JPH07182080A - Interface device - Google Patents

Abstract

PURPOSE:To use a device as any interface of a data terminal equipment and a data channel terminating device and to perform various connection by one cable with a simple operation. CONSTITUTION:In this interface device provided with an RS232C connector used for connection between the data channel terminating device and the data terminal equipment and the connection between the data terminal equipments, etc., for transmitting and receiving signals through the RS232C connector, a terminal switching circuit 11 for mutually switching the input/output of SD (transmission data) and RD(reception data,) RS (transmission request) and CS (transmission permission) and DR (data set ready) and ER (data terminal ready) by one changeover switch 16 is connected between the RS232C connector and a signal processing circuit for processing the transmitted and received signals and the input/output of the terminals of the RS232C connector are reversed at the time of the connection between the same kind of the devices which is the connection between the data terminal equipments.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is a 25-pin RS232.
The present invention relates to an interface device having a C connector and transmitting / receiving a signal via the RS232C connector.

[0002]

2. Description of the Related Art An interface device of this type is, for example, a data terminal device (DTE [Data Termi
nal Equipment]), a data line terminating device (DCE [Data Communication Equipment]) such as a modem.

For example, when data communication is performed between the computer 1 and another computer (terminal) 2 through the modems 3 and 4, the computer 1 and the modem 3 are connected as shown in FIG.
Connect with other computer (terminal)
Connect the modem 4 to 2. Then, the modems 3 and 4 are connected to each other via a data line such as a telephone line.

Specifically, the computer 1 and the modem 3
Each has a 25-pin RS232C connector 1a,
3a, a signal processing circuit including an RS232C driver IC for transmitting and receiving signals via these RS232C connectors 1a, 3a is provided, and as shown in FIG. 4, each terminal of these RS232C connectors 1a, 3a is provided. The computer 1 and the modem 3 are electrically connected via the.

The shape and terminal arrangement of these RS232C connectors 1a and 3a are defined by JIS (Japanese Industrial Stan).
dard: Japanese Industrial Standard) is standardized in general. For example, as another standard, EIA (Electronic I
ndustries Association: Electronics Industry Association, CCITT
(The International Telegraph and Telephone Consul
tative Committe: International Telegraph and Telephone Advisory Committee).

According to this JIS standard, the RS232C connectors 1a and 3a have a terminal arrangement as shown in FIG.

For example, the second pin (S
(D: transmission data) is an output terminal of the transmission data to the outside, so the second pin of the modem 3 side (SD: transmission data)
Connect to. This is because the second pin (SD: transmission data) on the modem 3 side is an input terminal for a signal to be output to the data line.

Further, the third pin (R
Since D: received data) is an input terminal for externally received data, it is connected to the third pin (RD: received data) on the modem 3 side. This is because the third pin (RD: received data) on the modem 3 side is an output terminal for a signal input from the data line.

As described above, since the terminals are connected in a straight line between the computer (data terminal device) 1 and the modem (data circuit terminating device) 3, the cable 5 commonly called "straight cable" is used. It was supposed to connect. The connection between the terminal (data terminal device) 2 and the modem (data circuit terminating device) 4 is the same as the connection of the computer 1 and the modem 3
The 232C connectors 2a and 4a are connected by the straight cable 6.

When the computer 1 and another computer (terminal) 2 are connected, each computer (data terminal device) is used in addition to the case where the modems 3 and 4 are used.
It is also conceivable to directly connect 1 and 2 to each other. In such a case, the terminals of the RS232C connectors 1a and 2a of the computers 1 and 2 must be connected by crossing predetermined terminals as shown in FIG.

That is, for example, the second pin (SD: transmission data), which is the output terminal of one computer 1, is connected to the third pin (RD: reception data), which is the input terminal of the other computer (terminal) 2. While connecting, pin 3 (R
D: received data) is connected to pin 2 (SD: transmitted data) which is an output terminal on the other computer (terminal) 2 side.

Further, the fourth pin (RS: transmission request) on one computer 1 side is connected to the fifth pin (CS: transmission possible) on the other computer 2 side, and the fifth pin on one computer 1 side is connected. The pin (CS: transmission possible) is connected to pin 4 (RS: transmission request) on the other computer 2 side.

