JPH0575215B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a multiplexing and distribution device (hereinafter referred to as TDM), and particularly provides a TDM that is effective for data transmission using a mutual activation method.

[Background of the invention]

As described in Japanese Unexamined Patent Publication No. 58-46422, conventional TDM faithfully reproduces received data regardless of the transmission control procedure of the communication control processing device (hereinafter referred to as CCP) side and the terminal device. To deliver. Accordingly
If a collision occurs in data collection and distribution between devices communicating within TDM, data delays are unavoidable as the data is held within TDM, but by controlling traffic, the data is delivered to its destination. However, half-duplex communication based on the mutual activation method disrupts the transmission control procedure.

Below, according to FIG. 3, an operation sequence in which a collision occurs in TDM and the transmission control procedure is disrupted is shown.

When the CCP 1 side transmits an ENQ sequence A to obtain the transmission right, it is received by the TDM 2 on the CCP 1 side and sent through the relay line 4 to the TDM 8 on the terminal device 5 side, which is a dependent station. On the other hand, when the terminal device 5 similarly transmits ENQ sequence B to obtain the transmission right, the TDM 8 transmits the low-speed line 7.
ENQ sequence B is received from TDM8, and a collision occurs within TDM8. In this case, TDM8 receives the ENQ that is being received while transmitting the eng sequence a that arrived first.
Sequence B is held on hold, and after the transmission of the eng sequence is completed, ENQ sequence B is sent to the relay line 4 via the relay modem 3, and the CCP 1 side receives it as the eng sequence b. In this state, since the CCP1 side is the priority station, it transmits the ENQ sequence A again in response to the reception of the eng sequence b, and expects an ackσ response. On the other hand, the terminal device 5, which is a dependent station,
Upon reception of eng sequence a, an ACKO is returned. CCP1 side receives ackσ while waiting for ackσ response, but actually this ackσ response is the first ENQ.
Although this is a response to sequence A, it will be treated as the second time and the process will proceed to TEXT transmission. On the other hand, the terminal device 5 returns ACKO again as a response to the second eng sequence a. This ACKO
is received on the CCP1 side after sending TEXT, so
This means TEXT retransmission, and the same message is sent again.
TEXT is sent, and a double message is generated at the terminal device 5. In this way, the transmission control procedure between the CCP 1 side and the terminal device 5 is disturbed.

[Purpose of the invention]

The purpose of the present invention is to multiplex communication lines.
The objective is to prevent the transmission control procedure from being disrupted due to the generation of data that passes each other due to the character hold time caused by installing TDM.

[Summary of the invention]

The original function of TDM is to multiplex and transfer collected data, reproduce it, and distribute it, but the feature of the present invention is that when there is a collision between collected data and distributed data between devices communicating within TDM. , the purpose is to discard data on one side, making it the same state as half-duplex communication without TDM.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a system configuration in which TDMs 2 and 8 are installed facing each other between a CCP 1 and a terminal device 5. In this configuration, when data transmission is performed using the mutual activation method (contention method) of SYN synchronous half-duplex communication, the CCP1 side and the terminal device 5
It will start up arbitrarily and establish a data link. At this time, if the startups of both are close to each other,
A collision (contention state) occurs in the low-speed line adapter 6 of the TDMs 2 and 8. In FIG. 1, 3 is a relay modem, 4 is a relay line, and 5 is a low-speed line.

FIG. 2 shows an operation sequence when a collision occurs in the TDM 8 on the terminal device 5 side. When CCP1 side, which is the priority station, sends ENQ sequence A to obtain the transmission right, TDM2 on CCP1 side
The received signal is received by the terminal device 5 and transmitted through the relay line 4 to the TDM 8 on the terminal device 5 side, which is a dependent station. On the other hand, when the terminal device 5 similarly transmits the ENQ sequence B in order to obtain the transmission right, the TDM 8 sets the "receiving state" flag and starts reception in order to receive the ENQ sequence B from the low-speed line 7. ENQ sequence A sent from TDM2 on the CCP1 side to TDM8 through trunk line 4 in this state
When this ENQ sequence A is received, after receiving the ENQ sequence B from the terminal device 5 side,
The TDM 8 then discards the received ENQ sequence B, resets the reception status flag, and sends the received ENQ sequence B to the relay circuit 4. As a result, the subordinate station waits for a response, while the priority station restarts by receiving eng.
ENQ sequence A will be issued to maintain normal transmission control procedures. This is also handled in the same way when a response sequence (such as a response to a previous text) sent from the relay line 4 is delayed and causes a collision while a text is being received.

In the above explanation, data discarding was explained in the receiving state, but when the multiplex collection and distribution device of the present invention receives data from the terminal line (or communication control line) in the transmitting state, after the transmission is completed, It has a function to discard data from the communication control line) within the multiplex device.

〔Effect of the invention〕

As explained above, it has the functions of the present invention.
By using TDM, errors due to double message reception that may occur in the transmission procedures on the CCP side and the terminal can be prevented, and as a result, line downs can be avoided.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an example of a system configuration to which the present invention is applied, Fig. 2 is an operation sequence diagram of a transmission procedure based on the present invention, and Fig. 3 is a diagram showing a conventional TDM
FIG. 2 is an operation sequence diagram in FIG. In the figure, 1... communication control processing device (CCP),
2, 8...multiplex distribution device (TDM), 3...relay modem, 4...relay line, 5...terminal device, 6...low speed line adapter, 7...low speed line.

Claims (1)

[Claims] 1. In a multiplex collection and distribution device that connects a low-speed line and a relay line, if data is sent from the relay line while the data is being received from the low-speed line, discarding the data from the trunk line after the receiving state ends;
In addition, if data is sent from the low-speed line during a transmission state in which data from the relay line is being transmitted to the low-speed line, the data from the low-speed line is discarded after the transmission state ends. A multiple collection and delivery device characterized by having a disposal means.