CN108337113B - Transmission line switching device and method - Google Patents

Abstract

The transmission line switching device and method of the present invention shorten the time required to resume communication. In the communication terminal device group (2), there is no request to send a message, and the current does not flow through the transmission line of the A system (the transmission line of the main system) (3) The state continues for a predetermined time (T) (for example, 5 ms) or more When the transmission line (4) of the B system (standby system) is switched to the transmission line of the main system (by setting the switch (5) to the interval state and the switch (6) to the mark state, the main system is switched from the A system into B system). Thereby, when the next message is sent after the transmission line (4) of the B system (standby system) is switched to the transmission line of the main system, there is no need to wait for the voltage (VS') inside the power supply device (1) to be adjusted to be stable, The time to restart communication can be shortened.

Description

Transmission line switching device and method

technical field

The present invention relates to a transmission line switching device and method used in a communication system that communicates by a current loop method.

Background technique

Conventionally, a communication system that communicates by a current loop method has been used. The current loop method refers to a communication method that transmits a signal according to a change in the current value, and transmits a communication signal to a communication terminal device connected to a transmission line according to the ON (eg, 30mA) and OFF (eg, 2mA) of the loop current. method of communication.

In this communication method, a communication signal when the loop current is turned on is called a mark signal, the loop current at this time is called a mark current, and a communication signal when the loop current is turned off is called a gap (Space) signal, the loop current at this time is called a space current (for example, refer to Patent Document 1).

FIG. 8 is a diagram showing an example of a conventional communication system in which transmission lines are duplexed using a current loop method. In the figure, 1 is a power supply device, 2 is a group of communication terminal devices, and the transmission line between the power supply device 1 and the group of communication terminal devices 2 is doubled. That is, in this communication system 100, the power supply device 1 and the communication terminal device group 2 are connected via the transmission line 3 of the A system and the transmission line 4 of the B system.

In addition, in FIG. 8, for convenience of description, the communication terminal apparatus group 2 is divided into two and shown, but the actual communication terminal apparatus group 2 is one. The communication terminal device group 2 is constituted by series-connected main units, sub units, and the like, and is connected to the line of the transmission line 3 of the A system and the transmission line 4 of the B system as a common load.

In addition, in this example, the switch 5 is provided on the transmission line 3 of the A system, and the switch 6 is provided on the transmission line 4 of the B system. Transistors can be used as switches 5 , 6 . The transmission line 3 of the A system is set as the transmission line of the main system by setting the switch 5 in the marked state (state in which the current easily flows). The transmission line 4 of the B system is set as the transmission line of the backup system by setting the switch 6 in an interval state (a state in which a current does not easily flow (2 mA or less)).

In the communication system 100, the communication terminal device group 2 turns on the circulating current of the transmission line 3 of the A system (main system) by changing the value of the current flowing in the transmission line 3 of the A system (main system). (for example, 30mA) or set to OFF (for example, 2mA) to transmit a message.

[Transmission line switching device]

As shown in FIG. 9 , the communication system 100 is provided with a transmission line switching device 7 . The transmission line switching device 7 monitors whether there is a message transmission request in the communication terminal device group 2, and when there is a message transmission request, confirms the transmission line 3 and Whether the loop of the two systems, the transmission line 4 of the B system (standby system), is established.

Here, when the loop of the transmission line 3 of the A system (main system) is not established and the loop of the transmission line 4 of the B system (backup system) has been established, it is determined as the transmission line of the A system (main system). 3 is disconnected, and the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system (see FIG. 10 ). That is, by setting the switch 5 in the interval state and setting the switch 6 in the flag state, the main system is transferred from the A system to the B system.

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Laid-Open No. 11-68856

Patent Document 2: Japanese Patent No. 4451718

SUMMARY OF THE INVENTION

The technical problem to be solved by the invention

Recently, as the power supply device 1, a method of adjusting the internal voltage VS' according to the load has been adopted (for example, refer to Patent Document 2). According to this method, the voltage adjustment operation is eliminated, and the operability is improved, but on the other hand, there occurs a failure to stabilize the voltage VS' inside the power supply device 1 after connecting the communication terminal device group 2 (maximum 2 seconds). during the communication.