Further, pin 6 (DR: Data Set Ready) on one computer 1 side is connected to pin 20 (ER: Data Terminal) on the other computer 2 side.
Ready) and pin 20 on one computer 1 side (ER: Data Terminal Ready)
Is connected to pin 6 (DR: Data Set Ready) on the other computer 2 side. The other terminals are connected straight.

As described above, since the data terminal devices are connected to each other through the terminals, the straight cables cannot be used. For this reason, the cables commonly known as "cross cables" have been used for connection.

[0015]

However, in such a conventional device, for example, once a product is completed as an interface device of a data terminal device,
When connecting another data terminal device or a data line terminating device to this, there is a problem that it cannot be used as an interface device of the data line terminating device unless they are connected by a cross cable and a straight cable, respectively.

Therefore, the present invention is intended to provide an interface device which can be used as any interface device of a data terminal device and a data line terminating device and which can be connected in various ways with a single cable by a simple operation. It is a thing.

[0017]

The present invention is provided with an RS232C connector used for connection between data line terminal devices and data terminal devices, connection between data terminal devices, and the like.
In an interface device for transmitting and receiving a signal via an S232C connector, a heterogeneous device connection between a data line terminating device and a data terminal device in which a terminal array based on the RS232C standard is directly used as a terminal array of the RS232C connector, and an RS232C connector A single switching signal output means for outputting a switching signal for connecting the same type of devices between data terminal devices in which input / output of a predetermined input / output terminal is reversed, and a switching signal from this switching signal output means Terminal switching means for switching the input / output of a predetermined input / output terminal of the RS232C connector.

[0018]

In the present invention having such a structure, when the switching signal is output from the switching signal output means, the input / output of the predetermined input / output terminal of the RS232C connector is switched by the terminal switching means based on the switching signal. RS232C
The terminal arrangement of the connector is a terminal arrangement for connection between different kinds of devices or connection between same kinds of devices.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment in which the present invention is applied to a connecting portion of a terminal device for performing data communication will be described below with reference to the drawings.

FIG. 1 is a diagram showing the configuration of a terminal switching circuit 11 as terminal switching means provided in the connection portion of this embodiment. This terminal switching circuit 11 is, for example, a signal processing circuit provided in a terminal device. (Not shown) and the RS232C connector 12 are connected.

This signal processing circuit processes a signal transmitted and received via the RS232C connector 12, and for example, a CPU (central processing unit) which constitutes the main body of the control unit of the terminal device, a RS232C driver IC, that is, It is composed of a serial communication LSI or the like for transmitting and receiving a signal via the RS232C connector 12.

Specifically, each terminal on one side of the terminal switching circuit 11 is connected to the corresponding terminal of the signal processing circuit, and each terminal on the other side is, as shown in FIG. Each is connected to a predetermined terminal of the RS232C connector 12.

For example, the a terminal is the RS232C connector 1
It is connected to the 2nd pin 2 (SD: transmission data),
The b terminal is the third pin (RD: of the RS232C connector 12).
(Received data).

The c terminal is the RS232C connector 12
No. 4 pin (RS: request to send) and the d terminal is connected to No. 5 pin (CS: possible to send) of the RS232C connector 12.

Further, the e terminal is the RS232C connector 1
Pin 2 of 20 (ER: Data Terminal Ready)
, And the f terminal is RS232C connector 12
It is connected to the 6th pin (DR: Data set ready).

The terminal switching circuit 11 is specifically, as shown in FIG. 1, SD-RD terminal switching circuit 13, RS-.
CS terminal switching circuit 14, DR-ER terminal switching circuit 15,
And a changeover switch 16 as a changeover signal output means for changing over the terminals of these changeover circuits 13, 14, 15.

These SD-RD terminal switching circuit 13, RS
The -CS terminal switching circuit 14 and the DR-ER terminal switching circuit 15 have the same configuration. That is, the switching circuits 13, 14 and 15 include a pair of line driver / receiver circuits 21 and 22, 24 and 25, 27 and 28.

