CN116300673A - Device for protecting internal circuit of PLC digital quantity input module based on intermediate relay - Google Patents

Abstract

The invention discloses a device for protecting an internal circuit of a PLC digital quantity input module based on an intermediate relay, which comprises the intermediate relay, wherein the intermediate relay is connected with external field equipment and an external PLC digital quantity input module, the intermediate relay is connected with a protection circuit module through contacts, the protection circuit module is connected with a front end acquisition input module, the front end acquisition input module is connected with a CPU module, the CPU module is connected with an isolation output module, and is also connected with an early warning module, a communication module, a power input module and a reset module; the invention can replace a switch signal transmitted by a field end to be input into a PLC digital quantity input module as an isolating device, so that the field device is not directly connected with the PLC digital quantity input module, a circuit inside the PLC digital quantity input module is protected from being impacted by external bad signals, the running reliability and stability of a PLC control system are improved, the failure occurrence rate of the device is reduced, and the waste heat recovery effect is ensured.

Description

Device for internal circuit protection of PLC digital input module based on intermediate relay

technical field

The invention relates to the field of electronic communication, in particular to an internal circuit protection device of a PLC digital quantity input module based on an intermediate relay.

Background technique

At present, the electrical control mode of waste heat recovery in the third workshop is controlled by Siemens programmable logic controller (hereinafter referred to as PLC). PLC adopts Siemens new generation ET200SP field distributed I/O system. It consists of several input and output modules (hereinafter referred to as I/O modules), base unit and a server module. The I/O module is inserted into the base and connected to the CPU module through the base. The system structure is designed to be modular, and the I/O The modules can be plugged into the passive base in any combination, making it a highly flexible and scalable system.

The I/O modules in this system include digital input module (referred to as DI module), digital output module (referred to as DQ module), analog input module (referred to as AI module) and communication module. Quantity and sensor analog signals are transmitted to the PLC CPU for processing, and the results are output through the PLC output module to control on-site valves, motors, etc. However, in actual use, the digital input module DI of the PLC is affected by various factors such as the on-site environment (electromagnetic environment) and power supply quality. Unstable voltage and current signals enter the internal circuit of the digital input module DI, and the The internal components of the DI module are burned. This situation often occurs, affecting the operation of on-site waste heat recovery equipment, resulting in reduced waste heat recovery efficiency and increased energy consumption.

Therefore, there is an urgent need for a device that can avoid the burning point of the PLC digital input module DI due to external factors, so as to ensure the effective operation of the waste heat recovery equipment.

Contents of the invention

In order to solve the above-mentioned existing technical problems, the present invention provides a device for protecting the internal circuit of a PLC digital input module based on an intermediate relay.

Technical scheme of the present invention is realized like this:

The device for protecting the internal circuit of the PLC digital input module based on the intermediate relay includes an intermediate relay, the input end of the intermediate relay is connected to the external field device, the output end is connected to the external PLC digital input module, and the intermediate relay is connected through contacts Protect the input end of the circuit module, the output end of the protection circuit module is connected to the input end of the front-end acquisition input module, the output end of the front-end acquisition input module is connected to the input end of the CPU module, the output end of the CPU module is connected to the input end of the isolation output module, the The CPU module is also connected with an early warning module, a communication module, a power input module and a reset module, the output terminal of the isolation output module is connected with the intermediate relay, and the CPU module is also connected with a display screen, and the display content of the display screen includes signal source information and circuit status information.

The protection circuit module includes a current limiting unit and an antistatic unit, the current limiting unit adopts a series resistor to limit current, and the antistatic unit adopts an instantaneous voltage surge suppressor to suppress static electricity.

The front-end acquisition input module includes an impedance matching unit, which is used to transmit all received signals to the CPU module, and there will be no signal reflection back to the source point. The impedance matching method is to use an intelligent algorithm to obtain impedance matching parameters. The impedance is equal to the impedance of the CPU module, that is, the modules and arguments of the two are equal, and the impedance of the CPU module can obtain signal transmission without distortion; when the conjugate value of the impedance in the signal source is equal to the impedance of the CPU module, that is, the modules of the two are equal and the arguments If the sum is zero, the maximum power can be obtained from the impedance of the CPU module; when the internal impedance of the signal source is not equal to the impedance of the CPU module, that is, the modes of the two are not equal, the impedance matching unit will change the impedance of the input end of the CPU module or adjust the wavelength of the transmission line. All signals are transmitted to the CPU module without reflection or distortion.

