JPH01209812A - Isolation type input/output circuit - Google Patents

Abstract

PURPOSE:To simplify the connection with an external device by using an external connector for an input photocoupler and an output photocoupler in common and connecting an external device by two connector pins and a signal wire. CONSTITUTION:The isolated input/output circuit has an output photocoupler 16 provided with a light emitting element 12 driven by an output driver circuit 10 and with a photodetector 14 receiving the light of the light emitting element 12 and outputting externally and has an input photocoupler 24 provided with a light emitting element 18 driven by an external input signal and with a photodetector 22 receiving the light of the light emitting element 18 and outputting it to an input receiver circuit 20. Then the photodetector 14 of the output photocoupler 16 and the light emitting element 18 of the input photocoupler 24 are connected in series between terminals of an external connector 26. In the reception of an external signal by the input photocoupler 24, the output driver circuit 10 always stimulates and drives the light emitting element 12 of the output photocoupler 16.

Description

[Detailed Description of the Invention] [Summary] With regard to isolated input/output circuits using photocouplers, the purpose of this invention is to provide high flexibility with simple external connection configuration and software control. It has an output photocoupler that is driven and outputs a received light signal to the outside, and an input photocoupler that is driven by an external signal and outputs a received light signal to the input receiver circuit, and includes a light receiving element of the output photocoupler and a light emitting element of the input photocoupler. Connect in series between the terminals of the external connector.

[Industrial Field of Application] The present invention relates to an isolated input/output circuit using a photocoupler.

For example, in F and A computer systems that are interconnected via a network, the external interface of the FA computer is equipped with an isolated input/output circuit using a photocoupler. By providing isolation between the two units, it is possible to easily interconnect them even if the signal formats are different.

[Prior Art] As an insulated input/output circuit using such a photocoupler, the one shown in FIG. 5, for example, is known.

In FIG. 5, 10 is an output driver circuit, and 20 is an input receiver circuit.

The output of the output driver circuit 10 is given to the output coupler 16, which drives the light emitting diode 12a to emit light and outputs the light reception signal from the phototransistor 14a to the external connector 26.

Further, an external signal inputted from the external connector 26 drives the light emitting diode 18a of the input photocoupler 24 to emit light, and outputs the light reception signal of the phototransistor 22a to the input receiver circuit 20.

This output photocoupler 16 and input photocoupler 24 can provide isolation (insulation @) from external devices, and even if there are differences in signal format, signals can be exchanged with external devices without affecting each other. Can send and receive.

[Means for solving the problem] However, in such conventional isolated input/output circuits, the output driver system equipped with an output photocoupler and the input receiver system equipped with an input photocoupler are independent of each other. Because the circuit was fixed, the number of external connector pins increased and a dedicated input/output signal line was required between the unit and the circuit, and since the circuit function was fixed, software There was a problem that there was no room for control intervention, and that flexibility was lacking.

The present invention has been made in view of these conventional problems, and an object of the present invention is to provide a highly flexible isolated input/output circuit that has a simple external connection configuration and can be controlled by software. .

[Means to solve the problem] FIG. 1 is a diagram explaining the principle of the present invention.

In FIG. 1, the isolated input/output circuit of the present invention is an output photocoupler that includes a light emitting element 12 driven by an output driver circuit 10 and a light receiving element 14 that receives light from the light emitting element 12 and outputs it to the outside. 16, an input photocoupler 24 equipped with a light emitting element 18 driven by an external input signal and a light receiving element 22 that receives light from the light emitting element 18 and outputs it to the input receiver circuit 20. coupler 1
6 light receiving element 14 and input photocoupler 24 light emitting element 1
8 are connected in series between the terminals of the external connector 26.

Here, when the input photocoupler 24 receives an external signal, the output driver circuit 10 constantly drives the light emitting element 12 of the output photocoupler 16 to emit light.

In addition, the output photocoupler 16 by the output driver circuit 10
When driving, the light receiving output is simultaneously obtained from the light receiving element 22 of the input photocoupler 24, so the light receiving output at this time can be monitored by the input receiver circuit 20.

[Function] According to such an isolated input/output circuit of the present invention, an output driver system equipped with a photocoupler and an input receiver system can be integrated so that they can be connected to the same connector pin of an external connector, and can be connected to an external device. The connection configuration can be simplified.

In addition, the circuit function as an output driver or input receiver is switched by software control, and especially when it is used as an output driver, software can check whether the signal output is being performed correctly by monitoring the light reception output from the input photocoupler. can be monitored and can effectively deal with the occurrence of output errors.

[Embodiment] FIG. 2 is a block diagram showing an embodiment of the present invention, taking an external interface of an FA personal computer or the like as an example.

