JPH0748736B2 - Signal transmission device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to, for example, a local area network (LA).
N) in the terminal station failure detection and its processing.

[Prior Art] Generally, in a LAN, a so-called "call" is made from the master station, which detects whether the terminal station is operating normally after a gap between data transmissions between the master station and the terminal station. Is regularly performed.

The configuration of a conventional signal transmission device in a LAN or the like will be described with reference to FIG.

In FIG. 2, a terminal station 10 of a conventional signal transmission device includes, for example, a one-chip CPU 1, an input / output circuit 2, a transmission transceiver 3, and an abnormality detection circuit 4 for detecting an abnormality of the CPU 1, It is connected to the master station 100 via the bus line 5.

Next, the operation of the conventional example will be described.

The data signal 101 from the master station 100 is input to the transmission transceiver 3 via the transmission bus line 5. The data signal 101 is converted into a predetermined reception signal 7 by the transmission transceiver 3.
Input to CPU1. The data signal 101 from the master station 100 converted into the received signal 7 is processed by the CPU 1 and output via the input / output circuit 2. The data signal input to the input / output circuit 2 is read by the CPU 1 and output as the transmission signal 6 to the transmission transceiver 3. The transmission signal 6 is converted into a predetermined transmission signal 11 by the transmission transceiver 3 and transmitted to the master station 100 via the transmission bus line 5.

When the CPU 1 is operating normally, it outputs the pulse signal 8 to the abnormality detection circuit 4 at a constant cycle. When the CPU 1 malfunctions due to noise or the like, the output of the pulse signal 8 is stopped or its cycle is changed. The abnormality detection circuit 4 has a pulse signal 8
And outputs a reset signal 9 to the CPU1. The CPU 1 is reset by the reset signal 9.

Call signal from the master station 100 through the data signal 101
102 is output to the terminal station 10. The calling signal 102 is converted into a predetermined signal 71 by the transmission transceiver 3 and
Input to U1. When the CPU 1 receives the signal 71, it outputs a signal 61 for a response to the transmission transceiver 3. Signal 61
Is converted into a predetermined response signal 12 by the transmission transceiver 3 and output to the master station 100 via the transmission bus line 5. The master station 100 receives the response signal 12 and confirms that the terminal station 10 is operating normally.

[Problems to be Solved by the Invention] The conventional signal transmission device can detect the abnormality of the CPU of the terminal station and reset the CPU, but the failure and malfunction of the master station or the like There is a problem that an abnormality due to a disconnection of the transmission bus line cannot be detected.

The present invention has been made to solve the above problems, and it is an object of the present invention to provide a signal transmission device capable of detecting an abnormality in a transmission function due to a failure of a master station or a disconnection of a transmission bus line. Has an aim.

[Means for Solving the Problems] A signal transmission device according to the present invention includes: (a) a master station that outputs a predetermined signal at predetermined cycles; and (b) a master station connected via a transmission line to the master station. Calculating means for outputting a predetermined response signal every time the predetermined signal is received from the master station; first abnormality detecting means for detecting whether or not an abnormality has occurred in the calculating means; By monitoring whether or not the response signal is output at each of the predetermined cycles, the abnormality occurs in the master station or the transmission line when the response signal is not output at each of the predetermined cycles. And a reset signal for resetting the arithmetic means when a predetermined abnormality is detected by one of the first abnormality detecting means and the second abnormality detecting means. Reset output in cycles And at least one terminal station having:

[Operation] The master station outputs a so-called interrogation signal for detecting whether or not the terminal station is normally operating at a predetermined cycle, for example, every 10 to 50 msec (arbitrary).

When the arithmetic means provided in the terminal station, for example, the CPU, receives the call signal from the master station, it outputs a response signal when it is operating normally. In addition, the computing means has a fixed period when it is operating normally, for example, 10 msec (arbitrary)
A pulse signal is output to the first abnormality detecting means for each.

When an abnormality such as a malfunction due to noise or the like occurs in the calculation means itself, the above-mentioned pulse signal is not output or the cycle changes. Therefore, the first abnormality detecting means detects the abnormality of the pulse signal from the calculating means and outputs the abnormality detecting signal to the reset means.

When the master station or the transmission line connecting the master station and the terminal station is broken or disconnected, the call signal from the master station is not input to the terminal station, and the calculation means of the terminal station does not output the response signal.
As a result, the second abnormality detecting means detects that the response signal has not been output within the predetermined time, judges that an abnormality has occurred in the master station or the transmission line, and outputs the abnormality detecting signal to the reset means. .

The reset means, when either the first abnormality detecting means or the second abnormality detecting means outputs an abnormality detection signal, outputs a reset signal for resetting the calculating means at a constant cycle, for example, every 100 msec. Outputs repeatedly until is reset.

[Embodiment] A signal transmission apparatus according to the present invention will be described with reference to FIG. 1 showing an embodiment. The elements with the same numbers as in the conventional example shown in FIG. 2 are the same.

In FIG. 1, a terminal station of a signal transmission device according to the present invention
20 is, for example, a one-chip CPU 1, an input / output circuit 2, a master station
A transmission transceiver 3 for exchanging signals with 100 in synchronization with a predetermined clock signal, an abnormality detection circuit 4 as first abnormality detection means for detecting an abnormality of the CPU 1, a transmission bus line 5 or a parent The reset circuit 9 receives the outputs of the monitoring circuit 21 which is the second abnormality detecting means for detecting the abnormality of the station 100, the OR circuit 25 connected to the abnormality detection circuit 4 and the monitoring circuit 21, and the OR circuit 25. A reset means including a reset circuit 26 is provided, a switch 22 is connected between the monitoring circuit 21 and the OR circuit 25, and a malfunction display element 24 is connected to the monitoring circuit 21.

