JPS63252043A - Line restoration method in data transmission system - Google Patents

Abstract

PURPOSE:To attain actual data transmission while having only to connect a slave station to the system simply and physically by sending a dummy signal in the slave station not in existence in a signal line input nor a loopback line input. CONSTITUTION:When a slave station 2c is not connected to a slave station 2b which is switched to reflect the signal line input to a loopback line, since the signal line input exists, the slave station 2c is brought into the data sending enable state. Conversely, if the slave station 2c is connected to a slave station 2d switched to reflect the loopback line input to the signal line, although no signal is supplied from the connected slave station without any modification provided, since the slave station 2c outputs a dummy signal and the slave station 2d receives the signal line input and the loopback line input, the station is switched into the data through state. Then, the slave station 2c is switched to reflect the loopback line input to the signal line to enable the data transmission.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a line recovery method in a data transmission system, and more specifically, the present invention relates to a line recovery method in a data transmission system. The present invention relates to a line restoration method for connecting additional slave stations and preventing erroneous disconnection of slave stations in a serially connected polling data transmission system.

<Conventional technology> As a polling-based data transmission system,
A system has been proposed in which data transmission from a master station and data transmission from a slave station are performed through a single transmission line, eliminating the need for switching control of a boat or the like corresponding to data transmission and data reception.

FIG. 1 is a diagram showing the configuration of such a data transmission system, in which a plurality of slave stations send out input signals after having undergone necessary processing to one master station, and They are connected in series by a loopback line that sends out the input signal as is.

FIG. 1A is a schematic diagram showing the status of each station, with one master station (1) and five slave stations (2a) (2b) - (2e
) are connected in series by a signal line (3) that sends out the input signal after performing the necessary processing, and a loopback line (4) that sends out the input signal as it is, and the entire line is looped. It is formed.

Therefore, data sent from the master station (1) is sequentially transmitted through the signal line (3) to the slave stations (2a) (2b)...(2).
e), the response data from each slave station can be supplied to the master station (1) through the signal line (3). To explain in more detail, the master station (1)
By using data that includes the address data of the slave station as the data sent from the slave station, it is possible to transmit data only to the desired slave station, and also include the own address in the data sent from the slave station. By this,
The master station (1) can identify which slave station the response data is from and perform necessary processing.

Further, each of the above-mentioned stations is automatically controlled to switch to different states depending on the presence or absence of signal line input and loopback line input, and the switching control method is different depending on the master station and the slave station.

Specifically, in the slave station, when both inputs are present, the slave station is switched to the data through state (see Figure 2 A) in which each signal line input is output respectively, and when only the signal line input is present, is switched to the state in which the signal line input is looped back to the loopback line and sent out (see Figure 2 B), and if only the loopback line input exists, the loopback line input is looped back to the signal line and sent out. When the state is switched to the state (see FIG. 2C) and there is no input, the state is switched to the state where the signal line input is looped back to the loopback line and sent out (see FIG. 2B).

In the master station, if both inputs are present and there is no input disconnection in the slave station, the state is switched to the state in which the signal line input is looped back to the loopback line and sent out (see Figure 2 B), and both If there is an input and there is an input disconnection at the slave station, it is switched to the data through state (see Figure 2 A) in which each signal line input is output respectively, and if only the signal line input is present, When the signal line input is switched to the loopback line and sent out (see Figure 2 B), and only the loopback line input exists, the loopback line input is turned back to the signal line and sent out! ! ! (See Figure 2 C), and if there is no input, the signal line input is looped back to the loopback line and sent out (See Figure 2 B). .

Therefore, if no disconnection occurs between any stations, a loop-like connection will be formed as shown in Figure 1A. If a disconnection condition has occurred, for example,
As shown in Figure B, the slave station (2b) is switched to a state where the signal line input is looped back to the loopback line (4), and the slave station (2c) is switched to the loopback line input. Switching control is performed so that the signal line is turned back to the signal line (3).

As a result, the main station (1)
The data is sequentially transmitted to the slave station (2a) (2b) through the signal line (signal line port), and then looped back at the slave station (2b) and transmitted to the slave station (2C) through the loopback line (4), Data is sequentially transmitted from the slave station (2c) to the slave stations (2d) (2e) through the signal line (3), and finally sent back to the master station (1).

Furthermore, even if a disconnection state occurs in other parts, each station is controlled to switch according to the signal input state, so that data transmission and data return to the master station can be performed in the same way.

<Problems to be solved by the invention> In the data transmission system with the above configuration, the slave station
Only the function to send response data as necessary only when data is supplied from the master station, and the function to automatically switch its own status based on the status of the signal line input and loopback line input. Therefore, unless data is supplied from the outside, it is impossible to switch its own state at all, and there is a problem in that the workability for connecting a new slave station decreases.

To explain in more detail, in the state shown in FIG. 1B above, when a new slave station is connected to the slave station (2b), a signal line input is given from the slave station (2b). As a result, the new slave station returns the signal line input to the loopback line, and the loopback line output of the new slave station is supplied to the slave station (2b), so the slave station (2b) automatically The target device enters a data-through state, and new slave stations can be easily connected.

However, when connecting a new slave station to the slave station (2c), data transmission is not possible just by physically connecting the two stations.

That is, the slave station (2C) connects the loopback line input to the signal line (3
), so no signal is supplied to the new slave station, and the signal line input is still looped back to the loopback line, and no signal is sent out at all. remain in the state. Therefore, the status of the slave station (2c) continues to be maintained as before, and the data transmission system including the new slave station is only physically connected and cannot actually perform data transmission. The condition remains.

As is clear from the above explanation, simply connecting the signal line (3) and the loopback line (4) does not mean that a data transmission system has been established. (
For example, the power must be cut off), and then the data transmission system as a whole must be started up, which not only complicates the operation, but also requires the data transmission system to be restarted after connecting a new slave station. The problem is that it takes a long time to get established.

This problem occurs not only when connecting a new slave station, but also when a disconnection occurs in a part of the data transmission system, and then when the disconnection occurs again, the same problem occurs when restoring any of the disconnections. It occurs in

The work can be easily done by connecting a new slave station or restoring a broken line to a slave station whose signal line input is looped back to the loopback line. However, it is almost impossible to easily identify the status of each slave station, and furthermore, it is not possible for workers to easily identify the connection order to the master station (1). There is a high possibility that the above problem will occur.

As a result, there is also the problem that it takes a long time to identify that the data transmission system is not completely established.

<Object of the invention> This invention was made in view of the above problems,
Easily connect additional slave stations and restore broken lines in a polling data transmission system in which multiple slave stations are connected to one master station using signal lines and loopback lines. The purpose is to provide a method for returning the line.

Means for Solving the Problems> In order to achieve the above object, the line restoration method of the present invention is such that a slave station in an unconnected state is in a loopback state from a signal line to a loopback line, and a signal line By sending dummy transmission data until at least one of the input and loopback line input is supplied, the slave station in the loopback state is forcibly switched to the data through state, and the slave station in the unconnected state is switched to the data through state. It's a way to connect.

However, the slave station in the unconnected state may be a station adjacent to the line disconnection part and may also be one that transmits dummy transmission data for a predetermined period of time; in this case,
Preferably, the predetermined time is longer than the longest time during which each station can detect a change in line status.

With the above line recovery method, multiple slave stations send out the input signal with the necessary processing performed on the signal line to the master station, and loopback where the input signal is sent out as is. They are connected in series by wires, and each station can change the data-through state of each line alone, the loopback state from the signal line to the loopback line, or the data-through state from the loopback line based on the status of the signal line input and loopback line input. In a polling data transmission system that has been switched to either the loopback state to the signal line, when connecting a new slave station or a slave station that has been disconnected due to a disconnection, , it is sufficient to simply connect the slave station physically, and a state in which data transmission is possible can be established as is.

That is, when the slave station is connected to a station that has been switched to a state in which the signal line input is looped back to the loopback line, the signal line input is present, so data transmission is possible as is. Conversely, if the above slave station is connected to a station whose loopback line input is switched back to the signal line,
If this is the case, no signal will be supplied from the already connected station, but since the slave station to be connected is outputting a dummy signal, the above station will have a signal line input and a loopback line input. is supplied, so the state is switched to a data through state, and as a result, the slave station has a loopback line input, so it is switched to a state where the loopback line input is looped back to the signal line, Data transmission becomes possible.