In FIG. 2, 10a is a photodriver with a function as an output driver circuit;
An output photocoupler 16 is provided on the output side of a. That is, the output photocoupler 16 includes a light emitting diode 12a and a phototransistor 14a, and the light emitting diode 12a
The anode side of the light emitting diode 12a is connected to the power supply element VC via a resistor R1, and the cathode side thereof is connected to the photo driver 10a, and when the output of the photo driver 10a is rOJ, a current flows through the light emitting diode 12a and the light emitting diode 12a is driven to emit light.

On the other hand, 20a is a photoreceiver having a function as an input receiver circuit, and an input photocoupler 24 is provided on the input side of the photoreceiver 20a. The input photocoupler 24 has a light emitting diode 18a that is driven to emit light by an external signal, and a phototransistor 22a.
The collector is connected to ground.

Such an output photocoupler 16 and input photocoupler 2
4, a light emitting diode 18a provided in the input photocoupler 24 and a phototransistor 14a provided in the output coupler 16 are connected in series and connected between connector pins 26a and 26b of the external connector 26.

Such an output photocoupler 16 and input photocoupler 2
External connector 2 for isolated input/output circuit with 4
The control unit 2 includes an address decoder 28a and an R/W control section 28b that performs continuous write control in order to perform input/output control of signals with an external device connected via 6.
8, a bus adapter 30 and a write register 32 are provided.

Address and R/W control signals are given to the control unit 28 from a microprocessor or the like.

When the control unit 28 sends data to an external device continuously, the R/W control unit 28b decodes the read control signal to control the bus adapter 30 and the write register 32.
The data obtained via the bus adapter 30 and the address data obtained by decoding by the address decoder 28a of the control unit 28 are written into the write register 32, respectively, and the data stored in the write register 32 is synchronized with the clock pulse. is converted into serial data by sequentially outputting it bit by bit, and outputting it to the photo driver 10a.

On the other hand, when writing a signal from an external device to a microprocessor or the like, the R
The /W control unit 28b decodes the write control signal to put the photoreceiver 20a into an operating state, and the photoreceiver 20
The received data obtained through the input photocoupler 24 in the operating state a is taken in through the bus adapter 30.

Furthermore, when converting the successive data stored in the write register 32 into serial data and outputting it to the outside via the output photocoupler 16 by the photodriver 1Qa, the control unit 28 puts the photoreceiver 20a into an operating state and converts the output data into serial data. Based on the driving of the output coupler 16, the received light output obtained from the phototransistor 22a of the input photocoupler 24 is transferred from the photoreceiver 20a to the bus adapter 3.
0 to the processor side, output photocoupler 1
It is possible to monitor on the processor side whether correct output data is sent out by driving 6.

Furthermore, when inputting an external signal via the input photocoupler 24, the control unit 28 controls the write register 3.
The output of No. 2 is controlled by the photodriver 10a to an output state in which the light emitting diode 12a of the output photocoupler 16 is always turned on.

Next, the operation when functioning as an output driver and the operation when functioning as an input receiver in the embodiment of FIG. 2 will be explained with reference to FIGS. 3 and 4.

FIG. 3 is an explanatory diagram of the operation when the first embodiment of FIG. 2 functions as an output driver, and shows the output photocoupler 16 and input photocoupler 24 provided in the embodiment of FIG.
The connection state of the input circuit section of the external device is extracted and shown.

In FIG. 3, 100 is a unit with a small number of isolated input/output circuits of the present invention shown in FIG.
00 is connected to another unit 200 as an external device through signal lines 50a and 50b. At this time, the unit 100 operates as an output driver and outputs a signal to the unit 200 as an external device, so the unit 200 includes a light emitting diode 36 and a phototransistor 3.
An input optocoupler 34 with 8 is provided.

When the units 100 and 200 are connected like this, the light emitting diode 12 of the output photocoupler 16 of the unit 100
For a, write register 32 as shown in FIG.
The output data stored in is serially converted and supplied to the photodriver 10a, and when the output of the photodriver 10a is "0", the light emitting diode 12a of the output photocoupler 16 is
is driven to emit light, the phototransistor 14a is turned on in response to the light generated by the light emitting drive of the light emitting diode 12a, and when the phototransistor 14a is turned on, the power supply +VC of the unit 200 connects the light emitting diode 36, the signal line 50a, and the light emitting diode 18a of the unit 100. , the phototransistor 14a, and a current flows through the path that becomes the signal line 5Qb.
The light emitting diode 36 of the unit 200 is driven to emit light, and the light reception output of the phototransistor 38 is output to the unit 100.
It is possible to receive data output from

At this time, the light emitting diode 18a of the input cuff coupler 24 of the unit 100 is simultaneously driven to emit light by the output photocoupler 16, and a light reception output matching the output data is obtained from the phototransistor 22a of the input cuff coupler 24. That is, by taking in the output signal of the photoreceiver 20a shown in FIG. 2 to the processor side via the bus adapter 30, it is possible to monitor (error check) whether or not data has been correctly output to the unit 200.