It is rare that communication needs to be performed immediately after the connection of the communication terminal apparatus group 2, so there is no problem in itself. However, in the communication system 100 in which the transmission lines are duplexed as described above, when the transmission line 3 of the A system (main system) is disconnected, the impedance load of the A system (main system) becomes extremely large, so that the adjustment of the power supply device 1 The function of the internal voltage VS' temporarily becomes unstable. Therefore, when the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system, it takes time until the voltage VS' inside the power supply device 1 is stabilized, and a time until the communication can be resumed The problem of getting longer.

The present invention has been made in order to solve such a technical problem, and an object thereof is to provide a transmission line switching device and method capable of shortening the time until communication can be resumed.

technical means to solve technical problems

In order to achieve such an object, the present invention relates to a transmission line switching device (7B) for use in a communication system (200), the communication system (200) comprising: a first transmission line (3); a second transmission line (4) ); a group of communication terminal apparatuses (2), which are configured such that the first transmission line and the second transmission line are used as the transmission line of the main system and the transmission line of the backup system, respectively, and the current flowing in the transmission line of the main system passes the current and a power supply device (1) that supplies a power supply voltage to the first transmission line and the second transmission line, and adjusts the internal voltage according to the load, and the transmission line switching device (7B) is composed of When an abnormality occurs in the first transmission line, the second transmission line is switched to the transmission line of the main system, and the transmission line switching device (7B) is characterized by comprising: a transmission line switching unit (70, 70') having a structure In order to determine that an abnormality has occurred in the first transmission line, when there is no request to send a message in the communication terminal device group and the current does not flow through the first transmission line for a predetermined time or longer, the second transmission line is switched to be the main one transmission line of the system.

According to the present invention, when there is no request to send a message in the communication terminal device group and the state where no current flows through the first transmission line (the transmission line of the main system) continues for a predetermined time or longer, it is determined that the first transmission line ( The transmission line of the main system is abnormal, and the second transmission line (the transmission line of the backup system) is switched to the transmission line of the main system.

Thus, in the present invention, the second transmission line (the transmission line of the backup system) is switched to the transmission line of the main system while there is no message transmission request in the group of communication terminal apparatuses. In addition, the adjustment of the internal voltage of the power supply device is also performed during the period when there is no message transmission request in the group of communication terminal devices. Therefore, when the next message is sent after the switching of the second transmission line (the transmission line of the backup system) to the transmission line of the main system, it is not necessary to wait for the adjustment of the voltage inside the power supply device to stabilize until it can be restarted again. The time until communication becomes shorter.

Furthermore, in the present invention, after the second transmission line (the transmission line of the backup system) is switched to the transmission line of the main system, the second transmission line becomes the transmission line of the main system, and the first transmission line becomes the transmission line of the backup system . That is, after the second transmission line (the transmission line of the backup system) is switched to the transmission line of the main system, the second transmission line becomes the first transmission line (the transmission line of the main system) in the present invention, and the first transmission line becomes the first transmission line (the transmission line of the main system). The line becomes the second transmission line (transmission line of the backup system) referred to in the present invention.

In addition, in the above description, as an example, the components on the drawings corresponding to the components of the invention are represented by reference numerals in which parentheses are attached.

Invention effect

Based on the above description, according to the present invention, when there is no message transmission request in the communication terminal device group, and the state in which the current does not flow through the first transmission line (the transmission line of the main system) continues for a predetermined time or longer, it is determined that the first transmission line is the first transmission line. An abnormality occurs in the transmission line (transmission line of the main system), and the second transmission line (transmission line of the backup system) is switched to the transmission line of the main system. When the next message is transmitted after the switching of the transmission line, it is not necessary to wait until the voltage inside the power supply device is stabilized, and the time until the communication can be resumed can be shortened.