If the above-mentioned unconnected slave station is a station adjacent to the line disconnection section and transmits dummy transmission data for a predetermined period of time, the data input existing between the adjacent slave stations is It is possible to prevent the occurrence of a virtual disconnection state due to a shift in the presence/absence detection timing, and to ensure a state in which data transmission is possible to all slave stations of the data transmission system.

Further, if the predetermined time in this case is set to a time longer than the longest time during which each station can detect a change in line status, the above effect can be reliably achieved.

<Example> Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 1 is a schematic diagram showing the configuration of a data transmission system implementing the line restoration method of the present invention, in which one master station (1)
A plurality of slave stations are connected in series by a signal line C3) and a loopback line (4). Figure 1A shows the master station (1) and all slave stations (2a) (2b
)...(2e) shows a state where they are connected in a loop, and FIG. 1B shows a state where a disconnection has occurred between the slave station (2b) and the slave station (2C), Figure 1C shows the master station (1
) and a slave station (2a), and the first diagram shows a state where a disconnection has occurred between a master station (1) and a slave station (2e), Figure 1 E shows the slave station (2C
) shows a state where a wire breakage has occurred on both sides.

Figure 2 is a diagram schematically showing the status of each station, and Figure 2A
indicates a data through state in which the signal line input and loopback line input are output as they are (however, the signal line input is output after being processed by the transmission control device (5) as necessary). , Fig. 2B outputs the signal line input as it is, and loops it back to the loopback line and outputs it (however, the signal line input is processed by the transmission control device (5) as necessary). Figure 2C shows the first folding state in which the loopback line input is folded back to the signal line.
) is shown in the second folded state, which is output in a state processed by ).

FIG. 3A is a schematic diagram showing the configuration for switching the state of the master station (1), in which a sensor (lla) for determining the presence or absence of a signal is connected to the signal line input section, and a signal line input is connected to the signal line input section. A relay contact (12a) is connected to cut it off.
A sensor for determining the presence or absence of a signal (ll
b) is connected, and a relay contact (12c) for cutting off the loopback line input is also connected. A transmission control unit (5) is connected between the signal line input unit and the signal line output unit, and a relay contact (12b) for blocking loopback line output is connected to the loopback line output unit, A relay contact (12d) for connecting the signal line and the loopback line with each other across the transmission control unit (5).
(12e) is connected. Note that the configuration for switching the status of the slave station is the same as that of the master station, so a description thereof will be omitted.

FIG. 3B is an electric circuit diagram showing a control circuit for driving each of the above-mentioned relay contacts in the master station, and the transmission control section determines whether or not there is a signal input to the signal line/loopback line of each slave station. It has a function. The above sensor (11a)
(1lb) of OR gates (13
The output signal from a) is inverted by an inverter (15a) and supplied to an OR gate (14a). In addition, the output signal of the sensor (lLa) is directly connected to the O
It is also supplied to the R gate (L4a). The output signal from the OR gate (14a) is directly supplied to the relay driving amplifier 14 (tea) (18b), and the relay;
The relay contacts (12a) and (12b) are controlled to open and close by controlling energization of the relay contacts (17a) and (17b).

The output signal of the sensor (lia) is transferred to the inverter (15b
) is inverted and supplied to the AND gate (13b). The output signal from the sensor (ttb) is supplied to AND gates (L3b) (L3c).

The slave station signal line disconnection signal (lie) from the transmission control section is A
It is supplied to the ND gate (18c). The output signal from the AND gate (13b) is output from the OR gate (14b).
) and relay drive amplifier (LED
), which controls the energization of the relay coil (17d) and controls the open/close state of the relay contact (12d).

The output signal from the OR gate (14b) to which the output signal from the AND gate (13c) is supplied is supplied to the relay driving amplifier (lee), and the output signal from the relay coil (17c) is supplied to the relay driving amplifier (lee).
) and controls the open/close state of the relay contact (12c). The output signal from the sensor (lla) is supplied to the AND gate (13d), and the slave station signal line disconnection signal (llc) from the transmission control section is
It is inverted by the inverter (15d) and the AND gate (
13d).

The output signal from the AND gate (13d) is supplied to the OR gate (14c). The output signal from the sensor (llb) is inverted by an inverter (15c) and supplied to an OR gate (L4c). O above
The output signal from the R-game (14c) is supplied to a relay drive amplifier (lee), which controls the energization of the relay coil (17e) and the open/close state of the relay contact (12e).

