JP2692338B2 - Communication device failure detection device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a failure detection device for a communication device that detects a failure in a transmission line in a communication device that performs multiplex communication via a duplicated transmission line.

(Prior art)

As a failure detection device for a conventional communication device, for example, a fourth
There is something like the one shown in the figure. FIG. 4 shows the receiving section of the communication device, and the first transmission line 1 and the second transmission line 2 are shown.
A differential receiver 300 that receives a transmission signal from the receiver and a receiver 200 that demodulates and decodes the data received by the differential receiver 300.
An edge detection circuit 511 for detecting whether or not there is a signal change on the first transmission line 1, a counter 512, a decoder 513 for decoding the value counted by the counter 512, and an output signal of the edge detection circuit 511 for resetting. A fault detection device 510 consisting of an RS flip-flop 514 set by the output signal, a fault detection device 520 having the same configuration as the fault detection device 510 connected to the second transmission line 2, and a control device 100 for controlling the entire receiving operation. It is composed of.

The configuration of the multiplex communication system is, for example, the fifth
Some are shown in the figure. FIG. 5 shows a master 610 which is a communication device for controlling communication, a slave group including slaves 1 and 620 to N630 which are communication devices which are controlled by the master 610, a first transmission line 1 and a second transmission line. It is a multiplex communication system composed of a transmission line 2.

Next, the operation of this communication device will be described based on FIG. 4 and FIG.

1) Communication method: The master 610 calls (polling) the slaves in a predetermined order, and only the called slaves can transmit. For example, the transmission unit (not shown) of the master 610 sends the transmission data to the first transmission line 1 and outputs the transmission data of the opposite phase obtained by inverting “0” and “1” of the transmission data. The signals are simultaneously sent to the second transmission line 2. When the transmission data is input via the first transmission line 1 and the second transmission line 2 to each reception unit of the slave group, the differential receiver 300 transmits the transmission data from the first transmission line 1 and the second transmission line 2. The data is received by detecting the difference in the signal level of, the data received by the receiving device 200 is decoded, it is determined whether or not the data is the transmission data sent to itself, and the data is the transmission data sent to itself. Transmission data to be transmitted to the master 610 is generated based on the transmission data received by the determined slave, and is transmitted to the first and second transmission lines 1 and 2.

2) Transmission line fault detection method: When there is no fault in the transmission line; when there is a signal change in the first transmission line 1 and the second transmission line 2, the edge detection circuit 511 detects the signal change and the edge detection signal “ 1 "is output, the RS flip-flop 514 is reset by the edge detection signal" 1 ", and the failure detection device 510 and the failure detection device 520 output the failure detection signal" 0 ", and it can be determined that no failure has occurred.
The counter 512 is cleared each time the edge detection circuit 511 outputs the edge detection signal “1”.
The RS flip-flop 514 is not set because the output of the RS does not become the value indicating the predetermined time and the output of the decoder 513 does not become "1".

When a failure occurs in the transmission line; for example, when a failure occurs such that the first transmission line 1 is shorted to the ground and transmission data cannot be transmitted, a signal change disappears in the first transmission line 1, so that the edge detection circuit. When 511 does not detect a signal change and outputs an edge detection signal "0", the counter 512 continues counting up, and when the decoder 513 monitors the output of the counter 512 and detects that a predetermined time has elapsed, it outputs "1". , The RS flip-flop 514 is set by the output signal of the decoder 513, and the fault detection device 510 outputs the fault detection signal "1" to detect the occurrence of the fault on the first transmission line. Further, when the obstacle of the first transmission line is overcome and the data can be transmitted through the first transmission line 1, the edge detection circuit 511.
Outputs an edge detection signal and resets the RS flip-flop 514 to output a failure detection signal "0" of the failure detection device 510.

Further, even if some failure occurs in one of the first transmission line 1 and the second transmission line 2, the remaining other transmission line does not impair the function of the differential receiver 300.
The transmission signal can be received by and the communication can be continued.

[Problems to be solved by the invention]

However, such a conventional fault detection device for a communication device has the following problems. Since it is the method of detecting the failure of the transmission path for each transmission path, the predetermined time counted by the counter is set in order to determine whether any communication device is not transmitting or the failure of the transmission path. It is necessary to set the time longer than a time (1 message time) required to transmit a data group (hereinafter referred to as a message) including a signal such as a header that can be transmitted at a time determined by the communication format. Therefore, there is a problem in that it takes more than one message time to detect a failure that has occurred in the transmission path, and it takes time to detect a failure that has occurred in the transmission path.