Description of drawings

FIG. 1 is a diagram showing a main part of a communication system using a transmission line switching device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of the hardware configuration of the transmission line switching device in the communication system.

3 is a flowchart showing a first example (Embodiment 1) of the processing operation executed by the CPU in the transmission line switching device.

4 is a diagram showing a state in which the transmission line of the B system (standby system) is switched to the transmission line of the main system by the transmission line switching device (the state of the main system being changed from the A system to the B system).

5 is a functional block diagram of a main part of a transmission line switching device that executes the processing operation of the first embodiment.

6 is a flowchart showing a second example (Embodiment 2) of the processing operation executed by the CPU in the transmission line switching device.

7 is a functional block diagram of a main part of a transmission line switching device that executes a second example of the processing operation of the second embodiment.

FIG. 8 is a diagram showing an example of a conventional communication system in which transmission lines are duplexed using a current loop method.

FIG. 9 is a diagram illustrating a situation in which the transmission line of the B system (standby system) is switched to the transmission line of the main system in the conventional communication system (state before switching).

FIG. 10 is a diagram illustrating a situation (state after switching) of switching the transmission line of the B system (standby system) to the transmission line of the main system in the conventional communication system.

Detailed ways

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing a main part of a communication system 200 using a transmission line switching device according to an embodiment of the present invention. In this figure, the same reference numerals as those in FIG. 9 denote the same or equivalent components as those described with reference to FIG. 9 , and the description thereof will be omitted.

Hereinafter, in order to distinguish from the transmission line switching device 7 in the conventional communication system 100 shown in FIG. 9 , the transmission line switching device 7 in the conventional communication system 100 is denoted by reference numeral 7A, and the communication according to the present embodiment is denoted by reference numeral 7B The transmission line switching device 7 in the system 200 .

In addition, in this communication system 200, similarly to the conventional communication system 100, in the transmission line 3 of the A system, the switch 5 is set to the marked state (state in which the current easily flows), and the transmission line of the B system In step 4, the switch 6 is set to an interval state (a state in which a current does not easily flow (2 mA or less)). That is, the transmission line 3 of the A system is set as the transmission line of the main system, and the transmission line 4 of the B system is set as the transmission line of the backup system.

FIG. 2 shows an outline of the hardware configuration of the transmission line switching device 7B. The transmission line switching device 7B includes a central processing unit (CPU) 7-1, a random access memory (RAM) 7-2, a read only memory (ROM) 7-3, interfaces 7-4, 7-5, and the Connect the busbars 7-6.

In the transmission line switching device 7B, a transmission line switching program is installed as a program unique to this embodiment. The CPU 7-1 operates according to the installed transmission line switching program while accessing the RAM 7-2 and the ROM 7-3 by processing the information input through the interface 7-4.

[Embodiment 1]

Next, a first example (Embodiment 1) of the processing operation executed by the CPU 7 - 1 in accordance with the transmission line switching program will be described using the flowchart shown in FIG. 3 .

In Embodiment 1, the CPU 7-1 confirms whether there is a message transmission request in the communication terminal device group 2 (step S101), and when there is no message transmission request, checks the transmission line 3 in the A system (main system). The current IM(IA) flowing in the current IM(IA) (step S102).

Here, when there is no request to transmit a message in the communication terminal device group 2 (“None” in step S101 ) and the current does not flow through the transmission line 3 of the A system (main system) (the state of IM=0) continues When the predetermined time T (for example, 5 ms) is longer than (YES in step S102 ), the CPU 7 - 1 determines that the transmission line 3 of the A system (main system) is disconnected (abnormal) (step S103 ), and sets the B system The transmission line 4 of the (standby system) is switched to the transmission line of the main system (step S104, see FIG. 4). That is, by setting the switch 5 in the interval state and setting the switch 6 in the flag state, the main system is switched from the A system to the B system.

