JPH0728291B2 - Bus type multiplex transmission system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a Seniter device at one end of one bus type transmission line,
The present invention also relates to a bus-type multiplex transmission system in which, for example, a resistance terminator is arranged at the other end, and a plurality of terminals are connected between these ends to enable mutual communication.

2. Description of the Related Art A conventional bus type multiplex transmission system of this type has a configuration as shown in FIG.

In FIG. 4, 1 is a center device, which is a line L from the outside.
It also has the function of a terminal device. Reference numeral 2 denotes a resistance terminator, which is arranged at the ends of the down line R from the center device 1 and the up line T to the center device 1. 3, 4 and 5 are terminals, which are connected between the center device 1 and the resistance terminator 2 and are connected to the upstream line T.
And the down line R.

Here, the flow of signals on the transmission paths R and T when the center device 1 and the terminals 3 and 5 are communicating using the channel A (communication path) A and B, respectively, is shown in FIG. a) ~
It is as shown in (e).

That is, the terminal 3 receives the signal transmitted to the down line R (see FIG. 5 (a)), synchronizes under the frame synchronization bit, and transmits the signal to the channel B via the up line T (first). 5 (b)). On the other hand, the signal sent from the center device 1 is received by the terminal 5 after passing through the transmission delay 6 of the transmission line (see FIG. 5 (c)). The terminal 5 synchronizes with the frame synchronization bit F from this signal and transmits the signal to the channel A through the upstream line T (see FIG. 5 (d)).

The transmission signal to the channel B shown in FIG. 5B and the transmission signal to the channel A shown in FIG.
When it reaches, the signal is affected by the transmission delay 6 and signal overlap (collision) 7 occurs as shown in FIG. 5 (e), and there is a problem that accurate transmission cannot be performed. In a conventional system, the center device 1 and / or the terminal 3 ...
Mutual communication between the five is possible.

Problems to be Solved by the Invention As described above, in the above-described conventional transmission system, in addition to the problem that the overlap of signals due to transmission delay limits the transmission distance, the downlink from the center device and the center device Since there is an upstream line configuration, direct intercommunication between terminals can be realized only inefficiently.

The present invention solves such a problem, and it is possible to prevent overlapping of signals due to transmission delay and efficiently realize communication between arbitrary terminals of a plurality of terminals connected on one bus type transmission path. it can. It is an object of the present invention to provide an excellent bus type time division multiplex bidirectional transmission system (hereinafter referred to as a bus type multiplex transmission system in this specification).

Means for Solving the Problems In order to achieve the above object, the present invention has a center device at one end and a terminating device at the other end on one bus type transmission line, and a plurality of terminals are provided between these devices. Connect and place. The center device inquires whether or not there is a request for channel connection to each of these terminals. Then, for each requested terminal, channels are sequentially allocated in the order closer to the center position and closer to the frame synchronization signal in the transmission frame. The center device notifies each terminal of this result to Issai. In this way, the channel setting according to the connection request of each terminal is realized, and at the same time, each terminal can transmit the signal in order according to the flow of the frame synchronization signal sent from the center device, and thus the signal on the transmission line is transmitted. It is designed to eliminate the overlap of.

Therefore, according to the present invention, even when the communication demand from a plurality of terminals connected to one bus type transmission line fluctuates with the passage of time, it can be adapted to this at an appropriate frequency. , A required channel can be allocated and corrected between each terminal and the center device or between any two terminals, whereby efficient communication can be performed in a state where signals do not overlap on the transmission path. It becomes possible to do.

Embodiment FIG. 1 is a block diagram showing a schematic configuration of a bus type multiplex transmission system which is an embodiment of the present invention.

