Protection circuit, digital quantity input module and electronic equipment

Abstract

The invention provides a protection circuit, a digital quantity input module and electronic equipment, which are applied to the technical field of automation control, the circuit comprises a current limiting circuit, a diagnosis circuit and a controller, the current limiting circuit is connected between a contact power supply of a DI module and a first contact, the diagnosis circuit is connected with the current limiting circuit in parallel, and the controller is connected with the diagnosis circuit. The controller comprises a diagnosis port and an acquisition port, the diagnosis port is connected with a control end of the diagnosis circuit, the acquisition port is connected with a second contact of the DI module, and the controller outputs a diagnosis signal in a diagnosis mode, so that the current limiting circuit fails and detects the DI module according to a preset corresponding relation between the diagnosis signal and a feedback signal; the fault detection of the DI module is realized, and the controller outputs an operation signal in a working mode to control the diagnosis circuit to be switched off, so that the current limiting circuit limits the current flowing through the DI module. According to the circuit, fault diagnosis can be carried out on the DI module, current limiting protection can be provided, and the safety and reliability of the DI module can be effectively improved.

Description

Technical Field

[0001] The present application relates to the field of automation control technology, and in particular to a protection circuit, a digital quantity input module and an electronic device. Background Art

[0002] In industrial control systems, DI (Digital Input) modules are widely used. By connecting a normally closed switch at the contacts of the DI module, the switch signal can be collected. The accurate collection of switch signals such as the control process, physical quantity threshold status, and fault alarm of equipment at all levels in the control system has an important impact on the normal operation and safety of the entire system. Therefore, the safety and reliability of the DI module during operation is particularly important.

[0003] In view of the importance of DI modules in industrial control systems, how to improve the safety and reliability of DI modules has become one of the technical problems that technical personnel in this field need to solve urgently. Summary of the invention

[0004] In view of this, the present application is committed to providing a protection circuit, a digital input module and an electronic device, which can perform fault diagnosis on the DI module and provide current limiting protection, and can effectively improve the safety and reliability of the DI module.

[0005] In a first aspect, the present application provides a protection circuit applied to a digital quantity input DI module, wherein the DI module includes a contact power supply, a first contact and a second contact, and the circuit includes: a current limiting circuit, a diagnostic circuit and a controller, wherein:

[0006] The input end of the current limiting circuit is connected to the contact power supply, and the output end of the current limiting circuit is connected to the first contact;

[0007] The diagnostic circuit is connected in parallel with the current limiting circuit;

[0008] The diagnostic port of the controller is connected to the control end of the diagnostic circuit, and the acquisition port of the controller is connected to the second contact point;

[0009] The controller outputs a diagnostic signal in a diagnostic mode, and detects the DI module according to a preset corresponding relationship between the diagnostic signal and a feedback signal;

[0010] Wherein, the diagnostic signal is used to control the closing of the diagnostic circuit to disable the current limiting circuit and trigger the DI module to generate the feedback signal;

[0011] The controller outputs an operation signal in the working mode, and the operation signal is used to control the diagnosis circuit to be disconnected so that the current limiting circuit limits the current flowing through the DI module.

[0012] In a possible implementation, the diagnostic circuit includes a switch circuit and a protective resistor, wherein:

[0013] The switch circuit is connected in series with the protection resistor to form a series branch;

[0014] The series branch is connected in parallel with the current limiting circuit;

[0015] The control end of the switch circuit serves as the control end of the diagnosis circuit.

[0016] In a possible implementation, the switch circuit includes a first voltage divider circuit and a first optical coupler, wherein:

[0017] The first voltage-dividing circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor, wherein:

[0018] One end of the first voltage-dividing resistor is connected to a first driving power supply, and the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor, and the first driving power supply is used to provide a driving voltage for the first optical coupler;

[0019] The other end of the second voltage-dividing resistor is connected to the diagnostic port;

[0020] The input end of the first optical coupler is connected in parallel with the second voltage-dividing resistor, and the output end of the first optical coupler is connected in series with the protection resistor.

[0021] In a possible implementation, the current limiting circuit includes a first switch tube, a second switch tube and a start-up resistor, wherein:

[0022] The emitter of the first switch tube is connected to one end of the starting resistor, and the resulting connection point serves as the input end of the current limiting circuit;

[0023] The base of the first switch tube, the other end of the starting resistor and the emitter of the second switch tube are connected;

[0024] The collector of the first switch tube, the base of the second switch tube and the collector of the second switch tube are connected, and the obtained connection point serves as the output end of the current limiting circuit.

[0025] In a possible implementation manner, the protection circuit provided in the first aspect of the present application further includes: a filter circuit, wherein:

[0026] The filter circuit includes: a first filter capacitor, a second filter capacitor and a filter resistor, wherein:

[0027] The first end of the first filter capacitor and the first end of the second filter capacitor are respectively connected to the contact power supply;

[0028] The second end of the first filter capacitor is connected to one end of the filter resistor, and the connection point between the first filter capacitor and the filter resistor is connected to the output end of the current limiting circuit;

[0029] The second end of the second filter capacitor is connected to the other end of the filter resistor, and the connection point between the second filter capacitor and the filter resistor is connected to the first connection point.