[Means for solving the problem]

The present invention has been made in view of the above-mentioned problems, and the failure detection device of a communication device determines whether or not there is transmission data on the first and second transmission paths for each bit of the transmission data and transmits the data. First and second carrier sense means for outputting a signal when it detects that there is data, and first logical operation means and 2 for performing a logical sum operation of two inputs.
A second and a third logical operation means for performing an exclusive OR operation of two inputs, and a connection point connecting the input terminal of the first carrier sense means to the first transmission line is a first input end,
The connection point where the input terminal of the second carrier sense means is connected to the second transmission line is the second input end, and the output terminals of the first and second carrier sense means are connected to the respective input terminals of the first logical operation means. , An output terminal of the first carrier sense means and an output terminal of the first logic operation means are connected to respective input terminals of the second logic operation means, and an output terminal of the second carrier sense means and an output of the first logic operation means. Terminal is third
The output signals of the second and third logical operation means are connected to the respective input terminals of the logical operation means, and the output terminals of the second and third logical operation means are the first and second output terminals, respectively. It is an object of the present invention to solve the above-mentioned problems by adopting a failure detection signal output when a failure is detected in each of the first and second transmission paths.

[Action]

The failure detection device of the communication device determines whether or not there is transmission data on the first and second transmission lines, for each bit of the transmission data, by separately determining signal changes by the first and second carrier sense means, and performing carrier sense. First to output signal of the means
Since the configuration is such that the respective faults of the first and second transmission lines are detected by performing the arithmetic processing by the third logical operation means, it is determined whether no communication device is transmitting or the fault of the transmission line. Can be easily determined, the monitoring time of the transmission path can be set to 1 bit time, and the failure of the transmission path can be detected quickly.

〔Example〕

 Hereinafter, description will be made based on specific examples.

FIG. 1 is an embodiment showing the present invention. FIG. 1 is a diagram showing the configuration of a receiving unit of a communication device, where 1 is the first
Transmission line, 2 is the second transmission line, and the first transmission line 1 and the second transmission line
The transmission data A1 and A2 from the transmission line 2 are input to the differential receiver 300, and the output terminals of the differential receiver 300 are input to the receiving device 200. In addition, the transmission data A1 and A2 from the first transmission line 1 and the second transmission line 2 are also input to the respective input terminals of the carrier sense means 410 and 420 that constitute the failure detection device 400, and the output of the carrier sense means 410 and 420. The signals a1 and a2 form the failure detection device 400.
To an input terminal of the logical operation means 430 (hereinafter referred to as an OR circuit) and one input terminal of second and third logical operation means 440 and 450 (hereinafter referred to as an E-OR circuit) for performing an exclusive OR operation. The input signal b output from the OR circuit 430 is input to the other input terminals of the E-OR circuits 440 and 450. E-OR
The output signals c1 and c2 of the circuits 440 and 450 are the first transmission line 1 and the second transmission line 1, respectively.
A fault detection signal that conveys the occurrence of a fault in the transmission path 2 is input to the control device 100, and the clock signal CL output from the control device 100 is supplied to the receiving device 200 and the fault detection device 400, and The output control signals CTR1 and CTR2 are input to the receiving device 200 and the fault detecting device 400, respectively.
The control signal CTR1 is a signal for instructing the receiving device 200 about the current communication state and processing of received data, and the control signal CTR2 is a reset signal for the fault detecting device 400.

