JP2572427Y2 - Data receiving 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 the present data transmitting / receiving circuit, the transmitting side and the receiving side are insulated by the photocoupler 2 and the constant current is compensated by the constant current circuit even if the resistance component of the transfer line 3 and the like slightly changes. Therefore, the reliability of data transmission is improved. 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 / reception circuit has a function of compensating for some variation 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 in order to solve such disadvantages of the prior art, and by adding a simple configuration, outputs an abnormal signal when a remarkable increase in a resistance component occurs in a transfer line or the like. It is an object of the present invention to provide a data receiving circuit having an abnormality determination function and further improve its reliability.

[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 an input side of a receiving unit such as a photocoupler via a transfer line. A constant current circuit is formed by transmitting and connecting an output side corresponding to an input side of the receiving section to a connection section between an inverting input terminal of the operational amplifier and a resistor whose other side is grounded via a feedback line. A data comparing circuit for detecting a voltage between an input side and an output side of the receiving unit, and an abnormality determining unit for outputting an abnormal signal when an output voltage from the voltage comparing circuit falls below a set value. A circuit is added.

[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 output side C of the light emitting diode 4 is connected to the inverting input terminal of the operational amplifier 1 via a feedback line 5 and the other end of the resistor 6 is connected to the ground. And a reception transistor that receives and amplifies a light emission signal from the light emitting diode 4 by a phototransistor 7 disposed opposite to the light emitting diode 4 to obtain received data. There is no difference from the data transmission / reception 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 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 of (1) forms a constant current circuit in which the connection section A is controlled to the same voltage as the input voltage of the transmission data, and the constant current is compensated even if the resistance component of the transfer line 3 and the like slightly fluctuates. But the same is true.

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 voltage between the input side B and the output side C of the receiving unit, and 9 denotes an abnormal signal when the output voltage from the voltage comparison circuit 8 exceeds a set value. Is output, and these constitute the abnormality determination means. Thus, 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, an abnormal state such as a remarkable increase in contact resistance or disconnection occurs, and the constant current circuit compensates. If the current becomes lower and the current drops, it is detected as a voltage fluctuation by the voltage comparator circuit 8, and the result is input to the abnormality determination circuit 9. The abnormality determination circuit 9 compares the detection voltage when the transmission data is in the H level state with a preset set value, and outputs an abnormal signal when the detected value falls below the set value. Incidentally, if the set value is set to a value obtained by multiplying the lower limit current value of the photocoupler 2 constituting the receiving section by its input impedance, the value becomes abnormal when the photocoupler enters a danger area where malfunction occurs. Since the relation for outputting the signal is established, the condition is good. As described above, in the data transmission / reception circuit, the occurrence of an abnormality in the transfer line relationship can be recognized by the output of the abnormal signal, so that various appropriate measures can be taken. In addition,
In the above description, the case where a photocoupler is used as the receiving mechanism has been described, but 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 the abnormality occurring in the transfer line relation in the data transmission / reception circuit is determined by hardware, the reliability of the transmission / reception state is further improved in addition to the conventional software abnormality determination and the compensation function by the constant current circuit. Thus, the reliability and safety of the whole system using the data transmitting / receiving circuit 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 / reception 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

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 3/46 H04Q 9/00 311

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 an input side of a receiving unit including a photocoupler via a transfer line, and an output side corresponding to the input side of the receiving unit is transmitted. Is connected to a connection between an inverting input terminal of the operational amplifier and a resistor whose other side is grounded via a feedback line, thereby forming a constant current circuit. A voltage comparison circuit for detecting a voltage between the voltage comparison circuit and an abnormality determination circuit for outputting an abnormality signal when an output voltage from the voltage comparison circuit falls below a set value. circuit.