JPH0827304B2 - Failure detection device - Google Patents

Description

The present invention relates to a device for detecting a failure of a frequency determination device.

[Prior Art] Conventionally, in order to prevent malfunction of a signal processing device and the like, only a normal signal is input to the processing device, and other signals are not input, a device for determining an input signal is provided. Thus, the input signal is checked and only the regular signal is input to the signal processing device. An example is shown in FIG. 3, and the signal is input to the signal processing device 102 through the frequency determination device 101. The frequency determining device 101 checks the frequency of the input signal, and if it is equal to the frequency of the regular input signal, the input signal is determined to be regular and is output to the signal processing device 102. , No signal is output as it is not a legitimate signal.

On the other hand, even when outputting the processing result in the signal processing device, if it is intended to output only a normal signal to the device connected to this, whether the output signal of the signal processing device is a normal signal or not. After confirming whether or not it is output. An example thereof is shown in FIG. 4, in which the output signal of the signal processing device 102 is input to the frequency determination device 101 to check it. The frequency determination device 101 determines that this signal is a regular signal only when the frequency of the input signal is equal to the frequency of the regular signal, and outputs it.

[Problems to be Solved by the Invention] By the way, when a signal is determined using such a frequency determination device, even if a normal signal is input when this determination device fails, a signal is output from this device. No
The output is fixed to either the logic level "1" or the logic level "0", for example. Since such an output is the same as the output of the frequency determination device when no signal is input, the signal processing device enters a standby state as if no signal was input.

Further, if the frequency determination device outputs a signal other than a normal signal due to a failure, this causes a malfunction of the signal processing device.

An object of the present invention is to provide a highly reliable fault detection device for detecting a fault in a frequency determination device in order to solve such a problem.

[Means for Solving Problems] The present invention relates to a device for detecting a failure of a frequency determination device which outputs a signal only when an input signal has a predetermined frequency. When a first control signal and a second control signal indicating the timing to perform a test at a predetermined time interval are generated and the first control signal is output, the predetermined signal is input Only when the control means outputs the second control signal, and when the control means outputs the second control signal,
A failure detecting means for detecting a failure of the frequency determining device based on a signal output from the frequency determining device, a first contact and a second contact which are mechanically interlocked to be turned on (lifted) or turned off (dropped). And outputs the predetermined signal, which indicates ON or OFF of the second contact, to the control means when the first control signal is input, and inputs the test signal through the first contact. And a relay for inputting the test signal input to the terminal to the frequency determination device.

[Operation] When the control means outputs the first control signal, the first contact of the relay is turned on, and the test signal input to the test signal input terminal is input to the frequency determination device.
Further, at this time, the relay outputs a predetermined signal indicating ON or OFF of the second contact to the control means. Upon receipt of this, the control means outputs a second control signal to the failure detection means on the assumption that the relay has certainly operated by the first control signal. The failure detection means outputs the second control signal,
Failure detection of the frequency determination device is performed based on the signal output by the frequency determination device to which the test signal is input.

[Embodiment of the Invention] Next, an embodiment of the present invention will be described.

FIG. 1 shows a block diagram of the present embodiment. The frequency determination device 101 checks the frequency of the input signal, and if it is equal to the frequency of the regular input signal, the input signal is determined to be regular and the signal is determined. The signal is output to the processing device 102, and if the frequencies are different, the signal is not output because it is not a normal signal.
The output signal of the frequency determination device 101 is input to the signal processing device 102 through the AND gate 103. The failure detection device 10 according to the present invention detects a failure of the frequency determination device 101.

The test signal input terminal 1 is for inputting a test signal t having the same frequency as that of a regular input signal, and the test signal input to the test signal input terminal 1 is sent to the frequency determination device 101 via a switch operated by a relay 4 described later. input. Control circuit 2
Generates a control signal C ₁ and a control signal C ₂ having a logic level “1” indicating the timing at which the test should be performed at predetermined time intervals. The control signal C ₁ is output to the relay 4, which will be described later, and the control signal C ₁ is output.
C ₂ is output to the failure detection circuit 3 described later and the AND gate 103. However, the control signal C ₂ is output only when a voltage of +5 V is input to the terminal 21 as a signal when the control signal C ₁ is output.