Thus, in the present embodiment, the transmission line 4 of the B system (backup system) is switched to the transmission line of the main system while there is no message transmission request in the communication terminal apparatus group 2 . In addition, the adjustment of the internal voltage VS' of the power supply device 1 is also performed during the period in which there is no message transmission request in the communication terminal device group 2. Therefore, when the next message is sent after the switching of the transmission line 4 of the B system (backup system) to the transmission line of the main system, it is not necessary to wait until the adjustment of the voltage VS' inside the power supply device 1 is stabilized until it can be resumed again. The time until communication starts is shortened.

FIG. 5 shows a functional block diagram of the main part of the transmission line switching device 7B of the first example (Embodiment 1) that executes the above-described processing operations. In Embodiment 1, the transmission line switching device 7B includes, as the transmission line switching unit 70 , the message transmission request presence/absence confirmation unit 71 , the A-system transmission line current confirmation unit 72 , and the line switching unit 73 .

In the transmission line switching unit 70 , the message transmission request presence/absence confirmation unit 71 confirms whether or not there is a message transmission request in the communication terminal device group 2 . The A-system transmission line current confirmation unit 72 confirms whether or not the state in which the current does not flow through the A-system (main system) transmission line 3 continues for a predetermined time T or more. In a state where the message transmission request presence/absence confirmation unit 71 confirms that there is no message transmission request in the communication terminal device group 2, the A-system transmission line current confirmation unit 72 confirms that current does not flow through the A-system (main system) transmission line When the state of 3 continues for a predetermined time T or longer, the line switching unit 73 determines that the transmission line 3 of the A system (main system) is disconnected, and switches the transmission line 4 of the B system (standby system) to the transmission line of the main system. .

In addition, in Embodiment 1, after the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system, the transmission line 4 of the B system becomes the transmission line of the main system, and the transmission line 3 of the A system becomes the transmission line of the main system. Transmission lines for backup systems. That is, before the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system, the transmission line 3 of the A system is set as the first transmission line (the transmission line of the main system) in the present invention, The transmission line 4 of the B system is used as the second transmission line (the backup system transmission line) in the present invention, and after switching, the B system transmission line 4 becomes the first transmission line (the main transmission line) in the present invention. transmission line of the system), the transmission line 3 of the A system becomes the second transmission line (transmission line of the backup system) referred to in the present invention.

[Embodiment 2]

Next, a second example (Embodiment 2) of the processing operation executed by the CPU 7 - 1 in accordance with the transmission line switching program will be described using the flowchart shown in FIG. 6 .

In Embodiment 1, a logic means is added which detects the disconnection of the transmission line 3 of the A system (main system) while there is no message transmission request in the communication terminal device group 2, and adds the B system (main system). The transmission line 4 of the backup system) is switched to the transmission line of the main system.

However, in Embodiment 1, when the disconnection of the transmission line 3 of the A system (main system) is detected, the transmission line 4 of the B system (standby system) is immediately switched to the transmission line of the main system. At this time, when the transmission line 4 of the B system (backup system) is disconnected, the disconnection of the transmission line 4 of the B system (backup system) is detected as a disconnection of the transmission line of the main system, and the transmission line is immediately switched and returned. to the original state. Therefore, the transition from the A system to the B system and from the B system to the main system of the A system is repeated until the disconnection is improved.

In addition, after the power is turned on, the time until the automatic adjustment of the internal voltage VS' of the power supply device 1 is completed is the state in which the overvoltage protection functions (maximum 2 seconds) and no current flows. Therefore, both the transmission line 3 of the A system (main system) and the transmission line 4 of the B system (backup system) are in a state where disconnection is detected. Even in such a case, the transition from the A system to the B system and from the B system to the main system of the A system is repeated, which may cause a malfunction.

Therefore, in Embodiment 2, when there is no request to transmit a message in the communication terminal device group 2 (“None” in step S201 ), and the current does not flow through the transmission line 3 of the A system (main system) (IM= When the state of 0) continues for a predetermined time T (for example, 5 ms) or longer (YES in step S202), it is determined that the transmission line 3 of the A system (main system) is disconnected (abnormal) (step S203) , it is checked whether the loop of the transmission line 4 of the B system (standby system) is established (step S204).

