JPS6211828B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for controlling loopback connections for testing line quality.

Conventionally, this type of control method for lines in which terminal equipment, processing equipment, or exchanges are connected via modems requires a special interface to be controlled from data terminal equipment because the loopback function is included in the modem. The disadvantage is that it requires
Furthermore, since the loopback operation is performed immediately upon reception of a certain predetermined pattern on the remote side, there is a drawback that there is a possibility of malfunction due to line noise. Furthermore, when giving an instruction to cancel callback, the remote location does not confirm that callback has been canceled, so there is a drawback that cancellation is displayed even though the callback has not actually been canceled.

The present invention has been made in view of such drawbacks, and by adding instruction information to the data itself sent to the modem, loopback control can be performed without using a special modem, and a predetermined bit string can be transmitted. By starting the operation only after receiving the call, it is possible to prevent malfunctions due to line noise.In addition, when canceling the callback, by displaying a cancellation display after confirming that the callback has been canceled on the remote side, it is possible to ensure that the callback is canceled. The purpose of this invention is to provide a remote loop loopback control system for lines that can perform loopback control.

That is, in order to achieve such an objective, the present invention has the following features:
In a remote loopback control method for a line to which a terminal device, processing device, or exchange is connected directly or via a modem, the device is connected to the receiving line and compares the received data with a specific predetermined bit string to find a match. - A bit string matching and matching detection circuit that outputs a signal in response to a mismatch, and an up-down counter that increments based on the output of the detection circuit and has an addition count input, a subtraction count input, a reset input, and a load input. , a remote fold flip-flop which is set by the carry output of the counter and reset by the borrow output to indicate the folding state, and which actually switches the circuit according to the output, and sets the fold by an external instruction.・Constructed with a pattern generator that has the function of generating a predetermined specific bit pattern for cancellation and sending it to the transmission line, on each of the return instruction site and remote site. .

Hereinafter, the present invention will be explained based on embodiments shown in the drawings.

FIG. 1 is a block diagram of a device constituting an embodiment of the return control system of the present invention, which is installed at a return instruction location and a remote location, respectively. The embodiment of the apparatus shown in the figure includes a transmitter A that includes loopback setting/cancellation designation switches 101 and 102 and a pattern generator 10, bit string matching and matching detection circuits 20 and 40, and a control logic circuit 21.・41, n-ary up-down counter 22・
42, remote folding flip-flop 23.
43, and a receiving section B constituted by remote return displays 24, 44 and local return displays 25, 45. In addition, in FIG. 1, 20, 21, etc. are the symbols used to explain the devices shown in the same figure as devices installed on the side of the designated return location, and 40, 41, etc. in the box are for the remote location side. This is a code used when describing a device installed in a device.

The pattern generator 10 is activated when the folding setting instruction switch 101 or the folding cancellation instruction switch 102 is pressed, and sends a predetermined setting instruction bit string or cancellation instruction bit string to the line 11. This return setting instruction switch 101 includes the above-mentioned pattern generator 10 as well as
AND gates 28, 2 provided in receiving section B
It is also connected to 9 and 30.

The bit string matching detection circuits 20 and 40 are as follows:
When connected to line 12 and receiving data from line 12, depending on the content, YO output if it is a callback setting pattern, Y1 output if it is not a callback setting pattern, Y2 output if it is a callback cancellation pattern, and Y2 output if it is not a callback cancellation pattern. Time Y3
Output each output. Y0 output and Y2 output are connected to control logic circuits 21 and 41,
The outputs are Z0 and Z1, respectively. Also, Y1 output and Y
The third output is sent to the control logic circuit 2 via AND gates 26 and 27 whose gates are controlled by the Q output of a remote flip-flop, which will be described later.
1 and 41, and become outputs Z0 and Z3, respectively.

The up-down counters 22 and 42 have an addition input U, a subtraction input D, a reset input R, a load input L that can input an arbitrary value, a carry output C,
It has borrow output B and n/2 output, and the output Z0 is connected to U, Z1 to D, Z2 to R, and Z3 to L, respectively. The carry output C is output when the bits from the addition input U are added to n, and the borrow output B is output when the bits from the subtraction input D are subtracted to become zero. Further, the n/2 output is connected to the control logic circuit 21 via an AND gate 30 whose opening and closing are controlled by the output of the return setting designation switch 101, so that the count value of the up-down counter 22 at the time of subtraction is n/2. When it reaches 2, it outputs and activates the control logic circuit 21 to indicate Y.
Change the connection of 2 outputs from Z1 to Z0.

The above remote flip-flop flip-flop 23.
43 is set by the carry output C of the up-down counters 22 and 42, and the borrow output B
The remote loop display 24, 44 and the local loop display 25, 45 are reset via the AND gates 28, 29 by the Q output.
blinks, and a known line return switching circuit (not shown) is activated. The operation of this line return switching circuit is as follows:
This can be done by outputting 44 or local folding displays 25 and 45.

Next, the operation of the control system of the present invention will be explained with reference to FIG.

First, when setting callback to a remote location, when the callback setting instruction switch 101 is pressed, the pattern generator 10 operates and sends a predetermined setting instruction bit string to the line 11. When the bit string coincidence detection circuit 40 receives this bit string at the remote location and outputs Y0, it is inputted to the addition input U of the up-down counter 42 through the control logic circuit 41, and the counter 42 increments. . When the counter 42 reaches n, a carry output C is output, a remote folding flip-flop 43 is set, a folding switching circuit (not shown) is switched to the folding state, and the local folding display 45 lights up.

On the other hand, at the return instruction site, the bit string matching detection circuit 20 receives the setting instruction bit string sent from the local side and returned from a remote location.
Similarly to the above, a remote flip-flop 23 is set via a control logic circuit 21 and an up-down counter 22. Since the return setting instruction switch 101 is on, the AND gate 28 opens and the remote return display 24
lights up.

At this time, the bit string matching detection circuit 4
Y1 output of 0,20 is up/down counter 4
It is connected to the reset input R of 2 and 22, and n
If even one bit in the continuous bit string is erroneous due to line noise, the counters 42, 22 are restarted. That is, folding will not be set incorrectly due to noise.

Next, when canceling remote callback, when the callback cancellation instruction switch 102 is pressed, the pattern generator 10 is activated and sends out a predetermined cancellation instruction bit string to the line 11. At this time, when the bit string matching detection circuit 40 on the remote side receives this bit string, Y2 is outputted, and this output is connected to the subtraction input D of the up-down counter 42, and the counter 42 Step forward while subtracting. When the count value becomes zero, a borrow output B is output to reset the remote flip-flop 43 and turn off the local fold-back display 45.

On the other hand, on the release instruction site side, the release instruction bit string sent out by the local side is received back from the remote location, and the up-down counter 22 subtracts from n in the same manner as described above.

At this time, the Y3 output is connected to the load input L of the up-down counters 42 and 22, and if even one bit of the received bit string does not match the specified pattern, the subtraction from the count value n is restarted. do.

When the count value reaches n/2, the Y2 output is connected to the addition input U of the up-down counter 22, and this time it increments in the opposite direction in the addition direction. If there is no noise on the line, the counter 42 at the remote location reaches zero and the counter 22 at the designated location reaches n at the same time. After that, when loopback is canceled on the remote side, normal data that is not an instruction pattern is sent, so the up-down counter 22 is subtracted from n by the resulting Y3 output, and only when it reaches zero can remote loopback be started. The flip-flop 23 is reset and the remote return display 24 is turned off.

Note that when no normal pattern is sent from the remote location and only a return cancellation pattern is received, the up-down counter 22 continues to be incremented, and the indicated location does not consider it as cancellation.

As explained above, the present invention has the effect of preventing malfunctions caused by line noise by starting operation only after receiving n consecutive bit strings, and also has the effect of preventing malfunctions caused by line noise. By displaying the cancellation display after confirming that it has been canceled, it is effective to reliably control loopback. Furthermore, since the configuration is simple, it can be easily incorporated into a data terminal device, and there is an economical effect that an inexpensive modem without a loopback function can be used.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a device constituting an embodiment of the loopback control system of the present invention. DESCRIPTION OF SYMBOLS 10...Pattern generator, 101...Remote location loopback setting instruction switch, 102...Remote location loopback cancellation instruction switch, 20, 40...Bit string matching detection circuit, 21, 41...Control logic circuit, 22, 42...Up-down counter , 23・
43...Remote folding flip-flop, 2
4・44...Remote return display, 25・45...
Local wrap display.

Claims (1)

[Claims] 1. In a remote loopback control system for a line to which a terminal device, a processing device, or an exchange is connected directly or via a modem, A bit string matching and matching detection circuit that compares the bit string and outputs a signal in response to a match or mismatch, and an addition count input, a subtraction count input, a reset input, and a load input that increments based on the output of the detection circuit. a remote folding flip-flop which is set by the carry output of the counter and reset by the borrow output to indicate the folding state, and whose output actually switches the circuit; A pattern generator that has the function of generating a predetermined specific bit pattern for setting and canceling call-back and sending it to the transmission line according to instructions from the call-back instruction site and the remote site. A remote line loopback control system that is characterized by being equipped for each line.