The CPU module includes a feature recognition unit, a learning model unit and an output judgment unit,

The feature recognition unit processes and analyzes all the original signals transmitted by the front-end acquisition input module, extracts the high level duration, low level duration, and level change frequency of the signal and processes them into signal features, and transmits the features to learning model unit;

The learning model unit recognizes the real-time waveform according to the signal feature information obtained by identification and extraction in the feature recognition unit, and uses machine learning methods to use one or more classification algorithms in support vector machines, decision trees, and logistic regression to establish feature The learning model compares the signal characteristics with the waveform under normal working conditions, and uses the feature learning model to obtain the signal state to which the current waveform characteristics belong. When the signal characteristics are consistent with the waveform under normal working conditions, it means that the signal source is a good signal source , when a certain signal feature is abnormal, it means that the signal source is a bad signal source;

The output judgment unit judges the output state of the received signal according to the signal source state information provided in the learning model unit, and when the signal source is a good signal source, controls to open the output terminal of the isolated output module, that is, the switch circuit, the switch The circuit drives the coil of the intermediate relay to operate, thereby opening the intermediate relay so that the good signal source is completely output to the PLC digital input module. When the signal source is a bad signal source, the control closes the switching circuit and the intermediate relay to block the output of the bad signal. And transmit the bad signal information to the early warning module and the communication module.

The input end of the isolated output module includes a current limiting unit and a pulse absorbing unit, the output end is a switch circuit, the current limiting unit is a series resistor, and the pulse absorbing unit adopts one of capacitors, TVS diodes or clamping diodes , to isolate and absorb pulse signals generated by the coil in the intermediate relay, including spikes, surges, short circuits and overloads, and the switch circuit adopts one of MOS switch circuit, transformer switch circuit or optocoupler switch circuit.

The pre-warning module acquires bad signal source information after processing by the CPU module, and displays the warning information on an external display screen.

The communication module outputs the corresponding digital signal according to the signal obtained after the processing by the CPU module, and communicates with the communication module of the external controller, and the external controller monitors the internal signal and circuit operation status.

The reset module includes light-touch external buttons and a low-pass filter circuit. By connecting to the CPU module, when debugging, installing and testing, pressing the external button makes the switch circuit in the reset state, and then resets the intermediate relay and resets the information Displayed on the display and transmitted to the communication module.

The power input module includes a voltage stabilizing unit, which converts the unstable DC voltage into a stable DC voltage, performs voltage stabilization processing on the supply voltage, and outputs a preset output voltage.

Compared with the prior art, the beneficial effects of the present invention are: the isolation device protects the input pin of the CPU module by setting the protection circuit module, current limiting and anti-burning, anti-static breakdown pins, and the matching impedance of the front-end acquisition input module is set, Ensure that the signal source is completely transmitted to the CPU module without distortion. By setting the CPU module to identify the characteristics of the signal source and establishing a learning model, it can accurately judge whether the signal source is good or not. It can also accurately identify unfamiliar or weak bad signals. It will not misjudge a good signal, greatly reducing the possibility of not being able to identify whether it is a bad signal and allowing the bad signal to pass through. The system is normal or faulty, and the external operator can be notified in time through the early warning module, communication module and display screen. By setting the isolation output module to prevent the coil of the intermediate relay from damaging the pins of the CPU module, and closing the switch circuit to avoid the passage of bad signals, the isolation is formed through the intermediate relay, so as to replace the switching signal from the field end and input to the PLC digital input module. Make there is no direct connection between the field equipment and the PLC digital input module, protect the internal circuit of the PLC digital input module from the impact of external bad signals, improve the reliability and stability of the PLC control system operation, and reduce the incidence of equipment failure. Guarantee the effect of waste heat recovery and have a good market prospect.