[0030] In a possible implementation manner, the preset corresponding relationship includes: the diagnostic signal and the feedback signal have opposite logic levels;

[0031] The controller detects the DI module according to a preset corresponding relationship between the diagnosis signal and the feedback signal, including:

[0032] If the logic levels of the diagnostic signal and the feedback signal are opposite, it is determined that the DI module is normal;

[0033] If the diagnostic signal and the feedback signal have the same logic level, it is determined that the DI module is faulty.

[0034] In a possible implementation manner, the protection circuit provided in the first aspect of the present application further includes: a collection circuit, wherein:

[0035] The input end of the acquisition circuit is connected to the second contact point, and the output end of the acquisition circuit is connected to the acquisition port;

[0036] The acquisition circuit is used to generate the feedback signal based on the current in the DI module.

[0037] In a possible implementation, the acquisition circuit includes: a second voltage divider circuit, a second optical coupler, and a pull-up resistor, wherein:

[0038] The second voltage-dividing circuit includes a third voltage-dividing resistor and a fourth voltage-dividing resistor;

[0039] One end of the third voltage-dividing resistor is connected to the second contact point, and the other end of the third voltage-dividing resistor is connected to one end of the fourth voltage-dividing resistor;

[0040] The other end of the fourth voltage-dividing resistor is grounded;

[0041] The input end of the second optical coupler is connected in parallel with the fourth voltage-dividing resistor;

[0042] One end of the pull-up resistor is connected to a second driving power supply, and the other end of the pull-up resistor is connected to a first output end of the second optical coupler, wherein the second driving power supply is used to provide a high level;

[0043] The second output terminal of the second optical coupler is grounded;

[0044] A connection point between the pull-up circuit and the second optical coupler is connected to the acquisition port.

[0045] In a second aspect, the present application provides a digital quantity input module, comprising: a contact power supply, a first contact, a second contact, and a protection circuit as described in any one of the first aspects of the present application, wherein:

[0046] The protection circuit is respectively connected to the contact power supply, the first contact and the second contact;

[0047] The first contact and the second contact are used to connect a normally closed switch.

[0048] In a third aspect, the present application provides an electronic device, comprising: at least one digital quantity input module as described in the second aspect of the present application.

[0049] Based on the above content, the protection circuit provided by the present application includes a current limiting circuit, a diagnostic circuit and a controller. The current limiting circuit is connected between the contact power supply and the first contact of the DI module, and the diagnostic circuit is connected in parallel with the current limiting circuit. The controller includes a diagnostic port and an acquisition port. The diagnostic port is connected to the control end of the diagnostic circuit, and the acquisition port is connected to the second contact of the DI module. The controller outputs a diagnostic signal in the diagnostic mode to disable the current limiting circuit and detect the DI module according to the preset corresponding relationship between the diagnostic signal and the feedback signal fed back by the DI module, so as to realize the fault detection of the DI module. Furthermore, the controller outputs an operation signal in the working mode to control the disconnection of the diagnostic circuit so that the current limiting circuit limits the current flowing through the DI module. The protection circuit provided by the present application can perform fault diagnosis on the DI module and provide current limiting protection, thereby effectively improving the safety and reliability of the DI module. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention 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 present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 It is a structural block diagram of a protection circuit provided by an embodiment of the present invention.

[0052] Figure 2 It is a circuit topology diagram of a protection circuit provided by an embodiment of the present invention.

[0053] Figure 3 It is a structural block diagram of another protection circuit provided by an embodiment of the present invention.

[0054] Figure 4 This is a circuit topology diagram of another protection circuit provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0055] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0056] As mentioned earlier, in industrial control systems, DI (Digital Input) modules are widely used. By connecting a normally closed switch at the contacts of the DI module, the switch signal can be collected. Because the control process of equipment at all levels in the control system, the accurate collection of switch signals such as the threshold status of physical quantities and fault alarms has an important impact on the normal operation and safety of the entire system, the safety and reliability of the DI module during operation is particularly important.

[0057] Combined with practical application experience, the DI module has the risk of overcurrent burning in actual application. Moreover, due to the long-term operation of the DI module, the DI module may not be able to collect switch quantities normally, thereby affecting the safe operation of the system. Therefore, how to improve the safety and reliability of the DI module has become one of the technical problems that technical personnel in this field need to solve urgently.

[0058] In order to solve the above problems, the present application provides a protection circuit, including a current limiting circuit, a diagnostic circuit and a controller, wherein the current limiting circuit is connected between the contact power supply and the first contact of the DI module, and the diagnostic circuit is connected in parallel with the current limiting circuit. The controller includes a diagnostic port and an acquisition port, wherein the diagnostic port is connected to the control end of the diagnostic circuit, and the acquisition port is connected to the second contact of the DI module. The controller outputs a diagnostic signal in the diagnostic mode to disable the current limiting circuit and detect the DI module according to the preset corresponding relationship between the diagnostic signal and the feedback signal fed back by the DI module, thereby realizing fault detection of the DI module. Furthermore, the controller outputs an operation signal in the working mode to control the disconnection of the diagnostic circuit so that the current limiting circuit limits the current flowing through the DI module. The protection circuit provided in the present application can perform fault diagnosis on the DI module and provide current limiting protection, thereby effectively improving the safety and reliability of the DI module.

