JPS6133418B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a parent device and a plurality of child devices connected to the parent device via a transmission line in a multi-drop manner, and further enables switching between the parent device and terminal child devices using the transmission line. This invention relates to an improvement in a device for automatically disconnecting a defective line due to noise in a code transmitting/receiving device that is directly connected to a separate line by a separate line, and its purpose is to provide this type of device that automatically restores a disconnected line. It is something.

Regarding the defective line automatic disconnection device in the above-mentioned code transmitting/receiving device, Japanese Patent Application No. 51-156907 (Japanese Unexamined Patent Application Publication No. 1983-1988) filed by the same applicant as the present applicant has already been filed.
Although the details are described in the specification of Japanese Patent Application No. 80111, the present invention is a further effective improvement of the invention of the above-mentioned patent application. Therefore, as a premise for explaining the present invention, an outline of the invention of the above patent application will be described. First, in the above code transmitting/receiving device,
A transmission line that connects multiple child devices to a parent device in a multi-drop manner is called a regular line, and a line that directly connects the parent device and terminal child devices is called a detour line.
This detour line is intended to prevent the equipment from going down due to a disconnection of the regular line.
The parent device is equipped to be able to switch between regular and detour lines for transmitting and receiving codes. Further, for both regular and detour lines, the direction of code transmission from the parent device to the child device is called downstream, and the direction of code transmission from the child device to the parent device is called upstream.

As mentioned above, measures have been taken to prevent system failure due to disconnection of the regular line, but the above patent application was provided as a further preventive measure against system failure caused by noise entering the transmission line. invention of the ``defective line automatic disconnection device.'' That is, FIG. 1 shows a child device group B (i-
1), a regular downstream line MLD that connects B(i+1), etc. and terminal child device Bn to the parent device M in a multi-drop manner, an upstream line MLU, and a detour downstream line PLD that directly connects the parent device M and the terminal child device Bn. , a block diagram of a code transmitting/receiving device consisting of an upstream line PLU, etc. The defective line automatic disconnection device of the above patent application includes a code judger DTD shown inside the child device Bi,
Switch SWD represented by DTU and contact symbols
1, SWD2, SWU1, SWU2, hybrid transformer HYB1, HYB2, return push button switch
It consists of PBD, PBU, etc.

Note that the downstream receiving circuit R1, the upstream receiving circuit R2, the transmitting circuit S, the logic circuit LG, etc. are the original circuits of the child device.

Switch SWD1, SWD2, SWU1, SWU2
etc. are normally closed and codes are sent and received by the child device Bi, but now the child devices Bi and B
Suppose that noise enters point a of the regular line MLD between
Bi is received by the receiving circuit R1, and the sign determiner DTD
If it is determined that the noise is noise, first the switch SWD1 is opened using the output of the determination, thereby preventing further noise from flowing into the downstream slave devices. Switch SWD1 is automatically closed after a set fixed time, but switch SWD2 of child device Bi adjacent to point a is still closed even after switch SWD1 is opened, and noise flows into receiving circuit R1. For,
A noise judgment output is output again from the sign judgment device DTD and the switch SWD2 is opened. This state is maintained until the push button switch PBD is reset.

On the other hand, for the slave devices after slave device B(i+1), the reception input is stopped by opening the switch SWD1 of the front slave device Bi, so the noise judgment output will not be output again as described above, and each slave device Switch SWD2 remains closed. In this way, the faulty line including point a is connected to the child device adjacent to point a.
It is disconnected by switch SWD2 of Bi to prevent noise from being mixed into subsequent child devices.

The above is an outline of the invention of the above patent application. In this invention, in order to reconnect the line after the noise fault is recovered after disconnecting the line, the switch (SWD2 or SWU2) is closed by operating a push button switch (PBD or PBU) at the site. was. This means that in the case of a device equipped with a detour line, the purpose of the invention is to bring the regular line to a disconnection state in the event of noise interference, and to utilize the detour line to ensure the operation of the device. It was based on a philosophy that did not necessarily consider the restoration of downed lines to be an emergency.

The present invention reduces the number of defective line disconnection switches in the invention of the above patent application by half, takes measures to prevent noise from flowing into the logic circuit of a slave device, and furthermore, automatically disconnects the disconnected line when a noise problem is restored. It was designed to connect to.

Embodiments of the present invention will be explained below with reference to FIGS. 2 and 3. The blocks surrounded by the two-dot chain line in FIG.
Bk is a circuit block diagram showing the configuration of a child device Bk improved according to the present invention, in which child devices B(k-1),
Of course, B(k+1) also has a similar configuration. In the figure, H1 to H5 are all hybrid transformers, SW1 is a line disconnection switch inserted in the downstream regular line MLD, and SW2 is the upstream regular line.
A line disconnection switch inserted in the MLU,
DT1 is a reception code determination circuit that controls the opening and closing of the switch SW1, DT2 is a reception code determination circuit that controls the opening and closing of the switch SW2, and AG1 and AG2 are AND gates that prevent noise from flowing into the logic circuit LG. In addition, logic circuit LG, reception circuit R1, R
2. The transmitting circuit S is the original circuit of the child device as in FIG.

