JPH0230243A - Transmission line switching device for duplex transmission line - Google Patents

Abstract

PURPOSE:To switch a transmission line and to detect interruption of the transmission line in a short time by switching the transmission line depending on the quantity of a data number detected by 1st and 2nd data number detection sections. CONSTITUTION:A data is extracted from transmission lines I, II by the 1st and 2nd data number detection sections 20, 21, which count its data number and store the result. A switching control circuit 5 compares data number outputted from the 1st and 2nd data number detection sections 20, 21 to control a selector 9, which selects a transmission line having more data number. A timer 6 synchronizes data sample circuits 2a, 2b of the 1st and 2nd data number detection sections 20, 21, data number counters 3a, 3b, status latch circuits 4a, 4b and a switching control circuit 5 at a maximum delay time interval of data of the 1st transmission line 1 and a data of the 2nd transmission line II.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a transmission line switching device for a duplex transmission line that monitors irregular data on a duplex transmission line and switches transmission of the irregular data to a normal transmission line. .

[Conventional technology]

Transmission line switching by a conventional transmission line switching device was performed as follows.

As shown in FIG. 4, the maximum time interval T2 of irregular data to be transmitted is set in a timer, and during this T2, the transmission line 1
．． The number of data a passing through It was monitored to determine whether there was an abnormality in the transmission path I or (2). For example, transmission line I
is connected and used, data a of transmission paths I and ■ are monitored at intervals of T2, and the number of data a of transmission path I is O during T2, and the number of data a of transmission path ■ is O. If it is not 0, it is determined that the transmission line ■ is disconnected, and the transmission line ■
Switch the use to .

[Problem to be solved by the invention]

In the conventional transmission line switching device described above, since the presence or absence of a break in the transmission line (■) is determined based on the number of data transmitted during the maximum time interval T2 of the irregular data a, the disconnection of the transmission line (■) does not occur. There is a drawback that it is necessary to wait at least T2 hours before making a judgment after the judgment is made, and it takes a considerable amount of time to make the judgment.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned conventional problems and to provide a transmission line switching device for a duplex transmission line that can detect a disconnection of a transmission line and switch the transmission line in a short time.

[Means to solve the problem]

A transmission line switching device for a duplex transmission line according to the present invention includes a first data number detection unit and a second data number detection unit connected to each of a first transmission line and a second transmission line, and
and a switching control circuit that is connected to the output side of the second data number detection section and switches between the first and second transmission lines, and this switching control circuit and the first and second data number detection section. and a timer connected to the data sample circuit, and each of the first and second data number detection units includes a data sample circuit that extracts data from each of the transmission lines, and a data sample circuit that counts the number of data output from the data sample circuit. The switching control circuit includes a number counter and a state holding circuit that holds and outputs the number of data output from the data number counter, and the switching control circuit includes a state holding circuit that holds and outputs the number of data output from the data number counter and the state holding circuit. The timer compares the number of output data with the number of data output from the data number counter of the second data number detection section and the state holding circuit, and switches to the transmission line with the larger number of data. A data sample circuit and a data number counter of the first and second data number detection sections.

The present invention is characterized in that the state holding circuit and the switching control circuit are synchronized at a maximum delay time interval between data on the first transmission line and data on the second transmission line.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing a transmission line switching device for a duplex transmission line according to an embodiment of the present invention.

The transmission line switching device 1 includes a first data number detection unit 20, which includes a data sample circuit 2a, a data number counter 3a, and a state holding circuit 4a, which are connected in series to a lead line from the transmission line I; A second data number detection unit 2 consisting of a data sample circuit 2b, a data number counter 3b, and a state holding circuit 4b connected sequentially in series to a line branched from the
1, the data number counters 3a, 3b of the first and second data number detectors 20.21, the switching control circuit 5 connected to the output sides of the state holding circuits 4a, 4b, and the transmission lines (1) and (2).
The timer 6 triggers and synchronizes the data sampling circuits 2a, 2b, the data number counters 3a, 3b, the state holding circuits 4a, 4b, and the switching control circuit 5 at a time interval T1 corresponding to the maximum delay difference between data. ing.

The data sample circuits 2a, 2b are connected to the receivers 7a, 7b.
Transmission line 1. It detects the level of data input from II, takes out the data, and outputs it to data number counters 3a and 3b. This data extraction is performed in synchronization with the timer 6.

The data number counters 3a and 3b are connected to the data sample circuit 2.
It counts the number of data input from a and 2b and outputs the count value to the state holding circuits 4a and 4b and the switching control circuit 5 at the same time. This output is performed in synchronization with the timer 6, and simultaneously with the data number counters 3a and 3b.
The count value inside will be reset.