Next, the operation of the embodiment will be described.

The data signal 101 from the master station 100 is input to the transmission transceiver 3 via the transmission bus line 5. The data signal 101 is converted into a predetermined reception signal 7 by the transmission transceiver 3.
Input to CPU1. The data signal 101 from the master station 100 converted into the received signal 7 is processed by the CPU 1 and output via the input / output circuit 2. The data signal input to the input / output circuit 2 is read by the CPU 1 and output as the transmission signal 6 to the transmission transceiver 3. The transmission signal 6 is converted into a predetermined transmission signal 11 by the transmission transceiver 3 and transmitted to the master station 100 via the transmission bus line 5.

When the CPU 1 is operating normally, it outputs the pulse signal 8 to the abnormality detection circuit 4 at a constant cycle. When the CPU 1 malfunctions due to noise or the like, the output of the pulse signal 8 is stopped or its cycle is changed. The abnormality detection circuit 4 has a pulse signal 8
Abnormal state (stop or abnormal period) is detected and an abnormal state detection signal is output to the OR circuit 25. Upon receiving the abnormality detection signal from the abnormality detection circuit 4, the OR circuit 25 outputs, for example, a predetermined voltage to the reset circuit 26, and the reset circuit 26 outputs the reset signal 9 to the CPU 1. CPU1 outputs reset signal 9 to CPU1. The CPU 1 is reset by the reset signal 9.

Call signal from the master station 100 through the data signal 101
102 is output to the terminal station 20 at a constant cycle, for example, at an arbitrary interval of 10 to 50 msec. The call signal 102 is converted into a predetermined signal 71 by the transmission transceiver 3 and input to the CPU 1. When CPU1 receives signal 71, it sends a signal for response.
61 is output to the transceiver 3 for transmission. The signal 61 is converted into a predetermined response signal 12 by the transmission transceiver 3 and output to the master station 100 via the transmission bus line 5. The master station 100 receives the response signal 12 and confirms that the terminal station 20 is operating normally.

The monitoring circuit 21 is for monitoring whether or not the signal 61 for response is correctly output. If the master station 100, the transmission bus line 5 and the like are normal, the call signal 102 from the master station 100 is input to the terminal station 20 at the above-mentioned constant cycle, and the terminal station 2
The CPU 1 of 0 should output the signal 61 for the response at the constant cycle. On the other hand, if an abnormality such as a failure, disconnection, or short circuit occurs in the master station 100 or the transmission bus line 5, the terminal station 20
The interrogation signal 102 is not input to or the cycle thereof changes. Therefore, when the signal 61 for response is not output in the predetermined cycle, the monitoring circuit 21 determines that the master station
An abnormality detection signal is output assuming that 100 or the transmission bus line 5 has an abnormality. Normally, the switch 22 is on, and the abnormality detection signal is input to the OR circuit 25. OR circuit
25 outputs the predetermined voltage to the reset circuit 26 as in the case where the abnormality detection circuit 4 outputs the abnormality detection signal, and the reset circuit 26 outputs the reset signal 9 to the CPU 1. The CPU 1 is reset by the reset signal 9. At the same time, the monitoring circuit 21 outputs a predetermined voltage to the malfunction display element 24, and the malfunction display element 24 lights up to display a warning that an abnormality has occurred. If you do not need to reset CPU1 and want to retain the abnormality detection signal due to abnormality detection, switch 22
Turn off.

The reset circuit 26 outputs a reset signal 9 to the CPU 1 when either the abnormality detection circuit 4 or the monitoring circuit 21 outputs an abnormality detection signal to the OR circuit 25.
Since it cannot be guaranteed that the CPU1 is reset surely by one output of the reset signal, the reset signal 9 is repeatedly output until the CPU1 is reset at a constant cycle, for example, an interval of 100 msec. Abnormality detection circuit 4 when the reset of CPU1 is completed
Does not output the abnormality detection signal, the reset circuit 26
Also stops outputting the reset signal 9. In order to prevent the CPU 1 from being continuously reset, the repetition period of the reset signal 9 is made longer than the period of the call signal 102 from the master station 100, and the pulse width of the reset signal 9 is made sufficiently small. Nor.

In the above-mentioned embodiment, the LAN connection method is connected to the bus line type, but the LAN connection method may be a loop type, a star type, a ring type or the like, and the same effect can be obtained.

EFFECTS OF THE INVENTION As described above, according to the present invention, the response signal from the terminal station is monitored. Therefore, when the response signal is not correctly output, it is possible to detect an abnormality in the master station or the transmission line. It has the effect that

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of a signal transmission device according to the present invention, and FIG. 2 is a diagram showing a conventional signal transmission device. In the figure, 1 is a CPU, 4 is an abnormality detection circuit, 20 is a terminal station, 21 is a monitoring circuit, 26 is a reset circuit, and 100 is a master station.

Claims (1)

[Claims] 1. A master station which outputs a predetermined signal at a predetermined cycle, and a second station which is connected to the master station via a transmission line and receives the predetermined signal from the master station. Calculating means for outputting a predetermined response signal every time, first abnormality detecting means for detecting whether or not an abnormality has occurred in the calculating means, and the calculating means outputs the response signal for each predetermined cycle Second abnormality detecting means for detecting that an abnormality has occurred in the master station or the transmission line when the response signal is not output in each of the predetermined cycles by monitoring whether or not the response signal is output. At least one of a first abnormality detecting unit and a second abnormality detecting unit detects an abnormality, and a reset unit that outputs a reset signal for resetting the arithmetic unit at a predetermined cycle. Terminal station, A signal transmission device equipped with.