormal communication can be collected in the master station, and the search for the slave station with abnormal communication can be performed immediately.

[Brief explanation of drawings]

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

Claims (1)

[Claims] 1. In a communication system in which one master station and N (N is a positive integer) slave stations are connected in a loop through a transmission path and transmit and receive data having identification bits and error count bits, the slave stations include 1 to N are sequentially set as the node address, and the master station is set with N+ as the node address.
1 is set, and each of the slave stations is provided with replacement means for replacing the contents of the identification bit with the node address of each slave station + 1, and each of the slave stations and the master station is provided with an identification bit of the data. collation means for collating the contents of the bits and the node address; and storage means for storing a positive value determined by the contents of the identification bits and a value subtracted by one from the node address if there is a mismatch as a result of the collation; addition means for adding a value obtained by subtracting the content of the identification bit from the node address to the error count bit in the case of the mismatch; A detecting means for detecting an alarm by checking whether there is an alarm, and a collecting means for collecting a positive value stored in the storage means, and the master station sets the identification bit to 1 and records the error count. 1. An alarm detection method in a loop-shaped transmission line, characterized in that the data is transmitted by setting a bit to 0.