[0059] The protection circuit provided in the present application is applied to a DI module. The DI module includes a contact power supply 40, a first contact C1 and a second contact C2. In practical applications, the first contact C1 and the second contact C2 are used to connect a lower circuit, that is, the lower circuit is connected between the first contact C1 and the second contact C2, and the second contact C2 is grounded. For the DI module, the lower circuit connected thereto is usually a normally closed switch. Figure 1 In the embodiment shown, K1 is shown. It can be understood that when the first contact C1 is connected to the contact power supply 40, the normally closed switch K1 is closed, and the acquisition circuit (not shown) in the DI module acquires the switch value 1, and correspondingly, when the normally closed switch K1 is disconnected, the acquisition circuit of the DI module acquires the switch value 0.

[0060] Based on the above, see Figure 1 , Figure 1 It is a structural block diagram of a protection circuit provided by the present application. The protection circuit provided by the present application includes: a current limiting circuit 10, a diagnostic circuit 20 and a controller 30.

[0061] The input end of the current limiting circuit 10 is connected to the contact power supply 40, and the output end is connected to the first contact C1, that is, the current limiting circuit 10 is connected between the contact power supply 40 and the first contact C1. The diagnostic circuit 20 is connected in parallel with the current limiting circuit 10, that is, the diagnostic circuit 20 is also connected between the contact power supply 40 and the first contact C1.

[0062] The controller 30 includes a diagnostic port and a collection port, wherein the diagnostic port of the controller 30 is connected to the control end of the diagnostic circuit 20, and the collection port of the controller 30 is connected to the second connection point C2.

[0063] Since the detection process of the DI module cannot affect the normal collection of the switch quantity of the DI module, the protection circuit provided in the present application includes two operation modes, namely, a diagnosis mode and a working mode.

[0064] In the diagnostic mode, the controller 30 outputs a diagnostic signal, and the diagnostic circuit 20 is closed in response to the diagnostic signal. It is understood that since the diagnostic circuit 20 is connected in parallel with the current limiting circuit 10, when the diagnostic circuit 20 is closed, the current limiting circuit 10 can be short-circuited, even if the current limiting circuit fails. At the same time, the diagnostic signal also triggers the DI module to generate a feedback signal. It is understood that for a certain DI module, after connecting the normally closed switch K1, the following will be formed Figure 1 In the closed loop shown, when the acquisition function of the DI module is normal, the controller 30 outputs a diagnostic signal and can certainly receive a feedback signal corresponding to the diagnostic signal. If the controller 30 fails to receive the corresponding feedback signal after outputting the diagnostic signal during the diagnostic process, it can be proved that the acquisition function of the DI module is abnormal. In addition, the preset correspondence between the diagnostic signal and the feedback signal is also determined. For example, the diagnostic signal is at a high level and the corresponding feedback signal is at a low level. Of course, the corresponding feedback signal can also be at a high level. The correspondence between the diagnostic signal and the feedback signal depends on the specific circuit implementation. Based on this, the controller 30 can detect whether the DI module is normal according to the preset correspondence between the diagnostic signal and the feedback signal. The specific forms of the diagnostic signal and the feedback signal and the preset correspondence between the two will be expanded in the subsequent content and will not be described in detail here.

[0065] In the working mode, the diagnostic function of the protection circuit is turned off, and the controller 30 outputs an operating signal, which controls the diagnostic circuit 20 to be disconnected and restores the function of the current limiting circuit 10, that is, limiting the current flowing through the DI module, thereby providing current limiting protection for the DI module.

[0066] In summary, in the protection circuit provided by the present application, the controller outputs a diagnostic signal in the diagnostic mode, which makes the current limiting circuit invalid and detects the DI module according to the preset corresponding relationship between the diagnostic signal and the feedback signal fed back by the DI module, thereby realizing the fault detection of the DI module. Furthermore, the controller outputs an operation signal in the working mode to control the disconnection of the diagnostic circuit so that the current limiting circuit limits the current flowing through the DI module. The protection circuit provided by the present application can perform fault diagnosis on the DI module and provide current limiting protection, thereby effectively improving the safety and reliability of the DI module.

[0067] Further, in Figure 1 Based on the embodiment shown, the present application also provides another protection circuit. The specific circuit topology can be found in Figure 2 shown.

