JPS6251852A - Transmission line switching device - Google Patents

Abstract

PURPOSE:To avoid unnecessary switching and restoring operations of transmission lines for interrupted data break on transmission lines by giving a hysteresis to data reception to restore transmission lines only for continuity of several frames. CONSTITUTION:Data of a digital signal is transmitted to an internal device 14 through a main transmission line 1 and a gate 10. As long as data is received continuously from the main transmission line 1 by a receiver 3, the overflow output of a counter 6 is not outputted from a terminal Qn. Meanwhile, a frame signal is continuously inputted to the CLK terminal of an address counter 61, and the overflow output is outputted from a terminal Qm to a set terminal S of an FF 8, and the gate 10 is held in the conductive state. If data reception from the main transmission line 1 is broken, the counter 6 is overflowed to reset the address counter 61. AS the result, a gate 11 is made conductive to receive data from an auxiliary transmission line 2. When the main transmission line is restored thereafter and is broken again after reception of m-number of frames, the gate 10 is not opened because the overflow output of the counter 61 is not outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a transmission line switching device that appropriately switches and uses one of a transmission line having two thread lines, a main line and a sub line.

(Technical background of the invention and its problems) Conventionally, there is a means shown in FIG. 3 as an example of this type of device.

In preparation for 1lli line etc. of transmission line, main transmission line 1 and sub transmission line 2
, and data is always received using main transmission path 1 during normal times.

That is, numeral 3 is a receiving device for the main transmission path 1, where the data of the digital signal transmitted through the main transmission path 1 is transmitted to the internal device 14 via the gate 10.

5 is a clock which always sends pulses at constant intervals to the CLK terminal of the counter 6.7. Further, the data reception signal accepted by the receiving device 3 is applied to the CLKE terminal of the counter 6 and the set terminal S of the flip-flop 8. Therefore, as long as the data reception signal on the main transmission line 1 is normal, the count value counted by the counter 6 by the clock 5 is always reset by the data reception signal, and the counter 6 outputs an overflow (switching signal) as Q. 7 from terminal
It is not applied to the reset terminal R of the flip-flop 8, and the flip-flop 8 outputs from the Q terminal, making the gate 10 conductive. Note that since the data reception signal is sent backward from the receiving device 3, the flip-flop 8 continues to be set.

By the way, suppose that a disconnection failure occurs in the main transmission line 1.

Since the receiving device 3 cannot send the data reception signal backward, the counter 6 immediately overflows at the clock 5 and the signal is sent to the terminal Q. outputs a switching signal to the reset terminal R of the flip-flop 8, stops its Q output, and makes the gate 10 non-conductive.

At that time, the data reception signal received by the receiving device 4 from the sub-transmission line 2 is sent backwards and enters the CLK terminal of the counter 7, which resets the count of the clock 5 to the CLK terminal of the counter 7, causing an overflow. Since the switching signal at the time is not outputted to the R terminal of the flip-flop 9, the flip-flop 9 outputs an output Q by inputting the data reception signal from the receiving device 4 to the S terminal.

By the way, since the flip-flop 7O tube 8 does not output an output from the Q terminal, the inverter 12 has no input but has an output, and together with the Q output from the flip-flop 9, an AND gate (theory)!I! W4>13 outputs, gate 11 becomes conductive, and the data reception signal received from sub-transmission line 2 is sent to internal device 14 via rear gate 11.
sent to.

Then, when the disconnection of the main transmission line 1 is recovered, the gates 10 and 11 become non-conductive, and the normal state is restored.

In other words, in this conventional example, a main transmission line 1 and a sub-transmission line 2 are provided in preparation for transmission line breakage, etc., and a reception V; ,
The counter 6.7 is configured to be reset, and the time is measured by the time when valid data does not arrive. If valid data is not received for a certain period of time or more, it is determined that there is a failure, a switching signal is generated, and the transmission path is switched. In addition, in the case of a defect on the transmitting side, if the defective part on the transmitting side is removed, recovery is possible.

However, with this configuration, when data interruption occurs intermittently, such as when a transmission line has a poor contact, there is a risk that switching and recovery may be repeated, resulting in erroneous data.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to overcome the drawbacks of the conventional example and to provide a transmission line switching device that does not switch or restore in response to intermittent data interruptions in the transmission line.

