CN113268100A

CN113268100A - Single-port multi-level input-output circuit and method

Info

Publication number: CN113268100A
Application number: CN202110469855.9A
Authority: CN
Inventors: 胡肖松; 戢冰; 骈冰; 孙阳
Original assignee: Casi Vision Technology Luoyang Co Ltd; Casi Vision Technology Beijing Co Ltd
Current assignee: Casi Vision Technology Luoyang Co Ltd; Casi Vision Technology Beijing Co Ltd
Priority date: 2021-04-29
Filing date: 2021-04-29
Publication date: 2021-08-17
Anticipated expiration: 2041-04-29
Also published as: CN113268100B

Abstract

The application discloses a single-port multi-level input and output circuit and a method. The circuit comprises a single-port multi-level input circuit and a single-port multi-level output circuit, wherein the single-port multi-level input circuit further comprises: the circuit comprises an input switch circuit (10), an optocoupler conversion circuit (11), a differential input circuit (12), an input parallel circuit (13) and an MCU control circuit (14); the single-port multi-level output circuit further includes: the circuit comprises an MCU control circuit (14), an output parallel circuit (15), a voltage selection circuit (16), a logic output circuit (17), a differential output circuit (18) and an output switch circuit (19). The single-port multi-level input and output circuit and the method can realize that various logic levels share one interface, can control the switching of channels through manual control or MCU, and can cover differential signals and logic levels in an industrial control system by the types of input and output signals, thereby reducing the number of equipment interfaces and expanding the application occasions of the system.

Description

Single-port multi-level input-output circuit and method

Technical Field

The invention relates to the technical field of multilevel circuits, in particular to a single-port multilevel input circuit and/or output circuit and a control method thereof.

Background

Currently, in an industrial control system, the variety of industrial control devices is various, interface control signals of different types of devices are often different, and the interface signals of the same type of devices are also different greatly because a uniform standard is not formed. In industrial equipment application, the input or output control signals generally have RS422 differential signals, TTL logic signals of 5V, logic levels of 3.3V, logic signals of 12V, OC gates (open collector gates), optical coupling isolation, etc., and for signals of different levels, corresponding interface circuits are often required, otherwise, signals cannot be effectively transmitted or received.

For example, in an industrial machine vision defect detection system, the included hardware devices include: camera, light source controller, encoder, PLC (programmable logic) controller. The camera comprises an area-array camera and a line-array camera, wherein most external trigger signals adopted by the area-array camera are TTL (transistor-transistor logic) logic levels of 5V, and most input control signals of the line-array camera are RS422 differential signals; because the light source controller does not have a unified standard at present, input signals of the light source controller comprise TTL logic levels, RS422 differential signals or optical coupling open-circuit signals, and output end signals of the light source controller comprise TTL logic levels, RS422 differential outputs and the like; the signal output by the encoder after sensing the speed of the motion system is generally an RS422 differential signal; the signal output by the PLC is generally an OC gate, i.e., an open collector method is generally adopted.

Fig. 3 is a block diagram of a method for implementing level signal conversion in the prior art. A prior art method for implementing level signal conversion is given in fig. 3: for realizing logic level or differential signal input and/or for realizing logic level or differential signal output, four forms of signal conversion circuits are adopted, including four circuits: the circuit comprises a logic level input-logic level output circuit, a differential signal input-logic level output circuit, a logic level input-differential signal output circuit and a differential signal input-differential signal output circuit. Generally, a signal interface only supports a single type of signal input or output, so when an input is a logic level in an industrial control system, two different output circuits are required for outputting a differential signal or a logic level, and when the input is the differential signal, two different output circuits are required for outputting the differential signal or the logic level, and at this time, product forms of four different interfaces need to be defined, which undoubtedly increases the cost and the product types, and causes difficulty for users to select and use.

In the prior art, because the signal levels of various devices are not consistent in the same control system, multiple signal interfaces are often adopted, or devices with different interfaces are replaced, so that the application and the design of the devices or the systems become more complicated.

Disclosure of Invention

The invention provides a multi-level input/output circuit and a control method thereof. Switching different kinds of signals input at the signal input end to reach corresponding signal processing circuits respectively, and then inputting the signals in parallel into the MCU control system; the MCU control system at the signal output end outputs signals to processing circuits of different types, and then an output switch is switched to select different signal types for output; the invention solves the problem that control signals of various types of levels in an industrial control system can be input or output through the same interface.

In order to solve the above technical problem, the present invention provides a single-port multi-level input/output circuit, which comprises a single-port multi-level input circuit and a single-port multi-level output circuit,

the single-port multi-level input circuit further includes: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13 and an MCU control circuit 14;

the single-port multi-level output circuit further includes: the MCU control circuit 14, the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the output switch circuit 19;

the input switch circuit 10 is configured to receive a single-port input signal, and transmit an output signal to the optical coupler conversion circuit 11 or the differential input circuit 12 according to a first control signal output by the MCU control circuit 14;

the MCU control circuit 14 is configured to transmit the output signal of the input parallel circuit 13 to the output parallel circuit 15 after processing and operation; the MCU control circuit 14 is further configured to generate signals as required and transmit the signals to the control input switch circuit 10, the voltage selection circuit 16 and the output switch circuit 19;

the output switch circuit 19 is configured to receive a control signal three from the MCU control circuit 14, and then select a logic level signal from the logic output circuit 17 or a differential signal from the differential output circuit 18 to output a single-port output signal.

Preferably, the optical coupler conversion circuit 11 is configured to convert a logic level signal into a TTL signal and transmit the TTL signal to the input parallel circuit 13;

preferably, the differential input circuit 12 is configured to convert a differential signal into a TTL signal and transmit the TTL signal to the input parallel circuit 13;

preferably, the input parallel circuit 13 is configured to connect output TTL signals of the optical coupler conversion circuit 11 and the differential input circuit 12 in parallel and transmit the TTL signals to the MCU control circuit 14.

Preferably, the output parallel circuit 15 is configured to transmit TTL signals to the logic output circuit 17 and the differential output circuit 18 simultaneously;

preferably, the voltage selection circuit 16 is configured to receive a second control signal from the MCU control circuit 14, and output a voltage signal to the logic output circuit 17 after voltage selection;

preferably, the logic output circuit 17 is configured to receive the TTL signal of the output parallel circuit 15 and the voltage signal of the voltage conversion circuit 16, convert the TTL signal into a logic level signal, and transmit the logic level signal to the output switch circuit 19;

preferably, the differential output circuit 18 is configured to receive the TTL signal of the output parallel circuit 15, convert the TTL signal into a differential signal, and transmit the differential signal to the output switch circuit 19.

Preferably, according to the type of the single-port input signal, the MCU control circuit 14 determines that data is transmitted to the optical coupler conversion circuit 11 or the differential input circuit 12:

if the input signal is a logic level signal, the input switch circuit 10 transmits the signal to the optical coupling conversion circuit 11;

if the input signal is a differential signal, the input switch circuit 10 transmits the signal to the differential input circuit 12.

Preferably, an input circuit of the optical coupling conversion circuit 11 is connected to one output channel of the input switch circuit 10, and an output circuit of the optical coupling conversion circuit 11 is connected to one input channel of the input parallel circuit 13; the optical coupling conversion circuit 11 further includes: a photoelectric coupling device and an impedance device; the input part circuit and the output part circuit of the photoelectric coupling device are set to be in an isolated state.