[0068] The diagnostic circuit 20 includes a switch circuit 201 and a protection resistor R1. The switch circuit 201 includes a first optical coupler U1 and a first voltage divider circuit, wherein the first voltage divider circuit includes a first voltage divider resistor R3 and a second voltage divider resistor R4. Figure 2 As shown, one end of the first voltage-dividing resistor R3 is connected to the first driving power supply P1, and the other end is connected to one end of the second voltage-dividing resistor R4, and the other end of the second voltage-dividing resistor R4 is connected to the diagnostic port Out of the controller 30. The input end of the first optical coupler U1 is connected in parallel with the second voltage-dividing resistor R4, and the first optical coupler U1 includes two output ends, namely the first output end and the second output end, wherein the first output end of the first optical coupler U1 serves as an external connection end of the diagnostic circuit 20, and the second output end of the first optical coupler U1 is connected in series with one end of the protective resistor R2, and the other end of the protective resistor R2 serves as another external connection end of the diagnostic circuit. It should be noted that the first driving power supply P1 mentioned in the above content is used to provide a driving voltage for the first optical coupler U1.

[0069] Furthermore, the current limiting circuit 10 includes a first switch tube Q1, a second switch tube Q2 and a start-up resistor R1. Figure 2 As shown, the emitter of the first switch tube Q1 is connected to one end of the starting resistor R1, and the connection point between the first switch tube Q1 and the starting resistor R1 serves as the input end of the current limiting circuit 10 and is connected to the contact power supply 40. The base of the first switch tube Q1, the other end of the starting resistor R1 and the emitter of the second switch tube Q2 are connected. The collector of the first switch tube Q1, the base of the second switch tube Q2 and the collector of the second switch tube Q2 are connected. The connection point obtained by connecting the three serves as the output end of the current limiting circuit 10.

[0070] Based on the above content, it can be seen that the switch circuit 201 in the diagnostic circuit 20 is connected in series with the protection resistor R2 to form a series branch. The resulting series branch is connected in parallel with the current limiting circuit 10. After the parallel connection, it is connected between the contact power supply 40 and the first contact C1. The control end of the switch circuit 201 serves as the control end of the diagnostic circuit 20 and is connected to the diagnostic port Out of the controller 30.

[0071] In one possible implementation, Figure 2 The circuit topology shown in the figure also has an anti-reverse diode D1, combined with Figure 2 As shown, the anode of the anti-reverse diode D1 is connected to one end of the current limiting circuit 10, and the cathode is connected to the first contact C1. The anti-reverse diode D1 mainly prevents surge and power reverse connection, which may damage the switch tubes and cause the entire protection circuit to fail.

[0072] Combine the following Figure 2 The circuit topology diagram shown introduces the working process of the protection circuit.

[0073] In the diagnostic mode, the diagnostic port Out of the controller 30 outputs a low level (i.e., a diagnostic signal). At this time, due to the voltage-dividing effect of the first voltage-dividing circuit, a high level will be generated at both ends of the second voltage-dividing resistor R4, thereby driving the first optical coupler U1 to turn on, the switch circuit 201 to turn on, and the DC current output by the contact power supply 40 enters the first contact C1 through the switch circuit 201, the protection resistor R2 and the anti-reverse diode D1. At this time, the diagnostic circuit 20 short-circuits the current limiting circuit 10, and the current limiting circuit 10 fails. Furthermore, it returns to the acquisition port In of the controller 30 after passing through the normally closed switch K1 and the second contact C2.

[0074] In this embodiment, as an optional implementation, the DC current returned to the acquisition port of the controller 30 is used as a feedback signal. It can be understood that in actual applications, after the output side of the first optical coupler U1 is turned on, the magnitude of the current returned to the acquisition port Out is mainly determined by the protection resistor R2. The influence of the anti-reverse diode D1, the normally closed switch K1, etc. in the aforementioned conductive circuit on the current can be almost ignored. Therefore, by configuring the protection resistor R2, the current as the feedback signal after the controller 30 outputs the diagnostic signal can be limited to a preset range. Based on this, a preset corresponding relationship between the diagnostic signal and the feedback current, that is, the feedback signal, can be established. After the diagnostic port Out of the controller 30 outputs a diagnostic signal, if the acquisition port In of the controller 30 can accurately acquire the feedback current that satisfies the aforementioned preset corresponding relationship, it can be proved that the acquisition function of the DI module is normal, and then when the normally closed switch K1 is actually actuated, the switch quantity fed back by the normally closed switch K1 can also be acquired; on the contrary, if after the diagnostic port Out of the controller 30 outputs a diagnostic signal, the acquisition port In of the controller 30 fails to accurately acquire the feedback current that satisfies the aforementioned preset corresponding relationship, it can be proved that the acquisition function of the DI module is abnormal and cannot accurately acquire the switch quantity fed back by the normally closed switch K1.

[0075] In another possible implementation, a conversion circuit is provided inside the acquisition port In of the controller 30, for example, it may be a resistor with a known resistance value. After the acquisition port In acquires the feedback current, the current value is converted into a voltage value via the resistor. As mentioned above, when the DI module is normal, the current value of the feedback current is basically stable, and accordingly, the voltage value acquired by the controller 30 is also stable. By establishing a preset corresponding relationship between the diagnostic signal and the resistor voltage as the feedback signal, the diagnosis of the acquisition function of the DI module can be realized, that is, after the diagnostic port Out of the controller 30 outputs the diagnostic signal, if the acquisition port In of the controller 30 can accurately acquire the resistor voltage that satisfies the aforementioned preset corresponding relationship, it can be proved that the acquisition function of the DI module is normal, and then when the normally closed switch K1 is actually actuated, the switch quantity fed back by the normally closed switch K1 can also be acquired; on the contrary, if after the diagnostic port Out of the controller 30 outputs the diagnostic signal, the acquisition port In of the controller 30 fails to accurately acquire the resistor voltage that satisfies the aforementioned preset corresponding relationship, it can be proved that the acquisition function of the DI module is abnormal and the switch quantity fed back by the normally closed switch K1 cannot be accurately acquired.