FIG. 3 is a block diagram of an internal circuit showing an example of the configuration of the received code determination circuit DT1 or DT2, in which 1 is a counter for counting received codes, and its output count values k and l.
Then k<l, and k is equal to the number of bits of the normal code. 2 is a received code discrimination circuit that discriminates between the logical value "1" and "0" of each bit of the received code; 3 is a necessary check for the series of received codes, such as parity check, fixed mark check, and repetition check; This code verification circuit outputs a g signal when the test passes, and an ng signal when it fails.
4 is a defective number counter that counts the number of times the ng signal from the code verification circuit 3 or the count signal l from the received code counter 1 is received via the OR gate 5; 6 is a normal number counter that counts the g signal from the code verification circuit 3; The increment signals of counters 4 and 6 are also used as a reset signal for each counter,
Furthermore, both of the above-mentioned step signals pass through the OR gate 7 and become a reset signal for the received code counter 1.
8 is set by the count value signal n of the defective number counter 4, and is sent to the normal number counter 6 via the OR circuit 9.
The set output of the flip-flop 8 opens the contacts of the switch SW. 10 is a code end detection circuit that outputs a code end signal to the code verification circuit 3 if there is no rising edge of the received code for more than a certain time interval (generally several bits long), and 11 is a code end detecting circuit that receives data for more than a certain time interval (generally several code lengths). The line no-signal detection circuit outputs a no-signal detection signal and resets the flip-flop 8 via the OR gate 9 when the rising edge of the code is not detected.

The circuit configuration shown in FIG. 3 is common to the reception code determination circuits DT1 and DT2 shown in FIG. And gate AG on condition of that code test pass signal g
1, the received signal is supplied to the logic circuit LG. Similarly, when operating as DT2, switch
SW2 is controlled, and the reception signal of the reception circuit R2 is supplied to the logic circuit LG via the AND gate AG2.
Prevents noise from entering.

Next, to describe the main operation of noise detection in the circuit shown in Fig. 3, when the input noise is intermittent, a failure signal ng is output from the code verification circuit 3 each time the intermittent wave is interrupted, and the failure signal ng is output from the failure frequency counter 4. is n
When the fault code ng is continuously received, the n count value output of the counter 4 sets the flip-flop 8, and the set output causes the switch SW to open. In addition, if the noise is continuous, the failure count counter 4 increments each time the received code counter 1 receives up to a count value l, and when l×n bits are received, the count value of the counter 4 advances to n, and its output is Set the flip-flop 8 and open the switch SW. In order to reset the set flip-flop 8 and restore the switch SW to the closed state, the normal code is received m times in a row, and the output when the count value of the normal number counter 6 reaches m is fixed. This is performed using either the detection output of the line no-signal detection circuit 11 which detects that there is no received code for a period of time or more. Note that the output count value n of the defective number counter 4 and the output count value m of the normal number counter 6
Needless to say, the settings are made taking into account the quality of the line, the frequency of information generation, etc. In addition, although the above description has been made regarding the case where there are two lines with different transmission directions, and furthermore, a regular line and a detour line, the present invention is not limited to this, and the present invention is not limited to this, but only with one line with a fixed transmission direction. Of course, it can be applied even in the case of

As described above, according to the present invention, when a fault detection output is not detected for a certain period of time or when a normal code is received a certain number of times in succession, the disconnected line is automatically reconnected, so noise is generated. This saves the trouble of operating the reset button on-site after recovery from a failure, and as mentioned above, the number of switches inserted into the line has been halved, improving the reliability of the equipment. It has a much more effective effect.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a code transmitting/receiving device showing an overview of a conventional faulty line automatic disconnection device applied to a child device, and Fig. 2 is a circuit diagram in which an embodiment of the line disconnection device of the present invention is applied to a child device of the code transmitting/receiving device. block diagram,
FIG. 3 is a block diagram of a received code determination circuit that controls the line disconnection switch. MLD…downstream regular line, MLU…upstream regular line,
Bk, B(k-1), B(k+1)...child device, H1
~H5...Hybrid transformer, SW1, SW2
...Normally closed switch, DT1, DT2...Sign determination circuit,
AG1, AG2...AND gate, 1...Received code counter, 3...Code verification circuit, 4...Failure number counter, 6...Normal number counter, 8...Switch controlled flip-flop, 11...Circumstance interval no-signal detection circuit.

Claims (1)

[Claims] 1. In a code transmitting/receiving device in which a parent device and multiple child devices are cascade-connected via a transmission line with a defined transmission direction, it is determined whether the received code from the transmission line is in a predetermined format for each child device. a code determination circuit that determines the number of consecutive receptions of abnormal codes and the number of consecutive receptions of normal codes; The transmission line is cut off on the condition that the circuit continuously receives abnormal codes a predetermined number of times, and the transmission line is cut off on the condition that the circuit continuously receives normal codes a predetermined number of times or no received code is input within a certain period of time. A normally closed switch that automatically restores a cut-off transmission line, and a gate circuit that inputs the received code from the transmission line into the slave device on the condition that the code determination circuit generates an output indicating normal code reception is provided. A line disconnection device characterized by: