JPH0634482B2 - Data communication device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a data communication device having an insulating adapter and connected to a private line.

(Prior Art) A prior art of an insulation adapter used for such connection will be described with reference to FIGS. 6 to 8.

FIG. 6 is a diagram showing a conventional connection method between data communication devices. In the figure, 1 is a data communication device A, 2 is a partner data communication device B, 3 is a modem, 4 is a direct coupler, and 5 is a modemless facing connection cable.

Conventionally, in the case of connecting data communication devices (terminals or hosts) having a modem interface to each other, as shown in FIG. 6 (a), the data communication device A1 and the data communication device B2 are used even when the line on the premises is used. Modem 3 between
The method of putting in is generally performed. Also, FIG.
As shown in (b), there is a method of inserting a baseband modem called a direct coupler (or data set) 4 in place of the modem 3. Further, as shown in FIG. 6 (c), nothing is inserted between the data communication device A1 and the data communication device B2, and the direct connection is made using the modemless opposite connection cable 5 which is a special connection cable. There is also a method (modemless opposite connection). FIG. 7 is a diagram showing a conventional connection method in modemless opposite connection. In the figure, SD (transmission data), RD (reception data), ST ₁ (transmission signal element timing), RT (reception signal element timing), ER (data terminal ready), DR (data set ready), RS (transmission) Request), CS (possible to send) and CD
(Data channel reception carrier detection) is a well-known signal defined by the modem interface, and its meaning is the interface between the data line terminating equipment and the data terminal equipment.
It is explained in (JIS-C6361).

FIG. 8 is a diagram showing a connection method using a connection cable for a private line interface. Reference numeral 6 is a data communication device A, 7 is a data communication device B on the other side, and 8 is a connection cable for a private line interface. In this connection method, the data communication device A6 and the data communication device B7 are connected to each other by using a connection cable 8 of a private line dedicated interface for connecting the private line. Here, the premises line dedicated interface is an interface specifically defined for the premises because it is not necessary to use a specific communication line of the modem interface. Depending on the direction of current flow or current on / off, the signal " The current loop method, which means “1” or “0”, is widely used. As the connection cable 8, for example, a current loop method using a photocoupler can be used to guarantee insulation and reduce the number of signals.

(Problems to be Solved by the Invention) However, the configuration of the conventional art has the following problems.

In the method of inserting the modem 3 or the direct coupler 4 between the data communication devices A1 and B1 described with reference to FIGS. 6 (a) and 6 (b), two modems 3 or direct couplers 4 are required, and the cost is high. It had the drawback of becoming expensive. Also,
In the modemless opposite connection described in FIG. 6 (c), the cost is low, but the insulation between the data communication devices A1 and B2 is insufficient. For this reason, if there is a difference in the frame ground potential between the data communication devices, there is a risk that the modemless opposite connection cable 5 is transmitted and the drivers and receivers of the respective modem interfaces are destroyed during cable connection. Further, in a large-scale system configuration, when the data communication device of the connection partner suffers an insulation failure such as AC leak, the entire system may be destroyed, resulting in a long-term system failure. There was a flaw. In order to solve this problem, if an isolation coupler for the modem interface signal is inserted between the data communication devices, the number of modem interface signals is large, and the number of isolation couplers such as photo couplers increases and the cost becomes high. was there.

In the method of connecting between the data communication devices A6 and B7 using the connection cable 8 of the private line interface described in FIG. 8, the data communication device A6 has a fixed interface of the data communication device B7 to be connected, Since the modem interface signal cannot be controlled, a general-purpose modem interface cannot be connected, and a flexible system configuration cannot be achieved.

Therefore, whichever connection method is used, there is no one that guarantees the insulation between the data communication devices and uses the general-purpose modem interface for the data communication device on the other side to satisfy the requirements for low-cost connection. I couldn't do it.

The present invention provides a data communication device for connecting another data communication device having a modem interface to a first data communication device having a private line interface in an electrically insulated state.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a first data communication having a private line interface in a state where another data communication device having a modem interface is electrically insulated. A data communication device connected to the device, the data received from the first data communication device (RD
Receiver circuit for the private line interface that receives the signal) electrically isolated by a photo coupler circuit, and creates and outputs a pseudo timing signal synchronized with the output signal from the polarity change point of the output signal of the receiver circuit. A digital phase-locked loop circuit, and a flip-flop for sampling at approximately the center of the bits of the output signal of the receiver circuit based on the pseudo timing signal,
A first driver circuit that amplifies an output signal of the flip-flop to a modem interface level and outputs it as transmission data (SD signal) to the other data communication device, and a pseudo timing signal from the digital phase lock loop circuit to the modem interface. A second driver circuit for amplifying to a level and outputting to the other data communication device as a timing signal (STl) of an SD signal, and a modem interface for receiving received data (RD signal) from the other data communication device. A receiver circuit and a driver for a private line interface that converts received data from the receiver for the modem interface into transmission data (SD signal) of a private line interface and sends the data to the electrically isolated first data communication device. Circuit and other data communication device ER of the modem interface signal
And a return means for returning the signal from the signal to the DR signal, the RS signal to the CS signal and the CD signal and returning the signal from the other data communication device as a signal responding to the signal. .