[0076] It is understandable that since the diagnostic process of the DI module acquisition function cannot interfere with the normal signal acquisition, the duration of the diagnostic signal should not be too long, and it is sufficient to effectively acquire the feedback signal. Figure 2 In the circuit topology diagram shown, the diagnostic signal is low level, that is, the protection circuit is required to output a short low level in the diagnostic mode. When the feedback signal is successfully received, it means that the diagnosis is completed, the diagnostic signal is stopped, and a high level is output to shut down the diagnostic circuit 20. Based on this, when the diagnosis needs to be repeated multiple times, the diagnostic port Out of the controller 30 outputs Figure 2 The pulse waveform of the signal is shown.

[0077] It can also be understood that the diagnostic process of the ID module in the present application is essentially equivalent to operating the DI signal to change its position. Of course, the position change time is very short. Through the position change diagnosis, it can be identified whether the DI signal acquisition circuit can respond normally. If the diagnostic signal that meets the preset corresponding relationship is successfully received, it means that the DI module can collect the switch signal in time. Otherwise, it means that there is an abnormality in the DI module.

[0078] In the working mode, the diagnostic port Out of the controller 30 outputs a high level (i.e., an operating signal). At this time, a high level is applied to both ends of the second voltage-dividing resistor R4. Accordingly, the voltage difference between the two ends of the second voltage-dividing resistor R4 is very small, and the first optocoupler U1 cannot be driven to turn on. The switch circuit 201 is turned off, and the DC current output by the contact power supply 40 enters the first contact C1 through the current limiting circuit 10. At this time, the diagnostic circuit 20 is disconnected, and the current limiting circuit 10 normally performs its current limiting protection function.

[0079] Combination Figure 2 As shown, when the diagnostic circuit 20 is turned off, the base voltage of the second switch tube Q2 is approximately 0V, the emitter of the second switch tube Q2 is the output voltage of the contact power supply 40, which is generally 24V, and the voltage V between the base and collector of the second switch tube Q2 is be2 >0.6V, the second switch tube Q2 is turned on and outputs 24V. Furthermore, in this state, the current flowing through the start-up resistor R1 is small, resulting in a voltage V between the base and emitter of the first switch tube Q1 be1 <0.6V, the first switch tube Q1 is turned off.

[0080] When a ground fault occurs at the contact of the DI module, the current flowing through the starting resistor R1 increases rapidly. When the resistor voltage is greater than 0.6V, the first switch tube Q1 is turned on. Taking the resistance value of the starting resistor R1 as 56Ω as an example, the current limiting circuit 10 will limit the current of the entire circuit to 0.6V / 56Ω=10.7mA. Correspondingly, the base voltage of the second switch tube Q2 increases to 24V-0.6V=23.4V. At this time, the second switch tube Q2 works in the amplification area, and the entire current limiting circuit 10 limits the current to 10.7mA, thereby playing a role in current limiting protection.

[0081] It can be understood that the protection circuit provided in the present application can determine whether the DI module can effectively collect switch signals in the diagnostic mode, and can play a current limiting protection role in the working mode. In practical applications, the working mode of the protection circuit can be switched according to application requirements. It should be noted that the duration of the diagnostic mode should be short enough to effectively realize the diagnostic function as a basic requirement. During the working time of the DI module, the protection circuit is in the working mode most of the time.

[0082] Based on any of the above embodiments, the present application also provides another protection circuit. Figure 1 Take the protection circuit shown in the figure as an example. Figure 1 Based on the protection circuit shown in FIG. 1 , the protection circuit provided in this embodiment further includes a collection circuit 50, combined with Figure 3 As shown, the input end of the acquisition circuit 50 is connected to the second connection point C2, and the output end of the acquisition circuit 50 is connected to the acquisition port of the controller 30, that is, the acquisition circuit 50 is connected between the second connection point C2 and the acquisition port of the controller 30, and the acquisition circuit 50 generates the aforementioned feedback signal based on the current in the DI module.

[0083] Furthermore, Figure 4The illustrated embodiment provides an optional implementation of an acquisition circuit 50. In this embodiment, the acquisition circuit 50 includes: a pull-up resistor R8, a second optical coupler U2, and a second voltage divider circuit 501, wherein the second voltage divider circuit 501 includes a third voltage divider resistor R6 and a fourth voltage divider resistor R7.

