JPS6175651A - Modulator-demodulator - Google Patents

Abstract

PURPOSE:To obtain a modulator-demodulator not requiring manual operation for loopback by detecting/discriminating loopback data transmitted from the central side regardless whether the system is the full duplex communication system or the half-duplex communication system and looping back automatically the data. CONSTITUTION:Data received from a terminal 20 of a central side modulator- demodulator 3 is stored in a register 12 and transmitted to a discrimination control circuit 16 at the same time. The discrimination control circuit 16 uses a loopback control data 24 transmitted from the register 12 to discriminate whether or not the test is a loopback test, whether the system is the full duplex communication system or the half-duplex communication system and a loopback point in case of the loopback test. The loopback test data transmitted to a changeover swtich 13 is transmitted to a modulation circuit 14. The loopback test data modulated by the modulation circuit 14 is looped back via changeover switches 15, 19 switched by changeover switch control signals 27, 28 transmitted from the discrimination control circuit 16 and transmitted to a demodulation circuit 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to loopback testing of point-to-point lines, and more particularly to suitable modulation and demodulation equipment for fault isolation.

[Background of the invention]

In a point-to-point line, when a failure occurs in one line, a loopback test is sometimes performed to isolate the location of the failure. In this case, it is common to perform loopback sequentially at two locations each on the DTE@, I, and INE sides of the central modem and terminal modem. An example of a modulation/demodulation device that performs loopback tests is disclosed in Japanese Patent Application Laid-open No. 57
There is one described in JP-68955.

In the conventional technology, when performing a folding test, a switch at a folding point is manually operated.

The problem with this method is that a person must be dispatched to operate the modem installed in a remote location.

We cannot respond to cases where emergency recovery is required.

In addition, in the half-duplex communication system, the line support section on the communication control device side is a half-duplex communication facility, so sending and receiving cannot be performed at the same time.

A repeat test was not possible.

A modem having a remote loop function is known as an opposing test function between modems, but operation from one modem is required.

It does not have the function of returning commands from a central console device, etc.

[Purpose of the invention]

An object of the present invention is to eliminate the problems of the prior art as described above, and to provide a modulation/demodulation device that does not require manual operation for loopback.

[Summary of the invention]

The feature of the present invention is that it is possible to detect and judge return data sent from the center side and automatically return it regardless of whether the communication method is full-duplex or half-duplex. .

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIGS. 1 and 2.

In FIG. 1, in order to determine the location of a failure when a single line failure occurs, loopback tests at 7 to 10 loopback points may be sequentially performed. That is, 7 is transmitted from the central processing unit f1 via the communication control device 2.

When looping back on the DTE side of the central modem 3, 8 becomes 7.
Similarly, when looping back on the LINE side of the central modem 3, 9 is the LINE side of the terminal modem 4,
10 is a case where the signal is looped back on the DTE side of the terminal side modulation/demodulation device 4.

Next, specific operations will be explained with reference to FIG. For example, when performing loopback of 8 in FIG. 1, a flag indicating that it is a loopback test, an address indicating that it is a loopback of 8, and a full-duplex communication method are sent from the console device connected to the central processing unit 1. Input and transmit data identifying whether the test is a half-duplex communication method, return data, and finally a flag indicating the end of the return test.

The sent return test data is sent to the central modem 3 via the communication control device 2. Central modem 3
The data received from the RD 20 is stored in the register 12 and sent to the determination control circuit 16 at the same time. The determination control circuit 16 uses the loopback control data 24 sent from the register 12 to determine whether or not it is a loopback test, determine whether it is a full-duplex or half-duplex communication method, and determine the loopback point if it is a loopback test. I do. If the return data sent to the determination control circuit 16 is in full-duplex communication mode, the determination control circuit 16 sends a return data control signal 25 to the register 12 . The register 12 sends the stored return test data to the changeover switch 13 in response to the sent return data control signal. Changeover switch control signal 26
Since this is a turnaround of 8, there is no signal. Therefore, the return test data sent to the changeover switch 13 is sent to the modulation circuit 14. The loopback test data modulated by the modulation circuit 14 is looped back through the changeover switches 15 and 19 which are switched by changeover switch control signals 27 and 28 issued from the determination control circuit 16, and is sent to the demodulation circuit 18. The return test data sent to the demodulation circuit 18 is demodulated and sent to the changeover switch 17. Since the changeover switch control signal 29 is not emitted from the changeover switch 17, the changeover switch control signal 29 is sent as is to the central processing unit 1 via the communication control device 2 as 5D21. By checking the return test data returned in this manner, it is determined whether or not there is a failure.

If the return data sent to the judgment control circuit 16 is a half-duplex communication method, the return data control signal 25 sent from the judgment control circuit 16 conveys information that it is a half-duplex communication method to the register 12, and the register 12 Delay output for a certain amount of time. This is because the line support section of the communication control device 20 is compatible with the half-duplex communication system, so it takes time to switch to the receiving state. The subsequent operation is the same as in the full-duplex communication method. Note that the changeover switch control signals 27 and 28 issued from the judgment control are the judgment control circuit 16.
detects the flag indicating the end of loopback, the switch is reset and the changeover switches 15 and 19 return to their original states.
Prepare for the next call-back test or normal data transmission/reception.

The above operation is the same for the turning point 7.9.10.

〔Effect of the invention〕

According to the present invention, there is no need for manual operations for turning back, so it is effective to speed up the discovery of failure points and shorten online downtime. It has also become possible to perform loopback tests in the case of half-duplex communications, which was previously impossible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a turning point of a modulation/demodulation device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram of the modulation/demodulation device. 1...Central processing unit, 2...Communication control device 3.
...Central side modem 4...Terminal side modem 5...Terminal device, 6...Data communication line 1
1... Modulation/demodulation device, 12... Registers 13, 15
, 17 , 19... Changeover switch 14... Modulation circuit, 16... Judgment control circuit 18... Demodulation circuit
24... Return data 25... Return data control signal.

Claims (1)

[Claims] 1. In order to automatically perform a circuit loopback test on a data transmission line from an external device, a function to receive loopback data issued from an external device, a function to loop back the transmitting/receiving circuit based on the loopback information of the data, and a full duplex function for the data. 1. A modulation/demodulation device comprising a function of controlling loopback timing based on information on a communication method and a half-duplex communication method, and a function of transmitting test data of the data.