JPS6051293B2 - Loop test control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control method for a loop test (referred to as a loop test) of a communication system in which data communication devices are connected through a line etc., and particularly to a system that performs half-duplex communication using a two-wire line. Concerning an effective loop test control method.

As a conventional loop test method, for example,
-59807 and the method described in revised Recommendation V, 54 of the International Telegraph and Telephone Consultative Committee (abbreviated as CCIΠ), these loop tests Since it is configured to be applied when performing full-duplex communication using a line, in a communication system that performs half-duplex communication using a two-wire line, it is not possible to test by folding received data back into transmitted data. Can not.

For example, FIG. 1 shows an example of a communication system configuration using a two-wire line.

1 and 2 are data terminal devices, 3 and 4 are modulation devices, 5 and 6 are demodulation devices, and 7 and 8 are hybrid converters.

The modem together with the modem is hereinafter referred to as a modem. The data terminal device 1 modulates the transmission data using the modulation device 3, and sends the modulated data to the two-wire line via the hybrid converter 7. This signal is input to the modulation device 4 by the hybrid converter 8 and the received data is sent to the data terminal device 2. Data communication is performed in this way, but if the line is a two-wire system,
Transmission and reception cannot be performed at the same time; signals are transmitted in either direction. In such a communication system, for example, when testing the line and modem from the data terminal device 1, the data received by the demodulator 2 is looped back and input as transmission data to the modulator 4, and the data terminal device It had the disadvantage that it could not be sent to 1.

The present invention has been made to solve these drawbacks, and will be described in detail below with reference to the drawings.

FIG. 2 shows an example of a transmission control procedure according to the present invention. The procedure for entering and exiting the loop test state is described in the well-known CCITI' revised Recommendation V. 54.
For example, if the data terminal device DTEl is on the S side and the data terminal device DTE2 is on the R side, the data terminal device on the S side instructs the modem on the R side to start a loop test using a pseudo-random pattern PNl. send. Subsequently, an address/command code ACD specifying the loopback position and loopback process is sent. The modem on the R side has the address ●
In response to the command code ACD, the establishment of the loop test state is indicated by the pseudo-random pattern PN2.
Inform the other person. The final procedure is to complete the loop test.
The S side uses a pseudo-random pattern P to indicate that the test has finished.
Send the test end code n1 to the R side by N3, and then send the test end code n1 to the R side.
By sending the data to the side, each data communication device returns to normal data communication mode. The start and end procedures described above can also be operated on a two-wire line, but after receiving the address/command code in the R side modem, a loop is set up to loop back the received data as sent data. It is not possible to send the data as is to the S side.

In the present invention, as shown in the transmission control procedure in FIG. 2, the test code TESl is sent from the S side. After the received data is processed in the modem on the R side, a procedure is taken in which the test code TES2 is sent from the R side to the modem on the S side again. Third
The figure shows an example of a circuit configuration for performing a loop test.

The data terminal device 1 or ζ gives a loop test instruction to the modem through the terminal 9, and activates the transmission sequencer 10 which determines the modem sequence. The transmission sequencer 10 enters a loop test starting procedure, and the pseudo-random pattern generator 11 sends the code PNl through the selectors 12 and 313 to the line by the transmission circuit 14, which performs a normal modulation operation. Next, an address/command code is sent from the data terminal device 1 via the signal line 15. The modem on the R side outputs received data RD by the receiving circuit 416 that performs normal demodulation operation, and generates a pseudo-random pattern and an address.
The command code detector 17 decodes the address ●command code.

In the case of a 4-wire line, for example, if the address/command code is information that sets callback, the received data RD is connected to the sent data SD using a signal line so that it can be returned, but in the case of a 2-wire line, , this connection is not made.

The modem on the R side starts up the transmission sequencer 10 as a signal indicating that the test is ready, and starts the pseudo random pattern generator 1.
1, the code PN2 is sent.

The S-side modem detects the code PN2 by the pseudo-random pattern and address/command detector 17, activates the counter 18, and sends a certain bit of the test code TESl, which is a specific pattern, from the code generation circuit 19.

When the modem on the R side starts receiving the test code TES1, the reception sequencer 20 starts the count 21, and at the same time counts the number of received bits, the reference code generator generates the same code sequence as the pattern sent on the S side. The comparison circuit 23 compares the received data RD of 22 with the received data RD of 22.

At this time, if they do not match, the address indicated by the address counter 24 is incremented by 1, and the value of the count 21 is loaded into the memory 25. In this way, only the bit in which the error occurred in the received data RD is stored. count 2
After counting a certain number of bits of 1, the transmitting sequencer 10 is activated and the transmitting state is entered. At this time, the counter 18 is activated, and the output of the memory 25 and the output of the counter 18 are compared by the comparison circuit 26, and if they match, the code generator 19
The output is inverted and sent to the S side. Since this code is the code that received the test code TESl, a transmission error may have occurred, so it is written as a different test code TES2. The S side receives the code TE as in normal data reception operation.
S2 is output from the received data RD.

When the data terminal device DTEl finishes receiving the test code TES2, it inverts the RLB that instructs the loop test and enters the termination procedure. The pseudo-random pattern generator 11 sends the code PN3 to indicate that the test mode has ended.
After notifying the side modem, it sends a termination code TMD and returns to the normal data communication mode. The R-side modem detects the code PN3, receives the termination code TMD, and returns to the normal data communication mode.

Note that the counters 18 and 21, the comparison circuits 23 and 26, the code generator 19, and the reference code generator 22 can be easily shared;
Further, the code generator 19, the reference code generator 22, and the pseudo-random pattern generator 11 can be easily used in common.

As explained above, according to the present invention, a code generator is provided, its output is compared with received data, and the bit count value when the two differ is stored, so all of the received data is stored. There is no need to do this, and the circuit configuration can be simplified.

In addition, since it has a high degree of commonality with the loop test performed in full-duplex communication using a conventional 4-wire line, even if the communication system performs half-duplex communication using a 2-wire line, the line and modem This has the advantage that loop tests can be easily performed.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a communication system, FIG. 2 is an example of a flowchart of a transmission control procedure, and FIG. 3 is a circuit diagram of an embodiment of the present invention. 10...Transmission sequencer, 11...Pseudo random pattern generator, 12, 13...Selector, 14...Transmission circuit, 16...Reception circuit , 17...address 4 command sign detector,
18, 21... Counter, 19... Code generator, 20... Reception sequencer, 22...
...Reference code generator, 23, 26... Comparison circuit,
24...Andre counter, 25...memory.

Claims (1)

[Claims] 1 In a loop test control method that performs a loop test between a first and second data communication device that performs half-duplex communication using a two-wire line, a specific test code is generated in the first data communication device. a first code generation circuit is provided;
The second data communication device includes a counting circuit that counts the order of received bits, a second code generation circuit that generates the same test code as the first data communication device, and a test code that is sent from the first data communication device. a comparison circuit that compares the test code generated by the second code generation circuit with the test code generated by the second code generation circuit; a storage circuit that stores the bit order when the comparison result is different; and a circuit for inverting the sign of the bit order stored in the storage circuit when sending back the data.