[0084] Specifically, one end of the third voltage-dividing resistor R6 serves as the input end of the acquisition circuit 50 and is connected to the second contact C2. The other end of the third voltage-dividing resistor R6 is connected to one end of the fourth voltage-dividing resistor R7. The other end of the fourth voltage-dividing resistor R7 is grounded. At the same time, both ends of the fourth voltage-dividing resistor R7 serve as the output ends of the second voltage-dividing circuit 501 and are connected in parallel with the input end of the second optical coupler U2.

[0085] One end of the pull-up resistor R8 is connected to the second driving power supply P2, and the other end is connected to the first output end of the second optical coupler U2. The second output end of the second optical coupler U2 is grounded. The connection point between the pull-up circuit R8 and the second optical coupler U2 is used as the output end of the acquisition circuit 50 and is connected to the acquisition port In of the controller 30. The second driving power supply P2 is used to provide a high level.

[0086] It should be noted that, as mentioned above, the diagnostic circuit 20 is also provided with a first driving power supply P1. In practical applications, the first driving power supply P1 and the second driving power supply P2 can use the same power supply. Of course, the two can also be implemented with different power supplies. Without exceeding the core idea of ​​the present application, they also fall within the scope of protection of the present application.

[0087] It should also be noted that, based on the basic working principles of the optocoupler and the relevant requirements of functional safety, in each embodiment of the present application, the grounding point connected to the input side of the optocoupler is not the same as the grounding point connected to the output side. Specifically, the grounding point on the output side of the optocoupler is the signal ground, marked as SGND in the figure, and the grounding point on the input side of the optocoupler is a floating ground, marked as FGND in the figure. The grounding point setting of the optocoupler in this application is used here and will not be repeated in subsequent content.

[0088] As for Figure 4 The composition and connection methods of other sub-circuits of the protection circuit in the circuit topology shown can refer to the above Figure 2 The relevant contents in the illustrated embodiment will not be repeated here.

[0089] based on Figure 4In the circuit topology shown, in the diagnostic mode, the controller 30 outputs a low level (i.e., a diagnostic signal), the diagnostic circuit 20 is turned on, and the current limiting resistor 10 connected in parallel therewith fails, and the contact power supply 40 enters the acquisition circuit 50 through the first optical coupler U1, the current limiting resistor R2, the anti-reverse diode D1, the first contact C1, the normally closed switch K1, and the second contact C2. Based on the current flow path, it can be seen that the current size is mainly affected by the current limiting resistor R2. Therefore, by configuring the current limiting resistor R2, the current size flowing into the acquisition circuit 50 can be adjusted. In practical applications, the current limiting resistor R2 can be configured as a large resistance resistor, such as about 100kΩ. At this time, the current flowing into the acquisition circuit 50 is less than 0.24mA. Correspondingly, by configuring the resistance of each voltage-dividing resistor in the second voltage-dividing circuit 501, the actual voltage across the fourth voltage-dividing resistor R7 can be less than 5V after the voltage-dividing effect of the second voltage-dividing circuit 501. At this time, the second optical coupler U2 is stably turned off, which plays a role in temporarily turning off the field signal of the DI module. At the same time, the output voltage (high level) of the second driving power supply P2 in the acquisition circuit 50 is directly used as a feedback signal and fed back to the feedback port In of the controller 30 through the pull-up resistor R8. After receiving the high level, the controller 30 can determine that the acquisition function of the DI module is normal. On the contrary, if the controller 30 does not receive the corresponding feedback signal after outputting the diagnostic signal, it can be determined that the acquisition function of the DI module is abnormal.

[0090] Based on the above diagnostic process, it can be known that in this embodiment, the diagnostic signal is at a low level, while the feedback signal of the DI module is at a high level under normal conditions. That is to say, the preset corresponding relationship between the aforementioned diagnostic signal and the feedback signal is: the diagnostic signal and the feedback signal have opposite logical levels. For the controller, if the diagnostic signal and the obtained feedback signal have opposite logical levels, it can be determined that the DI module is normal; on the contrary, if the diagnostic signal and the obtained feedback signal have the same logical level, it is determined that the DI module is faulty. Of course, limited by the specific implementation of the circuit topology, this embodiment outputs a low level in the diagnostic mode and a high level in the operating mode. Therefore, the preset corresponding relationship in this embodiment only includes one, that is, the diagnostic signal is at a low level and the feedback signal is at a high level, and there is no situation where the diagnostic signal is at a high level and the feedback signal is at a low level, which is the opposite logical level.

[0091] Furthermore, for the controller, the diagnostic port and the feedback port use inverse logic, which can also effectively identify the adhesion fault between the pins of the diagnostic port and the pins of the feedback port, which is also important for improving the safety of the DI module.