Description of drawings

Fig. 1 is a structure diagram of a device for internal circuit protection of a PLC digital input module based on an intermediate relay in the present invention.

Fig. 2 is a structural schematic diagram of the device for protecting the internal circuit of the PLC digital input module based on the intermediate relay in the present invention.

Fig. 3 is a working flowchart of the device for protecting the internal circuit of the PLC digital input module based on the intermediate relay in the present invention.

Detailed ways

As shown in Figures 1-3, the present invention provides a device for protecting the internal circuit of a PLC digital input module based on an intermediate relay. In order to deepen the understanding of the present invention, the present invention will be further described in combination with implementation cases below. The present invention can be implemented in the following ways:

The device for protecting the internal circuit of the PLC digital input module based on the intermediate relay includes an intermediate relay, the input end of the intermediate relay is connected to the external field device, the output end is connected to the external PLC digital input module, and the intermediate relay is connected through contacts Protect the input end of the circuit module, the output end of the protection circuit module is connected to the input end of the front-end acquisition input module, the output end of the front-end acquisition input module is connected to the input end of the CPU module, the output end of the CPU module is connected to the input end of the isolation output module, the The CPU module is also connected with an early warning module, a communication module, a power input module and a reset module, the output terminal of the isolation output module is connected with the intermediate relay, and the CPU module is also connected with a display screen, and the display content of the display screen includes signal source information and circuit status information.

The protection circuit module includes a current limiting unit and an antistatic unit, the current limiting unit adopts a series resistor to limit current and prevent burning, and the antistatic unit adopts an instantaneous voltage surge suppressor to suppress static electricity and avoid static electricity from breaking down the pins of the CPU module.

The front-end acquisition input module includes an impedance matching unit, which is used to transmit all received signals to the CPU module, and there will be no signal reflection back to the source point. The impedance matching method is to use an intelligent algorithm to obtain impedance matching parameters. The impedance is equal to the impedance of the CPU module, that is, the modules and arguments of the two are equal, and the impedance of the CPU module can obtain signal transmission without distortion; when the conjugate value of the impedance in the signal source is equal to the impedance of the CPU module, that is, the modules of the two are equal and the arguments If the sum is zero, the maximum power can be obtained from the impedance of the CPU module; when the internal impedance of the signal source is not equal to the impedance of the CPU module, that is, the modes of the two are not equal, the impedance matching unit will change the impedance of the input end of the CPU module or adjust the wavelength of the transmission line. All signals are transmitted to the CPU module without reflection or distortion.

The CPU module includes a feature recognition unit, a learning model unit and an output judgment unit,

The feature recognition unit processes and analyzes all the original signals transmitted by the front-end acquisition input module, extracts the high level duration, low level duration, and level change frequency of the signal and processes them into signal features, and transmits the features to learning model unit;

The learning model unit recognizes the real-time waveform according to the signal feature information obtained by identification and extraction in the feature recognition unit, and uses machine learning methods to use one or more classification algorithms in support vector machines, decision trees, and logistic regression to establish feature The learning model compares the signal characteristics with the waveform under normal working conditions, and uses the feature learning model to obtain the signal state to which the current waveform characteristics belong. When the signal characteristics are consistent with the waveform under normal working conditions, it means that the signal source is a good signal source , when a certain signal feature is abnormal, it means that the signal source is a bad signal source;

The output judgment unit judges the output state of the received signal according to the signal source state information provided in the learning model unit, and when the signal source is a good signal source, controls to open the output terminal of the isolated output module, that is, the switch circuit, the switch The circuit drives the coil of the intermediate relay to operate, thereby opening the intermediate relay so that the good signal source is completely output to the PLC digital input module; when the signal source is a bad signal source, the control closes the switching circuit and the intermediate relay to block the output of the bad signal. And transmit the bad signal information to the early warning module and the communication module.

The input end of the isolated output module includes a current limiting unit and a pulse absorbing unit, the output end is a switch circuit, the current limiting unit is a series resistor, and the pulse absorbing unit adopts one of capacitors, TVS diodes or clamping diodes , can isolate and absorb the pulse signal generated by the coil in the intermediate relay, including spikes, surges, short circuits and overloads, etc., to prevent it from burning out the pins of the CPU module. The switch circuit uses a MOS switch circuit, a transformer switch circuit or an optocoupler switch One of the circuits can improve the drive capability of the pins of the CPU module and protect the output capability of the CPU module when driving, preventing the intermediate relay from damaging the CPU module.

The early warning module acquires bad signal source information after processing by the CPU module, and displays the warning information on an external display screen, so as to inform the operator in time.

The communication module outputs the corresponding digital signal according to the signal obtained after the processing of the CPU module, and communicates with the communication module of the external controller, and the external controller monitors the internal signal and circuit operation status to realize remote monitoring.

The reset module includes light-touch external buttons and a low-pass filter circuit. By connecting to the CPU module, when debugging, installing and testing, pressing the external button makes the switch circuit in the reset state, and then resets the intermediate relay and resets the information Displayed on the display and transmitted to the communication module.

The power input module includes a voltage stabilizing unit, which converts the unstable DC voltage into a stable DC voltage, performs voltage stabilization processing on the power supply voltage, and outputs a preset output voltage, which is used to adapt to the circuit voltage and ensure the stability of the internal circuit of the system Work.

Example 1

The device for protecting the internal circuit of the PLC digital input module based on the intermediate relay includes an intermediate relay, the input end of the intermediate relay is connected to the external field device, the output end is connected to the external PLC digital input module, and the intermediate relay is connected through contacts Protect the input end of the circuit module, the protection circuit module includes a current limiting unit and an antistatic unit, the output end of the protection circuit module is connected to the input end of the front-end acquisition input module, the front-end acquisition input module includes an impedance matching unit, and the front-end acquisition The output end of the input module is connected to the input end of the CPU module, the CPU module includes a feature recognition unit, a learning model unit and an output judgment unit, the output end of the CPU module is connected to the input end of the isolation output module, and the input end of the isolation output module includes a limiter flow unit and pulse absorption unit, the output end is a switch circuit, the CPU module is also connected with an early warning module, a communication module, a power input module and a reset module, the power input module includes a voltage stabilizing unit, and the reset module includes a light touch Type external button and low-pass filter circuit, the output terminal of the isolated output module is connected to the intermediate relay, and the CPU module is also connected with a display screen, and the display content of the display screen includes signal source information and circuit status information.

The signal enters the device through external field equipment transmission, the original signal enters the protection circuit module through the input terminal of the protection circuit module, eliminates static electricity through the instantaneous voltage surge suppressor, and prevents burning through the series resistor. The processed signal is sent by the protection circuit module The output terminal flows into the input terminal of the front-end acquisition input module, and the impedance matching parameters of the internal impedance of the signal source and the impedance of the CPU module are obtained through the impedance matching unit, and the mode and angle of the two are equal, and the signal is transmitted to the input of the CPU module without distortion At the end, use the feature recognition unit to extract the high-level duration, low-level duration, and level change frequency of the signal and process them as the characteristics of the signal, and transmit the feature information to the learning model unit. Using machine learning methods, use The decision tree classification algorithm establishes a feature learning model, compares the real-time signal features with the waveform under normal working conditions, and uses the feature learning model to obtain the signal state to which the current waveform features belong. The signal features are consistent with the waveform under normal working conditions, indicating that The signal is in a normal state, which is a good signal source. The signal source information is transmitted to the outside world through the communication module and the external display screen, and the switch circuit is controlled by the output judgment unit. The signal is output from the output terminal of the CPU module and enters the input terminal of the isolation output module. , the current is limited by series resistors, and the peak interference generated by the intermediate relay coil is absorbed by capacitive isolation, and the MOS switch circuit at the output end flows through, and drives the coil of the intermediate relay to operate, and transmits a good signal source to the intermediate relay, and then passes through the intermediate relay. The complete output is sent to the PLC digital input module to make the waste heat recovery equipment operate effectively.