FIG. 2 is a diagram showing a specific configuration of the carrier sense means 410. The input terminal of the carrier sense means 410 to which the transmission data A1 from the first transmission line 1 is input is the input terminal of the edge detection circuit 411. The output signal B of the edge detection circuit 411 which is the same and detects the rising edge of the transmission data A1
1 is the set terminal of RS flip-flop 414 and OR circuit 41
Control signal CT from the control device 100, which is input to the input terminal of 2
R2 is the reset terminal of the edge detection circuit 411 and the OR circuit 41.
The clock signal CL from the control device 100 is input to the input terminals of 2, 413 and is supplied to the edge detection circuit 411, the counter 415 and the decoder 416, and the output signal C1 of the OR circuit 412 is the counter.
The output signal D1− of the counter 415 is connected to the reset terminals of the T-type flip-flops 4150 to 4156 that compose 415.
1 to D1-5 are input to the respective data terminals of the D-type flip-flops 4161 to 4165 forming the decoder 416, and the D-type flip-flops 4161 to 4165 are inverter circuits.
Clock signal that the clock signal CL is inverted by 4160 ▲
Operated by ▼, D-type flip-flops 4161 to 4165
Is input to the input terminal of the AND circuit 4166, and the output signal of the AND circuit 4166 is ORed as the output signal E1 of the decoder 416.
The output signal of the circuit 413 is input to the reset terminal of the RS flip-flop 414, and the output signal of the RS flip-flop 414 is the carrier sense signal a1 which is the output of the carrier sense means.
Becomes The configuration of the carrier sense means 420 is the same as that of the carrier sense means 410 shown in FIG. 2 except that the edge detection circuit detects the trailing edge of the transmission signal A2 from the second transmission path 2. Is.

The configuration of the multiplex communication system is the same as that of the conventional example shown in FIG.
The configuration is such that 0 and a slave group consisting of slave 1 620 to slave N 630, which are communication devices controlled by the master 610, are connected to the first transmission line 1 and the second transmission line 2.

Next, the operation will be described with reference to FIGS. FIG. 3 shows a timing chart of the fault detection device 400 and the carrier sense means 410, 420 shown in FIGS. 1 and 2, and the signal names shown in FIG.
First, except that B2 indicates the output signal of the edge detection circuit forming the carrier sense means 420 (not shown)
It matches the signal names shown in the figures and FIG.

Here, in the communication control method, the master 610 makes a call (polling) to the slaves in a predetermined order,
It is assumed that only the addressed slave can transmit, and the communication format uses, for example, the RWM method as the data modulation code of the transmission signal, the data modulation rate of the transmission signal is 72 times that of the clock signal CL, and the message of the transmission signal is It is assumed that the length is set to 29 bits.

1) Communication method: For example, the transmission unit (not shown) of the master 610 sends the transmission data A1 to the first transmission line 1 and inverts “0” and “1” of the transmission data A1. The reverse phase transmission data A2 is simultaneously sent to the second transmission line 2. When the transmission data A1 and A2 are input via the first transmission line 1 and the second transmission line 2, the reception unit of the slave group receives the differential receiver 3
00 is transmission data from the first transmission line 1 and the second transmission line 2.
Data is received by detecting the difference between the signal levels of A1 and A2, the receiving device 200 decodes the data and determines whether or not it is the transmission signal sent to itself, and the transmission signal sent to itself The transmission data generated based on the data received by the slave determined to be is transmitted to the master 610 via the first transmission line 1 and the second transmission line 2.

2) Operation of carrier sense means: When the transmission data A1 from the first transmission line 1 is input to the edge detection circuit 411, the edge detection circuit 411 is generated according to the rising edge of the transmission data A1.
Output signal B1 of "1" and the edge detection circuit 411 rises every time it detects an edge, the RS flip-flop 414 is set and the carrier sense signal a1 becomes "1" and T
Mold flip-flops 4150-4156 are reset and counter
415 starts counting up from 1. The output signals D1-1 to D1-5 of the counter 415, which are input to the decoder 416, are inverted by the D-type flip-flops 4161 to 4165 in order to prevent glitches and the like that occur when they are decoded.
Resynchronize with ▼ to read. While the transmission data A1 is normally transmitted, since there is a rising edge for each bit, the counter 415 is reset for each bit and the output signal E1 of the decoder 416 does not become "1". Further, when the signal change of the transmission data A1 disappears, the output signal B1 of the edge detection circuit 411 does not become "1", so the counter 415
Is not reset and continues counting up, and when a predetermined time elapses, the decoder 416 which monitors the output of the counter 415
Output signal E1 of "1" becomes, and the output signal E1 "1" becomes OR circuit.
It is input to the reset terminal of the RS flip-flop 414 via 413, the RS flip-flop 414 is reset, and it is detected that the carrier sense signal a1 becomes "0" and there is no transmission data. When the transmission data A2 from the second transmission line 2 is input to the edge detection circuit 411, the transmission data A2
The output signal B2 of the edge detection circuit 411 becomes "1" in response to the trailing edge of 2, and the carrier sense signal a2 is output by the same operation as the above-mentioned carrier sense method of the first transmission path.

