JPH0720126B2 - Double loop data link system - Google Patents

Description

The present invention relates to a dual loop data link system, in particular, two sets of receiving means and transmitter means, and a plurality of link units each having a central processing unit. The present invention relates to a dual loop data link system in which the above-mentioned receive means and transmitter means of a link unit are sequentially connected, one of which is a master station and the other is a slave station.

[Conventional technology]

A conventional double loop data link system of this type has a master station and a plurality of slave stations each having a central processing unit, and is provided between the central processing unit of the master station and the central processing unit of the slave station, or Data is transmitted and received between the central processing unit of the slave station and the central processing units of other slave stations, and the transmitted and received data is transmitted by being carried on an HDLC transmission frame or the like. If an error occurs during data link using one loop, stop the data link once, check the error point and repair it, and switch to the other loop to restart the data link. It

[Problems to be solved by the invention]

Since the conventional double loop data link system is configured as described above, there is a problem in that when an error occurs, the data link must be stopped and the location of the error must be checked.

The present invention has been made to solve the above problems, and provides a double loop data link system capable of switching at high speed and with high reliability so that a data link can be continued over a sound transmission path when an error occurs. The purpose is to

[Means for solving problems]

A double loop data link system according to the present invention comprises one master station having two combinations of receive means and transmitter means and a plurality of slave stations having two combinations of receive means and transmitter means. In a dual loop data link system provided with transmitter means and receive means of adjacent stations connected in sequence,
The slave station has a central processing unit, and demodulates the output of the receiving means for each combination, and the error at the time of demodulation is caused by the fact that the output of the receiving means is a signal other than the signal modulated according to a predetermined rule. Demodulation / demodulation error detection means for detection, selection means for selectively outputting either the demodulation output of this demodulation / demodulation error detection means or the output from the central processing unit, and the output of this selection means according to a predetermined rule And a modulation means for performing modulation based on the above and inputting it to the transmitter means, and the selection means for each combination in the respective master and slave stations selectively outputs the demodulation output of the demodulation / demodulation error detection means of its own combination. In such a state, the first loop for transmitting data from the master station to the master station via the plurality of slave stations and returning to the master station and the first loop And the second loop to transmit data in the reverse direction is formed, either one of the slave stations demodulation /
When the demodulation error detecting means detects an error during demodulation, the selecting means of this combination is switched and set so that the output from the central processing unit of this slave station is selectively output. Outputs an error signal having information for identifying its own station, this error signal is normally modulated through the modulation means of this combination, and is transmitted to the master station by the loop on the side of this combination. If an error occurrence in either one of the first and second loops is recognized based on the normally modulated error signal received, data transmission by the other loop that is sound is performed, and an error occurrence in both the first and second loops. If it recognizes, the first and second loops are set so that the slave station loops back to the slave station on the master station side at each error occurrence location based on the normally modulated error signal. It sends a connect command, in which to perform the data transmission on the loop.

[Work]

In the double loop data link system according to the present invention, demodulation / demodulation of any one of the combinations provided in any one of the slave stations corresponding to each loop and each having the receiving means and the transistor means. When an error at the time of demodulation is detected by the time error detecting means, the selecting means of this combination is switched and set so that the output from the central processing unit of this slave station is selectively output. Outputs an error signal having information for identifying its own station, this error signal is normally modulated through the modulation means of this combination, transmitted to the master station by the loop on the side of this combination, and the master station receives it. If an error occurrence in either the first loop or the second loop is recognized based on the normally modulated error signal If data transmission by the other loop is performed and the occurrence of an error in both the first and second loops is recognized, the relevant slave station of the master station side at each error occurrence point is detected based on the normally modulated error signal. A command is sent to connect the first and second loops so that the slave station loops back, and data is transmitted by loopback.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. First
In the figure, 1 is a link unit which is a master station, 2 ₁ to 2 _n are link units which are slave stations, and 3 and 4 are the receive means R and transmitter means D of the adjacent link units 1 2 ₁ to 2 _n. Are sequentially connected to form a first loop, for example, a P loop and a second loop, for example, an S loop, as a connecting path.

That is, in this double loop denter link system, as in the case of the conventional example, the master station 1 and the plurality of slave stations 2 ₁ to 2 _n each having a central processing unit are provided.
It is configured such that data can be exchanged between the central processing unit of No. 1 and the central processing unit of any of the slave stations, between the central processing unit of the slave station and the central processing units of other slave stations, and the like.

FIG. 2 is a block diagram showing an internal structure of one of the link units 1, 2 ₁ to 2 _n , 11 and 12 are a combination of the receiving means R and the transmitter means D, 13 is a central processing unit, and 14 is a central processing unit.
Reference numerals ₁ and 14 ₂ receive the output of the receiving means R, demodulate the output of the receiving means R, and demodulate when the output of the receiving means R is a signal other than a signal modulated according to a predetermined rule. It is a demodulation / demodulation error detection means for detecting and outputting a time error, for example, a demodulation and demodulation error detection circuit. Reference numerals 15 ₁ and 15 ₂ are selection means, for example, selectors for selecting the demodulation outputs of the demodulation and demodulation error detection circuits 14 _{1 to} 14 _{2 and} the output of the central processing unit (hereinafter referred to as CPU) 13. 16 _1, 16 ₂ as an input the output of the selector 15 _1, 15 _2, to the output of the selector 15 _1, 15 _2, modulates based on a predetermined rule, the combined body modulated output
It is a modulation circuit, for example, a modulation circuit, which is supplied to 11, 12 transmitters D.

Taking the case where a signal encoded by the Manchester code is transmitted to the cables 3 and 4, as in the case where an HDLC transmission frame based on the Manchester code is transmitted,
As is well known, for example, "1" data changes from "H to L" during 1-bit data time, and "0" data changes from "L to H", so data "1" is continuous. The level of the signal transmitted by the cables 3 and 4 is changed even when the data "0" is continuously transmitted. Therefore, in a normal state, the signal level on the cables 3 and 4 always changes both during the transmission of the HDLC transmission frame and during the idle state.

Demodulation and demodulation error detection circuits 14 ₁ and 14 ₂ are cable 3,
If the level of the signal transmitted by 4 changes within a predetermined time and it can be demodulated, it is judged as normal and the cable
If the signal level transmitted by the cables 3 and 4 is fixed to "1" or "0" due to disconnection etc. in 3 and 4, and it is not possible to demodulate, it is determined that there is an error and an error occurs. It is configured to output a detection signal.

Next, the operation will be described. Now, the selector in the slave station 2 ₂
15 ₁ is in a state of being set to select the demodulation output of the demodulation and demodulation error detection circuit 14 ₁ , and during the data link by the P loop shown in FIG. ₁ , P between slave stations 2 ₁ and 2 ₂
When the cable 3 is disconnected at a point, demodulation and demodulates time error detection circuit 14 ₁ in the slave station 2 ₂ detects an error, and supplies the error detection signal to the CPU 13. Therefore, CPU13
Switching the selector 15 ₁ to the state of selecting the output of the CPU 13, P
The normal data transmission by the loop is interrupted and the CP
The selector 15 ₁ from U13, the modulation circuit 16 _1, towards the slave station 2 ₃ via a transmitter means D with an error signal LEP which predetermined modulation has been performed, teach cable break to the master station 1.

Incidentally, the data received by the slave station 2 ₂ also normal data via the error detection data also both always modulation circuit 16 ₁ in the demodulation Error detection circuit, to the next station and re-modulated by the modulation circuit 16 ₁ Sent. Therefore, the data whose error has been detected by the demodulation and demodulation error detection circuit 14 ₁ is also remodulated and sent to the next station, so that the demodulation and demodulation error detection circuit 14 ₁ of the next station does not detect an error.

That is, only the slave station immediately after the disconnection position errors detection signal is output from the demodulation and demodulating the time error detection circuit 14 _1, always modulation circuit slave station downstream than the slave station from the preceding slave station Since the signal modulated by is received, the occurrence of a failure is not detected by the error detection signal of the local station.

Also, during data link by S loop, between slave stations 2 ₁ and 2 ₂
If the cable 4 in S ₁ points or broken, demodulation and demodulates time error detection circuit 14 ₂ of the slave station 2 ₁ detects an error, and supplies the error detection signal to the CPU 13. Therefore, CPU31
Switches the selector 15 ₂ and the selector from the CPU 13
The master station 1 through 15 ₂ , the modulation circuit 16 ₂ and the transmitter means D
The error signal LES is output toward. The error signals LEP, LES, LEW each have information for identifying its own station.

On the other hand, during the data link by the P loop, the slave stations 2 ₂ , 2 ₃
When the cable 3 is disconnected between the slave stations 2 ₃ and 2 ₄ and the cable 4 is disconnected at the S ₂ point, the CPU 13 in the slave station 2 ₃ receives both the demodulation and demodulation error detection circuits 14 ₁ and 14 ₂ . Receive error detection signal. For this reason, the CPU 13 uses the switched selector 1
5 ₁ , a modulation circuit 16 ₁ , a transmitter D, and a slave station 2
Toward the ₄ P / S loop error signal when LEW outputs the Dojiniko station 2 ₂ selector 15 ₂ is switched towards the modulation circuit 1
6 ₂ Outputs the P / S loop error signal LEW through the transmitter D.

When the master station 1 receives any of the error signals LEP, LES, LEW, the loopback instruction signal to the slave station on the master station side from the error occurrence point, that is, the receiving means R and the transmitter of one combination in the slave station Cable 3, via means D,
Transmits an instruction signal that directly connects the four.

In the case of the error signals LES and LEP, the cables 3 and 4 are connected by the loopback instruction signal, but as described in the prior art, the data link is continued in the other healthy loop and the loopback is not performed. . In the case of the error signal LEW, since an error has occurred in both loops, loopback is performed.

Hereinafter, the operation will be specifically described based on the flowchart. First, the processing of the slave station when a P loop error occurs during the data link by the P loop will be described with reference to the flowchart of FIG. After the start, when a P loop error occurs, it is determined whether or not an S loop error is occurring (step 3
-1), if yes, send P / S loop error signal LEW to P / S loop (step 3-2), if no, send P loop error signal LEP to P loop (step 3-3) To do. Next, is LES / LEW reception (step 3-
4), it is determined whether or not an S loop error has occurred (step 3-5). If Yes, the process returns to step 3-2. If No, it is determined whether or not an instruction is received from the master station (step 3-5). 3-6). If Yes, loop back the S loop to the P loop according to the instruction from the master station, and if No, a certain time (time to ensure receipt of a message transmitted to another station) has elapsed. (Step 3-7), the process returns to Step 3-3 if Yes, and the process returns to Step 3-4 if No.

During the above P loop data link, P loop error signal LE
The processing of the master station when the P, P / S loop error signal LEW is received will be described with reference to the flowchart of FIG.
After the start, it is judged whether or not another message (another P loop error signal LEP, P / S loop error signal LEW) is received from the P loop (step 4-1). If Yes, on the P loop Then, the one sent from the slave station closest to the master station is stored (step 4-2), and if No, a fixed time (the slave station sends a message, that is, the P loop error signal LEP is changed to the P / S loop error signal LEW). Then, it is determined whether or not the time that is expected to be changed (step 4-3). Then, if No, the process returns to step 4-1. If Yes, a loopback instruction for returning the S loop to the P loop according to the above-mentioned storage is transmitted (step 4-4), and the process returns to the loopback preparation state.