The state holding circuits 4a, 4b are data number counters 3a, 3.
When the next count value is input from the data counters 3a and 3b, the count value input from the timer 6 is held, and in synchronization with the timer 6, the control circuit 5 switches the count value that was being held at the same time as the input of the next count value. This is what is output to.

The switching control circuit 5 converts the current data count value from the data number counter 3a and the data count value from T7 hours ago from the state holding circuit 4a into first information (i.e., 2
Similarly, the data count value from the data number counter 3b and the state holding circuit 4b is defined as the second information (the number of data sent from the transmission path I during the time 2T3). The number of data sent from these first
and the second information, and when the number of data of the first information is smaller than the number of data of the second information, it has a function of switching from the transmission line (2) to the transmission line (2). This switching is performed by the switching control circuit 5 controlling the selector 9 and sending only the data on the transmission line H to the drivers 8a and 8b.

The transmission line switching device 1 is used as shown in FIG.

That is, three transmission line switching devices 1 (la, lb, lc) are arranged in series between the communication devices 10 and 11, and transmission devices 12a, 12a, 12a, 12a, 12a, 12a, 12a, 12a, 12a, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 22, 22, 22, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3 3 3 3 Transmission path I having 12b and transmission device 13a
, 13b are connected in parallel, and similarly transmission devices 14a, 1 are connected between the transmission path switching device 1b and lcO.
Transmission line ■ having 4b and transmission devices 15a, 15
It is used in a transmission system configured by connecting transmission lines (2) in parallel.

Transmission data from the communication device 10 passes through the transmission path switching device 1a, is transmitted to the transmission paths I and H by the transmission devices 12a and 13a, is received by the transmission devices 12b and 13b, and reaches the transmission path switching device 1b. The transmission line switching device 1b is
The transmission path on which normal data is being transmitted is selected from transmission path I and transmission path ■. The selected data is transmitted to the transmission lines (1) and (2) by the transmission devices 14a and 15a, received by the transmission devices 14b and 15b, and reaches the transmission line switching device IC.

A transmission path is selected by the transmission path switching device IC, and the data reaches the communication device 11.

Next, an example of the switching operation of this embodiment will be explained.

As shown in FIG. 3, data b is transmitted to the transmission path I.

b2. b,,... are transmitted, and data b is on the transmission path ■.
,, bz, b, . . . and the same content data cl, c2 . c3. ... is being transmitted, and the transmission line I is connected to the transmission lines m and rv via the selector 9. However, data b,,b2. b.

. . . and data c1□C2, C:l, . . . The maximum delay time is assumed to be T1. Therefore, the timer 6 measures the time interval T.

The data sample circuits 2a and 2b and the data number counter 3
a, 3b, state holding circuits 4a, 4b, and switching control circuit 5
operate in synchronization with. In Figure 3, 1. ．． 12
,1. , . . . indicate the trigger time of the timer 6.

Between 1 and -12, data bl+cl is input to data sample circuits 2a and 2b, respectively, and taken out as data, and counted as a count value 1 by data number counters 3a and 3b. The signal indicating this count value 1 is
Data number counter 3a.

3b to the state holding circuits 4a, 4b and the switching control circuit 5. This count value 1 is the state holding circuit 4.
It is held only between t2 and t3 by a and 4b. t2～
During t3, transmission path 1. Data from II is not input to data sample circuits 2a, 2b. Therefore, the data number counters 3a, 3b transmit a signal indicating the count value O to the state holding circuit 4a.

4b and the switching control circuit 5. At this time, the state holding circuits 4a and 4b output a signal indicating the count value 1 between t and t2 to the switching control circuit 5.

The switching control circuit 5 inputs the signals of the data count value 1 between t1 and t2 and the data count value 0 between t2 and t3 of the transmission path 3 from the data number counter 3a and the state holding circuit 4a, and uses them as first information. , the data count value 1 between t and t2 of the transmission path ■ and the data count value O between t2 and t3 are input from the data number counter 3b and the state holding circuit 4b and are used as second information (hereinafter, these signals will be referred to as second information). information (the number of data input from the state holding circuits 4a and 4b T1 time ago).

The number of data input from the data number counters 3a and 3b at the current time) i: Write). The switching control circuit 5 compares the first information (1, O) and the second information (1°0) between 2T3 and recognizes that the number of data from the transmission paths I and ■ is equal,
Continue using transmission path I.

Similarly, between t4 and t6, the first information and second information input to the switching control circuit 5 are (0, O) and (1, 0).
It is. The switching control circuit 5 compares the first information and the second information, recognizes that the number of data from the transmission line I is smaller than the number of data from the transmission line ■ Switch to use.