Preferably, the differential input circuit 12 further includes: a differential signal receiving device.

Preferably, the voltage selection circuit 16 is a circuit formed by a two-channel multiple-selection one-to-multiple analog switch chip; under the control of the control signal two output by the MCU control circuit 14, the voltage selection circuit 16 switches on the two channels of switches at the same time and switches on a voltage signal of a certain level, and then outputs the voltage signal to the logic output circuit 17.

Preferably, the logic output circuit 17 is used for outputting logic level signals with different voltages; the highest amplitude of the output logic level signal is determined by the voltage signal of the voltage selection circuit 16; the frequency and pulse width of its output logic level signal are determined by the TTL signal of the output parallel circuit 15.

Preferably, the differential output circuit 18 further includes: a differential signaling device.

Preferably, the output switch circuit 19 selects the logic output circuit 11 or the differential output circuit 18 to output data according to the control signal three of the MCU control circuit 14;

if the control signal three is a logic level signal, selecting the logic output circuit 17 to output;

and if the control signal three is a differential signal, selecting the differential output circuit 18 to output.

In order to solve the above technical problem, the present invention further provides a control method for a single-port multi-level input/output circuit, including the following steps:

step 11: the input switch circuit 10 receives a single-port input signal and a first switch signal of a first selection switch 21, and then outputs a signal to the optical coupling conversion circuit 11 or the differential input circuit 12;

step 12: the optical coupling conversion circuit 11 converts the logic level signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the differential input circuit 12 converts the differential signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the input parallel circuit 13 connects the output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 in parallel and transmits the output TTL signals to the MCU control circuit 14;

step 13: the MCU control circuit 14 processes and calculates an output signal input into the parallel circuit 13 and transmits the output signal to the output parallel circuit 15, and meanwhile, the MCU control circuit generates a signal to control the first selection switch 21, the second selection switch 22 and the third selection switch 23 according to needs;

step 14: the output parallel circuit 15 transmits the TTL signals to the logic output circuit 17 and the differential output circuit 18 at the same time;

step 15: the voltage selection circuit 16 receives a second switching signal from the second selection switch 22, and outputs a voltage signal to the logic output circuit 17 after voltage selection; the logic output circuit 17 receives the TTL signal of the output parallel circuit 15 and the voltage signal of the voltage conversion circuit 16, converts the TTL signal into a logic level signal, and transmits the logic level signal to the output switch circuit 19; the differential output circuit 18 receives the TTL signal of the output parallel circuit 15, converts the TTL signal into a differential signal, and transmits the differential signal to the output switch circuit 19;

step 16: the output switch circuit 19 receives a switch signal three of the selection switch three 23, and then outputs a single-port output signal after selecting a logic level signal from the logic output circuit 17 or a differential signal from the differential output circuit 18;

and step 17: the first selection switch 21 outputs a first switching signal according to the first control signal of the MCU control circuit 14, the second selection switch 22 outputs a second switching signal according to the second control signal of the MCU control circuit 14, and the third selection switch 23 outputs a third switching signal according to the third control signal of the MCU control circuit 14.

Preferably, in step 11, the input switch circuit 10 determines, according to the type of the single-port input signal, that data is transmitted to the optical coupler conversion circuit 11 or the differential input circuit 12 by the first selection switch 21, and transmits the data to the optical coupler conversion circuit 11 if the input signal is a logic level signal, and transmits the data to the differential input circuit 12 if the input signal is a differential signal.

Preferably, in step 16, the output switch circuit 19 selects the logic output circuit 17 or the differential output circuit 18 for data output according to the type of the single-port output signal and determined by the switch signal three of the selection switch three 23, selects the logic output circuit 17 for output if the output signal is a logic level signal, and selects the differential output circuit 18 for output if the output signal is a differential signal.

Preferably, in the step 17,

the input end of the first selector switch 21 is connected with the MCU control circuit 14 and used for receiving a first control signal, and the output end of the first selector switch is connected with the input switch circuit 10 and used for outputting a first switch signal;

the input end of the second selection switch 22 is connected with the MCU control circuit 14 and used for receiving a second control signal, and the output end of the second selection switch is connected with the voltage selection circuit 16 and used for outputting a second switching signal;

the input end of the third selection switch 23 is connected with the MCU control circuit 14 for receiving the third control signal, and the output end is connected with the output switch circuit 19 for outputting the third switch signal.

In order to solve the above technical problem, the present invention further provides a single-port multi-level input circuit, including: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13 and an MCU control circuit 14; the input switch circuit 10 is configured to receive a single-port input signal, and transmit an output signal to the optical coupler conversion circuit 11 or the differential input circuit 12 according to a first control signal output by the MCU control circuit 14.

In order to solve the above technical problem, the present invention further provides a single-port multi-level output circuit, including: the MCU control circuit 14, the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the output switch circuit 19;

preferably, the MCU control circuit 14 is configured to transmit the output signal to the output parallel circuit 15 after processing and operation; the MCU control circuit 14 is further configured to generate signals as required and transmit the signals to the voltage selection circuit 16 and the output switch circuit 19;

preferably, the output switch circuit 19 is configured to receive a control signal three from the MCU control circuit 14, select a logic level signal from the logic output circuit 17 or a differential signal from the differential output circuit 18, and output a single-port output signal.

In order to solve the above technical problem, the present invention further provides a control method for a single-port multi-level input circuit, comprising the following steps:

step 21: the input switch circuit 10 receives a single-port input signal and a first switch signal of a first selection switch 21, and then outputs a signal to the optical coupling conversion circuit 11 or the differential input circuit 12;

step 22: the optical coupling conversion circuit 11 converts the logic level signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the differential input circuit 12 converts the differential signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the input parallel circuit 13 connects the output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 in parallel and transmits the output TTL signals to the MCU control circuit 14;

step 23: the first selection switch 21 outputs a first switching signal according to a first control signal of the MCU control circuit 14.

Preferably, in step 21, the input switch circuit 10 determines, according to the type of the single-port input signal, that data is transmitted to the optical coupler conversion circuit 11 or the differential input circuit 12 through the first selection switch 21, and transmits the data to the optical coupler conversion circuit 11 if the input signal is a logic level signal and transmits the data to the differential input circuit 12 if the input signal is a differential signal.

Preferably, in the step 23,

the input end of the first selection switch 21 is connected to the MCU control circuit 14 for receiving the first control signal, and the output end is connected to the input switch circuit 10 for outputting the first switching signal.

In order to solve the above technical problem, the present invention further provides a method for controlling a single-port multi-level output circuit, comprising the following steps:

step 31: the MCU control circuit 14 transmits the output signals to the output parallel circuit 15 after processing and operation, and simultaneously generates signals to control the second selection switch 22 and the third selection switch 23 according to the requirements;

step 32: the output parallel circuit 15 transmits the TTL signals to the logic output circuit 17 and the differential output circuit 18 at the same time;

step 33: the voltage selection circuit 16 receives a second switching signal from the second selection switch 22, and outputs a voltage signal to the logic output circuit 17 after voltage selection; the logic output circuit 17 receives the TTL signal of the output parallel circuit 15 and the voltage signal of the voltage conversion circuit 16, converts the TTL signal into a logic level signal, and transmits the logic level signal to the output switch circuit 19; the differential output circuit 18 receives the TTL signal of the output parallel circuit 15, converts the TTL signal into a differential signal, and transmits the differential signal to the output switch circuit 19;

step 34: the output switch circuit 19 receives a switch signal three of the selection switch three 23, and then outputs a single-port output signal after selecting a logic level signal from the logic output circuit 17 or a differential signal from the differential output circuit 18;

step 35: the second selection switch 22 outputs a second switching signal according to a second control signal of the MCU control circuit 14, and the third selection switch 23 outputs a third switching signal according to a third control signal of the MCU control circuit 14.

Preferably, in step 34, the output switch circuit 19 selects the logic output circuit 17 or the differential output circuit 18 for data output according to the type of the single-port output signal and determined by the switch signal three of the selection switch three 23, selects the logic output circuit 17 for output if the output signal is a logic level signal, and selects the differential output circuit 18 for output if the output signal is a differential signal.

Preferably, in said step 35, said step,

The beneficial effects of the invention include: the multi-level input signal can be input from one interface and/or output from one interface, multiple logic levels can share one interface, the input and output signal types cover differential signals and logic levels in an industrial control system through manual control or MCU control channel switching, the number of equipment interfaces is reduced, and the application occasions of the system are expanded.

Drawings

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present invention, the drawings used in the description of the embodiments or prior art will be briefly described below, it is obvious that the drawings in the following description are only a part of the embodiments or prior art, and other similar or related drawings can be obtained by those skilled in the art without creative efforts.

Fig. 1 is a block diagram of an implementation scheme of a single-port multi-level input/output circuit according to an embodiment of the present invention.

Fig. 2 is a block diagram of another implementation scheme of the single-port multi-level input/output circuit according to the embodiment of the present invention.

Fig. 3 is a block diagram of a method for implementing level signal conversion in the prior art.

Fig. 4 is a specific circuit diagram of the input switch circuit 10 and the first selection switch 21 according to the embodiment of the invention.

Fig. 5 is a specific circuit example diagram of the optical coupler conversion circuit 11, the differential input circuit 12, and the input parallel circuit 13 according to the embodiment of the present invention.

Fig. 6 is a specific circuit diagram of the MCU control circuit 14 according to an embodiment of the present invention.

Fig. 7 is a specific circuit diagram of the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18, and the second selection switch 22 according to the embodiment of the invention.

Fig. 8 is a specific circuit diagram of the output switch circuit 19 and the selection switch three 23 according to the embodiment of the invention.

Detailed Description

The present invention will be described in detail with reference to examples. The present invention will be described in further detail below to make the objects, aspects and advantages of the present invention clearer and more clear, but the present invention is not limited to these examples.

The invention provides a single-port multi-level input circuit and/or an output circuit, which comprises the following circuit components: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13 and an MCU control circuit 14; the single-port multi-level output circuit comprises: the MCU control circuit 14, the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the output switch circuit 19.

The input switch circuit 10 receives a single-port input signal, and then outputs a signal to the optical coupling conversion circuit 11 or the differential input circuit 12 according to a first control signal of the MCU control circuit 14; the optical coupling conversion circuit 11 converts the logic level signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the differential input circuit 12 converts the differential signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the input parallel circuit 13 connects the output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 in parallel and transmits the output TTL signals to the MCU control circuit 14; the MCU control circuit 14 processes and calculates the output signal of the input parallel circuit 13 and transmits the output signal to the output parallel circuit 15, and meanwhile, the MCU control circuit generates signals to control the input switch circuit 10, the voltage selection circuit 16 and the output switch circuit 19 according to the requirement; the output parallel circuit 15 transmits the TTL signals to the logic output circuit 17 and the differential output circuit 18 at the same time; the voltage selection circuit 16 receives a second control signal from the MCU control circuit 14, and outputs a voltage signal to the logic output circuit 17 after voltage selection; the logic output circuit 17 receives the TTL signal of the output parallel circuit 15 and the voltage signal of the voltage conversion circuit 16, converts the TTL signal into a logic level signal, and transmits the logic level signal to the output switch circuit 19; the differential output circuit 18 receives the TTL signal of the output parallel circuit 15, converts the TTL signal into a differential signal, and transmits the differential signal to the output switch circuit 19; the output switch circuit 19 receives the control signal three of the MCU control circuit 14, selects the logic level signal from the logic output circuit 17 or the differential signal from the differential output circuit 18, and transmits the selected signal to the single-port output signal.

The input switch circuit 10 determines that data is transmitted to the optical coupling conversion circuit 11 or the differential input circuit 12 by the MCU control circuit 14 according to the type of the single-port input signal, if the input signal is a logic level signal, the data is transmitted to the optical coupling conversion circuit 11, and if the input signal is a differential signal, the data is transmitted to the differential input circuit 12; the logic level signal refers to that the negative terminal of an input signal is connected with a signal ground or a low level, the positive terminal is a positive electrode or a high level, the positive terminal is a high level which refers to a level which is judged to be high in a digital circuit, and the voltage of the level can be 3.3V, 5V, 12V, 24V or other types of voltages; differential signals are here signals of equal amplitude and opposite phase.

One solution of the input switch circuit 10 is as follows: the main device of the circuit adopts a double-channel single-input double-output analog switch chip, or adopts two single-channel single-input double-output analog switch chips, or adopts a double-channel single-input multi-output analog switch chip, the device supports the control of channel switching, the positive voltage of a power supply is not less than the maximum voltage value of all input signals during the work, and the absolute value of the negative voltage of the power supply is not less than the absolute value of the minimum voltage value of all input signals during the work; in order to match the impedance of the input circuit or the output circuit of the input switch circuit 10, a plurality of resistors are generally disposed on the signal loop.

In a further implementation of the input switch circuit 10, the method further includes: the input end of the circuit is a single input signal, the output end can be switched to a plurality of different channels for output, the signals of the output end comprise the same type or other types of signals except logic level signals or differential signals, at the moment, the signals of different types are only required to be transmitted to corresponding processing circuits, and then the signals are connected in parallel at the input end of the input parallel circuit 13.

The input circuit of the optical coupling conversion circuit 11 is connected with one of the output channels of the input switch circuit 10, and the output circuit is connected with one of the input channels of the input parallel circuit 13; the optical coupling conversion circuit 11 mainly comprises an optical coupling device and a plurality of impedance devices, and an input part circuit and an output part circuit of the optical coupling device are generally isolated; the input circuit part of the photoelectric coupling device is generally a photodiode, the photodiode forms the input circuit part through a series current-limiting resistor, a parallel filter capacitor and a parallel anti-reverse diode, the output circuit part of the photoelectric coupling device can be an open collector gate (also called an OC gate) or a logic conversion circuit, if the output circuit part is the OC gate, a pull-up resistor is needed to be at a high level, and if the output circuit part is the logic conversion circuit, a pull-down resistor is selected to be at a signal ground.

The differential input circuit 12 mainly comprises a differential signal receiving device, wherein the differential signal receiving device is generally an RS422 receiving chip or an RS485 receiving chip, or a circuit formed by chips meeting RS422 or RS485 interface standards; the differential input circuit 12 further includes a resistor for performing impedance in the input circuit or the output circuit, or a resistor for voltage matching; in order to make the differential input circuit output a low-level signal when no signal arrives, the input positive terminal of the differential signal receiving device is generally connected with a resistor to a signal ground, the input negative terminal of the differential signal receiving device is generally connected with a resistor to pull up to a high level, and the output terminal of the differential signal receiving device is generally connected with a resistor to a signal ground.