The line driver / receiver circuits 21 and 22, 24 and 25, 27 and 28 are connected to the terminals on the signal processing circuit side, ie, DI terminal and RO terminal, and RS232.
It is provided with a DO terminal and an RI terminal connected to terminals on the C connector 12 side, and an STBY terminal for switching these terminals.

One line driver / receiver circuit 2
The STBY terminals of 1, 24, 27 are connected to the inverting output terminals of the inverters 23, 26, 29, respectively, and the input terminals of these inverters 23, 26, 29 are respectively the other line driver / receiver circuits 22, 25, 28
And is connected to one terminal of the changeover switch 16.

One terminal of the changeover switch 16 is connected to the power supply terminal Vc via the resistor 17, and the other terminal is grounded.

The line driver / receiver circuit 21,
The signals from the DI terminal and the RO terminal of 22 are input to the signal processing circuit at the logic level SD (transmission data) and RD, respectively.
It is designed to be input / output as (received data).

Further, the line driver / receiver circuit 21
Of the line driver / receiver circuit 22 is connected to the terminals a and b, respectively.
The terminal and the RI terminal are connected to the b terminal and the a terminal, respectively.

The line driver / receiver circuit 24,
The signals from the 25 DI terminal and the RO terminal are sent to the signal processing circuit at the logic level by RS (transmission request) and CS, respectively.
It is designed to be input / output as (sendable).

Further, the line driver / receiver circuit 24
The DO and RI terminals of the line driver / receiver circuit 25 are connected to the c and d terminals, respectively.
The terminal and the RI terminal are connected to the d terminal and the c terminal, respectively.

The line driver / receiver circuit 27,
Signals from the DI terminal and the RO terminal of 28 are input / output as DR (data set ready) and ER (data terminal ready) to the signal processing circuit at a logic level.

Further, the line driver / receiver circuit 27
Of the line driver / receiver circuit 28 are connected to the f terminal and the e terminal, respectively.
The terminal and the RI terminal are connected to the e terminal and the f terminal, respectively.

When one of the line driver / receiver circuits 21 and 22, 24 and 25, 27 and 28 is supplied with an H level signal from the STBY terminal, the Do terminal and the Ro terminal are in a high impedance state. .

For example, when the Do terminal and Ro terminal of one of the line driver / receiver circuits 21, 24, 27 are in a high impedance state, as shown in FIG.
The terminals, c terminals, and e terminals serve as input terminals, and the b terminals, d terminals, and f terminals serve as output terminals. The RS232C connector 12 in this state is in the same terminal connection state as when connected by a cross cable.

That is, 2 of RS232C connector 12
The pin No. 4, the pin No. 4, and the pin No. 20 serve as input terminals of RD (received data), CS (transmittable), and DR (data set ready), respectively.

Pins 3, 5, and 6 of the RS232C connector 12 serve as SD (transmission data), RS (transmission request), and ER (data terminal ready) output terminals, respectively.

On the other hand, when the Do terminal and the Ro terminal of the other line driver / receiver circuits 22, 25, 28 are in a high impedance state, as shown in FIG. 2B, the a terminal, the c terminal, and the e terminal. The terminals serve as output terminals, and the b terminal, d terminal, and f terminal serve as input terminals. The RS232C connector in this state is in the same terminal connection state as when it is connected with a straight cable.

That is, 2 of RS232C connector 12
The pin No. 4, the pin No. 4, and the pin No. 20 serve as output terminals for SD (transmission data), RS (transmission request), and ER (data terminal ready), respectively.

Pins 3, 5 and 6 of the RS232C connector 12 serve as input terminals for RD (received data), CS (transmittable) and DR (data set ready), respectively.

In this embodiment having such a structure, when the change-over switch 16 is turned on, an H level signal is supplied to the STBY terminals of the one line driver / receiver circuits 21, 24 and 27. Together with the STBY of the other line driver / receiver circuit 22, 25, 28
An L level signal is supplied to the terminal.