Between t7 and t9, the first information and the second information are (0, 1
) and (0, O). Therefore, the switching control circuit 5 switches the use to the transmission line (2).

tl. If a disconnection of the transmission line (2) occurs at the point in time, the data after b4 from the transmission line I will be interrupted. Therefore, in this example, the first information and the second information between t and t11 are
The information becomes (0,0) and (1,O). Therefore, the switching control circuit 5 compares the first information and the second information and switches to using the transmission line H. Thereafter, as long as the transmission line I continues to be disconnected, the information from the transmission line I is (0, O), and as a result, the use of the transmission line ■ is maintained.

In another embodiment, the switching control circuit 5 is the state holding circuit 4.
The data count value of at least one of a or 4b is 1
In the above case, when the transmission line switching condition is set, and the number of data of the first information is smaller than the number of data of the second information, the transmission line is switched from the transmission line ■ to the transmission line ■, and the state holding circuits 4a and 4b
When both data count values are O, an example can be considered in which the transmission state is maintained at that time without switching the transmission path.

An example of the switching operation of this embodiment will be explained based on FIG. 3.

Between t1 and t3, the count values from the state holding circuits 4a and 4b are both 1, so the switching condition by the switching control circuit 5 is satisfied. Therefore, the switching control circuit 5
is the first information (1,0) and the second information (1,0) between 2TIs.
, O), recognizes that the number of data from transmission paths I and (2) are equal, and continues using transmission path (2).

Similarly, between t4 and tb, the first information and second information input to the switching control circuit 5 are (0, O) and (1, O).
It is. Since this information satisfies the switching conditions of the switching control circuit 5, the switching control circuit 5 compares the first information and the second information and determines that the number of data from the transmission path I is greater than the number of data from the transmission path ■. Recognizing that the number is low, the selector 9 is activated to switch to using the transmission line H.

Between t and t9, the first information and the second information are (0, 1
) and (0, O), so the switching condition is not satisfied. Therefore, the use of transmission path H is maintained.

t a” ”+' t,. In between, the first information and the second information are (1, O) and (0, 1), so the switching condition is satisfied, but since the number of data is equal, the use of the transmission line (2) is maintained.

tl. If the transmission line (2) is disconnected at the point in time, the data after data c4 from the transmission line (2) will be interrupted. Therefore, in this example, tl. The first information and the second information between t12 and t12 become (1, O) and (0, 0). Since this satisfies the switching condition, the switching control circuit 5 compares the first information and the second information and switches to using the transmission line I. Thereafter, as long as the transmission line (2) continues to be disconnected, the information from the transmission line (2) is (0, O), and as a result, the use of the transmission line I is maintained.

〔Effect of the invention〕

As explained above, the transmission line switching device for a duplex transmission line according to the present invention uses the first data number detection section and the second data number detection section to detect the number of data within a time interval twice the maximum data delay time. is detected, and the switching control circuit switches the transmission line depending on the size of the number of data from the first and second data number detection parts, so it is possible to detect the disconnection of the transmission line and switch the transmission line in a short time. There is an effect that can be done.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a transmission line switching device for a duplex transmission line according to an embodiment of the present invention, FIG. 2 is a block diagram showing an application example of the transmission line switching device shown in FIG. 1, and FIG. FIG. 4 is a diagram explaining the switching determination time of the transmission line switching device of FIG. 1, and FIG. 4 is a diagram explaining the switching determination time of the conventional transmission line switching device. 1. la, lb, lc...transmission line switching device 2a, 2
b...Data sample circuits 3a, 3b...
Data number counters 4a, 4b...Status holding circuit 5...Switching control circuit 6...Timer

Claims (1)

[Claims] (1) A first data number detection section and a second data number detection section connected to each of the first transmission path and the second transmission path, and the outputs of these first and second data number detection sections a switching control circuit connected to the side for switching between the first and second transmission lines, and a timer connected to the switching control circuit and the first and second data number detection units, The first and second data number detection units each include a data sample circuit that extracts data from each transmission path;
The switching control circuit includes a data number counter that counts the number of data output from the data sample circuit, and a state holding circuit that holds and outputs the number of data output from the data number counter. The number of data output from the data number counter and state holding circuit of the data number detection section is compared with the number of data output from the data number counter and state holding circuit of the second data number detection section, and the number of data is large. The timer switches the data sample circuit, data number counter, state holding circuit, and switching control circuit of the first and second data number detection units to the data on the first transmission route. 1. A transmission line switching device for a duplex transmission line, characterized in that the data on the second transmission line are synchronized with the data on the second transmission line at a maximum delay time interval.