Here, only when it is confirmed that the loop of the transmission line 4 of the B system (backup system) is established (Yes in step S204 ), the transmission of the transmission line 4 of the B system (backup system) to the main system is performed. Line switching (step S205). That is, when it is not confirmed that the loop of the transmission line 4 of the B system (backup system) is established (NO in step S204 ), the transmission line of the transmission line 4 of the B system (backup system) to the main system is not performed. switch.

Thereby, only when the transmission line 4 of the B system (backup system) is normal, the transmission line 4 of the B system (backup system) is switched to the transmission line of the main system, and the problem of repeating the transition of the main system does not arise. .

FIG. 7 shows a functional block diagram of a main part of a transmission line switching device 7B that executes the second example (Embodiment 2) of the above-described processing operations. In the second embodiment, the transmission line switching device 7B includes, as the transmission line switching unit 70 ′, the message transmission request presence/absence confirmation unit 71 , the A system transmission line current confirmation unit 72 , the B system transmission line confirmation unit 74 , and the line switching unit 75 .

In the transmission line switching unit 70', the message transmission request presence/absence confirmation unit 71 confirms whether there is a message transmission request in the communication terminal apparatus group 2 or not. The A-system transmission line current confirmation unit 72 confirms whether or not the state in which the current does not flow through the A-system (main system) transmission line 3 continues for a predetermined time T or more. The B-system transmission line confirmation unit 74 confirms whether or not the B-system (standby system) transmission line 4 is normal. In a state where the message transmission request presence/absence confirmation unit 71 confirms that there is no message transmission request in the communication terminal device group 2, the A-system transmission line current confirmation unit 72 confirms that current does not flow through the A-system (main system) transmission line When the state of 3 continues for a predetermined time T or more, the line switching unit 75 determines that the transmission line 3 of the A system (main system) is disconnected, and confirms that the transmission line 3 of the B system is a system B (standby system) by the B system transmission line confirmation unit 74. As a condition that the transmission line 4 is normal, the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system.

Also in the second embodiment, after the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system, the transmission line 4 of the B system becomes the transmission line of the main system, and the transmission line 3 of the A system becomes the transmission line of the main system. It becomes the transmission line for the backup system. That is, before the transmission line 4 of the B system (standby system) is switched to the transmission line of the main system, the transmission line 3 of the A system is set as the first transmission line (the transmission line of the main system) in the present invention, The transmission line 4 of the B system is used as the second transmission line (the backup system transmission line) in the present invention, and after switching, the B system transmission line 4 becomes the first transmission line (the main transmission line) in the present invention. transmission line of the system), the transmission line 3 of the A system becomes the second transmission line (transmission line of the backup system) referred to in the present invention.

[Extension of Embodiment]

As mentioned above, although this invention was demonstrated with reference to embodiment, this invention is not limited to the said embodiment. Various changes that can be understood by those skilled in the art can be made within the scope of the technical idea of the present invention for the configuration and details of the present invention.

Symbol Description

1...power supply device; 2...communication terminal device group (load), 3...transmission line of system A; 4...transmission line of system B; 5, 6...switches; 7(7B)...transmission line switching device; 7-1 ...CPU; 7-2...RAM; 7-3...ROM; 7-4, 7-5...interface; 70, 70'...transmission line switching unit; 71...message transmission request presence/absence confirmation unit; 72...A system transmission Line current confirmation unit; 73...Line switching unit; 73, 74...B system transmission line confirmation unit; 75...Line switching unit; 200...Communication system.

