JPH046146B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] In a data interface device having a plurality of electrical connection conditions, before receiving a restart signal from a digital exchange, the electrical connection conditions to be selected are determined based on the voltage of the input signal. This method aims to shorten the connection time by determining the electrical connection conditions to be selected based on the communication operation after receiving the restart signal.

[Industrial application field]

The present invention relates to a data interface device, and more particularly to a method for selecting electrical connection conditions between a data interface device and devices connected thereto.

An example of a digital switching system including a data interface unit (DIU) is shown in FIG. As shown in the figure, data interface units (DIU) 1 and 2 are connected to data terminal equipment (DTE) 5 and data line termination equipment (DCE) via signal lines 3 and 4 using standardized RS-232C cables. )
6, respectively. The data terminal equipment (DTE) 5 includes a CRT display, a printer, a processor, and the like. A modem or the like is known as the data line terminating equipment (DCE) 6. Electrical connection conditions for data terminal equipment (DTE) and data circuit terminating equipment (DCE) are different.

In Fig. 2, 7 is a digital exchange, 8 is a switching circuit, 9 and 10 are DIU subscriber circuits, 11 is a subscriber circuit, 12 is a central office line trunk circuit, 13 is a central office, and 14 is a data line termination. 15 is a data terminal equipment (DTE). 8 to 12 are included in the digital exchange 7.

Figure 3 shows data interface unit (DIU) 1
FIG. 2 is a diagram illustrating connection switching between the device and an external device connected thereto.

As mentioned above, since the electrical connection conditions of the data interface unit (DIU) differ depending on the device to which it is connected, it is necessary to switch the signal lines 3 and 4 depending on the device to be connected. This switching is performed by a semiconductor switch. This will be explained with reference to FIG.

In Figure 3, data terminal equipment (DTE)
Terminal m of 5 serves as an input terminal of receiver 21, and terminal n serves as an output terminal of driver 22. On the other hand, the terminal m of the data line terminating device (DCE) 6 serves as the output terminal of the driver 23, and the terminal n serves as the input terminal of the receiver 24.

The data interface unit (DIU) 1 includes a control section 25, a driver 26, a receiver 27, and a semiconductor switch 28. The output of the driver 26 is connected to a switch contact S ₁ of a semiconductor switch 28, and the input of the receiver 27 is connected to a switch contact S ₂ of a semiconductor switch 28.

When connecting data terminal equipment (DTE) 5,
Since it is only necessary to connect the output of the driver 26 to the input of the receiver 21 and the output of the driver 22 to the input of the receiver 27, connect the contact S ₁ and the terminal m as shown in the solid line of the semiconductor switch 28, and connect the contact S ₂ and terminal n
Just connect.

When connecting the data line termination equipment (DCE) 5, the output of the driver 26 should be connected to the input of the receiver 24, and the output of the driver 23 should be connected to the input of the receiver ₂₇ . The semiconductor switch 28 is switched so that the terminal n is connected and the contact S ₂ and the terminal m are connected.

[Conventional technology]

Conventionally, switching of the semiconductor switch 28 has been performed by a manual switch 29 as shown in FIG. That is, the user operated the manual switch 29 according to the connection partner, and used the output of the manual switch 29 as control information for the semiconductor switch 28 to control the semiconductor switch 28.

The disadvantage of this conventional example is that if the user makes a mistake in setting the manual switch, as shown in FIG. It means being connected. The problem here is the connection between the drivers,
If one driver has a high level output and the other driver has a low level output, the output impedance of the driver is generally low (the standard is 300Ω or more), so an eddy current will flow from one driver to the other. This means that the other driver may be damaged.

Therefore, the present applicant proposed an automatic data communication mode selection system in Japanese Patent Application No. 59-263379. According to this prior art, as shown in FIG. 6, the input voltage of one receiver 27 in a data interface unit (DIU) is monitored, and it is determined whether the connection is correct or not based on the voltage. In other words, in the case of correct connection, that is, when the input of the receiver 27 is connected to the output of the connected driver 22, the receiver
The input voltage V of 27 is 5V according to the signal line RS-232C standard.
<|V|<15V (input impedance R is 3~7K
Ω). On the other hand, the input voltage when the receiver 27 is open is 2V or less according to the standard. Therefore, in case of correct connection, the power voltage V is 5<|V|<15 as shown in FIG. 6, and in case of incorrect connection, the input voltage V is as shown in FIG. |V|<2V. Taking advantage of this, the input voltage of the receiver 27 is continuously monitored while switching the semiconductor switch 2 at a certain period, and the switching of the semiconductor switch 28 is stopped when the input voltage V becomes 5<|V|<15. allows you to automatically select the connection mode.

