Signal acquisition circuit and method compatible with dry and wet contacts
By using voltage detection and processor control to switch circuit paths via relay modules, adaptive and compatible acquisition of dry and wet contact signals on a single interface is achieved. This solves the problems of wasted interface resources and insufficient system flexibility, and improves the integration and convenience of industrial control systems.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA ORDNANCE EQUIP GRP AUTOMATION RES INST CO LTD
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-05
AI Technical Summary
The existing technology's separate design of dry and wet contacts leads to wasted interface resources and insufficient system flexibility, and cannot be compatible with dry and wet contact signal acquisition.
By monitoring signal characteristics in real time through voltage detection points, and combining this with the processor's intelligent judgment of signal type and control of the relay module to automatically switch circuit paths, adaptive and compatible acquisition of dry and wet contacts on a single interface is achieved.
It effectively solves the problem of wasted interface resources, improves the integration and flexibility of industrial control systems, and reduces the complexity of manual operation.
Smart Images
Figure CN121978391A_ABST
Abstract
Description
Technical Field
[0001] This application relates to industrial control electronic circuit technology, specifically to a signal acquisition circuit and method compatible with dry and wet contacts. Background Technology
[0002] In industrial control, signal acquisition is a core component used for monitoring equipment status and transmitting control commands. Dry contacts and wet contacts are two common signal types widely used in various automation systems. A dry contact is a passive switching signal that only provides on / off status; it has no power supply of its own, and its switching is controlled by an external mechanical or electronic switch. A wet contact, on the other hand, is an active signal with its own voltage (such as 24V DC), and it transmits the signal by forming a loop through an external power supply. Due to the fundamental differences in characteristics between dry and wet contacts, current technology typically employs a separate design, developing independent acquisition circuits for dry and wet contacts to ensure the accuracy and reliability of signal processing.
[0003] Existing implementations are mostly based on a dry / wet contact separation design. The dry contact acquisition circuit is dedicated to handling passive signals and its design relies on an external power supply to drive the acquisition circuit; the wet contact acquisition circuit directly utilizes the voltage inherent in the signal for acquisition, requiring no additional power supply. While this separation design ensures the stability of each function, it leads to circuit redundancy and wasted interface resources. For example, in practical applications, the device needs to reserve both dry and wet contact interfaces, increasing hardware complexity and cost.
[0004] For dry contact data acquisition, common circuit designs include... Figure 1 As shown in the diagram, this circuit is powered by the system. When the external dry contact is closed, current flows through isolation components such as optocouplers, causing a level change at the output terminal "DI_IN", thus identifying the on / off state. This design is simple and reliable, but it is only suitable for passive signals.
[0005] For wet contact data acquisition, common circuits include... Figure 2 As shown, the input signal forms a loop through the "P" and "N" terminals, directly driving the acquisition circuit using the voltage inherent in the signal. The output "DI_IN" responds to changes in the input. This design avoids the need for external power supply, but it is not compatible with dry contact signals.
[0006] In summary, existing technologies achieve independent acquisition of dry and wet contacts through separate circuits, but lack compatibility, resulting in low interface resource utilization and insufficient system flexibility. This provides room for improvement in the integrated design of this application. Summary of the Invention
[0007] This application provides a signal acquisition circuit compatible with both dry and wet contacts, which solves the technical problem of wasted interface resources and inconvenience of use caused by the separate design of existing dry contact signal acquisition circuits and wet contact acquisition circuits.
[0008] This application is achieved through the following technical solution:
[0009] In a first aspect, this application provides a signal acquisition circuit compatible with both dry and wet contacts, comprising:
[0010] The input terminals include a first input terminal and a second input terminal that are connected to each other, for receiving external signals;
[0011] The relay module contains multiple sets of contacts and drive circuitry;
[0012] The system power supply is connected to the relay module to provide operating voltage to the circuit.
[0013] The voltage detection point is located in the input circuit between the first input terminal and the relay module, forming a detection connection with the processor.
[0014] The processor is connected to the drive circuits of the voltage detection point and the relay module respectively, and monitors the voltage signal in the input circuit in real time through the voltage detection point;
[0015] When an effective voltage is detected, it is identified as a wet contact signal, and the control relay module is kept in the default connection state, so that the input signal forms a complete acquisition loop through the first input terminal and the second terminal.
[0016] When no effective voltage is detected, it is identified as a dry contact signal. The drive circuit controls the relay module to switch the contact state, so that the system power supply is connected to the input circuit, providing working voltage for the external dry contact signal and forming a collection circuit.
[0017] A further optimization is that the voltage detection point is connected to a voltage acquisition circuit, which includes voltage divider resistors and filter components.
[0018] A further optimization is to configure the voltage divider resistors in the voltage acquisition circuit to convert the input voltage into a safe voltage range that the processor can recognize.
[0019] A further optimization is that the default connection state of the relay module is the wet contact signal direct acquisition circuit connection state.
[0020] A further optimization is that the switching state of the relay module is the power supply circuit connection state of the dry contact signal system.
[0021] A further optimization solution includes an optocoupler isolation element, positioned between the input terminal and the processor, for signal isolation.
[0022] Secondly, this application provides a signal acquisition method compatible with dry and wet contacts, applied in the signal acquisition circuit compatible with dry and wet contacts as described above, including the following steps:
[0023] After the system is powered on, the voltage at the input terminals is monitored through voltage detection points;
[0024] Signal type is determined based on voltage value;
[0025] If the signal is identified as a wet contact, maintain the default state of the relay module and directly acquire the input signal;
[0026] If the signal is identified as a dry contact signal, the control relay module switches to the switching state, allowing the system power supply to be connected to the input circuit before the signal is acquired.
[0027] A further optimized solution is that the signal type determination based on voltage value includes the following steps:
[0028] The analog voltage at the voltage detection point is converted from analog to digital to obtain a digital voltage value;
[0029] The digital voltage value is digitally filtered to obtain the voltage detection result;
[0030] The signal type of the external signal connected to the circuit input terminal is determined based on the comparison result between the voltage detection value and the preset threshold.
[0031] A further optimization is to ensure that the contacts of the relay module remain in the default connected state when the system is not powered on.
[0032] A further optimization is to automatically perform the voltage monitoring operation via voltage detection points every time the system is powered on, and the monitoring duration is the system's preset detection cycle.
[0033] Compared with the prior art, this application has the following advantages and beneficial effects:
[0034] By monitoring the characteristics of the input signal in real time through voltage detection points, and combining this with the processor's intelligent judgment of the signal type and control of the relay module to automatically switch the circuit path, adaptive and compatible acquisition of dry and wet contact signals on a single interface is achieved.
[0035] When a signal is identified as a wet contact, the direct acquisition circuit is maintained; when a signal is identified as a dry contact, the system power supply is automatically connected to form a power supply circuit. This innovative design effectively solves the problem of wasted interface resources in traditional solutions, significantly improves the integration and flexibility of industrial control systems, and reduces the complexity of manual operation through a fully automatic identification and switching mechanism. Attached Figure Description
[0036] To more clearly illustrate the technical solutions of the exemplary embodiments of this application, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of this application and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:
[0037] Figure 1 A schematic diagram of the structure of a prior art dry contact acquisition circuit provided in the embodiments of this application;
[0038] Figure 2 A schematic diagram of a prior art dry contact acquisition circuit provided for embodiments of this application;
[0039] Figure 3 A schematic diagram of a prior art wet contact acquisition circuit provided in the embodiments of this application;
[0040] Figure 4 The signal acquisition and electrical isolation circuit provided in the embodiments of this application;
[0041] Figure 5 The signal path switching relay circuit provided in the embodiments of this application;
[0042] Figure 6 The signal type detection and relay driving circuit provided in the embodiments of this application. Detailed Implementation
[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the embodiments and accompanying drawings. The illustrative embodiments and descriptions of this application are only for explaining this application and are not intended to limit this application.
[0044] First, some of the technical terms used in this application will be explained to help those skilled in the art understand this application.
[0045] DI_IN: Digital Input;
[0046] LS: Limit Switch, Relay;
[0047] DI_IN_P: Digital Input Positive;
[0048] DI_IN_N: Digital Input Negative;
[0049] System 24V Power.
[0050] Firstly, this application provides a signal acquisition circuit compatible with both dry and wet contacts, the schematic diagram of which is shown below. Figure 3 As shown, it includes:
[0051] Input terminal 10 includes a first input terminal and a second input terminal connected to each other, for receiving external signals;
[0052] Relay module 20 includes multiple sets of contacts and drive circuitry;
[0053] The system power supply 30 is connected to the relay module 20 to provide operating voltage to the circuit;
[0054] Voltage detection point 40 is set in the input circuit between the first input terminal and the relay module 20, and forms a detection connection with the processor 50;
[0055] The processor 50 is connected to the voltage detection point 40 and the drive circuit of the relay module 20 respectively, and monitors the voltage signal in the input circuit in real time through the voltage detection point 40.
[0056] When an effective voltage is detected, it is identified as a wet contact signal, and the relay module 20 is controlled to maintain the default connection state, so that the input signal forms a complete acquisition loop through the first input terminal and the second input terminal.