When the control circuit 2 outputs the control signal C ₂ , the failure detection circuit 3 detects the failure of the frequency determination device based on the signal output by the frequency determination device 101. The failure detection signal s indicating The relay 4 has switches 41, 42 which are turned on or off by mechanically interlocking contacts 4a, 4b. This relay 4 has contact 4
The a and 4b are configured to operate in a reliable manner.
When relay 4 is turned on, contact 411 of switch 41 and contact 4a
The test signal t is input to the frequency determination device 101 through
On the other hand, the voltage of + 5V is applied as a signal to the terminal 21 of the control circuit 2 through the contacts 421 and 4b of the switch 42. When the relay 4 is turned off, the input signal i input to the terminal 5 through the contacts 412, 4a of the switch 42 is applied to the frequency determination device 10.
Entered in 1.

Next, the operation will be described. Control circuit 2 is at logic level "1"
When the control signals C ₁ and C ₂ are not output, the input signal i is input to the frequency determination device 101 because the relay 4 is off. When this signal has a predetermined frequency, the frequency determining device 101 determines that it is a regular signal and outputs it to the AND gate 103, and when it has a different frequency, it determines that it is not a regular signal and does not output it. Since the control signal C ₂ input to the other terminal of the AND gate 103 has the logic level “0”, the signal output from the frequency determination device 101 is input to the signal processing device 102 through this AND gate. It

Since the control circuit 2 periodically detects the failure of the frequency determination device, the control signal of the logic level "1" is set at a predetermined time interval.
When C ₁ is output and this signal is output, relay 4
Operates to turn on the contacts 411, 421 of the switches 41, 42.
As a result, the test signal t input to the test signal input terminal 1 is input to the frequency determination device 101, while the switch 42
A voltage of + 5V is applied as a signal to the terminal 21 of the control circuit 2 through.

When the voltage of + 5V is applied to the terminal 21, the control circuit 2 outputs the control signal C ₂ of logic level “1” to the AND gate 103 and the failure detection circuit 3. Here, the reason why the control circuit 2 outputs the control signal C ₂ to cause the failure detection circuit 3 to perform the failure detection after the voltage of + 5V is applied to the terminal 21 is that the test signal t is surely the frequency determination device. This is because the failure detection is performed with the input to 101. That is, switch 41 and switch 42 are mechanically interlocked by relay 4, and contact 41
When 1 is on, contact 421 is always on. Therefore, if a voltage of + 5V is applied to the terminal 21, the relay 4 operates and the test signal t is surely input to the frequency determination device 101.

Since the control circuit 2 outputs the control signal C ₂ , the AND gate 103 closes the gate and prevents the signal from the frequency determination device 101 from being input to the signal processing device 102 while the failure detection is being performed. Then, the failure detection circuit 3 detects a failure of this frequency determination device based on the signal output from the frequency determination device 101, and when a failure is detected, outputs a failure detection signal s indicating this.

In this way, the failure detection of the frequency determination device 101,
It is carried out regularly and surely without affecting the original communication function.

Next, an embodiment for detecting a failure of the frequency determination device 101 connected to the output side of the signal processing device 102 will be described with reference to the block diagram shown in FIG.

The frequency determination device 101 examines the frequency of the output signal of the signal processing device 102, determines that the signal is normal if it is equal to the frequency of the regular output signal, and determines that the signal is regular if the frequencies are different. It is determined not to.

The test signal input terminal 1 of this failure detection device 11 is for inputting a test signal t having the same frequency as the normal output signal, and the test signal input thereto is passed through a switch 41 operated by the relay 4. Input to the frequency determination device 101. The control circuit 2 generates a control signal C ₁ and a control signal C ₂ having a logic level "1" indicating the timing at which the test should be performed at predetermined time intervals. The control signal C ₁ is output to the relay 4, which will be described later, and the control signal C ₁ is output.
C ₂ is output to the failure detection circuit 3. However, control signal C
_When the control signal C ₁ is output, ₂ is output only when a voltage of +5 V is input to the terminal 21 as a signal.

When the control circuit 2 outputs the control signal C ₂ , the failure detection circuit 3 detects the failure of the frequency determination device based on the signal output by the frequency determination device 101. The failure detection signal s indicating The relay 4 is a switch that is mechanically continuously turned on or off.
41 and 42, and their contacts 411 and 421 are turned on when the control signal C ₁ is output. As in the case of the previous embodiment, this relay 4 is configured so that the contact 421 operates in a reliable manner so that when one is on (or off), the other is always on (or off). ing. When the relay 4 is turned on, the test signal t is input to the frequency determination device 101 through the contact 411 of the switch 41, while the + 5V voltage is applied as a signal to the terminal 21 of the control circuit 2 through the contact 421 of the switch 42. When the relay 4 is turned off, the contact 412 of the switch 41 is turned on, and the signal input to the test signal input terminal 1 is output from the output terminal 5 as a regular output signal o.