[Summary of the invention]

In order to achieve the above object, the present invention provides hysteresis in switching and recovery by tightening the recovery conditions, since switching and recovery may occur frequently with conventional means. This is a transmission line switching device.

[Embodiments of the invention]

FIG. 1 shows a block diagram showing a circuit configuration in an embodiment of the present invention.

The same reference numerals do not represent the same or corresponding parts in all drawings.

FIG. 2 shows an aspect of transmission data applied to the present invention.

When sending data for n channels (hereinafter referred to as ch), the sending side sends 1c sequentially from Och.
h, 2ch..., nCh, and one frame is from Och to nch.

Since no address is sent, a reset signal is sent between each frame.

Therefore, in the present invention, in addition to the counter 6.7, counters 61 and 71 are arranged between the reception device 613.4 and the set terminal S of the flip-flops 8 and 9, and the frames received by the reception devices 3 and 4 are signal (that is, a reset signal that represents a blank reset time provided for each frame)
is received at the CLK terminal of counter 61.71, the overflow output of counter 6.7 is introduced into the CLK terminal of these counters 61.71, and
．． The overflow output from the output terminal Qm of 71 is applied to the set terminal S of 7 lip flop 8.9.

The operations of counters 6 and 7 are conventional.

Therefore, as long as reception is continuously received from the main transmission line 1 to the receiving device 3, the overflow output of the counter 6 is Q. It never comes out from the terminal.

On the other hand, since the frame signal is continuously input to the CLK terminal of the address counter 61 and no reset signal is input to the CLK terminal, the overflow output is QIl[
output from the child to the set terminal S of the flip-flop 8,
Gate 10 continues to be conductive.

Then, when the reception of data from the main transmission line 1 is interrupted, the counter 6 sends an overflow output to the terminal Q.

The address counter 61 is reset and the overflow output does not come out from the terminal Q, the flip-flop 8 does not send out the output from the Q terminal, the gate 10 becomes non-conductive, and the gate 11 becomes conductive for sub-transmission. Data from path 2 is received by internal device 14.

By the way, if the main transmission line 1 accepts m frames of data for a short period of time, and then stops accepting data again, the overflow output of the address counter 61 will be Q, and the overflow output from the terminal will not be output from the terminal. No, gate 10
is non-conductive, and gate 11 continues to be conductive.

In other words, the overflow of the address counter 61 is set to n, which is greater than m.

That is, on the receiving side, the number of data is counted by the address counter 6.
An address is generated by counting 1.71, and the address counter 61.71 is reset by a reset signal. Therefore, the address counter 61.71
From the CLK count, it can be known that the nth data has been received, the number of sent states is counted, and the state in which a predetermined number of frames have been completely sent is detected and recovery is performed. .

In this way, in the past, if one channel in one frame received data consecutively, it would recover, but in the present invention, the data data is received with hysteresis, and data is received consecutively for several (n) frames. This provides a means for making the return for the first time.

Note that it is clear that the receiving side of the sub-transmission line 2 performs exactly the same operation.

〔Effect of the invention〕

Thus, according to the present invention, data reception occurs by tightening the recovery conditions of the transmission path.

Unnecessary transmission line cutting and recovery operations can be avoided,
It significantly improves the reliability of transmitted data and greatly contributes to this field.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the circuit configuration in an embodiment of the present invention, FIG. 2 is a diagram showing the mode of received transmission data, and FIG.
The figure is an explanatory diagram of a conventional example. 1... Main transmission path, 2... Sub transmission path, 3.4... Receiving device, 5... Clock, 6.7.61.71...
Counter, 8.9...Flip-flop, 10.11
...Ge-l-112...Inverter (Negation circuit),
13...AND gate (logical product circuit), 14...internal equipment.

Claims (1)

[Claims] 1. The transmission line has two lines, a main transmission line and a sub line, and means for determining a failure in the main transmission line when no valid data is received for a certain period of time, and a means for determining a failure in the main transmission line, and a flow of data to the sub transmission line. a means for counting the number of frames consisting of each channel in a series of data; and a means for counting the number of frames consisting of each channel of data; A transmission line switching device comprising: a recovery function having a means for restoring data flow; and a transmission line switching device.