Digital signal output circuit

Abstract

The utility model provides a digital signal output circuit. The input end of an overcurrent and overvoltage protection circuit is connected with a first power supply; the first output end of the overcurrent and overvoltage protection circuit is used as the output end of the digital signal output channel; the second output end of the overcurrent and overvoltage protection circuit is connected with the input end of the read-back circuit; the control end of the overcurrent and overvoltage protection circuit is connected with the output end of the driving circuit; the input end of the control module is connected with the output end of the read-back circuit; the output end of the control module is connected with the input end of the driving circuit; namely, when the digital signal output circuit has faults such as overcurrent and the like, the overcurrent and overvoltage protection circuit can execute corresponding protection actions to realize protection of the digital signal output circuit.

Description

Technical Field

[0001] The utility model belongs to the technical field of power electronics, and more specifically, particularly relates to a digital signal output circuit. Background Art

[0002] In the field of general industrial control systems, such as the DCS system of a nuclear power plant, a DO (Digital Output) module is included for outputting control signals. The DO module can output the pulse signal specified in the command according to the control sent by the host computer, thereby improving the working efficiency of the industrial control system.

[0003] The connection relationship of the DO module and the faults in the devices connected thereto may cause overcurrent in the DO module, which may further lead to overcurrent damage to the DO module. Utility Model Content

[0004] In view of this, an object of the present utility model is to provide a digital signal output circuit, which is used to protect the digital signal output circuit when a fault such as overcurrent occurs in the digital signal output circuit.

[0005] The first aspect of the present application discloses a digital signal output circuit, comprising a control module and at least one digital signal output channel, wherein the digital signal output channel comprises: an overcurrent and overvoltage protection circuit, a drive circuit and a readback circuit;

[0006] The input end of the overcurrent and overvoltage protection circuit is connected to the first power supply;

[0007] The first output end of the overcurrent and overvoltage protection circuit serves as the output end of the digital signal output channel; the overcurrent protection and overvoltage protection in the overcurrent and overvoltage protection circuit have multiplexed resistors and switch tubes;

[0008] The second output terminal of the overcurrent and overvoltage protection circuit is connected to the input terminal of the readback circuit;

[0009] The control end of the overcurrent and overvoltage protection circuit is connected to the output end of the driving circuit;

[0010] The input end of the control module is connected to the output end of the readback circuit;

[0011] The output end of the control module is connected to the input end of the drive circuit.

[0012] Optionally, the overcurrent and overvoltage protection circuit includes: a first switch tube, a second switch tube, a first diode, a first resistor and a second resistor;

[0013] The first end of the first switch tube is connected to one end of the first resistor, and the connection point serves as the input end of the overcurrent and overvoltage protection circuit;

[0014] The control end of the first switch tube is respectively connected to the other end of the first resistor and the first end of the second switch tube;

[0015] The second end of the first switch tube is connected to the control end of the second switch tube and one end of the second resistor;

[0016] The second end of the second switch tube is connected to the anode of the first diode, and the connection point serves as the second output end of the overcurrent and overvoltage protection circuit;

[0017] The cathode of the first diode serves as the first output terminal of the overcurrent and overvoltage protection circuit;

[0018] The other end of the second resistor serves as a control end of the overcurrent and overvoltage protection circuit.

[0019] Optionally, the first diode is MBR1H100SFT3G; and / or, the first switch tube and the second switch tube are both triodes.

[0020] Optionally, the driving circuit includes: a third resistor and a first isolation optocoupler;

[0021] One end of the third resistor is connected to the second power supply;

[0022] A first end of the light emitting side of the first isolation optocoupler is connected to the other end of the third resistor;

[0023] The second end of the light emitting side of the first isolation optocoupler is used as the input end of the driving circuit;

[0024] The first end of the light-receiving side of the first isolation optical coupler serves as the output end of the driving circuit;

[0025] The second end of the first isolation optical coupler on the light receiving side is connected to the analog ground.

[0026] Optionally, the first isolation optical coupler includes: a first light emitting diode and a first phototransistor;

[0027] The anode of the first light emitting diode serves as the first end of the light emitting side of the first isolation optical coupler;

[0028] The cathode of the first light emitting diode serves as the second end of the light emitting side of the first isolation optical coupler;

[0029] The first end of the first phototransistor serves as the first end of the light-receiving side of the first isolation optical coupler;

[0030] The second end of the first phototransistor serves as the second end of the first isolation optocoupler on the light receiving side.