The input parallel circuit 13 mainly comprises a parallel diode and a voltage regulation resistor network, the parallel diode realizes that output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 are connected in parallel, and then the output TTL signals enter the voltage regulation resistor network to carry out voltage adaptation, and the main purpose is to regulate voltage so as to meet the level requirement of an input circuit of the MCU control circuit 14.

The MCU control circuit 14 generates a control signal I to control the input switch circuit 10 according to the user requirement, generates a control signal II to control the voltage selection circuit 16 according to the user requirement, and generates a control signal III to control the output switch circuit 19 according to the user requirement; that is to say, a user can control the input switch circuit 10 through the MCU control circuit 14 when necessary, and transmit a single-port input signal to the optical coupling conversion circuit 11 or the differential input circuit 12, the user can control the voltage selection circuit 16 through the MCU control circuit 14 when necessary, and select different output voltages to transmit to the logic output circuit 17, and the user can control the output switch circuit 19 through the MCU control circuit 14 when necessary, and select a logic level signal of the logic output circuit 17 or a differential signal of the differential output circuit 18 to output, thereby finally realizing a function that the single-port output signal can output a differential signal or a logic level signal of different voltages.

The output parallel circuit 15 performs voltage adaptation and adjustment on the output TTL signal of the MCU control circuit 14, and then respectively transmits the voltage adapted and adjusted output TTL signal to the logic output circuit 17 and the differential output circuit 18, and the output parallel circuit 15 may be formed by a resistor network or a level conversion chip, so as to implement conversion of different logic voltages.

The voltage selection circuit 16 mainly functions to output voltage signals of different levels to the logic output circuit 17, wherein one implementation mode is a circuit formed by a two-channel multi-selection one-analog switch chip, multiple different level voltages to be realized are respectively connected to corresponding switch input ends in the two channels, and then under the control of the level of a control signal two of the MCU control circuit 14, the two-channel switches are simultaneously turned on and are connected to a voltage signal of a certain level, and the voltage signal is output to the logic output circuit 17.

The logic output circuit 17 realizes the output of logic level signals with different voltages, the highest amplitude of the output logic level signal is determined by the voltage signal of the voltage selection circuit 16, and the frequency and the pulse width of the output logic level signal are determined by the TTL signal of the output parallel circuit 15; the logic output circuit 17 may adopt basic circuit units such as and gates, or gates, not gates and the like in a digital circuit to form a combined circuit with a transistor or a field effect transistor, so as to realize the functions of inputting TTL signals and outputting signals with different logic levels.

The differential output circuit 18 mainly comprises a differential signal transmitting device, wherein the differential signal transmitting device is generally an RS422 transmitting chip or an RS485 transmitting chip, or a circuit formed by chips meeting RS422 or RS485 interface standards; the differential output circuit 18 further includes a resistance for impedance matching in the input circuit or the output circuit, or a resistance for voltage matching.

The output switch circuit 19 determines to select the logic output circuit 11 or the differential output circuit 18 for data output according to the type of the single-port output signal by the control signal three of the MCU control circuit 14, selects the logic output circuit 17 for output if the output signal is a logic level signal, and selects the differential output circuit 18 for output if the output signal is a differential signal.

One solution of the output switch circuit 19 is as follows: the main device of the circuit adopts a double-channel double-input single-output analog switch chip, or adopts two single-channel double-input single-output analog switch chips, or adopts a double-channel multi-input single-output analog switch chip, the device supports the control of channel switching, the positive voltage of the power supply is not less than the maximum voltage value of all input signals during the work, and the absolute value of the negative voltage of the power supply is not less than the absolute value of the minimum voltage value of all input signals during the work; in order to match the impedance of the input circuit or the output circuit of the input switch circuit 10, a plurality of resistors are generally disposed on the signal loop.

Another implementation scheme of a single-port multi-level input circuit and/or an output circuit, the circuit composition of which comprises the single-port multi-level input circuit and/or the single-port multi-level output circuit, wherein the single-port multi-level input circuit composition comprises: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13, an MCU control circuit 14 and a first selection switch; the single-port multi-level output circuit comprises the following components: the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the output switch circuit 19 further comprise a second selection switch and a third selection switch.

The input switch circuit 10 receives a single-port input signal and a first switch signal of a first selection switch 21, and then outputs a signal to the optical coupling conversion circuit 11 or the differential input circuit 12; the optical coupling conversion circuit 11 converts the logic level signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the differential input circuit 12 converts the differential signal into a TTL signal and transmits the TTL signal to the input parallel circuit 13; the input parallel circuit 13 connects the output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 in parallel and transmits the output TTL signals to the MCU control circuit 14; the MCU control circuit 14 processes and calculates an output signal input into the parallel circuit 13 and transmits the output signal to the output parallel circuit 15, and meanwhile, the MCU control circuit generates a signal to control the first selection switch 21, the second selection switch 22 and the third selection switch 23 according to needs; the output parallel circuit 15 transmits the TTL signals to the logic output circuit 17 and the differential output circuit 18 at the same time; the voltage selection circuit 16 receives a second switching signal from the second selection switch 22, and outputs a voltage signal to the logic output circuit 17 after voltage selection; the logic output circuit 17 receives the TTL signal of the output parallel circuit 15 and the voltage signal of the voltage conversion circuit 16, converts the TTL signal into a logic level signal, and transmits the logic level signal to the output switch circuit 19; the differential output circuit 18 receives the TTL signal of the output parallel circuit 15, converts the TTL signal into a differential signal, and transmits the differential signal to the output switch circuit 19; the output switch circuit 19 receives a switch signal three of the selection switch three 23, selects a logic level signal from the logic output circuit 17 or a differential signal of the differential output circuit 18 and transmits the selected signal to the single-port output signal; the first selection switch 21 outputs a first switching signal according to the first control signal of the MCU control circuit 14, the second selection switch 22 outputs a second switching signal according to the second control signal of the MCU control circuit 14, and the third selection switch 23 outputs a third switching signal according to the third control signal of the MCU control circuit 14.

The optical coupling conversion circuit 11, the differential input circuit 12, the input parallel circuit 13, the output parallel circuit 15, the logic output circuit 17, and the differential output circuit 18 in the single-port multi-level input circuit and/or the output circuit described above have the same functions as those in the first implementation scheme, and are not described herein again, except that the input switch circuit 10, the MCU control circuit 14, the voltage selection circuit 16, the output switch circuit 19, the first selection switch 21, the second selection switch 22, and the third selection switch 23, which are further described below.

The input switch circuit 10 determines data to be transmitted to the optical coupling conversion circuit 11 or the differential input circuit 12 by the first selection switch 21 according to the type of the single-port input signal, if the input signal is a logic level signal, the data is transmitted to the optical coupling conversion circuit 11, and if the input signal is a differential signal, the data is transmitted to the differential input circuit 12; the logic level signal refers to that the negative terminal of an input signal is connected with a signal ground or a low level, the positive terminal is a positive electrode or a high level, the positive terminal is a high level which refers to a level which is judged to be high in a digital circuit, and the voltage of the level can be 3.3V, 5V, 12V, 24V or other types of voltages; differential signals are here signals of equal amplitude and opposite phase.

