JPH06311208A - Communication controller - Google Patents

Abstract

PURPOSE:To execute the abnormality detection of a receiving means each time a present station performs transmission by obtaining a signal at a minimum reception level and inputting it to the receiving means by attenuating a transmitted signal on a communication medium while the present station performs transmission. CONSTITUTION:An internal transmitted signal S1 as the output of a host processor 7 is outputted through a transmitting means 2 onto a communication medium 1. This output signal is inputted through an attenuating means 4 to a receiving means 3 while being attenuated to the minimum reception level to be received by the receiving means 3. Only while the internal transmitted signal S1 being the output of the host processor 7 is existent, a comparing means 6 detects level difference between an internal received signal S2 being the output of the receiving means 3 and the internal transmitted signal S1 being the output of the host device 7 by using a switching means 5. When the level difference exceeds a prescribed value, an abnormal state report signal S3 is outputted. This check is repeated each time the transmitting operation is performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a loopback function of a communication control device having a loopback function to constantly check a receiving means by a preset minimum reception level so that an abnormality can be detected. The present invention relates to a control device.

[0002]

2. Description of the Related Art Attenuation of signal level becomes a problem on a communication medium for long-distance communication. The communication control device with loopback function diagnoses the transmission / reception function by whether the communication device connected to the communication medium sends out the test signal addressed to itself and whether it can receive it normally. Is configured. However, since the conventional communication control device is intended to detect the abnormality of the receiving means itself by loopback, there is a problem that the abnormality of the minimum receiving level of the receiving means cannot be detected. there were.
Further, when detecting the above-mentioned abnormality, there is also a drawback that software for activating and controlling the loopback function of the communication control device must be built in the upper processing device.

[0003]

SUMMARY OF THE INVENTION In order to solve the above problems, an object of the present invention is to realize an apparatus capable of constantly performing abnormality detection of a minimum reception level by using a loopback function. It is in.

[0004]

In order to achieve this object, the present invention is a half-duplex communication system in which transmission and reception are performed on the same communication medium, by converting an internal transmission signal and transmitting on the communication medium. To the receiving means, which converts the signal on the communication medium to output as an internal received signal, and the signal on the communication medium to the minimum signal level that can be discriminated as a signal to the receiving means. Output signal attenuation means,

The presence / absence of the internal transmission signal is detected. When the internal transmission signal is not present, the signal on the communication medium is directly input to the receiving means. When the internal transmission signal is present, the signal on the communication medium is detected. A switching means for inputting a signal to the receiving means via the signal attenuating means, and one of the inputs being an internal transmission signal, the other input being an internal reception signal, and an internal transmission signal Of the internal transmission signal, and if the signals match, it is normal, and if the signals do not match, it is abnormal. And

[0006]

In the present invention, the internal transmission signal which is the output of the host processor is output onto the communication medium through the transmitting means.
The output signal is attenuated through the attenuating means to the minimum reception level that can be received by the receiving means and input to the receiving means. By using the switching means, the level difference between the internal received signal which is the output of the receiving means and the internal transmitted signal which is the output of the upper processing apparatus only while the internal transmitted signal which is the output of the upper processing apparatus is present. Is detected by the comparison means. When the level difference exceeds a predetermined value, an abnormal state notification signal is output. This check is repeated every transmission operation.

[0007]

The present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram showing an embodiment of the present invention. 1 is a medium used for communication, and usually a copper wire cable or an optical cable is used. Communication is performed by a half-duplex communication method using this medium. Reference numeral 2 is a transmission means for converting the internal transmission signal S ₁ to be transmitted into a predetermined communication frame and outputting it on the communication medium 1.

Reference numeral 3 is a receiving means which receives the signal on the communication medium 1 or its attenuated signal as an input and outputs it as an internal received signal S ₂ . Reference numeral 4 is a signal attenuating means for converting the signal on the communication medium 1 into a minimum signal level that the receiving means 3 can discriminate as a signal and outputting it to the receiving means 3. 5 detects the presence or absence of the transmission signals S ₁ of the inner, inside the transmission signals S ₁
If no inputs signals directly on the communication medium 1 to the receiving unit 3, when the transmission signals S ₁ inside there, the signals on the communication medium 1 signal attenuation means 4 the reception means 3 via It is a switching means for inputting to.