FIG. 5 is a flowchart showing the processing of the slave station when an S loop error occurs during the S loop data link, and FIG. 6 is a flowchart showing the processing of the master station when LEP and LEW are received during the S loop data link. Is the same as in FIGS. 3 and 4 above.

〔The invention's effect〕

As described above, in the double loop data link system according to the present invention, any one of the combination units provided in each slave station corresponding to each loop and each having the receiving means and the transmitter means When the demodulation / demodulation-time error detection means of the combination detects the error at the time of demodulation, the selection means of the combination is switched and set so as to selectively output the output from the central processing unit of this slave station. At the same time, this central processing unit outputs an error signal having information for identifying its own station, and this error signal is normally modulated through the modulation means of this combination, and is sent to the master station by the loop on the side of this combination. The master station, which is transmitted, receives an error signal in either the first loop or the second loop based on the normally modulated error signal received. If it recognizes that data is transmitted by the other loop that is sound, and if the occurrence of an error in both the first and second loops is recognized, the master station side of each error occurrence point based on the normally modulated error signal. A command to connect the first and second loops is sent to the slave station so that the slave station loops back, and data is transmitted by loopback. An error signal that is normally modulated is output from the slave station and quickly transmitted to the master station, and at the same time, the master station issues a switch instruction to perform data transmission on a sound transmission path, which is highly reliable. There is an effect that high-speed switching is possible, and furthermore, modulation can be performed even during idle time other than during data transmission. Therefore, high-speed switching is possible even when disconnection occurs during idle time. It enables an effect capable of improving overall system reliability.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a double loop data link system according to an embodiment of the present invention, FIG. 2 is a block diagram showing a configuration of a link unit, and FIGS. 3 to 6 are flow charts for explaining the operation of the present invention. Is. 1 is a link unit serving as a master station, 2 ₁ to 2 _n are link units serving as slave stations, 13 is a central processing unit, 14 ₁ and 14 ₂ are demodulation and error detection circuits at the time of demodulation, 15 ₁ and 15 ₂ are selectors, 16 ₁ , 1
6 ₂ is a modulation circuit, R is a receive means, and D is a transmitter means. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. A single master station having two combinations of receive means and transmitter means, and a plurality of slave stations having two combinations of the receive means and transmitter means. In a dual loop data link system in which the transmitter means and the receive means are connected in sequence, the slave station has a central processing unit, and the output of the receive means is demodulated for each of the combinations and at the time of demodulation. Demodulating / detecting an error by detecting that the output of the receiving means is a signal other than a signal modulated according to a predetermined rule
Demodulation error detection means, selection means for selectively outputting either the demodulation output of the demodulation / demodulation error effect production means or the output from the central processing unit, and the output of this selection means is modulated based on the predetermined rule. And the modulation means for inputting to the transmitter means, and the selection means of each combination in the master station and the slave station outputs the demodulation output of the demodulation / demodulation error detection means of its own combination. A first loop for transmitting data so as to return from the master station to the master station through a plurality of slave stations in a state of being set to selectively output, and data is transmitted in a direction opposite to the first loop. A second loop is formed,
When an error at the time of demodulation is detected by the demodulation / demodulation error detecting means of any combination of any of the slave stations, the output from the central processing unit of the slave station is selectively output. At the same time, the selective output of the combination is switched and set, and the central processing unit outputs an error signal having information for identifying its own station. This error signal is normally transmitted through the modulation means of the combination. And transmitted to the master station by a loop on the side of the combination, and the master station detects an error occurrence in either one of the first and second loops based on the received normally modulated error signal. If it is recognized, data transmission by the other loop that is sound is performed, and if the occurrence of an error in both the first loop and the second loop is recognized, it is based on the normally modulated error signal. Send a command to connect the above 1st and 2nd loops to the slave station on the master station side at each error occurrence point so that the slave station loops back, and perform data transmission by loopback. A double loop data link system characterized by: