JP2572425Y2 - Data transmission circuit with abnormality judgment function - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an abnormality judging technique for detecting an abnormality in a data transmission circuit between two devices used for various remote controllers and the like in a hardware manner.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional data transmission circuit. In FIG. 2, reference numeral 1 denotes an operational amplifier on the transmission side, and reference numeral 2 denotes a photocoupler on the reception side. Transmission data is input to a non-inverting input terminal of the operational amplifier 1, and an output side of the operational amplifier 1 is connected to a light emitting diode 4 constituting a photocoupler 2 via a transfer line 3.
The cathode side of the light emitting diode 4 is connected via a feedback line 5 to the inverting input terminal of the operational amplifier 1 and a resistor 6 whose other side is grounded.
Is connected to the connection part A. In the figure, reference numeral 7 denotes a phototransistor constituting the photocoupler 2, which is disposed to face the light emitting diode 4 and receives and amplifies a light emitting signal from the light emitting diode 4 to obtain received data.
However, when transmitting control data or the like between the two devices, the transmission data is input to the non-inverting input terminal of the operational amplifier 1 and output from the phototransistor 7 as reception data. In this case, the cathode side of the light emitting diode 4 is negatively connected to the connection A between the inverting input terminal of the operational amplifier 1 and the resistor 6 whose other side is grounded via the feedback line 5 as described above. Therefore, a constant current circuit in which the connection section A is controlled to the same voltage as the input voltage of the transmission data by the function of the operational amplifier 1 is formed. Therefore, as a feature of this data transmission circuit, the photocoupler 2
As a result, the transmission side and the reception side are insulated from each other, and the constant current circuit compensates for a constant current even if the resistance component of the transfer line 3 or the like slightly fluctuates, thereby improving the reliability of data transmission. . In general, further improvement in reliability is achieved by adding software abnormality determination means such as parity check and sum check for each block.

[0003]

As described above, the conventional data transmission circuit has a function of compensating for a slight change in the resistance component generated in the transfer line 3 and the like by the constant current circuit. When the resistance component of the transfer line 3 or the like increases remarkably, the constant current circuit cannot compensate, and has a disadvantage that the reliability of data transmission is greatly reduced. The present invention has been made to solve such disadvantages of the prior art.
By adding a simple configuration, it is possible to provide a data transmission circuit with an abnormality determination function that outputs an abnormality signal when a remarkable increase in a resistance component occurs in a transfer line or the like, and further improve its reliability. It is the purpose.

[0004]

According to the present invention, in order to solve the above-mentioned problems, transmission data input to a non-inverting input terminal of an operational amplifier is transmitted to a receiving unit including a photocoupler or the like via a transfer line. A constant current circuit is configured by connecting the other terminal of the receiving unit corresponding to the transfer line to a connection between the inverting input terminal of the operational amplifier and a resistor whose other side is grounded via a feedback line. A data comparison circuit for detecting a differential input voltage between a non-inverting input terminal and an inverting input terminal of the operational amplifier, and an abnormal signal when an output voltage from the voltage comparing circuit exceeds a set value. It is characterized by adding an abnormality judgment circuit for outputting.

[0005]