Example 2

The device for protecting the internal circuit of the PLC digital input module based on the intermediate relay includes an intermediate relay, the input end of the intermediate relay is connected to the external field device, the output end is connected to the external PLC digital input module, and the intermediate relay is connected through contacts Protect the input end of the circuit module, the protection circuit module includes a current limiting unit and an antistatic unit, the output end of the protection circuit module is connected to the input end of the front-end acquisition input module, the front-end acquisition input module includes an impedance matching unit, and the front-end acquisition The output end of the input module is connected to the input end of the CPU module, the CPU module includes a feature recognition unit, a learning model unit and an output judgment unit, the output end of the CPU module is connected to the input end of the isolation output module, and the input end of the isolation output module includes a limiter flow unit and pulse absorption unit, the output end is a switch circuit, the CPU module is also connected with an early warning module, a communication module, a power input module and a reset module, the power input module includes a voltage stabilizing unit, and the reset module includes a light touch Type external button and low-pass filter circuit, the output terminal of the isolated output module is connected to the intermediate relay, and the CPU module is also connected with a display screen, and the display content of the display screen includes signal source information and circuit status information.

The signal enters the device through external field equipment transmission, the original signal enters the protection circuit module through the input terminal of the protection circuit module, eliminates static electricity through the instantaneous voltage surge suppressor, and prevents burning through the series resistor. The processed signal is sent by the protection circuit module The output end flows into the input end of the front-end acquisition input module, and the impedance matching parameters of the internal impedance of the signal source and the impedance of the CPU module are obtained through the impedance matching unit, and the two modules are not equal. The impedance matching unit changes the impedance of the input end of the CPU module, Make the mode matching of the two equal, so that the signal is transmitted to the input end of the CPU module without distortion, and the duration of the high level, the duration of the low level, and the change frequency of the signal are extracted by the feature recognition unit and processed as the signal source feature, transfer the feature information to the learning model unit, use the machine learning method, use the support vector machine and the logistic regression classification algorithm, establish the feature learning model, compare the real-time signal features with the waveform in the normal working state, and use the feature learning The model obtains the signal state to which the current waveform feature belongs, and the analysis shows that the signal feature is inconsistent with the waveform in the normal working state. The duration of the high level is too long and the duration of the low level is too short. It is judged that the signal source is A bad signal source has the risk of burning point failure, so the signal source information will be transmitted to the outside world through the communication module and the external display screen, and the output judgment unit controls the closing of the switch circuit, and then controls the closing of the intermediate relay to block the output of bad signals. And through the early warning module and the communication module, the external early warning is used to intercept the signal entering the PLC digital input module, thereby avoiding the burning point failure of the PLC digital input module and protecting the internal circuit of the PLC digital input module.

The foregoing examples are illustrative only, and are used to explain some features of the methods described in the present invention. The appended claims are intended to claim the broadest scope conceivable and the embodiments presented herein are merely illustrations of selected implementations according to all possible combinations of embodiments. Accordingly, it is the applicant's intention that the appended claims not be limited by the selection of examples which characterize the invention. Certain numerical ranges used in the claims also include sub-ranges therein, and changes within these ranges should also be construed as being covered by the appended claims where possible.

Claims (9)

1. The device for internal circuit protection of the PLC digital input module based on the intermediate relay is characterized in that: it comprises an intermediate relay, the input end of the intermediate relay is connected with an external sensor, the output end is connected with an external PLC digital input module, and the intermediate relay The relay is connected to the input end of the protection circuit module through contacts, the output end of the protection circuit module is connected to the input end of the front-end acquisition input module, the output end of the front-end acquisition input module is connected to the input end of the CPU module, and the output end of the CPU module is connected to the isolation output module Input terminal, the CPU module is also connected with an early warning module, a communication module, a power input module and a reset module, the output terminal of the isolated output module is connected with an intermediate relay, and the CPU module is also connected with a display screen, and the display screen shows Content includes signal source information and circuit status information. 2. the device of PLC digital quantity input module internal circuit protection based on intermediate relay according to claim 1, is characterized in that: described protection circuit module comprises current-limiting unit and antistatic unit, and current-limiting unit adopts series resistance current limiting , The anti-static unit uses an instantaneous voltage surge suppressor to suppress static electricity. 3. the device of PLC digital quantity input module internal circuit protection based on intermediate relay according to claim 1, is characterized in that: described front-end acquisition input module comprises impedance matching unit, all signals that all receive are delivered to CPU module , there will be no signal reflection back to the source. The impedance matching method is to use an intelligent algorithm to obtain the impedance matching parameters. When the internal impedance of the signal source is equal to the impedance of the CPU module, that is, the modulus and argument angle of the two are equal, the impedance of the CPU module can obtain signal transmission without distortion; When the conjugate value of the internal impedance of the signal source is equal to the impedance of the CPU module, that is, the modules of the two are equal and the sum of the arguments is zero, then the maximum power can be obtained from the impedance of the CPU module; When the internal impedance of the signal source is not equal to the impedance of the CPU module, that is, the modes of the two are not equal, the impedance matching unit will transmit all signals to the CPU module without reflection and distortion by changing the impedance of the input end of the CPU module or adjusting the wavelength of the transmission line. 4. the device of PLC digital quantity input module internal circuit protection based on intermediate relay according to claim 1, is characterized in that: described CPU module comprises feature identification unit, learning model unit and output judging unit, The feature recognition unit processes and analyzes all the original signals transmitted by the front-end acquisition input module, extracts the high level duration, low level duration, and level change frequency of the signal and processes them into signal features, and transmits the features to learning model unit; The learning model unit recognizes the real-time waveform according to the signal feature information obtained by identification and extraction in the feature recognition unit, and uses machine learning methods to use one or more classification algorithms in support vector machines, decision trees, and logistic regression to establish feature The learning model compares the signal characteristics with the waveform under normal working conditions, and uses the feature learning model to obtain the signal state to which the current waveform characteristics belong. When the signal characteristics are consistent with the waveform under normal working conditions, it means that the signal source is a good signal source. When a certain signal characteristic is abnormal, it means that the signal source is a bad signal source; The output judgment unit judges the output state of the received signal according to the signal source state information provided in the learning model unit, When the signal source is a good signal source, the control opens the output terminal of the isolated output module, that is, the switch circuit, and the switch circuit drives the coil of the intermediate relay to operate, thereby opening the intermediate relay so that the good signal source is completely output to the PLC digital input module. When the signal source is a bad signal source, the switch circuit and the intermediate relay are controlled to be closed, the output of the bad signal is intercepted, and the bad signal information is transmitted to the early warning module and the communication module. 5. The device for internal circuit protection of the PLC digital input module based on the intermediate relay according to claim 1, wherein the input terminal of the isolated output module comprises a current limiting unit and a pulse absorbing unit, and the output terminal is a switching circuit , the current limiting unit is a series resistor, and the pulse absorbing unit adopts one of capacitors, TVS diodes or clamping diodes to isolate and absorb the pulse signals generated by the coil in the intermediate relay, including spikes, surges, short circuits and overloads, The switch circuit adopts one of MOS switch circuit, transformer switch circuit or optocoupler switch circuit. 6. the device of PLC digital quantity input module internal circuit protection based on intermediate relay according to claim 1, is characterized in that: described early warning module obtains the bad signal source information after CPU module has processed, and warning information is displayed on on the external display. 7. the device of PLC digital quantity input module internal circuit protection based on intermediate relay according to claim 1, is characterized in that: described communication module outputs corresponding digital quantity signal according to the signal that obtains after CPU module processing finishes, and The communication module of the external controller is connected through communication, and the external controller monitors the internal signal and the operating state of the circuit. 8. The device for internal circuit protection of the PLC digital input module based on the intermediate relay according to claim 1, characterized in that: the reset module includes light-touch external buttons and a low-pass filter circuit, by connecting the CPU module, when During debugging, installation and testing, press the external button to put the switching circuit in the reset state, then reset the intermediate relay, and display the reset information on the display screen and transmit it to the communication module. 9. The device for internal circuit protection of the PLC digital input module based on the intermediate relay according to claim 1, wherein the power input module includes a voltage stabilizing unit, which converts the unstable DC voltage into a stable DC voltage , to stabilize the supply voltage and output a preset output voltage.

Images