[0031] Optionally, the first isolation optical coupler is MOCD213.

[0032] Optionally, the readback circuit includes: a second diode, a second isolation optocoupler, a fourth resistor, a fifth resistor and a sixth resistor;

[0033] The cathode of the second diode serves as the input terminal of the readback circuit;

[0034] An anode of the second diode is connected to one end of the fourth resistor;

[0035] A first end of the light emitting side of the second isolation optical coupler is connected to the other end of the fourth resistor and one end of the fifth resistor respectively;

[0036] The first end of the light-emitting side of the second isolation optocoupler and the other end of the fifth resistor are both connected to the analog ground;

[0037] A first end of the light-receiving side of the second isolation optical coupler is connected to one end of the sixth resistor, and a connection point serves as an output end of the readback circuit;

[0038] The second end of the light receiving side of the second isolation optical coupler is connected to the reference ground;

[0039] The other end of the sixth resistor is connected to the second power supply.

[0040] Optionally, the second isolation optical coupler includes: a second light emitting diode and a second phototransistor;

[0041] The anode of the second light emitting diode serves as the first end of the light emitting side of the second isolation optical coupler;

[0042] The cathode of the second light emitting diode serves as the second end of the light emitting side of the second isolation optical coupler;

[0043] The first end of the second phototransistor serves as the first end of the light-receiving side of the second isolation optical coupler;

[0044] The second end of the second phototransistor serves as the second end of the second isolation optocoupler on the light receiving side.

[0045] Optionally, the second isolation optical coupler is MOCD213.

[0046] Optionally, the second diode is a voltage regulator diode.

[0047] It can be seen from the above technical scheme that a digital signal output circuit provided by the utility model includes an input end of an overcurrent and overvoltage protection circuit connected to a first power supply; a first output end of the overcurrent and overvoltage protection circuit serving as an output end of a digital signal output channel; a second output end of the overcurrent and overvoltage protection circuit connected to an input end of a readback circuit; a control end of the overcurrent and overvoltage protection circuit connected to an output end of a drive circuit; an input end of a control module connected to an output end of the readback circuit; and an output end of the control module connected to an input end of the drive circuit; that is, when a fault such as overcurrent occurs in the digital signal output circuit, the overcurrent and overvoltage protection circuit can perform corresponding protection actions to achieve protection of the digital signal output circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0049] Figure 1 It is a schematic diagram of a digital signal output circuit provided by an embodiment of the utility model;

[0050] Figure 2 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model;

[0051] Figure 3 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model;

[0052] Figure 4 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model;

[0053] Figure 5 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model;

[0054] Figure 6 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model;

[0055] Figure 7 It is a schematic diagram of another digital signal output circuit provided by an embodiment of the utility model. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solution and advantages of the embodiment of the utility model clearer, the technical solution in the embodiment of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiment of the utility model. Obviously, the described embodiment is a part of the embodiment of the utility model, not all of the embodiments. Based on the embodiment of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0057] In the present application, the term "comprise", "include" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or equipment. In the absence of more restrictions, the elements defined by the sentence "comprise one ..." do not exclude the existence of other identical elements in the process, method, article or equipment including the elements. In addition, the terms "first", "second", "third", "fourth", etc. (if present) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and do not have to be used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable in appropriate circumstances, so that the embodiments of the present application described here can be implemented in an order other than those illustrated or described here, for example.

[0058] The embodiment of the present application provides a digital signal output circuit, which is used to solve the problem in the prior art that the connection relationship of the DO module and the devices connected thereto are faulty, resulting in overcurrent in the DO module, which further causes overcurrent damage to the DO module.

[0059] See also Figure 1 The digital signal output circuit includes a control module and at least one digital signal output channel, see Figure 2 , digital signal output channel, including: over-current and over-voltage protection circuit, drive circuit and readback circuit.

[0060] An input end of the overcurrent and overvoltage protection circuit is connected to the first power supply.

[0061] The first power supply can be 24V or 48V, and of course it can also be other power supplies, which will not be elaborated here one by one. It depends on the actual situation and is within the protection scope of this application.

[0062] The first output terminal of the overcurrent and overvoltage protection circuit serves as the output terminal of the digital signal output channel.

[0063] That is to say, when the overcurrent and overvoltage protection circuit is in a closed state, the first power supply can be output to the output end of the digital signal output circuit through the overcurrent and overvoltage protection circuit, that is, the digital signal output circuit can transmit data; when the overcurrent and overvoltage protection circuit is in an off state, the first power supply is prohibited from being output to the output end of the digital signal output channel through the overcurrent and overvoltage protection circuit.

[0064] The second output terminal of the overcurrent and overvoltage protection circuit is connected to the input terminal of the readback circuit.

[0065] That is to say, the overcurrent and overvoltage protection circuit outputs a signal to the readback circuit, and the readback circuit can obtain the output signal of the overcurrent and overvoltage protection circuit.

[0066] The control end of the overcurrent and overvoltage protection circuit is connected to the output end of the driving circuit.

[0067] The overcurrent protection circuit is controlled by the driving circuit, and the overcurrent protection circuit performs corresponding actions according to the output signal of the driving circuit to achieve overcurrent and overvoltage protection for the digital signal output channel.

[0068] The input end of the control module is connected to the output end of the readback circuit.

[0069] That is, the control module receives the output signal of the overcurrent and overvoltage protection circuit read back by the readback circuit. The readback circuit reads back the output value of the digital signal output channel, that is, collects the output value of the digital signal output channel and transmits it to the control module.

[0070] The output end of the control module is connected to the input end of the driving circuit.

[0071] That is to say, the overcurrent and overvoltage protection circuit is connected to the control module through the drive circuit, and the overcurrent and overvoltage protection circuit is controlled by the control module through the drive circuit.

[0072] The control module can be a PLD (programmable logic device), which realizes the output control and dynamic diagnosis functions of the digital signal output channel; the drive circuit receives the control instruction of the control module to control the output of the digital signal output channel. PLD is produced as a general integrated circuit, and its logic function is determined according to the user's programming of the device. The general PLD has a high degree of integration, which is sufficient to meet the needs of designing general digital systems.

[0073] The control module, over-current and over-voltage protection circuit, readback circuit and drive circuit are combined to realize self-check of digital signal output channel. Specifically:

[0074] The control module can read the readback signal of the readback circuit (such as Figure 6The readback circuit reads the output signal of the overcurrent and overvoltage protection circuit (as shown in Figure ④). Figure 6 The control module can also apply short pulses to the drive circuit, such as Figure 6 A short pulse is applied at ① as shown in the figure. Specifically, if the control module reads the value of the readback signal of the readback circuit as "1", a pulse for shutting off the channel is applied to the drive circuit, and the drive signal output by the drive circuit (such as Figure 6 The signal at ② shown in the figure) will short-term shut off the output of the overcurrent and overvoltage protection circuit; if the control module reads the value of the readback signal of the readback circuit as "0", a pulse to open the channel is applied to the drive circuit, and the drive signal output by the drive circuit will short-term open the output of the overcurrent and overvoltage protection circuit. Of course, the pulse logic output by the control module can be other methods, which will not be described here one by one.

[0075] The control module can detect the output status of the output end of the overcurrent and overvoltage protection circuit through the readback circuit to realize the module output channel diagnosis. Specifically: after applying a short pulse to the drive circuit, if the output end of the readback circuit cannot detect the pulse signal within the channel diagnosis time, the channel self-check fails, it is judged as an output channel fault, and the fault quality is set to Bad. The diagnostic coverage of the digital signal output channel reaches 99%.

[0076] While achieving dynamic diagnosis of output channels, it will not cause malfunction of on-site equipment, and is safe and efficient.

[0077] The specific value of the diagnosis time is not specifically limited here and can be determined according to actual conditions, all of which are within the protection scope of this application.

[0078] In this embodiment, the input end of the overcurrent and overvoltage protection circuit is connected to the first power supply; the first output end of the overcurrent and overvoltage protection circuit serves as the output end of the digital signal output channel; the second output end of the overcurrent and overvoltage protection circuit is connected to the input end of the readback circuit; the control end of the overcurrent and overvoltage protection circuit is connected to the output end of the drive circuit; the input end of the control module is connected to the output end of the readback circuit; the output end of the control module is connected to the input end of the drive circuit; that is, when there is an overcurrent or other fault in the digital signal output circuit, the overcurrent and overvoltage protection circuit can perform corresponding protection actions to protect the digital signal output circuit.

[0079] It should be noted that overcurrent and overvoltage protection are implemented through two independent functional circuits; the current protection function is generally implemented by blowing a fuse or by controlling the switch tube through current detection; the overvoltage protection function is usually implemented by controlling the switch tube through voltage detection by a voltage-stabilizing diode or a voltage-dividing resistor, which is costly. In addition, the detection of the digital signal output channel is usually implemented by collecting the output voltage of the digital signal output channel or the state of the auxiliary contact, and the detection coverage is low.

[0080] In the present embodiment, there are reused resistors and switch tubes for overcurrent protection and overvoltage protection in the overcurrent and overvoltage protection circuit; thus, the overcurrent protection circuit and the overvoltage protection circuit can be combined into an overcurrent and overvoltage protection circuit, thereby reducing costs and simplifying the circuit; in addition, the readback circuit collects the output signal of the overcurrent and overvoltage protection circuit in real time and feeds it back to the control module, and the control module can also control the on and off of the overcurrent and overvoltage protection circuit through the drive circuit, thereby realizing the diagnosis of the digital signal output channel, with high diagnostic coverage, and supporting dynamic self-inspection of the digital signal output channel without affecting the operation of the on-site equipment, thereby meeting the high reliability application requirements of nuclear power plants.

[0081] Optional, see Figure 3 The overcurrent and overvoltage protection circuit includes: a first switch tube Q1, a second switch tube Q2, a first diode D1, a first resistor R1 and a second resistor R2.

[0082] A first end of the first switch tube Q1 is connected to one end of the first resistor R1 , and the connection point serves as an input end of the overcurrent and overvoltage protection circuit.

[0083] Specifically, a common end of the first switch tube Q1 and the first resistor R1 is connected to the first power supply to receive electric energy from the first power supply.

[0084] The control end of the first switch tube Q1 is connected to the other end of the first resistor R1 and the first end of the second switch tube Q2 respectively.

[0085] The second end of the first switch tube Q1 is connected to the control end of the second switch tube Q2 and one end of the second resistor R2.

[0086] The second end of the second switch tube Q2 is connected to the anode of the first diode D1, and the connection point serves as the second output end of the overcurrent and overvoltage protection circuit.

[0087] Specifically, a common end of the first switch tube Q1 and the first diode D1 is connected to an input end of the readback circuit.

[0088] The first switch tube Q1 and the second switch tube Q2 are arranged back to back.

[0089] The cathode of the first diode D1 serves as the first output terminal of the overcurrent and overvoltage protection circuit.

[0090] Specifically, the cathode of the first diode D1 serves as a digital signal output channel to output a corresponding signal.

[0091] The other end of the second resistor R2 serves as a control end of the overcurrent and overvoltage protection circuit.

[0092] Specifically, the other end of the second resistor R2 is connected to the output end of the driving circuit.

[0093] It should be noted that the overcurrent and overvoltage protection circuit realizes the overcurrent protection function of the output channel, and the threshold of the overcurrent protection can be set by the resistance value of the first resistor R1.

[0094] The resistance value of the first resistor R1 is not specifically limited here and can be determined according to actual conditions, all of which are within the protection scope of this application.

[0095] Optionally, the first diode D1 is MBR1H100SFT3G; of course, the first diode D1 may also be other types, which will not be described here one by one, and it depends on the actual situation, all of which are within the protection scope of this application.

[0096] The first switch tube Q1 and the second switch tube Q2 are both triodes, such as MJD350.

[0097] Specifically, the first end of the first switch tube Q1 and the first end of the second switch tube Q2 are the emitter E of the transistor, the second end of the first switch tube Q1 and the second end of the second switch tube Q2 are the collector C of the transistor, and the control end of the first switch tube Q1 and the control end of the second switch tube Q2 are the base B of the transistor.

[0098] More specifically, the emitter E of the first switch tube Q1 is connected to one end of the first resistor R1, and the connection point is connected to the first power supply. The base B of the first switch tube Q1 is respectively connected to the other end of the first resistor R1 and the emitter E of the second switch tube Q2; the collector C of the first switch tube Q1 is connected to the base B of the second switch tube Q2 and one end of the second resistor R2; the collector C of the second switch tube Q2 is connected to the anode of the first diode D1.