FIG. 4 is an operational explanatory diagram showing the state of connection with the unit 200 as an external device when the unit 100 side equipped with the isolated input/output circuit shown in the embodiment of FIG. 21 functions as an input receiver. be.

In this case, since data is output from the unit 200 as an external device to the unit 100, the signal line 50a side is connected to the power supply voltage +Vc via a resistor, and the light emitting diode 42 and phototransistor 44 are connected to the signal line 50b side. An output photocoupler 40 equipped with the above is connected.

In this way, in the operating state as an input receiver in which the unit 100 receives data output from the unit 200 as an external device, the light emitting diode 12a of the output photocoupler 16 is connected to the light register 3 shown in FIG.
The photodriver 10a for the output photocoupler 16 is kept in a continuous light emitting drive state by storing data that keeps it in an active state, and therefore the phototransistor 14a of the output photocoupler 16 is always turned on, and the units connected via the signal lines 50a and 50b A line loop is formed between 100 and 200.

When the phototransistor 14a of the output photocoupler 16 is turned on and the phototransistor 42 is turned on by driving the output photocoupler of the unit 200 as an external device, that is, by driving the light emitting diode 40 to emit light, the power supply voltage of the unit 200 + VC1 signal is turned on. line 50a1 unit 1
00 light emitting diode 18a, phototransistor 14
A, a current flows through the signal line 50b and further through the path that becomes the phototransistor 42 of the unit 200, and by driving the light emitting diode 18a of the unit 100 to emit light, a light reception signal corresponding to the data sent from the unit 200 is obtained from the phototransistor 22a. .

In addition, in the explanation of the operation in FIGS. 3 and 4, the unit 100
The case where the isolated input/output circuit of the present invention shown in FIG. 2 is provided on the side of the unit 200 is taken as an example; Often, when the isolated input/output circuit of the present invention is provided in each of the units 100 and 200, the input/output circuit of the transmitting unit is shown in FIG. 3, as is clear from the above operation description. It is sufficient to make it function as an output driver as shown, and at the same time make the input/output circuit of the receiving side unit function as an input receiver as shown in FIG.

In addition, in the above embodiment, the input/output photocoupler 1
Although a phototransistor has been taken as an example of the light receiving element in 6.24, it goes without saying that a photodiode may also be used.

[Effects of the Invention] As explained above, according to the present invention, by sharing the external connector sides of the input photocoupler and the output photocoupler, it is possible to connect to an external device with two connector pins and a signal line. The connection configuration with external devices is simplified, and the circuit function as an output driver and input receiver can be selectively controlled by software, which simplifies the circuit configuration. Furthermore, when the function as an output driver is disabled, an input photocoupler can be used. TeF! ! ! It is possible to monitor the data, and to deal with errors effectively through software processing.

[Brief explanation of the drawing]

Figure 1 is a diagram explaining the principle of the present invention. Figure 2 is a diagram showing the configuration of an embodiment of the present invention. Figure 3 is a diagram explaining the operation when functioning as an output driver. Figure 4 is a diagram explaining the operation when functioning as an input receiver. An explanatory diagram of the operation: FIG. 5 is an explanatory diagram of the prior art. In the figure, 10: Output driver circuit 10a: Photo driver 12.18: Light emitting elements 12a, 18a, 36.42: Light emitting diode 14.
22: Photodetector 14a, 22a, 38.44: Phototransistor 1
6.40: Output photocoupler 20: Input receiver circuit 20a: Photoreceiver 24.34: Input photocoupler 26: External connectors 26a, 26b:: I connector pin 28 Two control units 28a Near address decoder 28b: R/W control section 30 :Bus adapter 32Nilight register 5Qa, 5Qb:Signal line 100.200:Unit o (4 Otsu e month small force 艮 Tamari 4jishi mouth moon figure 1 *n)'Lihigh U to change 4 moves jjL Figure 3 of the Moon Map Input Receipt E in the 4th chart of Riverside L=Ji, Figure 5 of the Moon Map

Claims (1)

[Claims] (1) An output photocoupler (16) that includes a light emitting element (12) driven by an output driver circuit (10) and a light receiving element (14) that receives light from the light emitting element (12) and outputs it to the outside. and an input photocoupler (22) that includes a light emitting element (18) driven by an external input signal and a light receiving element (22) that receives the light from the light emitting element (18) and outputs it to the input receiver circuit (20). 24), the light receiving element (14) of the output photocoupler (16) and the light emitting element (18) of the input photocoupler (24) are connected in series between terminals of the external connector (26), and the input When the photocoupler (24) receives an external signal, the output driver circuit (10) outputs the photocoupler (16).
The light-emitting element (12) is always driven to emit light, and when the output photocoupler (16) is driven by the output driver circuit (10), the input receiver circuit (20) receives a light reception signal obtained from the input photocoupler (24). An isolated input/output circuit characterized by monitoring.