In FIG. 1, 10 is a time division multiplex bidirectional bus type transmission line,
Reference numeral 11 denotes a center device arranged at one end of the bus type transmission line 10. The center device 11 also serves as a terminal device for the line L from the outside line. 12 is the bus type transmission line 10
Is a resistance terminator disposed at the other end of the. 13 to 15 are terminals,
Each of these terminals 13 to 15 is connected to the bus type transmission line 10 between the center device 11 and the resistance terminator 12, and between each of the terminals 13 to 15 or between the center device 11 and each of the terminals 13 to 15. Can communicate with each other. Τ ₁ , τ ₂ and τ ₃ are the center device 11 and the terminal 13,
The signal delay times between the terminals 13 and 14 and between the terminals 14 and 15.

2 (a), (b), and (c) show an example of the structure of the multiframe used in the transmission system of FIG.
FIG. 3A shows the overall structure of the multiframe.
Here, before and after the data transmission frame F _D , the connection request polling frame F _X and the used channel notification frame F _Y are arranged at regular intervals. Further, FIG. 2B shows an example of the structure of the connection request polling frame F _X. This polling frame F _X is F _XS which plays a role of a frame synchronization signal, and is followed by the center device 11. It is composed of a terminal 1 which is connected to the closer order as each allocated connection request response region t _I ~t _N by N.

When this connection request polling frame F _X arrives, the terminal requesting the connection sends necessary information (connection request information) such as the number of the other terminal to connect to and the number of channels to acquire to the area designated by itself.

Upon receiving this connection request information, the center device 11 receives the frame synchronization signal F _S to the terminal close to the center device 11 according to an algorithm such as giving priority to the one that has been connected until now.
Channels close to are sequentially allocated.

The used channel designation information allocated to each terminal is notified to Ichisai using the used channel notification frame F _Y.

Here, the used channel notification frame F _Y is shown in FIG. 2 (c).
As shown in, F plays the role of a frame synchronization signal.
It is composed of _YS and the following channel notification areas S _I to SN allocated to the respective terminals _{I to N. The} channel notification areas S _{I to SN} include information such as the channel number to be used and the number of channels. Is stored.

Each terminal 13 to 15 (I to N in the above example), each time receiving this use channel notification frame F _Y from the center device 11, changing the use channel in accordance with the notification information. As a result, the terminal closer to the center device 11 always keeps the frame synchronization signal F _S
The state in which communication is performed using the channel on the side close to is maintained.

By doing so, for example, when the center device 11 and the terminal 15 and the terminal 13 and the terminal 14 are communicating in FIG. 1, the data transmission frame F _D shown in FIG. Channel D will be allocated to A and terminal 15.

Therefore, referring to FIG. 3, the data transmission frame F _D
The signal flow on the transmission path will be described with reference to FIG.

First, the center device 11 shows the frame synchronization signal F _S and its own transmission data in a bold frame. Send to. this Signal flows to the downstream side of the direction away from the center device 11 (arrow of broken line), and the terminal 13 synchronizes the frame synchronization signal F _S with the detected frame and is indicated by a thick frame. Send data to. Hereinafter, in the same manner, the terminal 14 is shown in a bold frame. Also, the terminal 15 is shown in a bold frame Send data to each The data sent to the center device 11 also flows upstream (indicated by a solid line arrow) in the direction toward the center device 11, and as shown in FIG. Reach and secure communication is performed.

At this time, the time interval between the frame synchronization signals F _S is at least Tmin
It is desirable to secure time.

Here, Tmin = T _FS + N × T _CH + 2τ T _FS : Occupancy time of frame synchronization signal T _CH : Occupancy time of channel τ: Transmission delay time from center device 11 to terminal 15, where τ = τ ₁ + τ ₂ + Τ ₂ .

In short, in FIG. 3, paths 21 to 23, 31 to 33, 41 to 43, 51 indicated by broken and solid arrows indicating channel propagation are shown.
53 indicates that communication (transmission in the arrow direction) can be realized between the terminal and the center device or between the terminals using the channel. For example, the routes 21, 22, and 23 enable data transmission from the center device 11 to the terminals 13, 14, and 15, respectively, and the routes 31, 32, and 33 are from the terminal 13 to the center device 11 respectively.
Data transmission from the terminal 13 to the terminals 14 and 15, respectively. As a result, communication between the center device and the terminals or between the terminals can be realized without signal collision.