(Operation) According to the present invention, since the data communication device is configured as described above, the technical means operates as follows. The receiver circuit works to receive the received data from the first data communication device while electrically or DC-insulating it, and the digital phase-locked loop circuit outputs a timing signal synchronized with the output signal of the receiver circuit. The flip-flop serves to sample at approximately the center of the bits of the output signal of the receiver circuit based on this timing signal. The driver circuit functions to generate transmission data and a timing signal of the modem interface from the output signals of the flip-flop and the digital phase lock loop circuit and output them to the second data communication device.

On the other hand, the signal conversion means serves to insulate the received data from the second data communication device and output it as the transmitted data to the first data communication device. The loopback means loops back the control signal of the modem interface from the second data communication device. Therefore, the problems of the prior art can be solved.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 5.

2 and 3 are views showing a connection method and a connection signal using the insulation adapter of the first embodiment according to the present invention. In the figure, 9 is a data communication device A, 10 is a data communication device B on the partner side, 11 is an insulating adapter, 12 is a connection cable for a private line interface, and 13 is a connection cable for a modem interface.

The data communication device A9 is connected to the data communication device B on the other side via the connection cable 12 for the private line interface, the insulation adapter 11 and the connection cable 13 for the modem interface.
Connected to 10.

FIG. 1 is a block diagram showing the internal structure of the insulation adapter 11. In the figure, 14 is a receiver circuit for the private line interface, 15 is a driver circuit for the private line interface, 16 is a data sample flip-flop, and 17 is a digital phase-locked loop circuit (hereinafter abbreviated as DPLL). , 18 is a clock pulse generator of the DPLL ₁₇ , 19a and 19b are driver circuits for modem interface, 20 is a receiver circuit for modem interface, and 21 is a power supply.

The receiver circuit 14 is a connection cable from the data communication device A9.
It has a function of converting the received data (RD signal) sent via 12 into a digital signal and insulating the data communication device A9 from the internal circuit of the insulation adapter. Fig. 4 (a)
FIG. 4 is a diagram showing an example of a receiver circuit 14, in which insulation is guaranteed by a photocoupler circuit and a current loop system is adopted. That is, the light emitting diode 14 of the photocoupler
Depending on the direction of the current flowing through a, the phototransistor 14b
The side is getting a digital signal.

The circuit configuration of DPLL ₁₇ can be realized by the one disclosed in JP-A-57-68946. That is, the flip-flop 16,
DPLL ₁₇ and clock pulse generator 18 are receiver circuits 14
Output signal of, that is, from the RD signal through the driver circuit 19,
It is a timing signal of transmission data (SD signal) and SD signal
It is provided to create the ST ₁ signal. DPLL
According to this conventional example, ₁₇ counts the output pulse of the clock pulse generator 18 and the differentiation circuit that detects the polarity change point of the output signal of the receiver circuit 14, and can preset by the output of the differentiation circuit and carry output. The output signal of the receiver 14 is configured by a counter that generates a predetermined correction value and a ROM that stores a predetermined correction value and gives a value corresponding to the content of the counter when the differentiating circuit generates an output to the counter as a preset value. It becomes possible to output the carry output of the counter at the timing such that the sampling can be performed at approximately the center of the bit as the RD signal timing signal.

The flip-flop 16 samples and holds the output signal of the receiver 14 using the timing signal from the DPLL ₁₇ as a clock.

The driver 15 converts the RD signal sent from the data communication device B10 via the connection cable 13 and the receiver 20 into an interface dedicated to the private line and outputs it as transmission data (SD signal) to the data communication device A9. FIG. 4B is a diagram showing an example of the driver circuit 15. As shown in the figure, the input digital signal is transferred to the transistor 15a via the resistor 15b.
The output current is turned on and off by turning on and off.