[0099] The overcurrent protection and overvoltage protection of the overcurrent and overvoltage protection circuit are explained below:

[0100] (1) Overcurrent protection: The first resistor R1 in the overcurrent and overvoltage protection circuit is a current limiting resistor. According to the on-state voltage UBEMAX between pins B and E of the first switch tube Q1, the maximum current passing through the circuit can be calculated as UBEMAX / R1. When the current in the circuit exceeds this maximum current, for example, when the output end of the digital signal output channel is short-circuited to the ground, the voltage between pins B and E of the first switch tube Q1 exceeds the on-state voltage UBE of the first switch tube Q1, and the first switch tube Q1 is turned on; because the voltage between pins B and E of the first switch tube Q1 is less than the on-state voltage of the second switch tube Q2, the second switch tube Q2 is not turned on. At this time, the circuit does not output to the outside, realizing the overcurrent protection function of the digital signal output channel, and by changing the resistance value of the first resistor R1, different overcurrent protection thresholds can be achieved.

[0101] (2) Overvoltage protection: The breakdown voltage of the first diode D1 is 100V. When the output end of the digital signal output channel is connected to a forward voltage of 60V, the first diode D1 is reversely cut off and will not cause circuit damage. When the output end of the digital signal output channel is connected to a reverse voltage of 60V, if the resistance value of the first resistor R1 is 34Ω, the first resistor R1 limits the output to about 0.85V / 34Ω=25mA, and the power consumption of the first switch tube Q1 and the second switch tube Q2 is (60V-0.85V-0.5V)V*25mA=1.48W. Since the maximum power consumption of the first switch tube Q1 and the second switch tube Q2 is 1.56, after the reverse voltage of 60V is connected, the actual power consumption of the switch tube is less than the maximum power consumption of the switch tube 1.56W, and the circuit will not be damaged at this time; that is, the ±60VDC overvoltage protection function can be met.

[0102] Optional, see Figure 4 , the driving circuit includes: a third resistor R3 and a first isolation optical coupler U1.

[0103] One end of the third resistor R3 is connected to the second power source VCC.

[0104] The first power supply and the second power supply VCC may be independent power supplies. Of course, other situations are not excluded and will not be described in detail here.

[0105] The output voltage of the first power supply is not specifically limited here and is within the protection scope of this application.

[0106] A first end of the light-emitting side of the first isolation optical coupler U1 is connected to the other end of the third resistor R3 .

[0107] The second end of the light-emitting side of the first isolation optical coupler U1 is used as the input end of the driving circuit and is connected to the output end of the control module.

[0108] That is to say, the second end of the light emitting side of the first isolation optocoupler U1 is connected to the input end of the control end.

[0109] The first end of the light-receiving side of the first isolation optical coupler U1 is connected as the output end of the driving circuit and the control end of the overcurrent and overvoltage protection circuit.

[0110] Specifically, the first end of the light-receiving side of the first isolation optocoupler U1 is connected to the other end of the second resistor R2 in the overcurrent and overvoltage protection circuit.

[0111] The second end of the light receiving side of the first isolation optical coupler U1 is connected to the analog ground AGND.

[0112] Optionally, the first isolation optocoupler U1 includes: a first light emitting diode and a first phototransistor. The anode of the first light emitting diode serves as the first end of the light emitting side of the first isolation optocoupler U1; the cathode of the first light emitting diode serves as the second end of the light emitting side of the first isolation optocoupler U1; the first end of the first phototransistor serves as the first end of the light receiving side of the first isolation optocoupler U1; and the second end of the first phototransistor serves as the second end of the light receiving side of the first isolation optocoupler U1.

[0113] Specifically, one end of the third resistor R3 is connected to the second power supply VCC; the anode of the first light-emitting diode serves as the first end of the light-emitting side of the first isolation optocoupler U1 and the other end of the third resistor R3; the cathode of the first light-emitting diode serves as the second end of the light-emitting side of the first isolation optocoupler U1 and is connected to the output end of the control module; the first phototransistor serves as the first end of the light-receiving side of the first isolation optocoupler U1 and is connected to the other end of the second resistor R2 in the overcurrent and overvoltage protection circuit; the second end of the first phototransistor serves as the second end of the light-receiving side of the first isolation optocoupler U1 and is connected to the analog ground AGND.

[0114] Optionally, the first isolation optocoupler U1 is MOCD213; of course, the first isolation optocoupler U1 may also be other types of devices, which will not be described here one by one, depending on the actual situation, and are all within the protection scope of this application.

[0115] The first isolation optical coupler U1 is provided to isolate the control module from the overcurrent and overvoltage protection circuit, that is, to isolate the control module from the output channel.