In FIG. 1, the center device 11 is provided at one end of the bus type transmission line 10.
Was described as an example in which the resistance terminator 12 is arranged at the other end, but is not limited to this, for example,
Two center devices 1 and 2 may be provided at both ends of the bus type transmission line, respectively.

In this case, for example, the first frame signal for polling the connection request is transmitted from the center device 1 to each terminal, and each terminal sends the response to the center device 2 using a predetermined time slot after the frame signal. To transmit. Center device 2
After receiving a connection request from each terminal or according to an algorithm, the channel is allocated to each terminal, and this allocation information is transmitted to each terminal using the time slot following the second frame signal. After transmitting this allocation information, the center device 2 sends the third frame signal for communication N times, and uses the time slot subsequent to the frame signal to communicate N terminals with each other or N times with the terminal and the center device. To do. According to this method, the loss of transmission delay time can be reduced.

Further, although an example using the bus type transmission line 10 has been described in FIG. 1, the present invention is not limited to this, and may be applied to a ring (loop) type transmission line, for example. In the above description,
When the center device 1 and the center device 2 are brought close to each other and then combined, a structure of a ring type transmission line is formed. In this example, the cooperative operation of the center device 1 and the center device 2 required in the above-mentioned bus type transmission line can be executed more efficiently, so that the functional characteristics are further improved.

EFFECTS OF THE INVENTION The present invention has the following effects, as is apparent from the above-described embodiments.

1) By listening to the connection request of each terminal by Ichisai polling from the center device and allocating the necessary channel,
It is possible to prevent competition for channel acquisition between terminals.

2) Because the terminal near the center equipment can always use the channel near the frame synchronization signal, the channel used by each terminal is reconfigured in Ichisai every time the connection status changes, so In this case, it is possible to prevent the occurrence of overlapping of signals, and thus to eliminate the limitation of the transmission distance which is caused by the transmission delay as in the past.

3) When communication demand from the center device and terminals is large,
In the conventional transmission system (see FIG. 4), the effective transmission capacity is significantly smaller than the maximum capacity of the line, but in the present invention, the ratio of the channel allocation time to the total time (for example, about 5%). It is possible to remarkably increase the effective transmission capacity only by the loss.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a bus type multiplex transmission system which is an embodiment of the present invention, and FIG. 2 is a conceptual diagram for explaining an example of a multiframe configuration used in the transmission system of FIG. , FIG. 3 is a conceptual diagram for explaining a signal flow on a transmission path by taking a data transmission frame as an example,
FIG. 4 is a block diagram showing a schematic configuration of a conventional bus type multiplex transmission system, and FIG. 5 is a conceptual diagram for explaining a signal flow on the transmission line of FIG. 11 …… Center device, 12 …… Resistance terminator, 13 to 15 …… Terminal, L …… Line, F _X …… Connection request polling frame,
F _D …… Data transmission frame, F _Y …… Used channel notification frame, A, B, C …… Channel.

Claims (1)

[Claims] 1. A sensor device is provided at one end of one bus type transmission line, and a terminating device is provided at the other end of the bus type transmission line. Notify the terminals of the connection request polling frame at the same time, and the terminal requesting the connection will enter the area specified by itself.
The center device, which has transmitted the necessary information such as the destination terminal number to be connected, the number of channels to be acquired, etc., and has received this connection request, is close to the sensor device according to an algorithm such as giving priority to a device that has not been connected until now. Channels close to the frame sync signal are sequentially allocated to the terminal,
The channel designation information allocated to each terminal is notified all at once using the channel notification frame, and the channel setting according to the connection request of each terminal is realized, and at the same time, the frame synchronization signal sent from the center device is transmitted. A bus-type multiplex transmission system in which each terminal transmits signals in sequence according to the flow to eliminate signal overlap on the transmission path.