The operation of the first embodiment of the present invention will be described. The transmission data (SD) sent from the data communication device A9 is an insulation adapter
The current signal received by the receiver circuit 14 of 11 is converted into reception data (RD) of a digital signal. The output signal of the receiver 14 is output to the flip-flop 16 and the DPLL ₁₇ , respectively. DPLL ₁₇ is the received data and clock pulse generator 18
A timing signal that is synchronized with the received data is created from the clock pulse of, and is input to the flip-flop 16. The flip-flop 16 uses this timing signal as a clock to sample at approximately the center of the bits of the received data. The timing signal output from the DPLL ₁₇ and the received data sampled by the flip-flop 16 are the ST ₁ signal and S
It becomes the phase relation of the D signal. Each of these received data and the timing signal driver 19a, is amplified by b to the level of the modem interface signals are always output to the data communication device B10 as SD signal and ST ₁ signal synchronized with each other has been taken. In this case, the ST ₁ signal has a characteristic that it slightly moves near the center of the bit of the SD signal but does not largely shift. These signals are passed from the SD signal to the RD signal and the ST ₁ signal to the RT signal to the data communication device B10 on the other side, so that the data communication device B10 looks as if they are connected to the modem. I can show you.

On the other hand, the SD signal from the data communication device B10 on the other side is received by the receiver of the insulation adapter 11 as the RD signal of the insulation adapter 11.
Entered in 20. This RD signal is amplified by the receiver 20 so as to drive the transistor of the driver 15, and is input to the driver 15. The input digital signal is converted into an SD signal of a current signal by the driver 15 and transmitted to the data communication device A9. The receiving unit of the data communication device A9 is the driver 14 used in the insulation adapter 11.
And since the same one as the receiver 15 is used, the insulation is likewise guaranteed. Further, as shown in FIG. 1, the ER and RS signals of the modem interface control signal from the data communication device B10 on the other side are, as shown in FIG. Since the signal is folded back into the signal, the insulation adapter 11 looks to the data communication device B10 as if it were a modem.

Next, the insulation adapter of the second embodiment according to the present invention
It will be described with reference to the drawings. FIG. 5 is a block diagram showing the internal structure of the insulation adapter 31 installed between the data communication devices A and B of the modem interface. 28a to 28d are receiver circuits for a modem interface, 29a to 29d are receiver circuits that electrically insulate input and output using a photocoupler, and 30a and 30b are power sources electrically insulated from each other.
Here, the receivers 29a to 29d can be realized by the same configuration as the receiver circuit 14 shown in FIG. 4 (a) described in the first embodiment.

The operation of the second embodiment will be described. Among the signals from the data communication device A, the transmission data (SD signal) and the timing signal (ST ₁ signal) are received by the receiver circuits 28a and 28c, respectively. The output signals of the receiver circuits 28a and 28c are passed through the receiver circuits 29a and 29c, respectively, so that the data communication device A side and the data communication device B side are electrically insulated, and then further passed through driver circuits 27b and 27d, respectively. It is output as transmission data (RD signal) and timing signal (RT signal) to the data communication apparatus B on the partner side. On the other hand, among the signals from the data communication apparatus B on the other side, the SD signal and the ST ₁ signal are similarly received by the receiver circuits 28b and 28d, respectively, and further the receiver circuits 29b and 29d and the driver circuits 27a and 27c are respectively received. It is output to the data communication device A via the RD signal and the RT signal. Here, the power supplies of the receivers 28a and 28c and the drivers 27a and 27c on the data communication device A side are from the power supply 30a, the receivers 28b and 28d on the data communication device B side, and the drivers 27b and 27d.
Since the power of each is divided and supplied from 30b,
The insulation between the modem interfaces of the data communication devices A and B is completely guaranteed. As shown in FIG. 5, signals other than the SD, RD, ST ₁ and RT signals are folded back to their interface side from the ER signal to the DR signal and from the RS signal to the CS signal and the CD signal, respectively. Data communication device A,
The insulation between B is maintained. Further, the data communication devices A and B
From the perspective, it can appear as if it is connected to a modem.

Although the power supplies 30a and 30b are separately provided and electrically insulated from each other, a power supply unit electrically insulated from each other by, for example, a DC-DC converter system may be used.

In the above embodiments of the present invention, a receiver circuit for insulation
Although the case where a photocoupler is used to electrically insulate 14, 29a to 29d has been described, it is clear that a receiver circuit that is galvanically isolated by using a pulse transformer or the like may be used.

The insulation adapter 11 according to the first embodiment creates the SD signal and ST ₁ signal of the modem interface signal from the RD signal of the private line interface signal and the function of electrically insulating the private line interface signal and the modem interface signal. It has a function of performing, a function of creating an SD signal of the local interface from the RD signal of the modem interface signal, and a function of returning other control signals of the modem interface. Therefore, the number of signals to be insulated can be greatly reduced, and the number of expensive drivers and receivers for insulation can be reduced, so that an insulation adapter which is an inexpensive insulation coupler can be realized.

Further, since the degree of freedom in connecting the data communication device on the modem interface side is increased, the system can be easily configured. Further, in the conventional method using the modemless opposite connection cable, the connection distance is about 15 m due to the limitation of the electrical condition of the modem interface, and it is impossible to extend it for a long time. However, the first embodiment of the present invention As shown in the example, if the data communication device A9 and the insulation adapter 11 employ a carrent loop type interface or the like as a private line dedicated interface, the effect that the connection distance can be greatly extended can be obtained.

A function of electrically insulating the insulating adapter 31 modem interface signals according to the second embodiment, the function of converting the conversion and ST ₁ signal -RT signal of the SD signal -RD signal, control of the modem interface other than these signals It has the function of returning signals. Therefore, both data communication devices can be connected by a device having a modem interface, so that the degree of freedom in connection is increased and the system configuration can be easily performed. Also, since only four signals in the modem interface signal line are required for insulation, a low-cost insulation adapter device can be constructed. Further, when viewed from both data communication devices, the present insulated adapter can be made to look like the modem itself, so that there is an effect that the data communication device can be connected without being particularly aware of the adapter.

(Effects of the Invention) As described above, according to the present invention, insulation between data communication devices is completely performed, and one data communication device is connected with a data communication device having a modem interface that is a general-purpose interface. There is an effect that it is possible to provide a possible data communication device with an inexpensive and simple configuration.

[Brief description of drawings]

FIG. 1 is a block diagram showing an insulation adapter of a data communication device of a first embodiment according to the present invention, and FIGS. 2 and 3 are diagrams showing a connection method and a signal connection using the insulation adapter of FIG. 1, respectively. FIG. 4 is a diagram showing an example of a receiver circuit and a driver circuit, FIG. 5 is a block diagram showing an insulation adapter of a data communication device of a second embodiment according to the present invention, and FIG.
FIG. 7 is a diagram showing a conventional connection method between data communication devices,
FIG. 8 is a diagram showing a connection method of a conventional modemless opposite connection, and FIG. 8 is a diagram showing a connection method using a connection cable of a private line interface. 9 ... Data communication device A, 10 ... Data communication device B 11 ... Insulation adapter, 14, 20 ... Receiver circuit 15, 19a, 19b ... Driver circuit 16 ... Flip-flop 17 ... Digital phase lock loop circuit 18 ... Clock pulse generator, 21 ... Power supply 27a to 27d ... Driver circuit 28a to 28d ... Receiver circuit 29a to 29d ... Receiver circuit, 30a, b ... Power supply

Front Page Continuation (56) References Seiichi Miyazaki, "Basics and Practice of Microcomputer Data Transmission," CQ Publishing, (Sho 59.30.), 169-176, 189-197. Transistor Technology, January 1984, pp. 361-368, "Methods for Successful RS-232C Interface"

Claims (1)

[Claims] 1. A data communication device for connecting to a first data communication device having a private line dedicated interface in a state where another data communication device having a modem interface is electrically insulated, the data communication device comprising: A receiver circuit for a private line dedicated interface for electrically receiving the received data (RD signal) from the data communication device No. 1 by a photo coupler circuit, and the output signal from the polarity change point of the output signal of the receiver circuit A digital phase-locked loop circuit that creates and outputs a pseudo timing signal that is synchronized with, a flip-flop that samples at approximately the center of the bits of the output signal of the receiver circuit based on the pseudo timing signal, and an output signal of the flip-flop Is amplified to the modem interface level and used as transmission data (SD signal) The first driver circuit and the timing signal of the amplified SD signal a pseudo timing signal to the modem interface level from the digital phase-locked loop circuit for outputting the other data communication apparatus (ST
1) A second driver circuit that outputs to the other data communication device, a receiver circuit for a modem interface that receives received data (RD signal) from the other data communication device, and a receiver for the modem interface The first data is obtained by converting the reception data from the transmission data (SD signal) of the private line interface and electrically insulating the data.
Driver circuit for a private line interface to be sent to the other data communication device, and the ER signal of the modem interface signal from the other data communication device to the DR signal, RS
A data communication device, comprising: a return unit that returns the signal to a CS signal and a CD signal and returns a signal from the other data communication device as a signal in response to the signal.