3) Fault detection method of transmission line: When the transmission data is normally transmitted from the first transmission line 1 and the second transmission line 2, both of the carrier sense signals a1 and a2 output from the carrier sense means 410 and 420 are "as described above. Since it becomes 1 ", the output signal b of the OR circuit 430 also becomes" 1 ". Furthermore, since "1" is input to all the input terminals of the E-OR circuits 440 and 450,
The output signals c1 and c2 output by 450 are both "0", indicating that the first transmission line and the second transmission line 2 are normal.

Here, if a failure occurs such that the first transmission path 1 is grounded at a time point X in FIG. 3 while a certain transmission device is transmitting the transmission data A1 and A2, the first transmission path after the time point X The signal change of the transmission data A1 from the transmission line 1 disappears, and only the signal change of the transmission data A2 from the second transmission line 2 is input to the failure detection device 400. In this case, after confirming that the carrier sense signal a1 of the carrier sense means 410 has no signal change for one bit time, "0" is output, and the carrier sense means 420 outputs the carrier sense signal a.
2 Output “1”. Since "1" is input to the input terminal of the OR circuit 430, the OR circuit 430 outputs the output signal b "1". E
Since "1" and "0" are input to the input terminal of the -OR circuit 440, the E-OR circuit 440 outputs the output signal c1 "1" and outputs the first signal.
This indicates that the transmission line 1 has an abnormality. Furthermore, E-
Since both "1" are input to the input terminals of the OR circuit 450,
The E-OR circuit 440 outputs the output signal c2 "0" and outputs the second transmission line 2
Is normal.

Further, when none of the communication devices sends out the transmission data A1 and A2, there is no signal change on the first and second transmission lines 1 and 2, so that the carrier sense signals output from the carrier sense means 410 and 420 are output. Both a1 and a2 become “0”, and O
The R circuit 430 outputs the output signal b “0”, and the E-OR circuits 440 and 450
"0" is input to each input terminal of the E-OR circuit
Since the output signals c1 and c2 of 440 and 450 are both "0", it indicates that both the first and second transmission lines 1 and 2 are normal.

In other words, the failure detection device 400 uses the first or second transmission line.
After the occurrence of a failure in either 1 or 2, the edge detection circuit 41 for each transmission line for the first 1st bit period of the received transmission data.
The output signals B1 and B2 of 1 are monitored to determine the presence / absence of transmission data, and the OR circuit 430 and the E-OR circuits 440 and 450 perform a logical operation on the result to transmit no transmission data to any communication device. Or the failure that occurred in the transmission line,
It is possible to output a failure detection signal at the next second bit, and it is possible to detect a failure on the transmission path in real time.

4) Processing at the time of detecting a failure in the transmission path: For example, even if some failure occurs in the first transmission path 1, the differential receiver 300 can receive the transmission signal without losing the function by the second transmission path 2 and communicate. When the fault detection device 400 detects a fault occurring in the first transmission line 1 by the method shown in 3), the control device 100 issues an alarm based on this result and informs the user. You can

Further, comparing the conventional example shown in FIG. 4 with the example shown in FIGS. 1 and 2, the fault detecting devices 510, 520 of the conventional example and the carrier sense means 410, 420 of this example have almost the same configuration. In the conventional example, since it is necessary to monitor the time required to transmit one message, the counter 512 requires 72 * 29 = 2088 clocks to count one message time, and a 13-bit binary counter is required. On the other hand, in this embodiment, since the transmission data is monitored in units of 1 bit time, the counter 415 only needs to be able to count 2 bit times, and can be realized by a 7 bit binary counter. That is, the failure detection device 400 of the present embodiment
Is a carrier sense means for detecting a signal change within a predetermined time to monitor the signal on the transmission path in units of one bit time, and the output signals of the carrier sense means are logically processed by the first to third logical operation means. The flip-flop size of the counter is 6 to 10 times the size of the 2-input OR circuit when compared at the transistor level because the configuration is such that the faults are detected by mutually monitoring the transmission lines. Even if the third logical operation means is added, the circuit scale of the failure detection device can be reduced as a whole.

