JPH0357359A - Remote loop control system - Google Patents

Abstract

PURPOSE:To facilitate the location of a faulty point by sending a remote loop start data and a collation data or adding a remote loop end data and recognizing the remote loop start data with a processor. CONSTITUTION:A remote loop start data X, a collation data Y and a remote loop end data Z are sent from a control side MODEM at system rising or at fault occurrence of a terminal equipment. When a processor 3 of the MODEM 1 recognizes the data X, the MODEM 1 controls it that the data Y succeeding to the X is not transferred to a terminal equipment via an interface section 5 and stores the data Y to a memory 4. When the data Z is recognized, the MODEM 1 finishes the storage to the memory 4. When the MODEM 1 detects carrier-off due to the end of the transmission of the control side MODEM, the MODEM 1 reads the data Y stored in the memory 4 and sends it to the control side MODEM from a transmission reception section 2. In this case, when part of the data Z is stored in the memory 4, it is required to send the data after eliminating the part of the data Z.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a remote loop control method for performing a pseudo remote loop in a modem of a half-duplex communication system.

Half-duplex communication systems, compared to full-duplex communication systems, cannot transmit and receive at the same time, so remote loops were considered impossible.

Therefore, it is not easy to perform 611 confirmation of the modem's normality or troubleshoot.

[Conventional technology]

As shown in FIG.
In a system connected by a loop 13 (including a switching network) via 2.14, in the case of a full-duplex communication system, data can be sent and received simultaneously between modems 12 and 14, but half-duplex communication is possible. In the case of a duplex communication system, when one modem is transmitting, it is not possible to transmit from the other modem.

For example, as shown in FIG. 4, data DI, D2, D3
and receive data l)a, Db, Dc, and Dd, in a full-duplex communication system, for example, while data D1 is being sent from modem l2, data Da sent from modem 14 is received. be able to. That is, transmission and reception can be performed simultaneously.

On the other hand, in a half-duplex communication system, for example, when the modem 12 is transmitting data Di, the modem 14
It is not possible to send data Da from
Upon carrier-off detection due to the end of transmission of the data Di of the modem 12, the modem 14 will transmit the data Da. Furthermore, when the modem 14 detects the carrier off due to the end of transmission of the data Da, the modem 12 transmits the next data D2.
This allows transmission of D3.

Therefore, in a full-duplex communication system, for example, when the modem 12 instructs the modem 14 to perform a remote loop and sends verification data from the modem 12, the modem 14 does not repeat the loop. Therefore, the verification data can be returned and sent to the modem 12 side. The modem 12 compares the transmitted verification data with the received verification data, and disconnects the terminal device 15 from the terminal device 15 to check the normality of the time vA13 and the modem 14. can be approved.

[Problem to be solved by the invention]

As mentioned above, in a full-duplex communication system, remote looping is possible, but in a half-duplex communication system, transmission and reception cannot be performed simultaneously, so a loop loop is used to loop back the verification data. It cannot be sent. That is, remote looping is not possible in a half-duplex communication system.

An object of the present invention is to confirm the normality of a modem by simulating a remote loop in a half-duplex communication system.

[Means to solve the problem]

The remote loop control method of the present invention prevents pseudo remote loops by temporarily storing verification data in a memory. That is, a modem 1 in a half-duplex communication system is provided with a transmitting/receiving section 2, a processor 3 that controls each section and recognizes remote loop start data, a memory 4, and an interface section 5 that connects a terminal device. , when the processor 3 recognizes the remote loop start data from the control side modem received by the transmitting/receiving unit 2, it stores the verification data following the remote loop start data in the memory 4, and stores it in the memory 4 upon carrier-off detection. The data for verification stored in the transmitter/receiver section 2 is sent to the modem on the control side. , [Operation] Sends remote loop start data and verification data from the modem on the control side. The modem 1 that has received the remote loop start data stores the verification data in the memory 4. Then, since the end of transmission from the control side modem can be recognized by carrier-off detection, the verification data stored in the memory 4 is read out and transmitted from the transmitting/receiving section 2 to the control side modem. That is, by temporarily storing verification data in the memory 4, remote loop control in a half-duplex communication system can be performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of main parts of an embodiment of the present invention, in which a modem 1 includes a transmitting/receiving section 2, a processor (CPU) 3, a memory 4, and an interface section 5. A line is also connected to the transmitter/receiver section 2, and a terminal device (not shown) is connected to the interface section 5. Data from the terminal device or data read from the memory 4 is modulated in the transmitter/receiver 2 and sent out to the line, and data received via the line is demodulated in the transmitter/receiver 2 and sent to the terminal device. Data is transferred to the terminal device via the interface unit 5 under the control of the processor 3, and remote loop start data and the like are recognized by the processor 3.