As a result, the Do terminal and Ro terminal of one of the line driver / receiver circuits 21, 24, 27 are in a high impedance state, and as shown in FIG.
RS232C connector 12 2nd pin, 4th pin, 20
The No. pin becomes an input terminal of RD (reception data), CS (transmission possible) and DR (data set ready) respectively, and the third pin, the fifth pin and the sixth pin are SD (transmission data) respectively. ), RS (request to send), and ER
(Data terminal ready) output terminal.

In this way, the RS232C connector 12 is
The terminal connection state is the same as when connecting with a cross cable.

Therefore, in this case, if the transmitting / receiving software is used for the data terminal device, this device can transmit and receive signals as the data terminal device.

On the other hand, when the changeover switch 16 is turned off, one of the line driver / receiver circuits 21, 2
The STBY terminals 4 and 27 are supplied with an L level signal and the other line driver / receiver circuit 2
An H level signal is supplied to the STBY terminals 2, 25 and 28.

As a result, the Do terminals and Ro terminals of the other line driver / receiver circuits 21, 24 and 27 are in a high impedance state, as shown in FIG. 2 (b).
RS232C connector 12 2nd pin, 4th pin, 20
The No. pin becomes an output terminal of SD (transmission data), RS (transmission request), and ER (data terminal ready), and Pins 3, 5, and 6 are RD (reception data), respectively. , CS (transmission possible), DR (data set ready) input terminals.

Thus, the RS232C connector 12 is
The terminal connection state is the same as when connecting with a straight cable.

Therefore, in this case, if the transmitting / receiving software is used for the data line terminating device, this device can transmit and receive signals as the data line terminating device.

When this terminal device (connecting device) is connected to another computer, as shown in FIGS. 2A and 2B, even when the terminal device is used as a data terminal device, the terminal device is also used. Even when is used as a data line terminating device, it suffices to connect it to the RS232C connector 12 of the terminal device (connection device) and the RS232C connector 31 of the connected device via the straight cable 5.

Thus, the input / output of a part (cross terminal) of the terminals of the RS232C connector 12 is changed over by the switch 16
Since the terminal switching circuit 11 that is switched by the operation is connected to the cross terminal of the RS232C connector 12,
A single straight cable can be used for various connections such as connection between data terminal devices and connection between data terminal device and data terminal device. Therefore, two cables, that is, a straight cable and a cross cable, are not required unlike the conventional case.

Further, since the data terminal devices can be connected to each other and the data terminal device and the data terminating device can be connected by switching one changeover switch 16, the data of the terminal device itself can be transferred only by exchanging the software. It can be used as either a terminal device or a data line terminating device.

[0055]

As described in detail above, according to the present invention, it can be used as any interface device of a data terminal device and a data line terminating device, and various connections can be made with a single cable by a simple operation. It is possible to provide an interface device capable of performing the above.

[Brief description of drawings]

FIG. 1 is a block diagram showing a terminal switching circuit of an interface device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a terminal arrangement when the terminal device and another computer are connected in the embodiment.

FIG. 3 is a diagram showing a connection relationship when a computer and a terminal are connected via a modem.

FIG. 4 is a diagram showing a connection state between the computer shown in FIG. 3 and a modem.

FIG. 5 is a diagram showing a connection state when the computers are connected to each other.

[Explanation of symbols]

 11 ... Terminal changeover circuit 16 ... Changeover switch 21, 24, 27 ... Line driver / receiver circuit 22, 25, 28 ... Line driver / receiver circuit

Claims (1)

[Claims] 1. An RS23 used for connection between a data circuit terminating device and a data terminal device, connection between data terminal devices, etc.
In an interface device including a 2C connector and transmitting and receiving a signal via the RS232C connector, a heterogeneous data line terminal device and a data terminal device in which a terminal arrangement based on the RS232C standard is directly used as the terminal arrangement of the RS232C connector A single switching signal output means for outputting a switching signal for connection between devices and connection between devices of the same kind between data terminal devices in which input / output of a predetermined input / output terminal of the RS232C connector is reversed;
An interface device comprising: terminal switching means for switching input / output of a predetermined input / output terminal of the RS232C connector based on a switching signal from the switching signal output means.