[Problems to be solved by the invention]

The above-mentioned prior art does not completely solve the connection problem. That is, commercially available RS−
Some 232C connectors do not meet the aforementioned RS-232C standard; for example, some connectors fix the receiver input voltage to a high level regardless of connection errors. When such a receiver is connected to the receiver 27 in the data interface unit (DIU) via the semiconductor switch 28, the input voltage V satisfies the condition 5<|V|<15, so it is determined that the connection is correct. , receivers are connected to each other, and drivers are connected to each other, and as mentioned above, there is still the problem that the drivers may be damaged.

On the other hand, in the conventional switching method using only a manual switch, the user only discovers an incorrect connection when data communication is not possible even when attempting to do so, and only then does the manual switch need to be switched.
The problem is that if it takes a long time from connecting the data interface device to an external device such as a data terminal device or data circuit termination device until discovering that the connection is incorrect, the possibility that the driver 22 or 26 will be damaged increases. There is a point.

[Means for solving problems]

FIG. 1 is a block diagram of the principle of the present invention. 1st
In the figure, a data interface unit (DIU) 100 according to the present invention is connected between a digital exchange 101 and an external device 102.
There are electrical connection conditions determined by the external device 102 between the two. Data interface device 10
0 includes a determining means 103 that determines the electrical connection condition to be selected based on the voltage of the input signal from the external device 102. The data interface device 100 also includes a manual switch 104 that determines the electrical connection condition to be selected based on the communication operation with the external device 102. The data interface device 100 further includes a control means 105 that generates a switching control signal SC by receiving a restart signal RS from the digital exchange 101, and a control means 105 that generates a switching control signal SC, and an output of a determining means 103 before generating this switching control signal SC. , after the switching control signal is generated, the output of the manual switch 104 is connected to the first switching means (SW ₁ ) 106 which uses the connection control signal CC, and to the input/output terminal I/O of the data interface device 100, and is connected to the input/output terminal I/O of the data interface device 100 to control the connection. and second switch means 107 for selecting one of the electrical connection conditions in response to the signal CC.

[Effect]

Data interface device 100 and external device 1
02 until the control means 105 in the data interface device 100 receives the restart signal from the digital exchange 101 (the first half), the second switch means is set in the automatic selection mode by the determination means 103. After receiving the restart signal (in the second half), the second switch means is controlled by the manual switch 104. Therefore, in the first half, there is no possibility of manual erroneous connection.
In the second half, there is no possibility of erroneous connection due to automatic selection mode. The possibility of erroneous connection due to the automatic selection mode in the second half may occur when a non-standard receiver is connected, but such erroneous connection rarely occurs and does not affect many people. Also,
Even if a manual connection is made incorrectly in the second half, the user can immediately determine that the connection is incorrect since communication is not possible, and can switch to a correct connection.

〔Example〕

FIG. 8 is a circuit diagram showing a data interface device according to an embodiment of the present invention. In the figure, a data interface unit (DIU) 200 is connected between a digital exchange 201 and an external device 202, and an external device 200 is connected between the external device 202 and the external device 202.
It has electrical connection conditions determined by 02. In the present invention, when the connection partner is a data terminal equipment (DTE), a data terminal ready signal (DTR) is transmitted.
If the connected device is a data circuit terminating equipment (DCE), the data set ready signal (DSR; response signal to DTR) signal line shall be monitored. That is, if the external device 202 is a data terminal device DTE, its terminal m is the input terminal of the receiver and its terminal n is the output terminal of the driver, so the signal line 208 must be DSR and the signal line 209 must be DTR. Must be. Furthermore, if the external device 202 is a data line termination device DCE, the terminal m is the driver output terminal and the terminal n is the receiver input terminal, so the signal line 208 is
DTR and signal line 209 must be DSR (see Figure 3).

The data interface device 200 includes a determination circuit 2031, an inversion circuit 2032, and a manual switch 20.
4. Control circuit 205, switching circuit 2 that switches between the output of the inverting circuit 2032 and the output of the manual switch 204
06, a semiconductor switch 207, a driver 260, and a receiver 270.

