JP2697481B2 - Redundant switching control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplex switching control system for switching data transmission sources in a system for transmitting data from a duplicated data transmission unit to one communication line. The communication apparatus has a configuration in which the data transmission source system is duplicated, one of which is in operation and the other is in standby, and when the active system becomes faulty, it immediately switches to the standby system to continue communication.

[0002]

2. Description of the Related Art FIG. 4 is a diagram showing a conventional switching control system in a conventional duplex system. In FIG. 4, reference numerals 1a and 1b denote alarm detectors, which monitor alarm information indicating whether the own system is normal or abnormal. When the system is operating normally without an alarm, "1" is output as an alarm detection signal. , Outputs "0" when an alarm occurs.

[0003] Reference numerals 2a and 2b denote switching control units which receive an alarm detection signal of the own system and a switching control signal of the other system to activate the own system (a state in which output data of the own device is transmitted to the line). It outputs "0" and "1" to be inactive.

[0004] Reference numerals 3a and 3b denote memories for storing the values of the switching control signals of the own system which have been output so far. Reference numerals 4a and 4b denote comparison circuits which monitor the switching control signals of the own system and the other system. If both systems are "1", the switching control signal is "1", otherwise, the switching control signal is "0". Output. 5a and 5b are 2: 1 selectors which receive the switching control signal of the own system and the output of the memory, and output the memory output when the selection control signal becomes "1", and the switching control signal of the own system at other times. Output as an output control signal.

The output control units 6a and 6b are active when the output control signal is "0" and transmit their own data to the line. When the output control signal is "1", the output control unit outputs their own data. Is not sent to the line.

FIG. 5 is an equivalent configuration diagram showing a logical relationship between input and output of 2a and 2b of the switching control unit of FIG. 4, and FIG. 6 is a switching logic diagram. In FIG. 5, what is input to the terminals A and B is the output of the alarm detectors 1a and 1b in FIG. 4, and the output from the terminals Q1 and Q2 corresponds to the switching control signal. As a result, QA and Q
The logic of B indicates the operation state of the data transmission device.

For example, at a certain point in time, when an alarm is detected in the condition 2 in FIG. 6, that is, when an alarm is detected in the B system, the switching control unit 2a of the A system sets "0" and the switching control unit 2b of the B system sets "0". 1 "is output and the A system becomes active, and data from the A system data transmission unit is transmitted to the communication line.

Next, assuming that the alarm of the system B is restored and the alarm is extinguished, the state transits to the condition 3 and the system A remains active. Next, when only the system A has an alarm, the condition 1 is satisfied, the system B is active, the system A is inactive, and data transmission from the system B is performed.

When one of the two systems is in a normal state, the data of the normal system is sent to the line. When both systems are in a normal state, the switching control signal does not change and the immediately preceding control state is maintained. When both systems transit to the presence of an alarm and the switching control signal becomes "1", the condition 4 is satisfied and the comparison circuit 4
Since a and b output "1", the selectors 3a and 3b select and output the memory output, and the previous state (data transmission from the system which was normal before) is performed.

[0010]

However, if either of the systems is in the alarm state from the normal state of either of them, the short period of time until the output of the immediately preceding output control signal from the selector is not valid in both systems. Becomes active. That is, there has been a problem that the active state is momentarily interrupted and the reliability is reduced.

In other words, there is a problem that an instantaneous interruption state occurs in which no system is connected to the communication line when the operating system is switched. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and occurs in a duplexed transmission device when both systems A and B enter an alarm state until one of the systems becomes active. The purpose is to prevent instantaneous interruption.

[0012]

FIG. 1 is a block diagram of a duplex switching control system according to the present invention. A for one channel communication line
A duplex switching control method in which data is transmitted from one of the duplicated data transmission units composed of a system and a B system, wherein each system has its own alarm signal and the first system of the other system. A first switching control unit 2a, 2b that receives a switching control signal and outputs a first switching control signal that is a NAND of both signals, a first switching control signal of the own system and a second switching control signal of the other system. Second switching control units 7a and 7b which receive a second switching control signal and output a second switching control signal which is a logical product of both signals, and provide a second switching control unit based on the second switching control signal. A switching control processing method, wherein data transmission from a system data transmission unit to a communication line is controlled.

