JPH03205944A - Communication switching system - Google Patents

Abstract

PURPOSE:To eliminate the need of a special serial IC and to make the substrate dimension small by switching and connecting a CPU to an optical communication terminal or a MODEM communication terminal by a state register for storing communication selection data, and a switching circuit. CONSTITUTION:As for a CPU 1, its serial port is connected to a switching circuit 5, and it is connected to an optical communication terminal 3 through an OR gate 6 and a buffer 8 of the switching circuit 5, and connected to a MODEM communication terminal 4 through an OR gate 7 and a buffer 9. The CPU 1, first of all, writes a selection but ('1' or '0') for selecting an optical communication on a MODEM communication in a state register 2 through a CPU bus. The switching circuit 5 is operated by receiving communication selection data stored in the state register 2, the communication terminal selected by the selection bit is connected to the CPU 1, and the communication can be executed. In such a way, since a special serial IC is not required, the substrate dimension can be made small.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention provides a method for switching and connecting a CPU that transmits and receives data via an optical communication terminal or a modem communication terminal to the above-mentioned optical communication terminal and a modem communication terminal. This invention relates to a communication switching system for

BACKGROUND ART As this type of communication switching system, there is a conventional communication switching system as shown in FIG. This communication switching system uses Norial IC (
An optical communication terminal 33 and a modem communication terminal 34 are connected to each serial port of the integrated circuit (integrated circuit) 32 via an RS-2320 interface, and the optical communication terminal 33
Alternatively, the CPU 3 1 that transmits and receives data via the modem communication terminal 34 is connected to the serial ■C via the CPU bus.
It is connected to 32. Then, under control from the CPU 31, switching between optical communication and modem communication is performed.

Problems to be Solved by the Invention> By the way, the above-mentioned conventional communication switching system requires a dedicated 2-channel port for the IC, so the usable I
Due to the problem of limited C, and the increasing size of ICs and the complexity of pattern routing, the dimensions of the board become thicker, and in the case of devices that require smaller dimensions of the board. There was a problem that it could not be applied.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a communication switching system that does not require a special serial IC and, therefore, can reduce the size of the board.

<Means for Solving the Problems> In order to achieve the above object, the present invention provides a CPU that transmits and receives data via an optical communication terminal or a modem communication terminal.
a communication switching system for switching and connecting the optical communication terminal and the modem communication terminal to the optical communication terminal and the modem communication terminal, and storing communication selection data for selecting either optical communication or modem communication sent from the CPU; The apparatus is characterized by comprising a register, and a switching circuit that receives communication selection data stored in the status register and switches and connects the CPU to the optical communication terminal or the modem communication terminal.

<Operation> The status register stores the communication selection data for selecting either optical communication or modem communication sent from the CPU, and the switching circuit receives the communication selection data stored in the status register and selects the communication selection data as described above. The CPU is switched and connected to the optical communication terminal or the modem communication terminal. In this way, since the CPU can be switched and connected to the optical communication terminal or the modem communication terminal using the status register and the switching circuit, a special serial IC is not required, and the board size can be reduced.

<Example> Hereinafter, the present invention will be explained in detail with reference to illustrated embodiments.

In FIG. 1, l is a CPU, 2 is a status register, 3 is an optical communication terminal, 4 is a modem communication terminal, 5 is an OR gate 6.
7 and a buffer 8.9, IO is an OR gate.

The real port of the CPUI is connected to the switching circuit 5 via an RS232C interface. The OR gate 6 and buffer 8 of this switching circuit 5
It is connected to an optical communication terminal 3 via an OR gate 7 and a buffer 9, and to a modem communication terminal 4 via an OR gate 7 and a buffer 9.

First, the CPU above writes the selection bit (
l or 0). This causes the switching circuit 5 to operate and the communication terminal selected by the selection bit to be connected to the CP.
It is connected to the UI and communication is possible. Also, when switching connections based on a communication request from the communication terminal side, first,
An interrupt is issued from the communication terminal side to the CPU 1 via the status register 2 and the OR gate IO using the CI (Calling Indicator) bit.

The CPU uses this signal as a trigger to read the request bit (CI bit) of the status register via the CPU bus. Then, it is determined from which communication terminal the communication request was made, and the selection bit is written into the status register 2 in the same manner as above. This selection bit connects the communication terminal that has requested communication to the serial port of the CPUI, enabling communication. When the cput and the communication terminal are connected, the CPU transmits data to the communication terminal and reads data from the communication terminal.

As shown in FIG. 2, the status register 2 consists of two registers: an output register and an input register.

By setting the SCON (serial control) bit of D2 of this output register to 0 or l from the CPUI, communication selection is performed as follows.

0: Modem communication l: Optical communication When optical communication is selected, the modem communication side enters a high impedance state and becomes disconnected.

In addition, the RS (request to send) bits and ER (equipment bits) of the DI and DO of the above output registers are
The communication terminal is controlled by setting the Ready bit to O or 1 from the CPUI. In addition, the CPUI reads the CD (carrier detect) bit, DR (data terminal ready) bit, and CS (clear to send) bit of input registers D7, D5, and D4, thereby determining the status of the communication terminal. Communication status can be monitored.

In this way, the CPU
Since I can be switched and connected to the optical communication terminal 3 and the modem communication terminal 4, there is no need for a special serial IC as in the conventional example, and the board size can be reduced.

In the above embodiment, when switching the connection in response to a communication request from the communication side, the CPU is activated by an interrupt from the communication system, but it may also be performed by polling from the CPU side.

Effects of the Invention> As is clear from the above, the communication switching system of the present invention includes a status register that stores communication selection data for selecting either optical communication or modem communication sent from the CPU, and the above-mentioned communication switching system. and a switching circuit that connects the CPU to an optical communication terminal or a modem communication terminal in response to communication selection data stored in a status register, and switches and connects the CPU to the optical communication terminal and the modem communication terminal. Therefore, a special unreal EC is not required, and the board pattern is not complicated, so the board size can be reduced, and it is also effective against the VCCI standard regarding unnecessary radiation.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a diagram showing the configuration of a status register in the above embodiment, and FIG. 3 is a block diagram of a conventional example. l... CPU, 2 status register, 3 optical communication terminal, 4... modem communication terminal, 5 switching circuit. Patent applicant Nyabu Co., Ltd. Agent
Patent Attorney Aoyama Aoyama Diagram (Output Register) D7 D6 D5 D4 D3 D2 DI Do SCON RS ER (Input Register) D7 D6 D5 D4 D3 D
2 01 DoCD-DR
CS 3 Figure 33

Claims (1)

[Claims] (1) A communication switching system for switching and connecting a CPU that transmits and receives data via an optical communication terminal or a modem communication terminal to the optical communication terminal and the modem communication terminal, the system comprising: a status register for storing communication selection data for selecting either communication or modem communication; and a switch connection of the CPU to the optical communication terminal or the modem communication terminal in response to the communication selection data stored in the status register. What is claimed is: 1. A communication switching system characterized by comprising a switching circuit that performs