In this embodiment, both the regular output signal of the signal processing device 102 and the test signal t are switched and output from the signal processing device 102.

Next, the operation will be described. Control circuit 2 is at logic level "1"
When the control signals C ₁ and C ₂ are not output, the contact 412 of the relay 4 is turned on, and the output of the signal processing device 102 is output from the terminal 5 as a regular signal.

Since the control circuit 2 periodically detects the failure of the frequency determination device, the control signal of the logic level "1" is set at a predetermined time interval.
When C ₁ is output and this signal is output, relay 4
Operates to turn on the contacts 411, 421 of the switches 41, 42.
As a result, the test signal t from the signal processing device 102 input to the test signal input terminal 1 is input to the frequency determination device 101 through the contact 411, while the + 5V voltage is output as a signal through the contact 421 to the terminal 21 of the control circuit 2. Applied to.

When the voltage of + 5V is applied to the terminal 21, the control circuit 2 outputs the control signal C ₂ of logic level “1” to the failure detection circuit 3. The control circuit 2 outputs the control signal C ₂ after the voltage of + 5V is applied to the terminal 21, so that the failure detection circuit 3 detects the failure while the test signal t is reliably input to the frequency determination device 101. To perform. Switch for relay 4
41 and the switch 42 are mechanically interlocked to turn on or off,
Since contact 421 is always on when contact 411 is on,
This is possible.

When the control circuit 2 outputs the control signal C ₂ , the failure detection circuit 3 detects the failure of the frequency determination device 101 based on the signal output from the frequency determination device 101, and when the failure is detected, A failure detection signal indicating that is output.

In this way, even when the frequency determination device 101 is provided on the output side of the signal processing device, its failure detection is performed regularly and reliably.

In these examples, a signal having the same frequency as the regular signal was input as the test signal from the test signal input terminal 1. However, by using a signal having a frequency different from the regular signal, it is possible to further ensure the failure detection. It can be anything. That is, when a signal having a frequency different from that of the regular signal is input to the frequency determination device 101 as the test signal t, this signal is not output if the frequency determination device is normal. Therefore, by configuring the failure detection circuit 3 so that the frequency determination device determines that the frequency determination device is normal at this time, it is possible to check whether the frequency determination device operates properly even when a signal other than a normal signal is input. it can.

[Effects of the Invention] As described above, the failure detection device of the present invention is a device for detecting a failure of a frequency determination device that outputs this signal only when an input signal has a predetermined frequency. A test signal input terminal for inputting a signal, a first control signal and a second control signal indicating the timing at which a test should be performed at a predetermined time interval are generated, and the first control signal is generated.
When the control signal is output, the control means outputs the second control signal only when a predetermined signal is input, and the frequency determining device when the control means outputs the second control signal. A failure detecting means for detecting a failure of the frequency determining device based on a signal output by the frequency determining device, and further having a first contact and a second contact which are mechanically interlocked to turn on or off. When the control signal No. 1 is output, the predetermined signal indicating ON or OFF of the second contact is input to the control means, and the test signal input terminal is input through the first contact. And a relay for inputting a test signal to the frequency determination device.

Therefore, by using the failure detection device of the present invention, the failure of the frequency determination device can be detected periodically, and the test can be performed while the test signal is being reliably input. This enables very reliable fault detection of the frequency determination device.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing another embodiment, and FIGS. 3 and 4 are frequency judgment devices for judging the normality of an input signal or an output signal. It is a block diagram which shows the conventional signal processing system which does. 1 ... Test signal input terminal, 2 ... control circuit, 3 ... fault detection circuit, 4 ... relay, 4a, 4b ... contact, 21 ... terminal, 41,42 ... switch.

Claims (1)

[Claims] 1. A device for detecting a failure of a frequency judgment device which outputs a signal only when an input signal has a predetermined frequency, and a test signal input terminal for inputting a test signal of the frequency and a predetermined time interval. First to indicate when the test should be done
And a second control signal, and when the first control signal is output, the control means outputs the second control signal only when a predetermined signal is input, and the control means. A failure detecting means for detecting a failure of the frequency determining device based on the signal output by the frequency determining device when the means outputs the second control signal; 1 contact point and 2nd contact point, when the above-mentioned 1st control signal is output,
The predetermined signal indicating ON or OFF of the second contact is input to the control means, and the test signal input to the test signal input terminal through the first contact is input to the frequency determination device. A failure detection device comprising a relay.