Therefore, when both the signal line input and the loopback line input are present and there is no input line break in the slave station, only the relay contacts (12a) (12b) (12e) are in a conductive state, and the master station (1) is in the first folded state (Fig. 2B
reference). Furthermore, when both the signal line input and the loopback line input are present, and there is an input line break in the slave station, only the relay contacts (12a), (12b), and (12c) become conductive, and the master station (1 ) enters a data-through state, as shown in FIG. 2A. Also, when there is a signal line input and there is no loopback line input, the relay contact (12a)
Only (12b) and (12e) become conductive, and the master station (1) enters the first folding state (see FIG. 2B). Furthermore, when there is no signal line input and there is a loopback line input, only the relay contacts (12c) and (12d) become conductive, and the master station (1) enters the second folding state (Fig. 2C reference).

FIG. 3C is an electric circuit diagram showing a control circuit for driving each of the above-mentioned relay contacts in a slave station, and shows a sensor (21a
) is supplied to the OR gate (24a), and is inverted by the inverter (23b) and output to the AN
It is supplied to the D gate (24b).

The output signal from the sensor (21b) is sent to the inverter (23
a) is inverted and supplied to the OR gate (24a), and is also supplied to the relay driving amplifier (2Bc) to control the energization of the relay coil (27c).Moreover, the inverter (23c) is inverted and supplied to the relay drive amplifier (28e), and the relay coil (
27e), and is also supplied to the AND gate (24b). OR gate (24a)
The output signal from the relay drive amplifier (28a) (2
ab) and relay coils (27a) (27b
), relay contacts (22a) (22b
) to control the opening/closing state. The output signal from the AND gate (24b) is sent to the relay driving amplifier (24b).
6d) to control energization to the relay coil (27d) and control the open/close state of the relay contact (22d).

The output signals from the sensors (21a) (21b) are OR
The output signal is inverted by an inverter (25d) and is supplied to an AND gate (24c).
d) and controls the output of the dummy signal.

Therefore, when both signal line input and loopback line input exist, relay contacts (22a) (22b) (2
2c) becomes conductive, and the slave station enters the data-through state (see FIG. 2C). When the signal line input is present and the loopback line input is not present, the relay contact (22a)
(22b) and (22e) become conductive, and the slave station
(See Figure 2B). When there is no signal line input and there is a loopback line input, only the relay contacts (22c) (22e) are in the conductive state, and the slave station is in the second folding state (see Figure 2C). . When neither signal line input nor loopback line input exists,
The relay contacts (22a), (22b), and (22e) become conductive, and the slave station enters the first folding state (see FIG. 2B). Also, at this time, from the AND gate (24d),
A dummy signal is output and sent to the signal line.

The operation of the data transmission system having the above configuration is as follows.

In the loop-shaped connection state shown in FIG. 1A, the master station (
1) The data sent as the signal line output is the signal line port)
The response data from each slave station is also sent back to the master station (1) through the signal line O).

Furthermore, as shown in FIG. 1B, C, and D, between slave stations,
Alternatively, if there is a disconnection in only one place between the master station and the slave station, the data sent from the master station (1) will be sent sequentially through the signal line c3) and the loopback line (4). The data is supplied to each slave station, and the response data from each slave station is also sent back to the master station (1) through the signal line t3) and the loopback line (4).

As shown in Figure 1E, if a disconnection occurs on both sides of the slave station (2C), data transmission to other slave stations other than the slave station (2C) and to the master station (1) data is returned.

When connecting the slave station (2C) to the slave station (2d) from the state shown in Figure 1E, as shown in Figure 1B, simply connect the slave station (2c) (2d). All you need to do is connect the signal line terminals and the loopback line terminals. To explain in more detail, if the above two slave stations are simply connected physically, the slave station (2d) will be in the second loopback state, so it will not supply any transmission data to the slave station (2C). It is not possible.

However, since neither the signal line input nor the loopback line input exists in the slave station (2C), it is switched to the first loopback state and is also in the state of sending out a dummy signal. This dummy signal is supplied to the slave station (2d). Therefore, the slave station (
2d) has both a signal line input and a loopback line input, is switched to the data through state, and supplies transmission data to the slave station (2C) through the signal line G). As a result, the slave station (2C) enters a state in which only the signal line input exists, and is switched to the second loopback state, receiving transmission data from the master station (1) and transmitting data to the master station (1). The state is now ready for data return.