FIG. 2 is an explanatory diagram of the operation of the embodiment of the present invention, in which remote loop start data Y and remote loop end data Z of n3-bit configuration are sent from the modem on the control side.

In the modem 1, when the processor 3 recognizes the remote loop start data
is controlled so that it is not transferred to the terminal device via the interface section 5, and the verification data Y is stored in the memory 4.

When the remote loop end data Z is recognized, the storage operation in the memory 4 is ended. Next, when carrier off is detected due to the end of transmission by the modem on the control side, memory 4
The verification data Y stored in is read out and transmitted from the transmitting/receiving section 2 to the modem on the side of the controller 1'B. In this case, memory 4
There is no problem when only the verification data Y is accumulated in the data, but if a part of the remote loop end data Z is accumulated, it is necessary to remove it before transmitting it.

Furthermore, the remote loop start data X and the remote loop end data Z need to be patterns that do not appear in normal data, so that they have some degree of redundancy. Note that if there are characters that are not used in normal telegrams, if they are used for remote loop start data X and remote loop end data Z, the bit length does not need to be increased.

Further, the number of bits n2 of the verification data Y is selected in consideration of the storage capacity of the memory 4, and for example, a 511 random pattern can be used. It is also possible to use characters such as alphabets and numbers.

Furthermore, if the number of bits n2 of the verification data Y is predetermined, the remote loop end data Z can be omitted. That is, it is sufficient to count the number of bits of the received verification data Y, and to finish storing the verification data Y in the memory 4 when a predetermined number of bits have been received.

Also, during remote loop control, even when carrier off is detected,
The interface section 5 is controlled so as not to accept a transmission request from a terminal device.

The modem on the control side compares the transmitted verification data Y and the returned verification data under the control of the Brosensor and calculates the error rate. In this error rate calculation, it is also possible to improve the accuracy of the error rate by repeating the sending and receiving of verification data by remote loop control a plurality of times.

The error rate ER is It is expressed as Note that i is the number of times of confirmation.

If this error rate ER is below the allowable value, the line and modem 1 are normal, and in the case of a failure that makes data communication impossible, it means that a failure has occurred in the terminal device, and it must be isolated from the terminal device. becomes possible.

Furthermore, since the memory 4 of the modem 1 only needs to have a storage capacity sufficient to store the verification data Y, it is also possible to use the internal memory of the processor 3.

〔Effect of the invention〕

As explained above, in the present invention, the modem 1 of the half-duplex communication system is provided with the transmitting/receiving section 2, the processor 3, the memory 4, and the interface section 5, and the remote loop start data By transmitting data Y or adding remote loop end data Z, and by recognizing the remote loop start data When detecting carrier off due to
The verification data Y stored in the memory 4 is sent back, and a remote loop in a half-duplex communication system can be realized. Therefore, there is an advantage that the point of failure between the modem and the terminal device in the half-duplex communication system can be easily isolated.

[Brief explanation of drawings]

FIG. 1 is a block diagram of main parts of an embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the embodiment of the present invention, and FIG. 3 is a system explanatory diagram.
FIG. 4 is an explanatory diagram of full duplex and half duplex. 1 is the modem, 2 is the transmitting/receiving unit, 3 is the processor (CPU)
, 4 is a memory, and 5 is an interface section.

Claims (1)

[Claims] A modem (1) in a half-duplex communication system includes a transmitting/receiving section (2), a processor (3) that controls each section and recognizes remote loop start data, and a memory (4). ,
an interface unit (5) for connecting a terminal device, and when the processor (3) recognizes remote loop start data from a modem on the control side received by the transmitter/receiver unit (2), the processor (3) transmits the remote loop start data. The verification data subsequent to the above is stored in the memory (4), and the verification data accumulated in the memory (4) by carrier-off detection is transmitted from the transmitting/receiving unit (2) to the control side modem. This remote loop control method is characterized by: