JPH05314036A - Interface equipment for communication - Google Patents

Abstract

PURPOSE:To provide and interface for communication capable of being used both as master and slave equipments to execute two-way communication through simple configuration using only three kinds of TTLICs. CONSTITUTION:Connectors 1 to 3 and buffer circuits 4 to 7 are included. In the case of use as a master I/F, a communication line is connected to the connector 1. A terminal 13 for drive signal is let fall to earth potential by the connector of a communication line side, and a drive signal is made low-level. Thus, the I/F for communication is set as the master I/F. In the case of the use as a slave I/F, since the communication line is not connected to the connector 1, the drive signal becomes high-level. Thus, the interface for communication is never set as the I/F for master equipment by mistake. In the configuration in which the I/F for communication is used as the master I/F, the communication line is connected to the connector 1, a master I/F is connected to the connector 2, and a slave I/F is connected to the connector 3 respectively. At that time, the drive signal becomes low, and the buffers 4 and 6 are turned into an enable state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication interface device for connecting a master device and a slave device to a communication line.

[0002]

2. Description of the Related Art In a conventional communication system, an interface for a master device (hereinafter, the interface is abbreviated as I / F) and an I / F for a slave device are often configured differently. .. If the I / Fs of both devices can be made common, it will be convenient when constructing a communication system that it is not necessary to check whether the I / Fs are for master devices or slave devices. There are many points. However, in order to make the I / F common, the I / F circuit for the master device and the I / F circuit for the slave device are combined into one I / F circuit.
Since it has to be mounted on / F, the configuration becomes complicated. In particular, when the master device and the slave device perform bidirectional communication with respect to the communication line, there are cases in which the number of control lines increases and unnecessary signals are output when they are shared.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and can be used as a master device and a slave device for bidirectional communication with a simple configuration using only three types of TTLICs. An object is to realize a communication interface device.

[0004]

According to the present invention, in a communication interface device for connecting a master device or a slave device to a communication line, a signal of a transmission / reception signal transmitted and received between the communication line and the master device and the slave device. A first connector having a transmission / reception signal terminal to which a line is connected, a drive signal terminal to which a drive signal signal line for setting an enable state or a disabled state is connected, and a transmission / reception signal terminal A second and a third connector, an inverter circuit that is connected to the drive signal terminal and outputs a drive signal output from this terminal and an inverted signal of the drive signal, and a communication line to the first connector. And a level setting means for connecting the drive signal terminal to a predetermined potential point to set the level of the drive signal to a predetermined level,
Latches input data, outputs the latched data from the output terminal in the enabled state, does not output the latched data in the disabled state, and a plurality of them are provided.
A buffer circuit including a drive signal supplied from the inverter circuit and a drive signal supplied from the inverter circuit is used, and when used as an interface of the master device, a communication line is connected to the first connector. The master device is connected to the second connector, the interface of the slave device is connected to the third connector, and the communication line is connected to the master device by the buffer circuit which is enabled by connecting the communication line to the first connector. When forming a two-way communication path with a slave device and using it as an interface of the slave device, the slave device is connected to the second connector and the interface of the master device is connected to the third connector. The buffer circuit that was enabled by not connecting the communication line to the first connector An interface device for communication and forming a path for bidirectional communication between the interface and the slave device of the apparatus.

[0005]

In the present invention as described above, three connectors are provided. Then, the first connector is configured to set the drive signal to the high level and the low level depending on whether the communication line is connected or not. Connected between the three connectors are one that is enabled when the drive signal goes high and one that is enabled when it goes low. When used as the interface of the master device, the communication line is connected to the first connector, the master device is connected to the second connector, and the interface of the slave device is connected to the third connector. The drive signal is set to one level by connecting the communication line to the first connector, and thus the buffer circuit in the enabled state forms a bidirectional communication path between the communication line and the master device and the slave device. .. When used as an interface for a slave device, connect the slave device to the second connector
Connect the interface of the master device to each connector. The drive signal is set to the other level by not connecting the communication line to the first connector, and thus the buffer circuit in the enabled state forms a bidirectional communication path between the interface of the master device and the slave device. ..

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram showing an embodiment of the present invention. In FIG. 1, 1 to 3 are connectors and 4 to 7 are buffer circuits.
In the connector 1, 11 is a control signal terminal to which a signal line of a control signal sent from the communication line to the master device and the slave device is connected, and 12 is a signal line of data sent from the master device and the slave device to the communication line. A data signal terminal 13 is a drive signal terminal to which a signal line of a drive signal for setting the buffer circuits 4 to 7 in the enable state or the disable state is connected. The connector 2 is provided with a control signal terminal 21 and a data terminal 22, and the connector 3 is provided with a control signal terminal 31 and a data terminal 32.

The buffer circuits 4 to 7 are circuits that latch input data, output the latched data from the output terminal in the enabled state, and do not output the latched data in the disabled state. Such a circuit is, for example,
It is realized by a buffer with an enable terminal. A1 and A2 of the buffer circuit are input terminals, and Y1 and Y2 are output terminals. In the buffer circuit 4, the input terminal A1 is connected to the control signal terminal 11, and the output terminal Y1 is the input terminal A.
2 and the control signal terminal 21. The output terminal Y2 is connected to the input terminal A2 of the buffer circuit 5 and the control signal terminal 31. The output terminal Y2 of the buffer circuit 5 is connected to the control signal terminal 21. The input terminal A2 of the buffer circuit 6 is connected to the data terminal 32. In the buffer circuit 7, the input terminal A2 is connected to the data terminal 22 and the output terminal Y2 is the data terminal 32.
It is connected to the.

Reference numeral 8 is an OR circuit, which takes the OR of the output signal of the output terminal Y2 of the buffer circuit 6 and the signal given from the data terminal 22 and outputs it to the data terminal 12. 9
Is an inverter, which inverts the drive signal output from the drive signal terminal 13. The signal before passing through the inverter 9 is applied to the G bar terminals of the buffer circuits 4 and 6 (the one with a bar above G is referred to as G bar), and the signal after passing through the inverter 9 is the buffer circuit 5. And 7 G-bar terminals. Since the buffer circuits 4 to 7 are active low, the buffer circuits 4 and 6 are enabled when the drive signal is low level, and the buffer circuits 5 and 7 are enabled when the drive signal is high level. 1
Reference numeral 0 is a level setting means, which sets the drive signal output from the data terminal 12 to a low level when the communication line is connected to the connector 1. This setting is performed by connecting the signal line of the drive signal, which has been raised to the high level potential by the pull-up resistor R, to the ground potential by connecting the communication line to the connector 1 and dropping it to the low level potential. In this configuration, the connector on the communication line side is provided with a pin connected to the ground potential, and when the connector on the communication line side is connected to the connector 1, this pin is connected to the drive signal terminal 13. Is realized by

The operation of the thus configured communication interface device will be described. When the communication interface device shown in FIG. 1 is used as an I / F of a master device, a communication line is connected to the connector 1. At this time, the drive signal terminal 13 is dropped to the ground potential by the connector on the communication line side, and the drive signal becomes low level. As a result, the communication interface device is set as the I / F for the master device. On the contrary, when used as an I / F of a slave device, a communication line is not connected to the connector 1, so the drive signal becomes high level. This prevents the communication interface device from being erroneously set as the I / F for the master device.

When the communication interface device is used as the I / F of the master device, the communication line is connected to the connector 1, the master device is connected to the connector 2, and the I / F of the slave device is connected to the connector 3. At this time, the drive signal becomes low level and the buffer circuits 4 and 6 are enabled. As a result, the control signal sent from the communication line is input to the control signal terminal 11 and sent to the master device and the slave device through the buffer circuit 4 and the control signal terminals 21 and 31. Further, the data sent from the master device and the slave device are output from the data terminals 22 and 32, and after being ORed by the OR circuit 8, they are sent to the communication line through the data terminal 12. In this way, bidirectional communication is performed between the communication line and the master device and the slave device.

When the communication interface device is used as the slave device I / F, the connector 3 is connected to the master device I / F, and the connector 2 is connected to the slave device. At this time, the drive signal becomes high level and the buffer circuits 5 and 7 are enabled. As a result, the control signal sent from the I / F of the master device is input to the control signal terminal 31, and the buffer circuit 5 and the control signal terminal 2 are input.
1 to the slave device. Further, the data sent from the slave device is output from the data terminal 22, passes through the buffer circuit 7, and is sent from the data terminal 32 to the I / F of the master device. In this way, bidirectional communication is performed between the I / F of the master device and the slave device.

FIG. 2 is a diagram showing an example of use of the communication interface device shown in FIG. In FIG. 2, L is a communication line, M is a master device, and S is a slave device. IF1
And IF2 are the communication interface devices shown in FIG. 1, and IF1 is used as the I / F of the master device.
2 is used as an I / F of the slave device. N is a connection line connecting the communication interface devices IF1 and IF2. In the communication interface devices IF1 and IF2, bidirectional communication is performed through the route shown by the arrow in the figure.

[0013]

According to the present invention, the following effects can be obtained. An I / F that can be used as a master device and a slave device that perform bidirectional communication with a simple configuration that only uses three types of TTLICs, which include a buffer circuit, an inverter, and an OR circuit.
Can be realized. The I / F for the master device and the I / F for the slave device can be easily set by attaching and detaching the connector.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of use of the present invention.

[Explanation of symbols]

 1 to 3 connectors 4 to 7 buffer circuit 9 inverter 10 level setting means 11, 21, 31 control signal terminal 12, 22, 32 data terminal 13 drive signal terminal

Claims (1)

[Claims] 1. A communication interface device for connecting a master device or a slave device to a communication line, for a transmission / reception signal to which a signal line of a transmission / reception signal transmitted / received between the communication line and the master device / slave device is connected. A first connector having a terminal, a drive signal terminal to which a signal line of a drive signal for setting an enable state or a disable state is connected, and second and third connectors each having a transmission / reception signal terminal, An inverter circuit that is connected to the drive signal terminal and outputs a drive signal output from this terminal and an inverted signal of the drive signal; and a drive signal terminal when a communication line is connected to the first connector. Is connected to a predetermined potential point to set the level of the drive signal to a predetermined level, and input data is latched to enable it in the enabled state. And outputs the latched data from the output terminal, the disabled state does not output the latched data, be provided a plurality,
A buffer circuit including a drive signal supplied from the inverter circuit and a drive signal inverted from the drive circuit; and when used as an interface of a master device,
Of the buffer which is enabled by connecting the communication line to the connector, the master device to the second connector, the interface of the slave device to the third connector, and connecting the communication line to the first connector. When a circuit forms a bidirectional communication path between the communication line and the master device and the slave device and is used as an interface of the slave device, the slave device is connected to the second connector and the master device is connected to the third connector. It is possible to form a bidirectional communication path between the interface of the master device and the slave device by the buffer circuit which is enabled by connecting the interfaces to each other and not connecting the communication line to the first connector. Characteristic communication interface device.