Claims (6)

1. A transmission line switching device used in a communication system, the communication system comprising:

1 st transmission line;

a 2 nd transmission line;

a communication terminal apparatus group configured to transmit a message by changing a value of a current flowing through a transmission line of a main system, with the 1 st transmission line and the 2 nd transmission line being a transmission line of a main system and a transmission line of a backup system, respectively; and

a power supply device that supplies a power supply voltage to the 1 st transmission line and the 2 nd transmission line and adjusts an internal voltage in accordance with a load,

the transmission line switching device is configured to switch the 2 nd transmission line to a transmission line of a main system when the 1 st transmission line is abnormal,

the transmission line switching device is characterized by comprising:

and a transmission line switching unit configured to determine that an abnormality has occurred in the 1 st transmission line and switch the 2 nd transmission line to a transmission line of a master system when there is no request for transmission of a message in the communication terminal apparatus group and a state where a current does not flow through the 1 st transmission line continues for a predetermined time or longer.

2. The transmission line switching device according to claim 1,

the transmission line switching unit is configured to determine that an abnormality has occurred in the 1 st transmission line when there is no request for transmission of a message in the communication terminal apparatus group and a state where a current does not flow in the 1 st transmission line continues for a predetermined time or longer, and to switch the 2 nd transmission line to a transmission line of a master system on the condition that the 2 nd transmission line is normal.

3. The transmission line switching device according to claim 1,

the transmission line switching unit includes:

a message transmission request confirmation unit configured to confirm whether or not a message transmission request is made in the communication terminal device group;

a 1 st transmission line current confirmation unit configured to confirm whether or not a state duration in which a current does not flow through the 1 st transmission line is equal to or longer than a predetermined time; and

and a line switching unit configured to determine that an abnormality has occurred in the 1 st transmission line and switch the 2 nd transmission line to a transmission line of a master system when the 1 st transmission line current confirmation unit confirms that a current has not flowed through the 1 st transmission line for a predetermined time or longer in a state where the message transmission request presence/absence confirmation unit confirms that there is no message transmission request in the communication terminal device group.

4. The transmission line switching device according to claim 1,

the transmission line switching unit includes:

a message transmission request confirmation unit configured to confirm whether or not a message transmission request is made in the communication terminal device group;

a 1 st transmission line current confirmation unit configured to confirm whether or not a duration of a state in which a current does not flow through the 1 st transmission line is equal to or longer than a predetermined time;

a 2 nd transmission line confirmation unit configured to confirm whether or not the 2 nd transmission line is normal; and

and a line switching unit configured to determine that the 1 st transmission line is abnormal when the 1 st transmission line current confirmation unit confirms that the duration of a state in which the 1 st transmission line current confirmation unit confirms that the current does not flow through the 1 st transmission line is equal to or longer than a predetermined time in a state in which the message transmission request presence/absence confirmation unit confirms that the message transmission request is not present in the communication terminal device group, and switch the 2 nd transmission line to a transmission line of a master system on the condition that the 2 nd transmission line confirmation unit confirms that the 2 nd transmission line is normal.

5. A transmission line switching method used in a communication system, the communication system comprising:

1 st transmission line;

a 2 nd transmission line;

a communication terminal apparatus group configured to transmit a message by changing a value of a current flowing through a transmission line of a main system, with the 1 st transmission line and the 2 nd transmission line being a transmission line of a main system and a transmission line of a backup system, respectively;

a power supply device that supplies a power supply voltage to the 1 st transmission line and the 2 nd transmission line and adjusts an internal voltage in accordance with a load,

the transmission line switching method switches the 2 nd transmission line to a transmission line of a main system when the 1 st transmission line is abnormal,

the transmission line switching method is characterized by comprising:

a transmission line switching step of, when there is no request for transmission of a message in the communication terminal apparatus group and a state where a current does not flow through the 1 st transmission line continues for a predetermined time or longer, determining that an abnormality occurs in the 1 st transmission line and switching the 2 nd transmission line to a transmission line of a master system.

6. The transmission line switching method according to claim 5,

in the transmission line switching step, when there is no request for transmission of a message in the communication terminal device group and a state where a current does not flow through the 1 st transmission line continues for a predetermined time or longer, it is determined that an abnormality occurs in the 1 st transmission line, and the 2 nd transmission line is switched to a transmission line of a master system on the condition that the 2 nd transmission line is normal.

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