One of the inputs 6 is an internal transmission signal S ₁ , the other input is an internal reception signal S ₂ , and when the internal transmission signal S ₁ is present, the internal transmission signal S ₁ The comparison means compares the internal reception signals S ₂ and determines that the signals are normal if they match, and abnormal if they do not match, and outputs the status notification signal S _3. is there. Reference numeral 7 is a host processor which outputs an internal transmission signal S ₁ , reads an internal reception signal S _2, and processes an abnormal state of transmission / reception when receiving an abnormal state notification signal S ₃ from the comparison means 6. is there.

FIG. 2 is a diagram for explaining a signal transition operation between the device and each means. The operation of each unit will be described with reference to this drawing. The vertical axis represents the state transition of signals of the host processor and main means. The horizontal axis represents the time indicates the time intervals corresponding to the main state transition T ₁ through T _9. This time interval varies depending on the contents of communication.

There is no communication during the time T ₁ . The upper processing device 7 stops transmission / reception, there is no signal on the communication medium 1, the switching means 5 is in a state where the communication medium 1 is connected to the receiving means 3, the comparing means 6 is stopped, and the status notification signal is Indicates a normal condition. During the time T ₂ , the local station is transmitting. The host processor 7 enters the transmission state and outputs the internal transmission signal S ₁ . Switching means 5
Detects this internal transmission signal S ₁ and connects the communication medium 1 to the attenuation means 4. At the same time, the comparison means 6 also sends the internal transmission signal S ₁
Is detected and activated, the internal transmission signal S ₁ and the internal reception signal S ₂ are compared, and if there is no difference, the status notification signal S ₃ is output as normal. A transmission signal is output from the transmission means 2 onto the communication medium 1 and the signal state is established.

The time T ₃ is similar to the time T ₁ . Time T ₄
Is a state in which another station is transmitting and the communication medium 1 is in a signal state, but since there is no internal transmission signal S ₁ , the switching means 5 directly sends the signal on the communication medium 1 to the receiving means 3. It has been switched to input. It should be noted that the comparison means 6 does not start up and maintains the state of T ₃ , and the high-order processing device 7 enters the receiving state. At time T ₅ , there is no communication as at time T ₁ . Time T ₆ is a state in which the local station is transmitting, as at time T ₂ . As long as there is no abnormality in the reception level, the above-mentioned states of T _{1 to} T ₆ are repeated.

When the minimum reception level of the receiving means 3 is out of the specified range at the time a at time T ₇ , that is, when the reception sensitivity is lowered or increased, the time T _{8 at which the} local station transmits next time At, the host processor 7 enters the transmission state, and upon detecting this, the switching means 5 connects the communication medium 1 to the attenuating means 4 and activates the comparing means 6. Here, since the reception level of the reception means 3 has changed, the reception means 3 cannot output the correct internal reception signal S ₂ with respect to the signal level output from the attenuation means 4. Therefore, the comparison means 6
Compares the internal transmission signal S ₁ and the internal reception signal S ₂ and detects if there is a certain difference, and outputs the status notification signal S _{3 as} an abnormal signal to notify the upper processing unit 7. In this way
It is possible to realize a communication control device that can always detect an abnormality of the minimum reception level of a reception function.

[0014]

According to the present invention, while the local station is transmitting, the transmission signal on the communication medium is attenuated to obtain the signal of the minimum reception level, and the signal is input to the receiving means. By only adding the attenuating means, the switching means, and the comparing means, it is possible to carry out the abnormality detection of the receiving means including the host processing device and the transmitting means each time the own station transmits. It also overcomes the drawback of having to build software in the host processor.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining a signal transition operation between a higher-level processing device and each means.

[Explanation of symbols]

1 communication medium 2 transmission unit 3 receiving means 4 attenuating means 5 switching means 6 comparing means 7 host processing apparatus S ₁ inside the transmission signal S ₂ inside the received signal S ₃ state signal

Claims (1)

[Claims] 1. In a half-duplex communication system in which transmission and reception are performed in the same communication medium, transmitting means for converting an internal transmission signal and outputting it on the communication medium, and converting the signal on the communication medium , A receiving means for outputting as an internal received signal, a signal attenuating means for converting a signal on a communication medium into a minimum signal level that can be discriminated as a signal and outputting the signal to the receiving means, and the presence or absence of the internal transmitted signal. If there is no internal transmission signal, the signal on the communication medium is directly input to the receiving means. If there is an internal transmission signal, the signal on the communication medium is passed through the signal attenuating means to the receiving means. When there is an internal transmission signal, and one of the inputs is the internal transmission signal, and the other is the internal transmission signal, the internal transmission signal and the internal reception signal are compared. And those signals Matching is normal if, communication control unit consists of a comparison means for determining that the signals are abnormal must match.