[0092] As mentioned above, in the operation mode, the controller 30 outputs a high level (operation signal), the diagnostic circuit 20 is turned off, and the current limiting resistor 10 operates normally to protect the safe operation of the DI module. At this time, if the normally closed switch K1 is closed, since there is no influence of the current limiting resistor R2, the current finally output to the acquisition circuit 50 is relatively large, which in turn causes the voltage generated at both ends of the second voltage-dividing resistor R7 in the second voltage-dividing circuit 501 to be greater than the driving voltage of the second optical coupler U2, the second optical coupler U2 is turned on, and the voltage received by the feedback port of the controller 30 is pulled down to 0V, that is, the controller 30 acquires the switch value 0; correspondingly, if the normally closed switch K1 is disconnected, no current flows through the acquisition circuit 50, the voltage at both ends of the fourth voltage-dividing resistor R7 in the second voltage-dividing circuit 501 is 0V, the second optical coupler U2 is turned off, and the high level output by the second driving power supply P2 is directly input to the acquisition port of the controller 30, and the controller 30 acquires the switch value 1.

[0093] It should be noted that in Figure 4 In the circuit shown, the collection circuit 50 also shows filter capacitors C3, C4 and C5, and their connection relationship can be referred to Figure 4 As shown, it will not be repeated here. By setting the filter capacitor, the stability of the output voltage of the corresponding circuit can be effectively improved, which helps to improve the reliability and control accuracy of the protection circuit.

[0094] Further, in Figure 4 The protection circuit provided in the illustrated embodiment further includes a filter circuit 60 , wherein the filter circuit 60 includes a first filter capacitor C1 , a second filter capacitor C2 , and a filter resistor R5 .

[0095] Combination Figure 4 As shown, the first end of the first filter capacitor C1 and the first end of the second filter capacitor C2 are respectively connected to the contact power supply 40, the second end of the first filter capacitor C1 is connected to one end of the filter resistor R5, and the connection point of the first filter capacitor C1 and the filter resistor R5 is connected to the output end of the current limiting circuit 10, further, the second end of the second filter capacitor C2 is connected to the other end of the filter resistor R5, and the connection point of the second filter capacitor C2 and the filter resistor R5 is connected to the first contact C1 via the anti-reverse diode D1. Based on the above connection relationship, it can be seen that the first filter capacitor C1, the second filter capacitor C2 and the filter resistor R5 constitute a π-type filter circuit, which is connected between the contact power supply 40 and the first contact C1. The stray voltage and current that affect the actual diagnostic effect of the protection circuit can be filtered out through the filter circuit 60, thereby improving the reliability of the protection circuit. As for the principle of the filter circuit 60 to realize the filtering function, reference can be made to the relevant technology, which will not be described in detail here.

[0096] It should be noted that the filter circuit 60 can also be applied to the protection circuit provided in any of the above embodiments, and is not limited to Figure 4The embodiment shown, for example, can also be applied to Figure 2 In the embodiment shown, the connection method and filtering principle are similar to Figure 4 The embodiments shown are the same and will not be described in detail here.

[0097] It should also be noted that in the protection circuit provided in any of the above embodiments, the controller includes a controller set inside the DI module itself (i.e., the existing controller of the DI module). Of course, it can also be a separately set controller. Both of these settings are within the scope of protection of this application.

[0098] Furthermore, the present application also provides a DI module, comprising: a contact power supply, a first contact, a second contact, and a protection circuit provided by any of the above embodiments, wherein:

[0099] The protection circuit is respectively connected to the contact power supply, the first contact and the second contact;

[0100] The first contact and the second contact are used to connect a normally closed switch.

[0101] Furthermore, the present application also provides an electronic device, comprising: at least one digital quantity input module as provided in the above embodiment.

[0102] Those skilled in the art will appreciate that the contents disclosed in this disclosure may be subject to various modifications and improvements. For example, the various devices or components described above may be implemented by hardware, or by software, firmware, or a combination of some or all of the three.

[0103] In addition, although the present disclosure makes various references to certain units in the system according to embodiments of the present disclosure, any number of different units can be used and run on the client and / or server. The units are only illustrative, and different aspects of the system and method can use different units.

[0104] Flowcharts are used in this disclosure to illustrate the steps of the method according to the embodiments of the present disclosure. It should be understood that the preceding or following steps are not necessarily performed precisely in order. On the contrary, various steps may be processed in reverse order or simultaneously. At the same time, other operations may also be added to these processes.

[0105] Those skilled in the art will appreciate that all or part of the steps in the above method can be completed by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, such as a read-only memory, etc. Optionally, all or part of the steps in the above embodiment can also be implemented using one or more integrated circuits. Accordingly, each module / unit in the above embodiment can be implemented in the form of hardware or in the form of a software functional module. The present disclosure is not limited to any particular form of combination of hardware and software.

[0106] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present disclosure belongs. It should also be understood that terms such as those defined in common dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined as such herein.

[0107] The above is an explanation of the present disclosure and should not be considered as a limitation thereof. Although several exemplary embodiments of the present disclosure are described, it will be readily understood by those skilled in the art that many modifications may be made to the exemplary embodiments without departing from the novel teachings and advantages of the present disclosure. Therefore, all such modifications are intended to be included within the scope of the present disclosure as defined in the claims. It should be understood that the above is an explanation of the present disclosure and should not be considered to be limited to the specific embodiments disclosed, and modifications to the disclosed embodiments and other embodiments are intended to be included within the scope of the appended claims. The present disclosure is defined by the claims and their equivalents.