The MCU control circuit 14 generates a control signal I to control the first selection switch 21 according to the user requirement, generates a control signal II to control the second selection switch 22 according to the user requirement, and generates a control signal III to control the third selection switch 23 according to the user requirement; that is to say, a user can manually control or control the first selection switch 21 through the MCU control circuit 14 when necessary, and transmit a single-port input signal to the opto-coupler switching circuit 11 or the differential input circuit 12, the user can manually control or control the second selection switch through the MCU control circuit 14 when necessary, and select different output voltages to transmit to the logic output circuit 17, the user can manually control or control the output switch circuit 19 through the MCU control circuit 14 when necessary, and select a logic level signal of the logic output circuit 17 or a differential signal of the differential output circuit 18 to output, thereby finally realizing a function that the single-port output signal can output the differential signal or the logic level signal of different voltages.

The input end of the first selection switch 21 is connected with the MCU control circuit 14 and used for receiving a first control signal, and the output end of the first selection switch is connected with the input switch circuit 10 and used for outputting a first switch signal; the first selection switch 21 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the input switch circuit 10, the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

The voltage selection circuit 16 mainly functions to output voltage signals of different levels to the logic output circuit 17, wherein one implementation mode is a circuit formed by a two-channel multi-selection one-analog switch chip, multiple different level voltages to be implemented are respectively connected to corresponding switch input ends in two channels, and then under the control of the level of a second switch signal of the second selection switch 22, the two-channel switches are simultaneously conducted and are connected to a voltage signal of a certain level, and the voltage signal is output to the logic output circuit 17.

The output switch circuit 19 determines to select the logic output circuit 11 or the differential output circuit 18 for data output according to the type of the single-port output signal by the switch signal three of the selection switch three 13, selects the logic output circuit 17 for output if the output signal is a logic level signal, and selects the differential output circuit 18 for output if the output signal is a differential signal.

Preferably, the input end of the second selection switch 22 is connected to the MCU control circuit 14 for receiving the second control signal, and the output end is connected to the voltage selection circuit 16 for outputting the second switch signal; the second selection switch 22 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the voltage selection circuit 16, the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

Preferably, the input end of the third selection switch 23 is connected to the MCU control circuit 14 for receiving the third control signal, and the output end is connected to the output switch circuit 19 for outputting the third switch signal; the third selection switch 23 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the output switch circuit 19, and the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

In order to solve the problem of multi-level single-port input or multi-level single-port output, the invention provides a single-port multi-level input and/or output circuit. Switching different kinds of signals input at the signal input end to reach corresponding signal processing circuits respectively, and then inputting the signals in parallel into the MCU control system; the MCU control system at the signal output end outputs signals to processing circuits of different types, and then an output switch is switched to select different signal types for output; the invention solves the problem that control signals of various types of levels in an industrial control system can be input or output through the same interface.

For contrast with the present invention, fig. 3 shows a method for implementing level signal conversion in the prior art, and four forms of signal conversion circuits are adopted for implementing logic level or differential signal input and/or for implementing logic level or differential signal output, including four circuits: the circuit comprises a logic level input-logic level output circuit, a differential signal input-logic level output circuit, a logic level input-differential signal output circuit and a differential signal input-differential signal output circuit. Generally, a signal interface only supports a single type of signal input or output, so when an input is a logic level in an industrial control system, two different output circuits are required for outputting a differential signal or a logic level, and when the input is the differential signal, two different output circuits are required for outputting the differential signal or the logic level, and at this time, product forms of four different interfaces need to be defined, which undoubtedly increases the cost and the product types, and causes difficulty for users to select and use.

The circuit implementation of this application has three kinds, contains: 1. a single-port multi-level input circuit; 2. a single-port multi-level output circuit; 3. the circuit comprises a single-port multi-level input circuit and an output circuit. That is, the single-port multi-level input circuit and/or the output circuit in the present application will be described below with reference to fig. 1 to 8, which can be applied to three applications by those skilled in the art according to the present application.

Example 1:

The technical solution adopted by this embodiment to solve its technical problem is composed of a single-port multi-level input circuit and/or a single-port multi-level output circuit, wherein the single-port multi-level input circuit is composed of: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13 and an MCU control circuit 14; the single-port multi-level output circuit comprises: the MCU control circuit 14, the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the output switch circuit 19.

The input switch circuit 10 determines, by the MCU control circuit 14, that data is transmitted to the opto-coupler switching circuit 11 or the differential input circuit 12 according to the type of the single-port input signal, and transmits the data to the opto-coupler switching circuit 11 if the input signal is a logic level signal, and transmits the data to the differential input circuit 12 if the input signal is a differential signal; the logic level signal refers to that the negative terminal of an input signal is connected with a signal ground or a low level, the positive terminal is a positive electrode or a high level, the positive terminal is a high level which refers to a level which is judged to be high in a digital circuit, and the voltage of the level can be 3.3V, 5V, 12V, 24V or other types of voltages; differential signals are here signals of equal amplitude and opposite phase.

One solution for the input switching circuit 10 is: the main device of the circuit adopts a double-channel single-input double-output analog switch chip, or adopts two single-channel single-input double-output analog switch chips, or adopts a double-channel single-input multi-output analog switch chip, the device supports the control of channel switching, the positive voltage of a power supply is not less than the maximum voltage value of all input signals during the work, and the absolute value of the negative voltage of the power supply is not less than the absolute value of the minimum voltage value of all input signals during the work; in order to match the impedance of the input circuit or the output circuit of the input switch circuit 10, a plurality of resistors are generally disposed on the signal loop.

An input circuit of the optical coupling conversion circuit 11 is connected with one of output channels of the input switch circuit 10, and an output circuit is connected with one of input channels of the input parallel circuit 13; the optical coupling conversion circuit 11 mainly comprises an optical coupling device and a plurality of impedance devices, an input part circuit and an output part circuit of the optical coupling device are generally isolated, the input circuit part of the optical coupling device is generally a photodiode, the photodiode forms the input circuit part through a series current limiting resistor, a parallel filter capacitor and a parallel anti-reverse diode, the output part circuit of the optical coupling device can be a collector open circuit gate (also called as an OC gate) or a logic conversion circuit, if the output part circuit is the OC gate, a pull-up resistor is needed to reach a high level, and if the output part circuit is the logic conversion circuit, a pull-down resistor is selected to reach a signal ground.

The input parallel circuit 13 mainly includes a parallel diode and a voltage regulation resistor network, the parallel diode realizes that output TTL signals of the optocoupler conversion circuit 11 and the differential input circuit 12 are connected in parallel, and then enter the voltage regulation resistor network for voltage adaptation, and the main purpose is to regulate voltage to meet the level requirement of the input circuit of the MCU control circuit 14.

The output parallel circuit 15 performs voltage adaptation and adjustment on the output TTL signal of the MCU control circuit 14, and then respectively transmits the voltage adapted and adjusted output TTL signal to the logic output circuit 17 and the differential output circuit 18, and the output parallel circuit 15 may be formed of a resistor network or a level conversion chip, so as to implement conversion of different logic voltages.