[0116] Optional, see Figure 5 The readback circuit includes: a second diode D2, a second isolation optocoupler U2, a fourth resistor R4, a fifth resistor R5 and a sixth resistor R6.

[0117] The cathode of the second diode D2 serves as the input end of the readback circuit and is connected to the second output end of the overcurrent and overvoltage protection circuit.

[0118] Specifically, the cathode of the second diode D2 is connected to the anode of the first diode D1 in the overcurrent and overvoltage protection circuit and the second end of the second switch tube Q2.

[0119] An anode of the second diode D2 is connected to one end of the fourth resistor R4.

[0120] Optionally, the second diode D2 is a voltage regulator diode.

[0121] The first end of the light emitting side of the second isolation optical coupler U2 is connected to the other end of the fourth resistor R4 and one end of the fifth resistor R5 respectively.

[0122] The first end of the light-emitting side of the second isolation optical coupler U2 and the other end of the fifth resistor R5 are both connected to the analog ground AGND.

[0123] The first end of the light-receiving side of the second isolation optical coupler U2 is connected to one end of the sixth resistor R6 , and the connection point serves as the output end of the readback circuit and is connected to the input end of the control module.

[0124] The second end of the light receiving side of the second isolation optical coupler U2 is connected to the reference ground GND.

[0125] The other end of the sixth resistor R6 is connected to the second power source VCC.

[0126] Optionally, the second isolation optocoupler U2 includes: a second light emitting diode and a second phototransistor.

[0127] The anode of the second light-emitting diode serves as the first end of the light-emitting side of the second isolation optocoupler U2; the cathode of the second light-emitting diode serves as the second end of the light-emitting side of the second isolation optocoupler U2; the first end of the second phototransistor serves as the first end of the light-receiving side of the second isolation optocoupler U2; and the second end of the second phototransistor serves as the second end of the light-receiving side of the second isolation optocoupler U2.

[0128] Specifically, one end of the sixth resistor R6 is connected to the second power supply VCC; the second phototransistor serves as the first end of the light-receiving side of the second isolation optocoupler U2, and is connected to the other end of the sixth resistor R6; the second end of the second phototransistor serves as the second end of the light-receiving side of the second isolation optocoupler U2, and is connected to the reference ground GND; the anode of the second light-emitting diode serves as the first end of the light-emitting side of the second isolation optocoupler U2, and is connected to the common end of the fourth resistor R4 and the fifth resistor R5; the cathode of the second light-emitting diode serves as the second end of the light-emitting side of the second isolation optocoupler U2, and is connected to the analog ground AGND.

[0129] Optionally, the second isolation optocoupler U2 is MOCD213; of course, the second isolation optocoupler U2 may also be other types of devices, which will not be described here one by one, depending on the actual situation, and are all within the protection scope of this application.

[0130] The second isolation optical coupler U2 is provided to isolate the control module from the overcurrent and overvoltage protection circuit, that is, to isolate the control module from the output channel.

[0131] like Figure 6 and Figure 7 As shown, Figure 6 A specific schematic diagram of the driving circuit, the overcurrent and overvoltage protection circuit and the readback circuit is shown. For the specific connection relationship between the driving circuit, the overcurrent and overvoltage protection circuit and the readback circuit, please refer to the above embodiments and will not be repeated here. Figure 7 A schematic diagram of a digital signal output channel and a digital signal output circuit is shown. For the specific connection relationship between the digital signal output channel and the digital signal output circuit, please refer to the above embodiment, which will not be described here one by one.

[0132] In this embodiment, it is safe, certain, and reliable. While realizing the diagnosis of the output circuit, it will not cause disturbance to the equipment of the nuclear power plant, ensuring the safe and stable operation of the equipment of the nuclear power plant, and meeting the safety, reliability, and stability requirements of the nuclear power plant. In addition, under the premise of safe and reliable operation of the nuclear power plant, the method and device can also greatly reduce the later operation and maintenance costs of the nuclear power plant, and has strong economic benefits.

[0133] The features recorded in the various embodiments in this specification can be replaced or combined with each other, and the same and similar parts between the various embodiments can refer to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system or system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can refer to the partial description of the method embodiment. The system and system embodiments described above are only schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the scheme of this embodiment. Ordinary technicians in this field can understand and implement it without paying creative work.

[0134] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present utility model.

