JPH02291754A - Interface circuit - Google Patents

Abstract

PURPOSE:To simplify a control signal and to reduce the number of parts, the mounting area, the power consumption, or the like by outputting a switching signal based on the control signal of a binary code, switching respective signal sources and sending signals from switched signal sources to a line. CONSTITUTION:A two-bit binary code is used as the control signal inputted to input terminals CONT1 and CONT2. Four kinds of state are determined by the two-bit binary code. This control signal is inputted to the input terminals 5A and 5B of a detector 5. The decoder 5 outputs a switching signal from output terminals 5C to 5E based on the control signal inputted to the input terminals 5A and 5B. This switching signal controls the switching states of switching circuits 2 to 4 in accordance with the state determined by the two-bit binary code.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is based on PCM (Pulse Code Mo
The present invention relates to an interface circuit used in a terminal station (duration).

[Prior Art] This type of interface circuit includes a P line (direct current signal line) interface circuit used in a communication road board of a PCM terminal station device. This P line interface circuit sends various signals to the P line. An example of such a P-line interface circuit is shown in FIG.

This conventional P line interface circuit consists of a switching circuit 11
．． 12. 13 and relay contacts r1, rj! relays RLI, RL2 each comprising a diode 1 and a diode 1;
4 and power supplies 15 to 18.

Switching of the switching circuits 11 to 13 of this P-line interface circuit is controlled via input terminals CONTI to CONT3. As a result, the P line connected to the output terminal P-WIRE has a positive voltage a15, a negative power source 16, and a ground voltage 1.
Four signals are sent: 9 and open.

[Problem to be solved by the invention]

The conventional P-line interface circuit described above uses three control signals and sends out four signals through a relay-based logic circuit. Therefore, the conventional P-line interface circuit has the disadvantage that the circuit configuration is complicated.

An object of the present invention is to provide an interface circuit that can eliminate such drawbacks and simplify the circuit configuration.

[Means to solve the problem]

The present invention provides an interface circuit that switches signals from a plurality of signal sources and sends them to a line, including a decoder section that outputs a switching signal based on a binary code control signal, and a decoder section that outputs a switching signal based on a binary code control signal; The present invention is characterized in that it includes a switching section that switches a signal source and sends a signal from the switched signal source to the line.

(Example) Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing one embodiment of the present invention. This interface circuit includes a switching section 1, a decoder 5,
It is composed of a positive power source 6 and a negative power source 7.

Furthermore, the switching section 1 is composed of switching circuits 2 to 4.

This interface circuit has input terminals CONTl, C
Depending on the control signal input to the ONT 2, four types of signals can be sent to the P line connected to the output terminal P'-WIRE.

In such an interface circuit, the positive power supply 6 is connected to the line 100 via the switching circuit 2.

A negative power source 7 is connected to a line 100 via a switching circuit 3.
Earth air 8 is connected to a line 100 via a switching circuit 4.

The control terminal 2A of the switching circuit 2 is connected to the output terminal 5 of the decoder 5. The control terminal 3A of the switching circuit 3 is connected to the output terminal 5D of the decoder 5. The control terminal 4A of the switching circuit 4 is connected to the output terminal 5C of the decoder 5.

The decoder 5 uses two input terminals 5A and 5B for control.

Next, the operation of this embodiment will be explained.

The control signals input to the human input terminals CONTI and CONT2 use a 2-bit pinary code. Four types of states can be determined using a 2-bit pinary code. Such control signals are input to input terminals 5A and 5B of the decoder 5.

Decoder 5 outputs switching signals from output terminals 50 to 5E based on control signals input to input terminals 5A and 5B. This switching signal controls the open/close states of the switching circuits 2 to 4 in accordance with the state determined by the 2-bit binary code.

This switching signal is applied to control terminals 2A to 4A of switching circuits 2 to 4.
Each is manually powered.

When the switching circuit 2 is brought into a closed state by this switching signal, a signal from the positive power source 6 is outputted from the switching circuit 2. Positive power supply 6
The signal from is sent to the P line via the output terminal P-WIRE.

When the switching circuit 3 is closed by the switching signal, the negative power supply 7
A signal is output from the switching circuit 3. A signal from the negative power supply 7 is sent to the P line via the output terminal P-WIRE.

When the switching circuit 4 is brought into a closed state by the switching signal, a signal of the earth air 8 is outputted from the switching circuit 4. The signal of the ground air 8 is sent to the P line via the output terminal P-WIRE.

Furthermore, when all of the switching circuits 3 to 4 are brought into an open state by the switching signal, an open signal is sent to the P line.

In this way, in this embodiment, the switching circuits 2 to 2 are connected to the line 100.
Power supplies 6, 7 and earth air 8 are connected via 4. Control terminals 2A-4A of switching circuits 2-3 are connected to three output terminals 50-5 of decoder 5, respectively. decoder 5
Connect the two input terminals 5A and 5B to the two input terminals CONT
Connect to I, CONT2. As a result, the positive power supply, negative power supply,
It can send out four signals: ground air and open air.

〔Effect of the invention〕

As explained above, since the present invention uses pinary codes, control signals can be simplified, and the number of parts and mounting area can be reduced.
This has the effect of reducing power consumption and the like.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional P-line interface circuit. 1...Switching section 2-4...Switching circuit 5...Decoder 6...Positive power supply 7...Negative power supply

Claims (1)

[Claims] (1) In an interface circuit that switches signals from a plurality of signal sources and sends them to a line, there is a decoder section that outputs a switching signal based on a binary code control signal, and a decoder section that outputs a switching signal based on a binary code control signal, and a switching signal from the decoder section that outputs the switching signal. An interface circuit comprising: a switching unit that switches a signal source and sends a signal from the switched signal source to the line.