A position pulse generating circuit and driving method thereof

Abstract

The embodiment of the present invention discloses a position pulse generating circuit and a driving method thereof. The main control module receives a level selection control signal transmitted by a host computer, and transmits the level selection control signal to a selection chip. The selection chip selects an output terminal to output an on or off control signal according to a signal received at an input terminal. A switch unit in the selection circuit is turned on or off according to a control signal received at its own control terminal, so that a pulse level selection circuit can select different first external voltage signals, thereby realizing flexible switching of levels of different specifications. The resistance value of the first resistor is positively correlated with the amplitude of a pulse signal formed by a first external voltage signal connected to the first terminal of the corresponding switch unit and a second external voltage signal connected to the second input terminal of an optocoupler isolation circuit. When different switch units in the pulse level selection circuit are turned on, the first resistor in the current limiting circuit can play a good current limiting role, thereby realizing compatibility of levels of different specifications.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of motor drive technology, and in particular to a position pulse generating circuit and a driving method. Background Art

[0002] With the development of industrial automation, the pulse input amplitude of servo drives has also increased to multiple level specifications.

[0003] However, the position pulse generating circuit in the existing servo drive is incompatible with levels of different specifications, which is not conducive to achieving flexible control of the motor. Summary of the invention

[0004] The present invention provides a position pulse generating circuit and a driving method thereof, so as to achieve compatibility with different level specifications and flexibly switch levels of different specifications.

[0005] In a first aspect, an embodiment of the present invention provides a position pulse generating circuit, comprising: a main control module, at least one pulse level selecting circuit, the pulse level selecting circuit comprising a selecting chip and n selecting circuits, n being an even number greater than or equal to 2; the position pulse generating circuit further comprising a position pulse input circuit corresponding to the selecting circuits one by one;

[0006] The main control module includes an input end and an output end. The main control module is connected to the host computer through the input end. The output end of the main control module is electrically connected to the input end of the selection chip. The main control module is used to receive the level selection control signal transmitted by the host computer and transmit the level selection control signal to the selection chip.

[0007] The selection circuit includes at least two switch units, wherein the control end of each switch unit is electrically connected to the output end of the selection chip in a one-to-one correspondence, and the selection chip is used to select the output end to output a turn-on or turn-off control signal according to the signal received at the input end; the first end of each switch unit in the same selection circuit is used to access a different first external voltage signal, and the switch unit is used to turn on or off according to the signal at its own control end;

[0008] The position pulse input circuit includes a current limiting circuit and an optocoupler isolation circuit, the optocoupler isolation circuit includes a first input end, a second input end, and a first output end; the current limiting circuit includes a first resistor corresponding to the switch unit one by one, the first end of the first resistor is electrically connected to the second end of the corresponding switch unit; the second end of the first resistor is electrically connected to the first input end of the optocoupler isolation circuit; the second input end of the optocoupler isolation circuit is used to access a second external voltage signal, and the position pulse input circuit is used to output a pulse signal through the first output end according to the first external voltage signal and the second external voltage signal;

[0009] The resistance of the first resistor is positively correlated with the amplitude of a pulse signal formed by a first external voltage signal connected to the first end of the corresponding switch unit and a second external voltage signal connected to the second input end of the optocoupler isolation circuit.

[0010] Optionally, the optocoupler isolation circuit also includes an optocoupler sensor, the first input terminal and the second input terminal are electrically connected to the third input terminal and the fourth input terminal of the optocoupler sensor respectively, and the first output terminal is electrically connected to the output terminal of the optocoupler sensor.

[0011] Optionally, the position pulse input circuit further includes a second resistor, and the second resistor is connected in parallel between the third input terminal and the fourth input terminal of the optical coupling sensor.

[0012] Optionally, the position pulse input circuit further includes a first diode and a first capacitor, the cathode of the first diode is electrically connected to the third input terminal of the optical coupling sensor, and the anode of the first diode is electrically connected to the fourth input terminal of the optical coupling sensor;

[0013] The first capacitor is connected in parallel between the third input terminal and the fourth input terminal of the optical coupling sensor.

[0014] Optionally, the optocoupler sensor includes a primary diode, a secondary diode and a secondary transistor, wherein the positive and negative electrodes of the primary diode serve as the third input terminal and the fourth input terminal of the optocoupler sensor respectively, the anode of the secondary diode is electrically connected to the control electrode of the secondary transistor, the first electrode of the secondary transistor serves as the output terminal of the optocoupler sensor, the second electrode of the secondary transistor is grounded, the cathode of the secondary diode is electrically connected to the output terminal of the optocoupler sensor through a third resistor, the cathode of the secondary diode is also electrically connected to the third power supply voltage input terminal, and the third power supply voltage input terminal is grounded through a second capacitor.

[0015] Optionally, the switch unit is a relay, a first end of a coil of the relay is electrically connected to an output end of the main control module as a control end of the switch unit, and a second end of the coil of the relay is grounded;

[0016] One of the pair of normally open contacts of the relay is connected to the first power supply voltage as the first end of the switch unit, and the other of the pair of normally open contacts of the relay is electrically connected to the second end of the switch unit.

[0017] Optionally, the position pulse generating circuit further includes a pulse counting circuit and a PWM wave driving circuit, wherein the input end of the pulse counting circuit is electrically connected to each position pulse input circuit, the output end of the pulse counting circuit is electrically connected to the main control module, and the pulse counting circuit is used to count the pulse signal and exchange information with the main control module;

[0018] The PWM wave driving circuit is electrically connected to the main control module, and is used for outputting a motor driving signal according to a signal output by the main control module to the PWM wave driving circuit.

[0019] Optionally, the position pulse generating circuit further comprises a pulse shaping filter circuit, wherein the pulse counting circuit is electrically connected to the position pulse input circuit via the pulse shaping filter circuit;

[0020] The pulse shaping filter circuit includes a level conversion circuit and a filter circuit. The level conversion circuit includes a fifth input terminal corresponding one-to-one to the position pulse input circuit and a second output terminal corresponding one-to-one to the fifth input terminal; wherein the fifth input terminal is electrically connected to the output terminal of the corresponding position pulse input circuit respectively, and the level conversion circuit is used to perform level conversion on the first pulse signal input by the fifth input terminal and transmit it to the corresponding second output terminal. Each second output terminal corresponds to the input terminal of a filter circuit, and the output terminal of the filter circuit serves as the output terminal of the pulse shaping filter circuit. The output terminal of the pulse shaping filter circuit is electrically connected to the input terminal of the pulse counting circuit.

[0021] Optionally, the pulse level selection circuit includes a first selection circuit, a second selection circuit, and a first position pulse input terminal corresponding to the first selection circuit and a second position pulse input circuit corresponding to the second selection circuit, the input terminal of the first position pulse input circuit is electrically connected to the output terminal of the first selection circuit, and the input terminal of the second position pulse input circuit is electrically connected to the output terminal of the second selection circuit;

[0022] The number of switch units included in the first selection circuit and the second selection circuit is equal and corresponds one to one; the first end of the switch unit of the first selection circuit and the first end of the corresponding switch unit of the second selection circuit are connected to the same first external voltage signal.

[0023] Optionally, the communication mode between the main control module and the selection chip is SPI serial communication or I 2 C communication.

[0024] In a second aspect, an embodiment of the present invention further provides a method for driving a position pulse generating circuit, which is executed by a main control module in the position pulse generating circuit provided in the first aspect. The method for driving the position pulse generating circuit includes:

[0025] According to the received host computer output signal, a level selection control signal is output to the selection chip, so that the selection chip selection output terminal outputs an on or off control signal, so that the corresponding switch unit in the selection circuit is turned on or off.

[0026] The position pulse generating circuit and driving method thereof provided by the embodiment of the present invention receive the level selection control signal transmitted by the host computer through the main control module, and transmit the level selection control signal to the selection chip, the selection chip selects the output end to output the on or off control signal according to the signal received at the input end, and the switch unit in the selection circuit is turned on or off according to the control signal received at its own control end, so that the pulse level selection circuit can select different pulse signal amplitudes for output, thereby realizing flexible switching of pulse signals with different amplitudes in the input position pulse input circuit, that is, realizing flexible switching of different specification levels; and by setting the position pulse input circuit to include a current limiting circuit and an optocoupler isolation circuit, the current limiting circuit includes a first resistor electrically connected to the switch unit in a one-to-one correspondence, and the resistance of the first resistor is positively correlated with the pulse signal amplitude composed of the first external voltage signal connected to the first end of the corresponding switch unit and the second external voltage signal connected to the second input of the optocoupler isolation circuit, so that when different switch units in the pulse level selection circuit are turned on, the first resistor in the current limiting circuit can play a good current limiting role, thereby making the current input to the optocoupler isolation circuit not too large, thereby ensuring the reliability of the position pulse generating circuit, and thereby realizing compatibility with different specification levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a structural schematic diagram of a position pulse generating circuit provided by an embodiment of the present invention;

[0028] Figure 2 It is a structural schematic diagram of a pulse level selection circuit in a position pulse generating circuit provided by an embodiment of the present invention;

[0029] Figure 3 It is a structural schematic diagram of a pulse level selection circuit in another position pulse generating circuit provided by an embodiment of the present invention;

[0030] Figure 4 It is a structural schematic diagram of a position pulse input circuit in a position pulse generating circuit provided by an embodiment of the present invention;

[0031] Figure 5 is a structural schematic diagram of another position pulse generating circuit provided by an embodiment of the present invention;

[0032] Figure 6 is a structural schematic diagram of another position pulse generating circuit provided by an embodiment of the present invention;

[0033] Figure 7 yes Figure 6 The schematic diagram of the structure of the pulse shaping filter circuit;

[0034] Figure 8 is a schematic diagram of the structure of two position pulse input circuits provided by an embodiment of the present invention;

[0035] Fig. 9 It is a flow chart of a driving method of a position pulse generating circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0036] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0037] As described in the background technology, the position pulse generating circuit in the existing servo drive has the problem of incompatibility with different specification levels, which is not conducive to realizing flexible control of the motor. The inventors have found that the reason for the above problem is that in the existing position pulse generating circuit, usually only a fixed amplitude pulse signal is set to be connected, that is, a fixed specification level is connected, and there is a lack of control circuits for inputting different specification levels. Correspondingly, the parameters of each component in the position pulse generating circuit only match the fixed level, so that once the access level changes, the position pulse generating circuit cannot work normally, and due to the lack of a control circuit to control the input circuits of different specifications, the level input cannot be flexibly switched.

[0038] Based on the above problems, an embodiment of the present invention provides a position pulse generating circuit. Figure 1 is a schematic diagram of a position pulse generating circuit provided by an embodiment of the present invention, with reference to Figure 1 , the position pulse generating circuit 100 comprises:

[0039] A main control module 110, at least one pulse level selection circuit 120, the pulse level selection circuit 120 includes a selection chip 101 and n selection circuits 102, n is an even number greater than or equal to 2; the position pulse generating circuit 100 also includes a position pulse input circuit 130 corresponding to the selection circuit 102 one by one;

[0040] The main control module 110 includes an input end and an output end. The main control module 110 is connected to the host computer 200 through the input end. The output end of the main control module 110 is electrically connected to the input end of the selection chip 101. The main control module 110 is used to receive the level selection control signal transmitted by the host computer 200 and transmit the level selection control signal to the selection chip 101;

[0041] The selection circuit 120 includes at least two switch units 121, wherein the control terminal B0 of each switch unit 121 is electrically connected to the output terminal of the selection chip 101 in a one-to-one correspondence, and the selection chip 101 is used to select the output terminal to output a turn-on or turn-off control signal according to the signal received at the input terminal; the first terminal B1 of each switch unit 121 in the same selection circuit 120 is used to access different first external voltage signals, and the switch unit 121 is used to turn on or off according to the signal of its own control terminal B0;

[0042] The position pulse input circuit 130 includes a current limiting circuit 131 and an optocoupler isolation circuit 132. The optocoupler isolation circuit 132 includes a first input terminal E1, a second input terminal E2, and a first output terminal F1. The current limiting circuit 131 includes a first resistor ( Figure 1 (not shown in the figure, the connection diagram of the first resistor can refer to other embodiments of the present invention), the first end of the first resistor is electrically connected to the second end of the corresponding switch unit 121; the second end of the first resistor is electrically connected to the first input end E1 of the optocoupler isolation circuit 132; the second input end E2 of the optocoupler isolation circuit 132 is used to access the second external voltage signal, and the position pulse input circuit 130 is used to output a pulse signal through the first output end F1 according to the first external voltage signal and the second external voltage signal;

[0043] The resistance of the first resistor is positively correlated with the amplitude of a pulse signal formed by a first external voltage signal connected to the first end of the corresponding switch unit 121 and a second external voltage signal connected to the second input end of the optical coupling isolation circuit 132 .

[0044] Optionally, the main control module 110 can be implemented using a DSP chip. Different types of selection chips 101 can be selected according to different communication methods. For example, when the communication method between the main control module 110 and the selection chip 101 is SPI serial communication, the selection chip 101 can use a 74HC164 chip. When the communication method between the main control module 110 and the selection chip 200 is I 2 When the communication mode C is used, the selection chip 101 can adopt the PCA9554ADH chip. The main control module 110 receives the level selection control signal output by the host computer 200 by communicating with the host computer 200, and transmits the level selection control signal to the selection chip 101. The selection chip 101 is used to select the output end to output the on or off control signal according to the signal received at the input end. The control signal can be a control signal for controlling the switch unit 121 in the selection circuit 102 to be on or off. For example, if a certain switch unit 121 is to be controlled to be on, the on control signal is output through the output end connected to the control end of the switch unit 121. If a certain switch unit 121 is to be controlled to be off, the off control signal is output through the output end connected to the control end of the switch unit 121.

[0045] Figure 1 The position pulse generating circuit shown can be used for a servo drive, because the position pulse signals of a servo drive are usually divided into three types, namely pulse plus direction (PD mode), positive and negative pulse (CW / CCW) and AB phase orthogonal type), thereby determining the stroke and direction of the motor movement, that is, the position pulse signal usually includes two pulse signals. Therefore, the position pulse circuit provided in this embodiment includes at least two selection circuits 102, and a position pulse input circuit 130 corresponding to the selection circuit 102, thereby ensuring that the pulse signal generated by the position pulse generating circuit can be at least two, thereby ensuring that it can be applied to a servo drive.

[0046] refer to Figure 1 The selection circuit 102 in the position pulse generating circuit includes n switch units 121, where n is an even number greater than or equal to 2. Figure 1 The position pulse generating circuit includes a selection circuit 102, and each selection circuit 102 includes two switch units 121. The control terminal B0 of each switch unit 121 is connected to an output terminal of the selection chip 101, so the on or off state of each switch unit 121 is controlled by the control signal of the output terminal of the selection chip 101 electrically connected thereto. Since the selection chip 110 selects the output terminal to output the on or off control signal according to the pulse level control signal received from the main control module 110, the on or off state of the switch unit 121 is controlled by the main control module 110. The first terminal of each switch unit 121 in the same selection circuit 102 is connected to a different first external voltage signal, and the second terminal B2 of each switch unit 121 is electrically connected to the input terminal of the corresponding position pulse input circuit 130, so that when the control terminal of the switch unit 121 receives the control signal, the selection circuit 102 can select a different first external voltage signal. For example, in the present embodiment, the two switch units in the same selection circuit 102 may be respectively recorded as the first switch unit and the second switch unit). When the control end of the first switch unit receives the on-control signal of the main control module 110, the first switch unit is turned on and the second switch unit is turned off. If the control end of the second switch unit receives the on-control signal output by the main control module 110, the second switch unit is turned on and the first switch unit is turned off, thereby realizing the selection output of different first external voltage signals when different switch units are turned on.

[0047] Continue to refer Figure 1The position pulse generating circuit of the present embodiment further includes a position pulse input circuit 130, wherein the position pulse input circuit 130 further includes a current limiting circuit 131 and an optocoupler isolation circuit 132, the current limiting circuit 131 includes a first resistor electrically connected to the switch unit 121 in a one-to-one correspondence, the optocoupler isolation circuit 132 includes a first input terminal E1, a second input terminal E2 and a first output terminal F1, the first end of the first resistor is connected to the first external voltage signal, Figure 1 For the position pulse generating circuit including two pulse level selection circuits 120 shown in the figure, the first external voltage signal connected to the first pulse level selection circuit is recorded as DI1+, and the first external voltage signal connected to the second pulse level selection circuit is recorded as DI2+; the second end of the first resistor is electrically connected to the first input end E1 of the optocoupler isolation circuit 132, the second input end E2 of the optocoupler isolation circuit 132 in the position pulse input circuit corresponding to the first pulse level selection circuit is connected to the second external voltage signal DI1-, and the second input end E2 of the optocoupler isolation circuit 132 in the position pulse input circuit corresponding to the second pulse level selection circuit is connected to the second external voltage signal DI2-. The second external voltage signal connected to the second input end E2 of each optocoupler isolation circuit 132 can be the same, and the first ends of different switch units in the same pulse level selection circuit 120 are connected to first external voltage signals of different magnitudes, so that when different switch units 121 are turned on, the pulse signal amplitudes composed of the first external voltage signal and the second external voltage signal input to the position pulse input circuit are different.

[0048] Taking the switch unit 121 connected to the pulse level selection circuit with the first external voltage signal DI1+ and the corresponding position pulse circuit as an example for exemplary explanation, the first external voltage signal DI1+ and the second external voltage signal DI1- can be provided by the PLC or the motion control card (wherein the first external voltage signal DI1+ and the second external voltage signal DI1- provided by the PLC or the motion control card can be differential input or single-ended input, and the difference between the first external voltage signal DI1+ and the second external voltage signal DI1- constitutes a pulse signal, wherein the voltage magnitudes of the first external voltage signals connected to different switch units 121 in the same pulse level selection circuit are different, and the second external voltage signals can be the same, and thus when different switch units 121 are turned on in the same selection circuit 102, switching of different pulse amplitudes can be achieved). The resistance value of the first resistor is positively correlated with the amplitude of the pulse signal formed by the first external voltage signal connected to the first end of the corresponding switch unit 121 and the second external voltage signal connected to the second input end E1 of the optocoupler isolation circuit 132, that is, the larger the amplitude of the pulse signal formed by the first end of the switch unit 121 electrically connected to the first resistor and the second input end of the optocoupler isolation circuit 132, the larger the resistance value of the first resistor. Therefore, by setting a current limiting circuit 131 including multiple first resistors, and the resistance value of the first resistor is positively correlated with the amplitude of the pulse signal formed by the first external voltage signal connected to the first end of the corresponding switch unit 121 The amplitude of the pulse signal formed by the first external voltage signal connected and the second external voltage signal connected to the second input terminal E1 of the optocoupler isolation circuit 132 is positively correlated, so that when different switch units 121 in the pulse selection circuit 102 are turned on, the first resistor in the current limiting circuit 131 can play a good current limiting role, so that the current input to the optocoupler isolation circuit 132 will not be too large, thereby ensuring the reliability of the position pulse generating circuit, and thus achieving compatibility with different specification levels, for example, it can achieve compatibility with the above-mentioned PLC and motion control card that provide different pulse signal amplitudes. Optionally, the technical personnel in this field can calculate the specific resistance value of the first resistor according to different level specifications and the current allowed to be input by the optocoupler isolation circuit 132, which is not specifically described here. The current limiting circuit 131 is electrically connected to the optocoupler isolation circuit 132, and finally the optocoupler isolation circuit 132 outputs a pulse signal.

[0049] The position pulse generating circuit provided in the present embodiment receives the level selection control signal transmitted by the upper computer through the main control module, and transmits the level selection control signal to the selection chip. The selection chip selects the output end to output the on or off control signal according to the signal received at the input end. The switch unit in the selection circuit is turned on or off according to the control signal received at its own control end, so that the pulse level selection circuit can select different pulse signal amplitudes for output, thereby realizing flexible switching of pulse signals with different amplitudes in the input position pulse input circuit, that is, realizing flexible switching of different specification levels; and by setting the position pulse input circuit to include a current limiting circuit and an optocoupler isolation circuit, the current limiting circuit includes a first resistor electrically connected to the switch unit in a one-to-one correspondence, and the resistance of the first resistor is positively correlated with the amplitude of the pulse signal composed of the first external voltage signal connected to the first end of the corresponding switch unit and the second external voltage signal connected to the second input end of the optocoupler isolation circuit, so that when different switch units in the pulse level selection circuit are turned on, the first resistor in the current limiting circuit can play a good current limiting role, thereby preventing the current input to the optocoupler isolation circuit from being too large, thereby ensuring the reliability of the position pulse generating circuit, and thereby realizing compatibility with different specification levels.

[0050] Figure 2 is a schematic diagram of a structure of a pulse level selection circuit in a position pulse generating circuit provided by an embodiment of the present invention, with reference to Figure 2 Optionally, the switch unit 121 is a relay 1211, a first end of a coil of the relay 1211 is electrically connected to an output end of the main control module 110 as a control end B0 of the switch unit 121, and a second end of the coil of the relay 1211 is grounded GND;

[0051] One of the pair of normally open contacts of the relay 1211 is used as the first end B1 of the switch unit 121 to access the first external voltage signal, and the other of the pair of normally open contacts of the relay 1211 is electrically connected to the second end B2 of the switch unit 121 .

[0052] Figure 2 The schematic diagram shows that the position pulse generating circuit includes two pulse level selection circuits, each pulse level selection circuit includes four switch units 121, and the selection chip 101 is a PCA9554ADH chip (the communication mode between the selection chip 101 and the main control module is I 2 C communication) as an example. Figure 2The first power pin VCC of the PCA9554ADH chip is connected to a +5V voltage, the second power pin VSS is grounded, the data pin SDA receives the data signal DSP-SDA transmitted by the main control module, the clock pin SCL receives the clock signal DSP-SCL transmitted by the main control module, the first output terminal IO0, the second output terminal IO1, the third output terminal IO2, and the fourth output terminal IO3 are respectively electrically connected to the first terminals of the four switch units 121 of a pulse level selection circuit in a one-to-one correspondence, and the fifth output terminal IO4, the sixth output terminal IO5, the seventh output terminal IO6, and the eighth output terminal IO7 are respectively electrically connected to the control terminals of the four switch units 121 of another pulse level selection circuit in a one-to-one correspondence. Optionally, the switch unit is a relay 1211. Taking a switch unit in which the first end of a pulse level selection circuit is connected to a first external voltage signal with a maximum voltage of +5V as an example, after the relay 1211 coil receives the conduction control signal of the first output end IO0 of the main control module 110, the relay 1211 coil of the switch unit 121 is energized, and the corresponding normally open contact is closed, so that the first external voltage signal with a maximum voltage of +5V is transmitted to the second end of the switch unit 121, wherein the second end of the switch unit 121 can be connected to the output end (DI1+_5V) corresponding to the pulse level selection circuit. In this embodiment, the output end DI1+_5V in the pulse level selection circuit can be connected to the following In the embodiment, the input terminal one VDI1+_5V of the current limiting circuit in the position pulse input circuit is electrically connected, the output terminal two DI1+_12V in the pulse level selection circuit in the embodiment can be electrically connected to the input terminal two VDI1+_12V of the current limiting circuit 131 in the position pulse input circuit in the following embodiment, the output terminal three DI1+_24V in the pulse level selection circuit in the embodiment can be electrically connected to the input terminal three VDI1+_24V of the current limiting circuit in the position pulse input circuit in the following embodiment, and the output terminal four DI1+_36V in the pulse level selection circuit in the embodiment can be electrically connected to the input terminal four VDI1+_36V of the current limiting circuit in the position pulse input circuit in the following embodiment.

[0053] Figure 3 is a schematic structural diagram of a pulse level selection circuit in another position pulse generating circuit provided by an embodiment of the present invention, Figure 3 The structure shown is Figure 2 The only difference is that the chip type used by the selection chip 101 is different. Figure 3 The selection chip 101 shown can be a 74HC164 chip (the communication method between the selection chip 101 and the main control module is SPI serial communication). Figure 3The power pin VCC of the 74HC164 chip is connected to the +5V power supply, the ground pin GN is grounded, the clock signal pin CP receives the clock signal DSP-CLOCK of the main control module, and the two data pins DSA and DSB receive the data signal of the main control module.

[0054] Figure 4 is a schematic diagram of a structure of a position pulse input circuit in a position pulse generating circuit provided by an embodiment of the present invention, with reference to Figure 4 The position pulse input circuit includes a current limiting circuit 131 and an optocoupler isolation circuit 132, and the optocoupler isolation circuit 132 is electrically connected to the pulse level selection circuit through the current limiting circuit 131; the current limiting circuit 131 includes a first resistor corresponding to the switch unit, and the first end of the first resistor is electrically connected to the second end of the corresponding switch unit; the second end of the first resistor is electrically connected to the optocoupler isolation circuit 132; optionally, the optocoupler isolation circuit 132 includes a first input terminal E1, a second input terminal E2, a first output terminal F1 and an optocoupler sensor 1321, wherein the first input terminal E1 of the optocoupler isolation circuit 132 is electrically connected to the second end of each first resistor, and the second input terminal E2 of the optocoupler isolation circuit 132 is connected to the second external voltage signal;

[0055] The first input terminal E1 and the second input terminal E2 are electrically connected to the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321 , respectively. The first output terminal F1 is electrically connected to the output terminal DI1 of the optical coupling sensor 1321 .

[0056] in, Figure 4 exemplarily shows that the current limiting circuit 131 includes four first resistors (corresponding to the case where the pulse selection circuit includes four switch units), namely resistor R11, resistor R12, resistor R13 and resistor R14, wherein the first end of the first resistor R11, the first end of the first resistor R12, the first end of the first resistor R13 and the first end of the first resistor R14 can be respectively used as four input ends of the current limiting circuit 131 (i.e. Figure 4 In the embodiment, the input terminal 1 VDI1+_5V of the current limiting circuit 131 in the position pulse input circuit can be connected to the input terminal 1 VDI1+_5V of the current limiting circuit 131 in the position pulse input circuit. Figure 3 In the corresponding embodiment, the output terminal 1 DI1+_5V in the pulse level selection circuit is electrically connected, and the input terminal 2 VDI1+_12V of the current limiting circuit 131 in the position pulse input circuit in this embodiment can be connected to Figure 3 In the corresponding embodiment, the output terminal 2 DI1+_12V in the pulse level selection circuit is electrically connected, and the input terminal 3 VDI1+_24V of the current limiting circuit 131 in the position pulse input circuit in this embodiment can be connected to Figure 3In the corresponding embodiment, the output terminal 3 DI1+_24V in the pulse level selection circuit is electrically connected, and the input terminal 4 VDI1+_36V of the current limiting circuit 131 in the position pulse input circuit in this embodiment can be connected to Figure 3 In the corresponding embodiment, the output terminal four DI1 in the pulse level selection circuit is electrically connected to +_36V.

[0057] Specifically, after the main control module controls the corresponding switch unit in the pulse level selection circuit to be turned on, for example, the main control module controls the switch unit connected to the first external voltage signal with a maximum voltage of +5V to be turned on, the pulse level selection circuit outputs a voltage with a maximum voltage of +5V. The voltage with a maximum voltage of +5V is input through the input terminal DI1+_5V of the current limiting circuit 131, and is connected to the first input terminal E1 of the optocoupler isolation circuit 132 after current limiting by the resistor R11. The second input terminal E2 of the optocoupler isolation circuit 132 is connected to the second external voltage signal. The optocoupler isolation circuit 132 includes an optocoupler sensor 1321, and the third input terminal G1 of the optocoupler sensor 1321 is electrically connected to the first input terminal E1 of the optocoupler isolation circuit 132, and the fourth input terminal of the optocoupler sensor 1321 is electrically connected to the second input terminal E2 of the optocoupler isolation circuit 132, so that the first power supply voltage output by the pulse level selection circuit is input to the third input terminal G1 of the optocoupler sensor 1321 through the corresponding first resistor, and the second power supply voltage signal input from the second input terminal E2 is input to the fourth input terminal of the optocoupler sensor 1321 through the resistor R' (the resistor R' can also play a current limiting role). The optocoupler sensor 1321 has an isolation effect and can effectively perform level conversion. After the signals input from the third input terminal G1 and the fourth input terminal of the optocoupler sensor 1321 are isolated and level converted by the optocoupler sensor 1321, the optocoupler sensor 1321 outputs a pulse signal through its own first output terminal F1.

[0058] It should be noted that Figure 4 Only one position pulse input circuit is schematically shown. The position generating circuit usually includes at least two Figure 4 The position pulse input circuit shown, for example, the pulse level selection circuit includes two selection circuits, and the position pulse generating circuit includes two position pulse input circuits, and the position pulse input circuits correspond to the selection circuits one by one, wherein one selection circuit and its corresponding electrically connected position pulse input circuit can be used to determine the stroke of the motor movement, and the other selection circuit and its corresponding electrically connected position pulse input short-circuit are used to determine the direction of the motor movement.

[0059] Continue to refer Figure 4 Optionally, the position pulse input circuit 130 further includes a second resistor R2 , and the second resistor R2 is connected in parallel between the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321 .

[0060] Specifically, the second resistor R2 connected in parallel between the third input terminal G1 and the fourth input terminal G2 of the optical coupler sensor 1321 can raise the current threshold of the optical coupler sensor 1321 to prevent the optical coupler sensor 1321 from being mis-conducted, thereby improving the anti-interference performance of the optical coupler sensor 1321.

[0061] Continue to refer Figure 4 Optionally, the position pulse input circuit 130 further includes a first diode D1 and a first capacitor C1, the cathode of the first diode D1 is electrically connected to the third input terminal G1 of the optical coupling sensor 1321, and the anode of the first diode D1 is electrically connected to the fourth input terminal G2 of the optical coupling sensor 1321;

[0062] The first capacitor C1 is connected in parallel between the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321 .

[0063] Specifically, since the optical coupling sensor 1321 generally includes a light emitting tube, the anode and cathode of the light emitting tube are electrically connected to the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321, respectively, the first diode D1 can play a reverse protection role, preventing the reverse voltage from being too high to break through the light emitting tube inside the optical coupling sensor 1321, and ensuring that the reverse voltage of the light emitting tube inside the optical coupling sensor 1321 does not exceed 0.7 V. In addition, the first capacitor C1 connected in parallel between the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321 can play a filtering role, thereby ensuring that the interference signal in the signal input to the optical coupling sensor 1321 is reduced.

[0064] Continue to refer Figure 4 Optionally, the optical coupling sensor 1321 includes a primary diode D2, a secondary diode D3 and a secondary transistor T1, wherein the positive electrode and the negative electrode of the primary diode D2 serve as the third input terminal G1 and the fourth input terminal G2 of the optical coupling sensor 1321 respectively, the anode of the secondary diode D3 is electrically connected to the control electrode of the secondary transistor T1, the first electrode H1 of the secondary transistor T1 serves as the output terminal of the optical coupling sensor 1321, the second electrode of the secondary transistor T1 is grounded, the cathode of the secondary diode D3 is electrically connected to the output terminal of the optical coupling sensor 1321 through the third resistor R3, the cathode of the secondary diode D3 is also electrically connected to the third power supply voltage input terminal U3, and the third power supply voltage input terminal U3 is grounded through the second capacitor C2.

[0065] Among them, the control electrode of the secondary transistor T1 can be the base of the transistor, the first electrode of the secondary transistor T1 can be the collector of the transistor, and the second electrode of the secondary transistor T1 can be the emitter of the transistor. Specifically, when the secondary transistor T1 is turned on, the first output terminal F1 outputs a first pulse signal; when the secondary transistor T1 is turned off, the third power supply voltage signal input by the third power supply voltage input terminal U3 pulls up the potential of the first output terminal F1 of the optocoupler isolation circuit 132 through the third resistor R3, that is, the third power supply voltage signal input by the third power supply voltage input terminal U3 can be a higher voltage, such as +5V. In addition, the second capacitor C2 can play a role in filtering out the wave.

[0066] Figure 5 is a schematic diagram of the structure of another position pulse generating circuit provided by an embodiment of the present invention, referring to Figure 5 Optionally, the position pulse generating circuit further includes a pulse counting circuit 140 and a PWM wave driving circuit 150, wherein the input end of the pulse counting circuit 140 is electrically connected to each position pulse input circuit 130, and the output end of the pulse counting circuit 140 is electrically connected to the main control module 110, and the pulse counting circuit 140 is used to count the pulse signal and exchange information with the main control module 110;

[0067] The PWM wave driving circuit 150 is electrically connected to the main control module 110 , and is used to output a motor driving signal according to a signal output by the main control module 110 to the PWM wave driving circuit 150 .

[0068] Optionally, the pulse counting circuit 140 can be implemented using an FPGA circuit. The pulse counting circuit 140 can count the input pulse signal and exchange information with the main control module 110, thereby facilitating the main control module 110 to make corresponding processing, and then output the processed signal to the PWM wave driving circuit 150. The PWM wave driving circuit 150 outputs a motor driving signal according to the signal output by the main control module 110 to the PWM wave driving circuit 150, thereby driving the motor 300 to operate.

[0069] Figure 6 is a schematic diagram of the structure of another position pulse generating circuit provided by an embodiment of the present invention, referring to Figure 6 , Optionally, the position pulse selection circuit further includes a pulse shaping filter circuit 160, wherein the pulse counting circuit 140 is electrically connected to the position pulse input circuit 130 via the pulse shaping filter circuit 160;

[0070] Figure 7 yes Figure 6 The schematic diagram of the pulse shaping filter circuit is shown in Figure 2. Figure 6 and Figure 7Optionally, the pulse shaping filter circuit 160 includes a level conversion circuit 161 and a filter circuit 162, the level conversion circuit 161 includes a fifth input terminal corresponding one-to-one to the position pulse input circuit 130 and a second output terminal corresponding one-to-one to the fifth input terminal; wherein the fifth input terminal is electrically connected to the output terminal of the corresponding position pulse input circuit 130, the level conversion circuit 161 is used to level-convert the first pulse signal input by the fifth input terminal and transmit it to the corresponding second output terminal, each second output terminal is correspondingly connected to the input terminal of a filter circuit 162, the output terminal of the filter circuit 162 serves as the output terminal of the pulse shaping filter circuit 160, and the output terminal of the pulse shaping filter circuit 160 is electrically connected to the input terminal of the pulse counting circuit 140.

[0071] in, Figure 7 The pulse shaping filter circuit shown corresponds to a position pulse generating circuit including two position pulse input circuits, and the output terminals DI1 and DI2 of the two position pulse input circuits are electrically connected to the corresponding fifth input terminals Q1 and Q2, respectively. Accordingly, the pulse shaping filter circuit 160 includes second output terminals W1 and W2 corresponding to the two fifth input terminals Q1 and Q2, respectively.

[0072] Optionally, the level conversion circuit 161 can use a SN74LVC2G17DCKR chip, wherein the power supply end of the SN74LVC2G17DCKR chip can be connected to a +3.3V voltage. Then, after a pulse signal is input to the fifth input end, for example, when the amplitude of the corresponding pulse signal is 5V, or other amplitudes such as 12V, 24V, etc., the SN74LVC2G17DCKR chip can be used for level conversion and then converted to a 3.3V voltage. Since 3.3V is more compatible with the drive signal of the motor, after level conversion by the level conversion circuit 161, it is more convenient to drive the motor. The filter circuit 162 can filter the output signal of the level conversion circuit 161 to obtain a pulse signal after filtering out interference and output it through the two output ends DI1-FPGA and DI2-FPGA of the pulse shaping filter circuit 160, thereby making the signal output by the pulse shaping filter circuit 160 less in interference signals, thereby making the signal output by the entire position pulse input circuit 130 to the motor less in interference signals, thereby facilitating accurate driving of the motor.

[0073] Continue to refer Figure 6 Optionally, the input end of the main control module 110 is connected to the host computer 200 via a communication circuit 170.

[0074] Optionally, the communication circuit 170 may be an RS485 communication circuit, or the communication circuit 170 may be a USB communication circuit, which is not specifically limited in this embodiment.

[0075] Optionally, the communication mode between the selection chip 101 and the main control module 110 is SPI serial communication or I 2 C communication.

[0076] Optionally, the pulse level selection circuit includes a first selection circuit and a second selection circuit (see Figure 2 , Figure 2 The two selection circuits 102 can be used as a first selection circuit and a second selection circuit respectively), and a first position pulse input terminal corresponding to the first selection circuit and a second position pulse input circuit corresponding to the second selection circuit, the input terminal of the first position pulse input circuit is electrically connected to the output terminal of the first selection circuit, and the input terminal of the second position pulse input circuit is electrically connected to the output terminal of the second selection circuit;

[0077] The number of switch units 121 included in the first selection circuit and the second selection circuit is equal and corresponds one to one; the first end of the switch unit 121 of the first selection circuit and the first end of the corresponding switch unit 121 of the second selection circuit are connected to the same first external voltage signal.

[0078] Figure 8 is a schematic diagram of the structure of two position pulse input circuits provided in an embodiment of the present invention, referring to Figure 8 , Figure 8 The two position pulse input circuits can be used as the first position pulse input circuit and the second position pulse input circuit respectively. The input terminal VDI1+_5V of the current limiting circuit 131 in the first position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal 1 DI1+_5V in the first selection circuit is electrically connected, and the input terminal 2 VDI1+_12V of the current limiting circuit 131 in the first position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal 2 DI1+_12V in the first selection circuit is electrically connected, and the input terminal 3 VDI1+_24V of the current limiting circuit 131 in the first position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal 3 DI1+_24V in the first selection circuit is electrically connected, and the input terminal 4 VDI1+_36V of the current limiting circuit 131 in the first position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal DI1+_36V in the first selection circuit is electrically connected; wherein the input terminal VDI2+_5V of the current limiting circuit 131 in the second position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal 1 DI2+_5V in the second selection circuit is electrically connected, and the input terminal 2 VDI2+_12V of the current limiting circuit 131 in the second position pulse input circuit can be connected to Figure 2In the corresponding embodiment, the output terminal 2 DI2+_12V in the second selection circuit is electrically connected, and the input terminal 3 VDI2+_24V of the current limiting circuit 131 in the second position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal 3 DI2+_24V in the second selection circuit is electrically connected, and the input terminal 4 VDI2+_36V of the current limiting circuit 131 in the second position pulse input circuit can be connected to Figure 2 In the corresponding embodiment, the output terminal DI2 in the second selection circuit is electrically connected to +_36V, and the output terminal DI1 of the first position pulse input circuit and the output terminal DI2 of the second position pulse input circuit serve as two input terminals of the selection circuit.

[0079] Furthermore, it should be noted that, in order to show that the devices in the first selection circuit and the second selection circuit are different, the figure marks of the resistor and capacitor devices in the second selection circuit are respectively marked with 0 added to the resistor and capacitor device marks of the first selection circuit to distinguish them. For example, the resistor R11 in the first selection circuit corresponds to the resistor R110 in the second selection circuit, and the resistor R12 in the first selection circuit corresponds to the resistor R120 in the second selection circuit, which will not be elaborated one by one here.

[0080] Combination Figure 2 , the first end of the switch unit 121 of the first selection circuit and the first end of the switch unit 121 of the corresponding second selection circuit are connected to the same first external voltage signal. When the main control module 110 controls the first external voltage signal input to the selection circuit, the corresponding switch unit 121 in the first selection circuit and the second selection circuit can be controlled to be turned on, so that the first selection circuit and the second selection circuit output the same first external voltage signal, thereby making the first position pulse input circuit and the second position pulse input circuit generate pulse signals with the same level specifications, thereby more in line with the existing drive signal requirements for the motor. By setting the position pulse generating circuit to include the first selection circuit, the second selection circuit, and the first position pulse input end corresponding to the first selection circuit and the second position pulse input circuit corresponding to the second selection circuit, the input end of the first position pulse input circuit is electrically connected to the output end of the first selection circuit, and the input end of the second position pulse input circuit is electrically connected to the output end of the second selection circuit, thereby making the position pulse generating circuit output two pulse signals, thereby determining the movement stroke and direction of the motor.

[0081] The embodiment of the present invention further provides a driving method of a position pulse generating circuit, which is executed by a main control module in the position pulse generating circuit provided by any of the above embodiments. Fig. 9 is a flow chart of a driving method of a position pulse generating circuit provided by an embodiment of the present invention, with reference to Fig. 9 , the driving method of the position pulse generating circuit includes:

[0082] Step 210: output a level selection control signal to the selection chip according to the received output signal of the host computer, so that the selection chip selection output terminal outputs an on or off control signal, so as to turn on or off the corresponding switch unit in the selection circuit.

[0083] The driving method of the position pulse generating circuit provided in the present embodiment receives the level selection control signal transmitted by the host computer through the main control module, and transmits the level selection control signal to the selection chip. The selection chip selects the output end to output the on or off control signal according to the signal received at the input end. The switch unit in the selection circuit is turned on or off according to the control signal received at its own control end, so that the pulse level selection circuit can select different pulse signal amplitudes for output, thereby realizing flexible switching of pulse signals with different amplitudes in the input position pulse input circuit, that is, realizing flexible switching of different specification levels; and by setting the position pulse input circuit to include a current limiting circuit and an optocoupler isolation circuit, the current limiting circuit includes a first resistor electrically connected to the switch unit in a one-to-one correspondence, and the resistance of the first resistor is positively correlated with the maximum difference between the first external voltage signal connected to the first end of the corresponding switch unit and the second external voltage signal connected to the second input end of the optocoupler isolation circuit, so that when different switch units in the pulse level selection circuit are turned on, the first resistor in the current limiting circuit can play a good current limiting role, thereby preventing the current input to the optocoupler isolation circuit from being too large, thereby ensuring the reliability of the position pulse generating circuit, and thereby realizing compatibility with different specification levels.