The determination circuit 2031 determines that if the input voltage of the receiver 270 is higher than the high level V _TH or lower than the low level V _TL , that is, the data interface device 200
If the connection with the external device 202 is correct, “1” is output to point A, and if the connection is incorrect, “0” is output to point A.
Output. High level V _TH and low level V _TL
may be +5V and -5V, respectively, but considering the margin, it is desirable that their absolute values be lower than 5V.

FIG. 9 shows the relationship between point A, point B which is the output of the inversion circuit 2032, and the clock signal.

When the output at point A is "1", that is, when it is determined that the connection is correct, the output point B of the inverting circuit 2032 is not inverted even by the clock signal and maintains the previous input state.

When the output at point A is "0", that is, when it is determined that there is an erroneous connection, the output point B of the inverting circuit 2032 is inverted at a cycle twice the cycle 1/fo of the clock signal.

The user's action steps are as follows.

A control circuit 105 within a data interface device 100 is connected to a digital exchange 101 via a modular cord.

An external device 102 such as a data terminal equipment (DTE) or a data circuit terminating equipment (DCE) is connected to the data interface device 200 .

By pressing the reset button in digital exchange 201, a restart signal is sent to control circuit 205. Control circuit 205 receives this restart signal and sends a confirmation signal ID indicating the number of data interface device 200 to digital exchange 201 . As a result, digital exchange 201 recognizes data interface device 200.

Communication is performed using a data interface device.

In the above procedure, from the time the external device 202 is connected to the data interface device 200 until the start signal is received from the digital exchange 201, the switching control signal SC is sent from the control circuit 205.
will not occur. Therefore, the switching circuit 206 outputs the output of the inverting circuit 2032 as the connection control signal CC. Upon receiving the restart signal from digital exchange 201, control circuit 205 generates switching control signal SC, which causes switching circuit 206 to output the output of manual switch 204 as connection control signal CC.

In this way, before the restart signal is generated, the semiconductor switch 207 is controlled by the inverting circuit 2032 without using the manual switch 204, and after the restart signal is generated, the semiconductor switch 207 is controlled by the manual switch 204. , the possibility of driver damage due to incorrect connection is greatly reduced.

Note that if the level of the output point B of the inverting circuit 2032 is different from the level of the output of the connection switch 204, the control circuit 205 uses a man-machine interface such as a lamp or a buzzer to notify the user of the abnormality. You may let them know.

In the above description of the embodiments, two types of external devices, the data terminal device DTE and the data line termination device, are mentioned as external devices connected to the data interface device, but the present invention is not limited to these. The device may have three or more types of electrical connection conditions with an external device.

〔Effect of the invention〕

As explained above, according to the present invention, the connection mode is automatically determined before the restart signal is received, and the connection mode is manually determined after the restart signal is received. The time for incorrect connections with external devices is greatly reduced and the possibility of driver damage is reduced.

[Brief explanation of drawings]

Figure 1 is a block diagram showing the principle of the present invention, Figure 2 is a block diagram showing the principle of the present invention.
The figures are a block diagram showing an example of a digital exchange system including a data interface device to explain the background of the present invention, FIG. 3 is a diagram explaining connection switching between the data interface device and an external device, and FIG. The figure shows a switching method of a semiconductor switch using a conventional manual switch, and Fig. 5 shows an incorrect connection caused by a manual switch in the case of Fig. 4.
FIG. 6 is a diagram showing a data communication automatic selection method in the prior art, FIG. 7 is a diagram showing determination of incorrect connection in the case of FIG. 6, FIG. 8 is a circuit diagram showing an embodiment of the present invention, and FIG. 9 is a waveform diagram illustrating the operation of the inversion circuit included in FIG. 8. 101... Digital exchange, 102... External device, 103... Judgment means, 104... Manual switch, 105... Control means, 106... First switch means, 107... Second switch means.

Claims (1)

[Claims] 1. Data interface device 10 connected between digital exchange 101 and external device 102
0, based on the voltage of the input signal from the external device,
Determination means 1 for determining electrical connection conditions to be selected
03; a manual switch 104 that determines the electrical connection condition to be selected; a control means 105 that generates a switching control signal by receiving a restart signal from the digital exchange; a first switch means 1 which uses the output of the determination means as a connection control signal, and after generation of the switching control signal, uses the output of the manual switch as a connection control signal;
06, and second switch means 107 connected to the input/output terminal of the data interface device and switching to one of the electrical connection conditions in response to the connection control signal. Ace device electrical connection condition selection method.