[0013]

Since the switching control sections are connected in two stages, even if both systems transition to an alarm, the output of the second switching control section retains the state before the transition, so that both systems are simultaneously inactive. The instantaneous interruption of data transmission is prevented, and the reliability of communication is improved. Further, since the selector and the memory are not used in the switching control device, there is an effect that the circuit is simplified.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. FIG. 1 is a block diagram of the duplex switching control system of the present invention, FIG. 2 is an equivalent diagram of the switching control of FIG. 1, and FIG. 3 is a switching logic diagram of FIG.

Reference numerals 1a and 1b denote alarm detectors, which monitor alarm information indicating whether or not a self-system device is normal or abnormal. If the device is operating normally without an alarm, it indicates "1". Outputs "0".

Reference numerals 2a and 2b denote first switching control units which receive the alarm detection signal of the own system and the first switching control signal of the other system, and perform the first control only when both inputs are "1". The switching signal "0" is output, and the others are output. Reference numerals 7a and 7b denote a second switching control unit which receives the first switching control signal of the own system and the second switching control signal of the other system, and outputs the second control signal only when both inputs are "1". Is output as "0", otherwise "1" is output.

Reference numerals 8a and 8b denote output control units using a three-state buffer, which are controlled by a second switching control unit of the own system.
When the second switching control signal of the own system is "1", it becomes active, and sends the data of the own system to the communication line. Is disconnected.

Next, the operation of the duplex switching control system according to the present invention having the above-described configuration will be described with reference to FIGS. In the switching control equivalent diagram of FIG. 2, four switching control units 2a and 2 of FIG.
b, 7a, 7b are NAND circuits NANDa ', NANDb', N
It corresponds to ANDa and NANDb, and the input to the A and B terminals is
These are the outputs of the alarm detectors 1a and 1b in FIG.
Is the first switching control signal which is the output of the first switching controller 2a, 2b, and the output from the QA and QB terminals is the second switching control which is the output of the second switching controller 7a, 7b. The logic of QA and QB represents the operation state of the data transmission device of each system. In this example,
When QA is "1" and QB is "0", data transmission of the A system becomes active, and when QA is "0" and QB is "1", data transmission of the B system becomes active.

According to FIG. 3 showing the input / output logic of the switching control equivalent diagram of FIG. 2, when an alarm occurs in both systems at the same time, the condition 4 corresponds to the condition from the first control unit to the second switching control unit. Since the first switching control signal to be input is "1" in both systems,
The output of the second switching control unit does not change while the previous state is maintained. Other conditions are the same as those of the conventional one-stage configuration except that the final output is inverted.

As described above, even if the state transits to any of the conditions of "both systems have no alarm" and "both systems have an alarm", the previous switching control state is maintained, so that the output control units 8a and 8b Does not become active or inactive at the same time in both systems, and instantaneous interruption and data collision are prevented.

[0021]

As described above, according to the duplex switching control method of the present invention, both outputs of the two systems can be prevented from becoming inactive, so that the operation can be performed without causing an instantaneous interruption for all state changes. It is possible to perform system switching, and there is an effect that the reliability of a data transmission device having a duplex configuration can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a duplex switching control system of the present invention.

FIG. 2 is a switching control equivalent diagram of FIG. 1;

FIG. 3 is a switching logic diagram of FIG. 2;

FIG. 4 is a configuration diagram of a conventional duplex switching control method.

FIG. 5 is a switching control equivalent diagram of FIG. 4;

6 is a switching logic diagram of FIG.

[Explanation of symbols]

1a, 1b ... alarm detector, 2a, 2b ... (first) switching controller,
7a, 7b ... second switching control unit, 6a, 6b, 8a, 8b ... output control unit

Claims (1)

(57) [Claims] 1. A duplex switching control method for controlling data to be transmitted from one of a duplexed data transmitting unit comprising a system A and a system B to a communication channel of one channel. A first switching control unit (2a, 2b) that receives an alarm signal of the own system and a first switching control signal of the other system and outputs a first switching control signal that is a NAND of both signals; A second switching control unit that receives the first switching control signal of the own system and the second switching control signal of the other system and outputs a second switching control signal that is the NAND of both signals (7a, 7b The switching control processing method, wherein data transmission from the data transmission unit of the own system to the communication line is controlled based on the second switching control signal.