The voltage selection circuit 16 mainly functions to output voltage signals of different levels to the logic output circuit 17, wherein one implementation manner is a circuit formed by a two-channel multi-selection analog switch chip, multiple different level voltages to be implemented are respectively connected to corresponding switch input ends in the two channels, and then under the control of the level of a control signal two of the MCU control circuit 14, the two-channel switches are simultaneously turned on and connected to a voltage signal of a certain level, so as to output the voltage signal to the logic output circuit 17.

The output switch circuit 19 selects the logic output circuit 11 or the differential output circuit 18 for data output according to the type of the single-port output signal determined by the control signal three of the MCU control circuit 14, selects the logic output circuit 17 for output if the output signal is a logic level signal, and selects the differential output circuit 18 for output if the output signal is a differential signal.

Example 2:

fig. 2 is a block diagram of another implementation of the single-port multi-level input/output circuit according to the embodiment of the present invention.

Another implementation scheme of the single-port multi-level input circuit and/or the single-port multi-level output circuit comprises the following circuit components: the circuit comprises an input switch circuit 10, an optical coupling conversion circuit 11, a differential input circuit 12, an input parallel circuit 13, an MCU control circuit 14 and a first selection switch 21; the single-port multi-level output circuit comprises the following components: the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18, the output switch circuit 19, the second selection switch 22, and the third selection switch 23.

The optical coupling conversion circuit 11, the differential input circuit 12, the input parallel circuit 13, the output parallel circuit 15, the logic output circuit 17, and the differential output circuit 18 in the single-port multi-level input circuit and/or the output circuit have the same functions as those of the first implementation scheme, and are not described herein again, except that the input switch circuit 10, the MCU control circuit 14, the voltage selection circuit 16, the output switch circuit 19, the first selection switch 21, the second selection switch 22, and the third selection switch 23, which are further described below.

The input switch circuit 10 determines that data is transmitted to the optical coupling conversion circuit 11 or the differential input circuit 12 by the first selection switch 21 according to the type of the single-port input signal, if the input signal is a logic level signal, the data is transmitted to the optical coupling conversion circuit 11, and if the input signal is a differential signal, the data is transmitted to the differential input circuit 12; the logic level signal refers to that the negative terminal of an input signal is connected with a signal ground or a low level, the positive terminal is a positive electrode or a high level, the positive terminal is a high level which refers to a level which is judged to be high in a digital circuit, and the voltage of the level can be 3.3V, 5V, 12V, 24V or other types of voltages; differential signals are here signals of equal amplitude and opposite phase.

The input end of the first selector switch 21 is connected with the MCU control circuit 14 and used for receiving a first control signal, and the output end of the first selector switch is connected with the input switch circuit 10 and used for outputting a first switch signal; the first selection switch 21 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the input switch circuit 10, the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

The voltage selection circuit 16 mainly functions to output voltage signals of different levels to the logic output circuit 17, wherein one implementation manner is a circuit formed by a two-channel multi-selection analog switch chip, multiple different level voltages to be implemented are respectively connected to corresponding switch input ends in the two channels, and then under the control of the level of the switch signal two of the second selection switch 22, the two-channel switches are simultaneously conducted and are connected to a voltage signal of a certain level, and the voltage signal is output to the logic output circuit 17.

The output switch circuit 19 selects the logic output circuit 11 or the differential output circuit 18 to output data according to the type of the single-port output signal determined by the switch signal three of the selection switch three 13, selects the logic output circuit 17 to output if the output signal is a logic level signal, and selects the differential output circuit 18 to output if the output signal is a differential signal.

Preferably, the input end of the second selection switch 22 is connected to the MCU control circuit 14 for receiving the second control signal, and the output end is connected to the voltage selection circuit 16 for outputting the second switching signal; the second selection switch 22 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the voltage selection circuit 16, the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

Preferably, the input end of the third selection switch 23 is connected to the MCU control circuit 14 for receiving the third control signal, and the output end is connected to the output switch circuit 19 for outputting the third switching signal; the third selection switch 23 may be composed of a dial switch and a matching resistor network, where one end of the dial switch is connected to the output switch circuit 19, and the series resistor is connected to the signal ground, and the other end is pulled up to a high level through the resistor.

Example 3:

as shown in fig. 4, 5, 6, 7, and 8, a specific circuit implementation of the present invention is shown, and two independent single-port multi-level input circuits and two independent output circuits are implemented; the input signal supports logic level input and differential signal input, and the high level voltage range of the logic level supports +3.3V to + 24V; the output signal supports logic level and differential signal output, and the output logic level voltage supports +5V and + 24V.

A specific circuit example of the input switch circuit 10 and the first selection switch 21 is given in fig. 4. A specific circuit example diagram of the optical coupler conversion circuit 11, the differential input circuit 12, and the input parallel circuit 13 is given in fig. 5. A specific circuit example diagram of the MCU control circuit 14 is given in fig. 6. A specific circuit example diagram of the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18 and the second selection switch 22 is shown in fig. 7. Fig. 8 shows a specific circuit example of the output switch circuit 19 and the selection switch three 23.

In fig. 4, the input switch circuit 10 includes resistors R5, R9, R6, R9, and analog switch chips U1 and U2; the circuit composition of the first selection switch 21 includes resistors R1, R2, R3, R4, R7, R8, and dip switches S1 and S2, and the signal SELT-RE1 and the signal SELT-RE2 are control signals one of the MCU control circuit 14 (shown in fig. 6); the signals OPT _ RE1+, OPT _ RE1-, OPT _ RE2+, OPT _ RE 2-are output logic level signals of the input switch circuit 10, and are connected to the optical coupler conversion circuit 11 (as shown in fig. 5), and the signals RS422_ RE1+, RS422_ RE1-, RS422_ RE2+, RS422_ RE 2-are differential signals of the output of the input switch circuit 10, and are connected to the differential input circuit 12 (as shown in fig. 5).

IN fig. 4, J1 is a first single-port input signal IN1, J2 is a second single-port input signal IN2, resistors R5, R9, R6, and R10 are input matching resistors, chip U1 and chip U2 are dual-channel single-input dual-output analog switch chips, model number is ADG5436BRUZ, supply voltage is 24V, control signals of pin 1 and pin 9 of U1 and U2 are used for switching channels, pin 3 and pin 11 of U1 and U2 are two electrodes of a single-port input signal, logic level input is positive and negative, differential signal input is positive and negative of differential input, pin 2 and pin 10 of U1 and U2 are output logic level signal pins of input switch circuit 10, pin 4 and pin 12 of U1 and U2 are differential signal output pins of input switch circuit 10; the single port input signal is output from the logic level signal interface when pin 1 and pin 9 of U1 and U2 are high, and the single port input signal is output from the differential signal interface when pin 1 and pin 9 of U1 and U2 are low.

Fig. 5 shows a specific circuit example of the optical coupling conversion circuit 11, the differential input circuit 12 and the input parallel circuit 13, wherein the optical coupling conversion circuit 11 comprises resistors R11, R18, R14 and R15, diodes D1 and D4, capacitors C1 and C2, and an optical coupler U3 with the model of HCPL 2232. The photoelectric coupling device U3 forms two independent optical coupling conversion circuits, the input circuit part is a photodiode which carries out current limiting through series current limiting resistors R11 and R18, parallel filter capacitors C1 and C2 and parallel anti-reverse connection diodes D1 and D4 form the input circuit part, and the output part circuit of the photoelectric coupling device is a logic conversion circuit and is pulled down to signal ground through resistors R14 and R15.