Further, when the failure detection device is integrated, the area occupied on the semiconductor chip can be reduced and the cost can be reduced.

In this embodiment, the data modulation code is the PWM code,
A code having a rising edge or a falling edge for each bit (for example, Mantiester code) may be used. Further, in the present embodiment, the communication method is used in which the transmission data in which “0” and “1” are inverted from each other are simultaneously transmitted through the first and second transmission lines 1 and 2. However, for example, the first transmission line 1 May be used as the main transmission path and the second transmission path 2 as the backup transmission path, and the same transmission data may be simultaneously transmitted via the first and second transmission paths 1 and 2.

〔The invention's effect〕

As described above with reference to the specific embodiments, the failure detection device of the communication device determines whether or not there is transmission data on the first and second transmission lines, and determines whether or not there is transmission data for each bit. First and second carrier sense means for outputting a signal when the presence of data is detected;
And a first logical operation means for performing an OR operation of two inputs for processing the output signal of the second carrier sense means and a second operation for an exclusive OR operation of the two inputs
And a third logical operation means, and a connection point at which the input terminal of the first carrier sense means is connected to the first transmission line is a first
The second input end is a connection point where the input terminal of the second carrier sense means is connected to the second transmission line as the input end, and the output terminals of the first and second carrier sense means are the respective inputs of the first logical operation means. Connected to the terminals, the output terminal of the first carrier sense means and the output terminal of the first logic operation means are connected to the respective input terminals of the second logic operation means, and the output terminal of the second carrier sense means and the first logic operation. The output terminal of the means is connected to the respective input terminals of the third logical operation means, and the output terminals of the second and third logical operation means are the first and second output terminals, respectively. Since the output signals of the three logical operation means correspond to the failure detection signals output when the failures of the first and second transmission lines are detected, respectively, there is a possibility that no communication device is transmitting. I It is possible to set the transmission line monitoring time for determining whether there is a transmission line fault to one bit time, and it is possible to quickly detect the transmission line fault and to solve the above problems. .

[Brief description of the drawings]

FIG. 1 is a block diagram of a receiving section of a communication device showing an embodiment of the invention, FIG. 2 is a block diagram of a carrier sense means showing an embodiment of the invention, and FIG. 3 is a carrier sense means. 4 is a waveform diagram showing the operation of FIG. 4, FIG. 4 is a configuration diagram of a receiving unit of a conventional communication device, and FIG. 5 is an overall configuration diagram of a communication system. 1,2 ... Transmission path, 100 ... Control device, 200 ... Reception device, 300 ... Differential receiver, 400,510,520 ... Fault detection device, 410,420 ... Carrier sense means, 440,450 ... E-OR circuit, 411,511 ... Edge detection circuit, 430,412,413 ... OR circuit, 414, 514 ... RS flip-flop, 415, 512 ... Counter, 4150-4156 ... T-type flip-flop, 416, 513 ... Decoder, 4160 ... Inverter circuit, 4161-4165 ... D-type flip-flop, 4166 ...
AND circuit, 610 ... Master, 620,630 ... Slave

Claims (1)

(57) [Claims] 1. A communication device for performing multiplex communication of transmission data generated by using a data modulation code in which a signal rises or falls every one bit of data via a duplicated transmission line. Also, it is determined whether or not the transmission data is present on the second transmission path for each bit of the transmission data, and when it detects that the transmission data is present, first and second carrier sense means for outputting a signal and two A first logical operation means for performing an OR operation of inputs and a second and a third logical operation means for performing an exclusive OR operation of two inputs, the input terminal of the first carrier sense means being the first terminal. The connection point connected to the transmission line is the first input end, and the input terminal of the second carrier sense means is the second input end, the connection point connected to the second transmission line is the first and second carriers. An output terminal of the sense means is connected to each input terminal of the first logical operation means, and an output terminal of the first carrier sense means and an output terminal of the first logical operation means are each of the second logical operation means. Of the second carrier sense means and the output terminal of the first logic operation means are connected to respective input terminals of the third logic operation means, and the second and third logic operation means are connected. Each of the output terminals of the arithmetic means has first and second output terminals, and is output when the output signals of the second and third logical operation means detect a fault in the first and second transmission paths, respectively. Failure detection device for a communication device, wherein the failure detection device corresponds to a failure detection signal.