Conversely, when connecting the slave station (2c) to the slave station (2b), since the slave station (2b) outputs transmission data through the signal line, simply connect the signal line terminals to each other and the loopback line terminal. Simply by physically connecting them, a state is created in which transmission data can be received from the master station (1) and data can be sent back to the master station (1).

In other words, when a physical connection is made to a slave station on either side, a data transmission system including a new slave station can be automatically established without starting up the entire system. I can do what I do. After the data transmission system is established, the transmission of the dummy signal is stopped, so that only the necessary transmission data is transmitted or returned.

Furthermore, the state shown in FIG. 1E above may occur even when an actual disconnection occurs only between the slave station (2b) and the slave station (2c), but in the above embodiment, , it is possible to reliably prevent the occurrence of such a situation.

To explain in more detail, when the input presence/absence determination operation in each slave station is performed asynchronously, the slave station (2b)
A situation may occur in which the slave station (2d) detects that a disconnection occurs between the slave station and the slave station (2c) and the signal line input no longer exists before the slave station (2c) detects that the signal line input no longer exists. be.

In this case, first, the slave station (2d) is controlled to switch to the second loopback state, so that the slave station (2c) becomes completely isolated.

However, if this situation occurs, the slave station (2c) will send out a dummy signal, so if there is no physical disconnection between the slave stations (2c) and (Zd), the slave station (2c) will transmit a dummy signal.
d) is automatically controlled to switch to the data through state (first
(see Figure F), the slave station (2d) is controlled to switch over.
2C) is controlled to switch to the second folding state, the state shown in FIG. 1B is returned to again with only a slight time delay.

That is, the switching of slave stations is controlled only in response to the location where a true disconnection has occurred, and it is possible to completely eliminate the existence of slave stations that are disconnected even though no disconnection has occurred.

Although the above explanation has focused on the slave station (2c), even if a disconnection occurs in another slave station, similar switching control can be performed to automatically restore the line.

Note that this invention is not limited to the above-mentioned embodiments; for example, it is possible to use a microcomputer or the like to switch the status of each station, and various designs may be made without changing the gist of this invention. It is possible to make changes.

<Effects of the Invention> As described above, the present invention transmits a dummy signal at a slave station where neither signal line input nor loopback line input exists, so it is possible to simply connect the physical connection. It is possible to return to a state in which actual data transmission can be performed simply by securing the state, and this has the unique effect of simplifying the return operation.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a data transmission system for implementing the line restoration method of the present invention, FIG. 2 is a schematic diagram explaining the switching state of each station, and FIG. 3A is a diagram showing the switching state of the master station. Figure 3B is an electrical circuit diagram showing the control circuit for driving each relay contact in the master station, and Figure 3C is the control circuit for driving each relay contact in the slave station. Electrical circuit diagram showing a circuit. (1) --- Master station, (2a) (2b) -(2e)-
Slave station, (3)...Signal line, (4)...Loopback line, (5)...Transmission control section Fig. 3 (C)

Claims (1)

[Claims] 1. Multiple slave stations receive input signals from the master station. Send after performing necessary processing on Leave the signal line and input signal as is. in series by the loopback line that sends out connected, and each station has a signal line input, and the state of the loopback line input. Data through status of each line alone, signal line? to the loopback line, or Wrap pattern from loopback line to signal line A port that has been switched to one of the states ring-type data transmission system. and an unconnected slave station is connected to the signal line. If it is in the state of returning to the loop back line. Also, signal line input, loopback line input until at least one of the By sending dummy transmission data Data transfer the slave station that is in the loopback state. Forcibly switch to loop state, above unconnected It is characterized by connecting the status slave stations. How to restore a line in a data transmission system Law. 2. An unconnected slave station is located next to the disconnected line. It is a station that connects to the station and only for a specified time. This is to send dummy transmission data. Data set forth in claim 1 above A line recovery method in a transmission system. 3. For a specified period of time, each station detects changes in the line status. The time is longer than the longest detectable time. The data set forth in claim 2 above Line recovery method in data transmission system.