The differential input circuit 12 in fig. 5 includes resistors R19, R20, R21, R22, R23, R24, R25, R26, R27, and R28, and a differential receiving device U4, U4 with a model of MAX3095 CSE; u4 is an RS422 differential receiving chip, resistors R19 and R20 are pull-down resistors for pulling down the positive pole of the differential input to the signal ground, resistors R27 and R28 are pull-up resistors for pulling up the negative pole of the differential input to the high level +5V, and resistors R23 and R24 are matching resistors between the positive pole of the input and the negative pole of the input; the resistors R25 and R26 are pull-down resistors of two paths of output signals.

The input parallel circuit 13 in fig. 5 comprises diodes D2, D3, D5 and D6, and resistors R12, R13, R16 and R17; the diodes D2, D3, D5 and D6 are output parallel diodes of the optical coupler conversion circuit 11 and the differential output circuit 12, so that output TTL signals of the optical coupler conversion circuit 11 and the differential input circuit 12 are connected in parallel, the resistors R12, R13, R16 and R17 are voltage regulation resistor networks, and the voltage is mainly regulated to meet the level requirement of the input circuit of the MCU control circuit 14.

Fig. 6 shows a specific circuit example of the MCU control circuit 14, a core processing chip of the MCU control circuit 14 may adopt an FPGA, a single chip, an ARM, or a CPU, and here, only a few main pins used by the control circuit are shown, and a person skilled in the art should be able to write related logic control programs through the pin functions to implement the required functions, and a detailed description is omitted here.

Fig. 7 shows a specific circuit example of the output parallel circuit 15, the voltage selection circuit 16, the logic output circuit 17, the differential output circuit 18, and the second selection switch 22.

The output parallel circuit 15 in fig. 7 includes resistors R41, R42, R43, and R44, and the signals MCU _ TR1 and MCU _ TR2 are output TTL signals of the MCU control circuit 14, and are respectively transmitted to the logic output circuit 17 and the differential output circuit 18 after voltage adaptation and adjustment are performed by the resistors R41, R42, R43, and R44.

The voltage selection circuit 16 in fig. 7 is composed of resistors R51, R52, R55, R56, a chip U9, and reference voltages +5V and + 24V; the chip U9 is a two-channel one-out-of-two analog switch chip with the model number of ADG5436BRUZ and the working voltage of + 24V; the voltage selection circuit 16 realizes a function of outputting one of voltage levels to the logic output circuit 17 under the control of the level of the control signal two of the MCU control circuit 14, wherein the voltage signal of two different levels, namely +5V and + 24V;

the logic output circuit 17 in fig. 7 includes chips U8, U10, resistors R49, R50, R57, R58, transistors V1, V2, magnetic beads L1, L2; the resistors R50 and R57 receive the output voltage signal of the voltage selection circuit 16, the chips U8 and U10 are NOR gate integrated chips, receive the output TTL signal of the output parallel circuit 15, and drive the transistors V1 and V2, so that the pulse width and the period of the output logic level signal and the input TTL signal are synchronous.

The differential output circuit 18 in fig. 7 is composed of resistors R39, R40, a chip U7; the chip U7 is a differential signal transmitting device meeting the RS422 signal standard, and the model is MAX3041 ESE;

the second selection switch 22 in fig. 7 comprises resistors R45, R46, R47, R48, R53 and R54, and toggle switches S5 and S6; one end of each of the resistors R53 and R54 is connected to a second control signal of the MCU control circuit 14, here, the signal names of the resistors LOGIC1 and LOGIC2, one end of each of the dip switches S5 and S6 is pulled up to a high level through pull-up resistors R46 and R48, and one end of each of the dip switches S5 and S6 is pulled down to a signal ground through resistors R45 and R47, and meanwhile, connection points of the dip switches S5 and S6 and the resistors R45 and R46 are connected to resistors R53 and R54, respectively, and a second switch signal is output and connected to the voltage selection circuit 16.

Fig. 8 shows a specific circuit example of the output switch circuit 19 and the selection switch three 23.

The output switch circuit 19 in fig. 8 is composed of resistors R33, R37, R34, R38, an analog switch chip U5 and U6; the signals OPT _ TR1+, OPT _ TR1-, OPT _ TR2+, OPT _ TR 2-are input logic level signals of the output switch circuit 19, connected to the logic output circuit 17 (shown in fig. 7), and the signals RS422_ TR1+, RS422_ TR1-, RS422_ TR2+, RS422_ TR 2-are differential signals of the input of the output switch circuit 19, connected to the differential output circuit 18 (shown in fig. 7).

The third selection switch 23 in fig. 8 includes resistors R29, R30, R31, R32, R35, R36, toggle switches S3, S4, and resistors R35, R36, one end of which is connected to the control signal three of the MCU control circuit 14, here the signal names SELT _ TR1, SELT _ TR2, one end of the toggle switches S3, S4 is pulled up to high level through pull-up resistors R30 and R32, and one end is pulled down to signal ground through resistors R29 and R31, meanwhile, the connection points of the toggle switches S3 and S4 and the resistors R29 and R31 are connected to resistors R35 and R36, respectively, and the third output switch signal is connected to the output switch circuit 19.

In fig. 8, J3 is a single-port output signal OUT1, J4 is a single-port output signal OUT2, resistors R33, R37, R34 and R38 are input matching resistors, chip U5 and chip U6 are dual-channel dual-input single-output analog switch chips, model number ADG5436BRUZ, supply voltage is 24V, control signals of pin 1 and pin 9 of U5 and U6 are used for switching channels, pin 3 and pin 11 of U5 and U6 are two electrodes of the single-port output signal, pin 2 and pin 10 of U5 and U6 are output logic level signal pins of the logic output circuit 17, and pin 4 and pin 12 of U5 and U6 are differential signal output pins of the differential output circuit 18; the single-port output signal selects a logic level signal to be output from the interface when pins 1 and 9 of U5 and U6 are at a high level, and selects a differential signal to be output from the interface when pins 1 and 9 of U5 and U6 are at a low level.

Although the present invention has been described with reference to a few embodiments, it should be understood that the present invention is not limited to the above embodiments, but rather, the present invention is not limited to the above embodiments, and those skilled in the art can make various changes and modifications without departing from the scope of the invention.

Claims

1. A single-port multi-level input/output circuit comprises a single-port multi-level input circuit and a single-port multi-level output circuit,

the single-port multi-level input circuit further includes: the circuit comprises an input switch circuit (10), an optocoupler conversion circuit (11), a differential input circuit (12), an input parallel circuit (13) and an MCU control circuit (14);

the single-port multi-level output circuit further includes: the circuit comprises an MCU control circuit (14), an output parallel circuit (15), a voltage selection circuit (16), a logic output circuit (17), a differential output circuit (18) and an output switch circuit (19);

the input switch circuit (10) is used for receiving a single-port input signal and outputting a signal to the optocoupler conversion circuit (11) or the differential input circuit (12) according to the state of a control signal I output by the MCU control circuit (14);

the MCU control circuit (14) is used for transmitting the output signal of the input parallel circuit (13) to the output parallel circuit (15) after processing and operation; the MCU control circuit (14) is further used for generating signals according to needs and transmitting the signals to the control input switch circuit (10), the voltage selection circuit (16) and the output switch circuit (19);

and the output switch circuit (19) is used for receiving a control signal III of the MCU control circuit (14), and then selecting a logic level signal from the logic output circuit (17) or a differential signal of the differential output circuit (18) to output a single-port output signal.