By employing the above technical means, an abnormal signal is output if the current drops below a set value due to a remarkable increase in the resistance component of the transfer line or the like. The state can be monitored, and an abnormal state relating to the contact resistance and the like in the transfer line can be determined by hardware.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram showing a main part of an embodiment of the present invention. In the figure, 1 is an operational amplifier on the transmitting side, 2 is a photocoupler which is a specific example of a receiving unit, and the transmission data is input to a non-inverting input terminal of the operational amplifier 1, and the output side is via a transfer line 3. The light emitting diode 4 constituting the photocoupler 2 is connected to the anode side of the light emitting diode 4, and the cathode side of the light emitting diode 4 is connected via a feedback line 5 to the inverting input terminal of the operational amplifier 1 and a resistor 6 whose other side is grounded. The conventional data is obtained by receiving and amplifying a light-emitting signal from the light-emitting diode 4 by a phototransistor 7 connected to the connection portion A and disposed opposite to the light-emitting diode 4 to obtain received data. There is no difference from the transmission circuit. However, when transmitting control data and the like between the two devices, the transmission data is input to the non-inverting input terminal of the operational amplifier 1 and output from the phototransistor 7. In this case, the light emitting diode 4
Is negatively connected to the connection A between the inverting input terminal of the operational amplifier 1 and the resistor 6 whose other side is grounded through the feedback line 5 as described above. The function forms a constant current circuit in which the connection portion A is controlled to the same voltage as the input voltage of the transmission data, and the constant current is compensated even if a slight variation occurs in the resistance component of the transfer line 3 or the like. It is.

Next, the abnormality determining means which is a feature of the present invention will be described. In FIG. 1, reference numeral 8 denotes a voltage comparison circuit for detecting a differential input voltage between the non-inverting input terminal and the inverting input terminal of the operational amplifier 1, and 9 denotes a case where the output voltage from the voltage comparing circuit 8 exceeds a set value. An abnormality determination circuit that outputs an abnormality signal, and these constitute an abnormality determination unit. As a result, abnormal conditions such as a remarkable increase in contact resistance or disconnection occur in the transfer line relationship, that is, in the transfer line 3 itself, the light emitting diode 4 and the feedback line 5 forming the constant current circuit, and the constant current circuit compensates. When the voltage cannot be completely increased, the potential of the connection A decreases due to the decrease in the current, and the differential input voltage between the non-inverting input terminal and the inverting input terminal of the operational amplifier 1 increases.
This is detected by the voltage comparison circuit 8, and the result is input to the abnormality determination circuit 9. The abnormality determination circuit 9 compares the differential input voltage detected by the voltage comparison circuit 8 with a preset set value, and outputs an abnormal signal when the differential input voltage exceeds the set value. I do. Therefore, since the occurrence of an abnormality in the transfer line can be recognized by the output of the abnormality signal, various appropriate measures can be taken. In the above description, the case where the photocoupler is used as the receiving mechanism has been described.
It goes without saying that other types can be used as long as the constant current circuit can be formed.

[0008]

According to the present invention, the following effects can be obtained based on the above configuration. (1) Since an abnormality occurring in the transfer line relationship in the data transmission circuit is determined in a hardware manner, the reliability of the transmission state is further improved in addition to the conventional software abnormality determination and the compensation function by the constant current circuit. The reliability and security of the entire system using this data transmission / reception can be further improved. (2) In addition, since it is specified that the detected abnormal part is related to the transfer line, it is easy to respond thereafter. (3) The configuration to be added is simple, and there are few troubles.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing a main part of an embodiment of the present invention.

FIG. 2 is a conceptual diagram showing a main part of a conventional data transmission circuit.

[Explanation of symbols]

 1 operational amplifier 2 photocoupler 3 transfer line 4 light emitting diode 5 feedback line 6 resistor 7 phototransistor 8 voltage comparison circuit 9 abnormality determination circuit

Claims (1)

(57) [Scope of request for utility model registration] 1. A transmission data input to a non-inverting input terminal of an operational amplifier is transmitted to a receiving unit such as a photocoupler via a transfer line, and a terminal on the other side of the receiving unit corresponding to the transfer line. Is connected to a connection between an inverting input terminal of the operational amplifier and a resistor whose other side is grounded through a feedback line, thereby forming a constant current circuit, wherein the non-inverting input terminal of the operational amplifier and Abnormality judgment characterized by adding a voltage comparison circuit for detecting a differential input voltage between inverting input terminals and an abnormality judgment circuit for outputting an abnormality signal when an output voltage from the voltage comparison circuit exceeds a set value; Data transmission circuit with function.