[0135] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A digital signal output circuit, characterized in that: It includes a control module and at least one digital signal output channel, wherein the digital signal output channel includes: an over-current and over-voltage protection circuit, a driving circuit and a readback circuit; The input end of the overcurrent and overvoltage protection circuit is connected to a first power supply; The first output end of the overcurrent and overvoltage protection circuit serves as the output end of the digital signal output channel; the overcurrent protection and overvoltage protection in the overcurrent and overvoltage protection circuit have multiplexed resistors and switch tubes; The second output terminal of the overcurrent and overvoltage protection circuit is connected to the input terminal of the readback circuit; The control end of the overcurrent and overvoltage protection circuit is connected to the output end of the driving circuit; The input end of the control module is connected to the output end of the readback circuit; The output end of the control module is connected to the input end of the drive circuit.

2. The digital signal output circuit according to claim 1, characterized in that: The overcurrent and overvoltage protection circuit comprises: a first switch tube, a second switch tube, a first diode, a first resistor and a second resistor; The first end of the first switch tube is connected to one end of the first resistor, and the connection point serves as the input end of the overcurrent and overvoltage protection circuit; The control end of the first switch tube is respectively connected to the other end of the first resistor and the first end of the second switch tube; The second end of the first switch tube is connected to the control end of the second switch tube and one end of the second resistor; The second end of the second switch tube is connected to the anode of the first diode, and the connection point serves as the second output end of the overcurrent and overvoltage protection circuit; The cathode of the first diode serves as the first output terminal of the overcurrent and overvoltage protection circuit; The other end of the second resistor serves as a control end of the overcurrent and overvoltage protection circuit.

3. The digital signal output circuit according to claim 2, characterized in that: The first diode is MBR1H100SFT3G; and / or, the first switch tube and the second switch tube are both triodes.

4. The digital signal output circuit according to claim 1, characterized in that: The driving circuit comprises: a third resistor and a first isolation optical coupler; One end of the third resistor is connected to the second power supply; A first end of the light emitting side of the first isolation optocoupler is connected to the other end of the third resistor; The second end of the light emitting side of the first isolation optocoupler is used as the input end of the driving circuit; The first end of the light-receiving side of the first isolation optical coupler serves as the output end of the driving circuit; The second end of the first isolation optical coupler on the light receiving side is connected to the analog ground.

5. The digital signal output circuit according to claim 4, characterized in that: The first isolation optical coupler includes: a first light emitting diode and a first phototransistor; The anode of the first light emitting diode serves as the first end of the light emitting side of the first isolation optical coupler; The cathode of the first light emitting diode serves as the second end of the light emitting side of the first isolation optical coupler; The first end of the first phototransistor serves as the first end of the light-receiving side of the first isolation optical coupler; The second end of the first phototransistor serves as the second end of the first isolation optocoupler on the light receiving side.

6. The digital signal output circuit according to claim 4, characterized in that: The first isolation optical coupler is MOCD213.

7. The digital signal output circuit according to claim 1, characterized in that: The readback circuit includes: a second diode, a second isolation optocoupler, a fourth resistor, a fifth resistor and a sixth resistor; The cathode of the second diode serves as the input terminal of the readback circuit; An anode of the second diode is connected to one end of the fourth resistor; A first end of the light emitting side of the second isolation optical coupler is connected to the other end of the fourth resistor and one end of the fifth resistor respectively; The first end of the light-emitting side of the second isolation optocoupler and the other end of the fifth resistor are both connected to the analog ground; A first end of the light-receiving side of the second isolation optical coupler is connected to one end of the sixth resistor, and a connection point serves as an output end of the readback circuit; The second end of the light receiving side of the second isolation optical coupler is connected to the reference ground; The other end of the sixth resistor is connected to the second power supply.

8. The digital signal output circuit according to claim 7, characterized in that: The second isolation optical coupler includes: a second light emitting diode and a second phototransistor; The anode of the second light emitting diode serves as the first end of the light emitting side of the second isolation optical coupler; The cathode of the second light emitting diode serves as the second end of the light emitting side of the second isolation optical coupler; The first end of the second phototransistor serves as the first end of the light-receiving side of the second isolation optical coupler; The second end of the second phototransistor serves as the second end of the second isolation optocoupler on the light receiving side.

9. The digital signal output circuit according to claim 7, characterized in that: The second isolation optical coupler is MOCD213.

10. The digital signal output circuit according to claim 7, characterized in that: The second diode is a voltage regulator diode.

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