Claims

1. A protection circuit, characterized in that: Applied to a digital quantity input DI module, the DI module includes a contact power supply, a first contact and a second contact, the circuit includes: a current limiting circuit, a diagnostic circuit and a controller, wherein: The input end of the current limiting circuit is connected to the contact power supply, and the output end of the current limiting circuit is connected to the first contact; The diagnostic circuit is connected in parallel with the current limiting circuit; The diagnostic port of the controller is connected to the control end of the diagnostic circuit, and the acquisition port of the controller is connected to the second contact point; The controller outputs a diagnostic signal in a diagnostic mode, and detects the DI module according to a preset corresponding relationship between the diagnostic signal and a feedback signal; Wherein, the diagnostic signal is used to control the closing of the diagnostic circuit to disable the current limiting circuit and trigger the DI module to generate the feedback signal; The controller outputs an operation signal in the working mode, and the operation signal is used to control the diagnosis circuit to be disconnected so that the current limiting circuit limits the current flowing through the DI module.

2. The protection circuit according to claim 1, characterized in that: The diagnostic circuit includes a switch circuit and a protective resistor, wherein: The switch circuit is connected in series with the protection resistor to form a series branch; The series branch is connected in parallel with the current limiting circuit; The control end of the switch circuit serves as the control end of the diagnosis circuit.

3. The protection circuit according to claim 2, characterized in that: The switch circuit includes a first voltage divider circuit and a first optical coupler, wherein: The first voltage-dividing circuit includes a first voltage-dividing resistor and a second voltage-dividing resistor, wherein: One end of the first voltage-dividing resistor is connected to a first driving power supply, and the other end of the first voltage-dividing resistor is connected to one end of the second voltage-dividing resistor, and the first driving power supply is used to provide a driving voltage for the first optical coupler; The other end of the second voltage-dividing resistor is connected to the diagnostic port; The input end of the first optical coupler is connected in parallel with the second voltage-dividing resistor, and the output end of the first optical coupler is connected in series with the protection resistor.

4. The protection circuit according to claim 1, characterized in that: The current limiting circuit includes a first switch tube, a second switch tube and a starting resistor, wherein: The emitter of the first switch tube is connected to one end of the starting resistor, and the resulting connection point serves as the input end of the current limiting circuit; The base of the first switch tube, the other end of the starting resistor and the emitter of the second switch tube are connected; The collector of the first switch tube, the base of the second switch tube and the collector of the second switch tube are connected, and the obtained connection point serves as the output end of the current limiting circuit.

5. The protection circuit according to claim 1, characterized in that: Also includes: Filter circuit, where The filter circuit includes: a first filter capacitor, a second filter capacitor and a filter resistor, wherein: The first end of the first filter capacitor and the first end of the second filter capacitor are respectively connected to the contact power supply; The second end of the first filter capacitor is connected to one end of the filter resistor, and the connection point between the first filter capacitor and the filter resistor is connected to the output end of the current limiting circuit; The second end of the second filter capacitor is connected to the other end of the filter resistor, and the connection point between the second filter capacitor and the filter resistor is connected to the first connection point.

6. The protection circuit according to any one of claims 1 to 5, characterized in that: The preset corresponding relationship includes: the diagnostic signal and the feedback signal have opposite logic levels; The controller detects the DI module according to a preset corresponding relationship between the diagnosis signal and the feedback signal, including: If the logic levels of the diagnostic signal and the feedback signal are opposite, it is determined that the DI module is normal; If the diagnostic signal and the feedback signal have the same logic level, it is determined that the DI module is faulty.

7. The protection circuit according to claim 6, characterized in that: Also includes: Acquisition circuit, where The input end of the acquisition circuit is connected to the second contact point, and the output end of the acquisition circuit is connected to the acquisition port; The acquisition circuit is used to generate the feedback signal based on the current in the DI module.

8. The protection circuit according to claim 7, characterized in that: The acquisition circuit includes: a second voltage divider circuit, a second optical coupler and a pull-up resistor, wherein: The second voltage-dividing circuit includes a third voltage-dividing resistor and a fourth voltage-dividing resistor; One end of the third voltage-dividing resistor is connected to the second contact point, and the other end of the third voltage-dividing resistor is connected to one end of the fourth voltage-dividing resistor; The other end of the fourth voltage-dividing resistor is grounded; The input end of the second optical coupler is connected in parallel with the fourth voltage-dividing resistor; One end of the pull-up resistor is connected to a second driving power supply, and the other end of the pull-up resistor is connected to a first output end of the second optical coupler, wherein the second driving power supply is used to provide a high level; The second output terminal of the second optical coupler is grounded; A connection point between the pull-up circuit and the second optical coupler is connected to the acquisition port.

9. A digital input module, characterized in that: include: A contact power supply, a first contact, a second contact, and a protection circuit as claimed in any one of claims 1 to 8, wherein: The protection circuit is respectively connected to the contact power supply, the first contact and the second contact; The first contact and the second contact are used to connect a normally closed switch.

10. An electronic device, characterized in that: include: At least one digital input module as claimed in claim 9.

Images