2. The single-port multi-level input-output circuit according to claim 1,

the optical coupler conversion circuit (11) is used for converting the logic level signal into a TTL signal and transmitting the TTL signal to the input parallel circuit (13);

the differential input circuit (12) is used for converting differential signals into TTL signals and transmitting the TTL signals to the input parallel circuit (13);

and the input parallel circuit (13) is used for connecting output TTL signals of the optocoupler conversion circuit (11) and the differential input circuit (12) in parallel and transmitting the output TTL signals to the MCU control circuit (14).

3. The single-port multi-level input-output circuit according to claim 1,

the output parallel circuit (15) is used for simultaneously transmitting TTL signals to the logic output circuit (17) and the differential output circuit (18);

the voltage selection circuit (16) is used for receiving a control signal II from the MCU control circuit (14), and then outputting a voltage signal to the logic output circuit (17) after voltage selection;

the logic output circuit (17) is used for receiving the TTL signal of the output parallel circuit (15) and the voltage signal of the voltage conversion circuit (16), converting the TTL signal into a logic level signal and transmitting the logic level signal to the output switch circuit (19);

the differential output circuit (18) is used for receiving the TTL signals of the output parallel circuit (15), converting the TTL signals into differential signals and transmitting the differential signals to the output switch circuit (19).

4. The single-port multilevel input-output circuit according to claim 1, wherein the MCU control circuit (14) determines whether data is transmitted to the optical coupler conversion circuit (11) or the differential input circuit (12) according to a type of a single-port input signal:

if the input signal is a logic level signal, the input switch circuit (10) transmits the signal to the optical coupling conversion circuit (11);

if the input signal is a differential signal, the input switch circuit (10) transmits the signal to a differential input circuit (12).

5. The single-port multi-level input-output circuit according to claim 1, wherein an input circuit of the optical coupling conversion circuit (11) is connected with one output channel of the input switch circuit (10), and an output circuit of the optical coupling conversion circuit (11) is connected with one input channel of the input parallel circuit (13); the optical coupling conversion circuit (11) further comprises: a photoelectric coupling device and an impedance device; the input part circuit and the output part circuit of the photoelectric coupling device are set to be in an isolated state.

6. The single-port multilevel input-output circuit of claim 1, wherein the differential input circuit (12) further comprises: a differential signal receiving device.

7. The single-port multi-level input-output circuit according to claim 1, wherein the voltage selection circuit (16) is formed by a two-channel multi-selection one-selection analog switch chip; and the voltage selection circuit (16) is controlled by a control signal II output by the MCU control circuit (14), and switches of two channels are simultaneously conducted and switched on to a voltage signal of a certain level, and then the voltage signal is output to the logic output circuit (17).

8. The single-port multi-level input-output circuit according to claim 1, wherein the logic output circuit (17) is configured to output logic level signals of different voltages; the highest amplitude of the output logic level signal is determined by the voltage signal of the voltage selection circuit (16); the frequency and the pulse width of the output logic level signal are determined by the TTL signal of the output parallel circuit (15).

9. The single-port multilevel input-output circuit according to claim 1, wherein the differential output circuit (18) further comprises: a differential signaling device.

10. The single-port multi-level input-output circuit according to claim 1, wherein the output switch circuit (19) selects the logic output circuit (11) or the differential output circuit (18) for data output according to the control signal three determination of the MCU control circuit (14);

if the control signal three is a logic level signal, selecting the logic output circuit (17) to output;

and if the control signal III is a differential signal, selecting the differential output circuit (18) to output.

11. A control method of a single-port multi-level input-output circuit is characterized by comprising the following steps:

step 11: the input switch circuit (10) receives a single-port input signal and a first switch signal of a first selection switch (21), and then outputs a signal to the optical coupling conversion circuit (11) or the differential input circuit (12);

step 12: the optical coupling conversion circuit (11) converts the logic level signal into a TTL signal and transmits the TTL signal to the input parallel circuit (13); the differential input circuit (12) converts the differential signal into a TTL signal and transmits the TTL signal to the input parallel circuit (13); an input parallel circuit (13) connects output TTL signals of the optocoupler conversion circuit (11) and the differential input circuit (12) in parallel and then transmits the output TTL signals to an MCU control circuit (14);

step 13: the MCU control circuit (14) transmits output signals input into the parallel circuit (13) to the output parallel circuit (15) after processing and operation, and simultaneously generates signals to control the first selection switch (21), the second selection switch (22) and the third selection switch (23) according to needs;

step 14: the output parallel circuit (15) transmits the TTL signals to the logic output circuit (17) and the differential output circuit (18) at the same time;

step 15: the voltage selection circuit (16) receives a second switch signal from the second selection switch (22), and outputs a voltage signal to the logic output circuit (17) after voltage selection; the logic output circuit (17) receives the TTL signal of the output parallel circuit (15) and the voltage signal of the voltage conversion circuit (16), converts the TTL signal into a logic level signal and transmits the logic level signal to the output switch circuit (19); the differential output circuit (18) receives the TTL signals of the output parallel circuit (15), converts the TTL signals into differential signals and transmits the differential signals to the output switch circuit (19);

step 16: the output switch circuit (19) receives a switch signal III of the selection switch III (23), and then selects a logic level signal from the logic output circuit (17) or a differential signal of the differential output circuit (18) to output a single-port output signal;

and step 17: the first selection switch (21) outputs a first switching signal according to the first control signal of the MCU control circuit (14), the second selection switch (22) outputs a second switching signal according to the second control signal of the MCU control circuit (14), and the third selection switch (23) outputs a third switching signal according to the third control signal of the MCU control circuit (14).

12. The control method of the single-port multi-level input-output circuit according to claim 11, wherein in the step 11, the input switch circuit (10) determines data to be transmitted to the optical coupling conversion circuit (11) or the differential input circuit (12) by the first selection switch (21) according to the type of the single-port input signal, and transmits the data to the optical coupling conversion circuit (11) if the input signal is a logic level signal and transmits the data to the differential input circuit (12) if the input signal is a differential signal.

13. The control method of the single-port multi-level input-output circuit according to claim 11, wherein in the step 16, the output switch circuit (19) selects the logic output circuit (17) or the differential output circuit (18) to output data according to the type of the single-port output signal determined by the switch signal three of the selection switch three (23), if the output signal is a logic level signal, the logic output circuit (17) is selected to output, and if the output signal is a differential signal, the differential output circuit (18) is selected to output.

14. The method for controlling a single-port multi-level input-output circuit according to claim 11, wherein in the step 17,

the input end of the first selector switch (21) is connected with the MCU control circuit (14) and used for receiving a first control signal, and the output end of the first selector switch is connected with the input switch circuit (10) and used for outputting a first switch signal;

the input end of the second selection switch (22) is connected with the MCU control circuit (14) and used for receiving a second control signal, and the output end of the second selection switch is connected with the voltage selection circuit (16) and used for outputting a second switching signal;

the input end of the selection switch III (23) is connected with the MCU control circuit (14) and used for receiving the control signal III, and the output end of the selection switch III is connected with the output switch circuit (19) and used for outputting the switch signal III.