[0084] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A position pulse generating circuit, characterized in that: include: A main control module, at least one pulse level selection circuit, wherein the pulse level selection circuit comprises a selection chip and n selection circuits, where n is an even number greater than or equal to 2; the position pulse generating circuit further comprises a position pulse input circuit corresponding one-to-one to the selection circuit; Wherein, the main control module includes an input end and an output end, the main control module is connected to the host computer through the input end, the output end of the main control module is electrically connected to the input end of the selection chip, and the main control module is used to receive the level selection control signal transmitted by the host computer, and transmit the level selection control signal to the selection chip; The selection circuit comprises at least two switch units, wherein the control end of each switch unit is electrically connected to the output end of the selection chip in a one-to-one correspondence, and the selection chip is used to select the output end to output a turn-on or turn-off control signal according to the signal received at the input end; the first end of each switch unit in the same selection circuit is used to access a different first external voltage signal, and the switch unit is used to turn on or off according to the signal at its own control end; The position pulse input circuit includes a current limiting circuit and an optocoupler isolation circuit, and the optocoupler isolation circuit includes a first input end, a second input end, and a first output end; the current limiting circuit includes a first resistor corresponding to the switch unit one by one, and the first end of the first resistor is electrically connected to the second end of the corresponding switch unit; the second end of the first resistor is electrically connected to the first input end of the optocoupler isolation circuit; the second input end of the optocoupler isolation circuit is used to access a second external voltage signal, and the position pulse input circuit is used to output a pulse signal through the first output end according to the first external voltage signal and the second external voltage signal; The resistance value of the first resistor is positively correlated with the amplitude of a pulse signal formed by a first external voltage signal connected to the first end of the corresponding switch unit and a second external voltage signal connected to the second input end of the optical coupling isolation circuit; Wherein, the main control module includes a DSP chip.

2. The position pulse generating circuit according to claim 1, characterized in that: The optical coupling isolation circuit also includes an optical coupling sensor. The first input terminal and the second input terminal are electrically connected to the third input terminal and the fourth input terminal of the optical coupling sensor respectively, and the first output terminal is electrically connected to the output terminal of the optical coupling sensor.

3. The position pulse generating circuit according to claim 2, characterized in that: The position pulse input circuit also includes a second resistor, which is connected in parallel between the third input terminal and the fourth input terminal of the optical coupling sensor.

4. The position pulse generating circuit according to claim 2, characterized in that: The position pulse input circuit further includes a first diode and a first capacitor, wherein a cathode of the first diode is electrically connected to the third input terminal of the optical coupling sensor, and an anode of the first diode is electrically connected to the fourth input terminal of the optical coupling sensor; The first capacitor is connected in parallel between the third input terminal and the fourth input terminal of the optical coupling sensor.

5. The position pulse generating circuit according to claim 2, characterized in that: The optocoupler sensor includes a primary diode, a secondary diode and a secondary transistor, wherein the positive electrode and the negative electrode of the primary diode serve as the third input terminal and the fourth input terminal of the optocoupler sensor respectively, the anode of the secondary diode is electrically connected to the control electrode of the secondary transistor, the first electrode of the secondary transistor serves as the output terminal of the optocoupler sensor, the second electrode of the secondary transistor is grounded, the cathode of the secondary diode is electrically connected to the output terminal of the optocoupler sensor through a third resistor, the cathode of the secondary diode is also electrically connected to the third power supply voltage input terminal, and the third power supply voltage input terminal is grounded through a second capacitor.

6. The position pulse generating circuit according to claim 1, characterized in that: The switch unit is a relay, a first end of the coil of the relay is electrically connected to the output end of the main control module as the control end of the switch unit, and a second end of the coil of the relay is grounded; One of the pair of normally open contacts of the relay is connected to the first power supply voltage as the first end of the switch unit, and the other of the pair of normally open contacts of the relay is electrically connected to the second end of the switch unit.

7. The position pulse generating circuit according to claim 1, characterized in that: It also includes a pulse counting circuit and a PWM wave driving circuit, wherein the input end of the pulse counting circuit is electrically connected to each of the position pulse input circuits, and the output end of the pulse counting circuit is electrically connected to the main control module, and the pulse counting circuit is used to count pulse signals and exchange information with the main control module; The PWM wave driving circuit is electrically connected to the main control module, and is used to output a motor driving signal according to a signal output by the main control module to the PWM wave driving circuit.

8. The position pulse generating circuit according to claim 7, characterized in that: It also includes a pulse shaping filter circuit, wherein the pulse counting circuit is electrically connected to the position pulse input circuit through the pulse shaping filter circuit; The pulse shaping filter circuit includes a level conversion circuit and a filter circuit, the level conversion circuit includes a fifth input terminal corresponding to the position pulse input circuit one by one and a second output terminal corresponding to the fifth input terminal one by one; wherein the fifth input terminals are respectively electrically connected to the corresponding output terminals of the position pulse input circuit, the level conversion circuit is used to perform level conversion on the first pulse signal input from the fifth input terminal and transmit it to the corresponding second output terminal, each of the second output terminals is correspondingly connected to an input terminal of the filter circuit, the output terminal of the filter circuit serves as the output terminal of the pulse shaping filter circuit, and the output terminal of the pulse shaping filter circuit is electrically connected to the input terminal of the pulse counting circuit.

9. The position pulse generating circuit according to claim 1, characterized in that: The pulse level selection circuit includes a first selection circuit, a second selection circuit, and a first position pulse input terminal corresponding to the first selection circuit and a second position pulse input circuit corresponding to the second selection circuit, wherein the input terminal of the first position pulse input circuit is electrically connected to the output terminal of the first selection circuit, and the input terminal of the second position pulse input circuit is electrically connected to the output terminal of the second selection circuit; Among them, the number of switch units included in the first selection circuit and the second selection circuit is equal and corresponds one to one; the first end of the switch unit of the first selection circuit and the first end of the corresponding switch unit of the second selection circuit are connected to the same first external voltage signal.

10. The position pulse generating circuit according to claim 1, characterized in that: The communication mode between the main control module and the selection chip is SPI serial communication or I 2 C communication.

11. A method for driving a position pulse generating circuit, characterized in that: The driving method of the position pulse generating circuit is performed by a main control module in the position pulse generating circuit according to any one of claims 1 to 10, and includes: According to the received host computer output signal, a level selection control signal is output to the selection chip, so that the selection chip selection output terminal outputs an on or off control signal, so that the corresponding switch unit in the selection circuit is turned on or off.

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