[0057] When no effective voltage is detected, it is identified as a dry contact signal. The drive circuit controls the relay module 20 to switch the contact state, so that the system power supply 30 is connected to the input circuit, providing working voltage for the external dry contact signal and forming a collection circuit.
[0058] This embodiment monitors the input signal characteristics in real time through voltage detection point 40, and, combined with processor 50 intelligently determining the signal type and controlling relay module 20 to automatically switch circuit paths, achieves adaptive and compatible acquisition of dry and wet contact signals on a single interface: when identified as a wet contact signal, the direct acquisition loop is maintained; when identified as a dry contact signal, the system power supply 30 is automatically connected to form a power supply loop. This innovative design effectively solves the problem of wasted interface resources in traditional solutions, significantly improves the integration and flexibility of the industrial control system, and reduces the complexity of manual operation through a fully automatic identification and switching mechanism.
[0059] In one embodiment, please refer to Figure 4This is a schematic diagram of a signal acquisition circuit compatible with dry and wet contacts provided in this application embodiment. After receiving external signals, the input terminals 10 (such as DI_IN_P and DI_IN_N) first pass through a signal acquisition and electrical isolation circuit. This circuit serves as the standardized terminal of the system, and its core is an optocoupler isolation element (such as LS1) to achieve electrical isolation between the field signal and the control system (such as the VDD_3.3V side). Resistor R3 (10kΩ / 1%) provides a current path for the signal, and its voltage DIO_IN_A serves as a detection point, ultimately converting the signal into a safe digital signal that can be read by the MCU.
[0060] In one embodiment, the relay module 20 includes multiple sets of contacts. When the system is not powered on, the relay LS3 contact in the relay module is in a default connection state (e.g., A2-A3, B2-B3, C2-C3 connected); under the control of the processor 50, it can be switched to a switching state (e.g., A2-A1, B2-B1, C2-C1 connected). For a detailed implementation of the relay module 20, please refer to [reference needed]. Figure 5 , Figure 5 The circuit shown serves as the system's automatic selection switch, with a multi-channel relay (such as RELAY1) at its core. In the default state (coil RL_POWER is de-energized), the contacts (groups A, B, and C) are in the default connected state, allowing the input signal to pass directly. When the processor 50 controls the drive circuit, the contacts switch to the switching state, connecting the system power supply 30 (such as System_24V) to the circuit.
[0061] In one embodiment, the default connection state of the relay module 20 is the wet contact signal direct acquisition circuit connection state.
[0062] In one embodiment, the switching state of the relay module 20 is the power supply circuit connection state of the dry contact signal system power supply 30.
[0063] In one embodiment, the voltage detection point 40 (i.e. Figure 6 Point A in the diagram is located in the input circuit between the first input terminal and the relay module 20, forming a detection connection with the processor 50. Please refer to... Figure 6 Voltage detection point 40 is connected to processor 50 through voltage divider resistors (such as R5 and R8) and filter components to attenuate the input voltage before sending it to the ADC for measurement. Processor 50 (such as MCU) determines the signal type based on the voltage value and drives the relay through GPIO to control optocoupler (such as LS2), realizing a sensing-judgment-control closed loop.
[0064] In one embodiment, the voltage detection point 40 is connected to a voltage acquisition circuit, which includes a voltage divider resistor and a filter element. Specifically, the voltage detection point 40 is connected in series with the acquisition pin of the processor 50 through the voltage divider resistor to achieve voltage scaling, while the filter element is connected in parallel to ground to suppress noise interference.
[0065] In one embodiment, the voltage divider resistors in the voltage acquisition circuit are configured to convert the input voltage to a safe voltage range recognizable by the processor 50.
[0066] In one embodiment, an optocoupler isolation element is also included, disposed between the input terminal 10 and the processor 50, for signal isolation.
[0067] Based on the characteristics of dry and wet contacts, including whether they have their own power supply, this application innovatively designs a voltage acquisition circuit to identify the signal type. Accordingly, a relay module automatically switches the circuit path, thus achieving adaptive and compatible acquisition of dry and wet contact signals on a single interface. This design saves hardware resources by using a shared interface and eliminates manual operation with its adaptive identification and switching mechanism, fundamentally overcoming the problem of wasted interface resources in existing technologies and significantly improving the system's integration and ease of use.
[0068] Secondly, this application provides a signal acquisition method compatible with both dry and wet contacts, applied in the aforementioned signal acquisition circuit compatible with both dry and wet contacts, comprising the following steps:
[0069] Step S1: When the system is not powered on, the contacts of the relay module 20 are always in the default connected state. After the system is powered on, it first enters the dry / wet contact detection stage, monitoring the voltage at the input terminal 10 through the voltage detection point 40. More specifically, the system automatically enters the dry / wet contact detection stage each time it is powered on, and monitors the voltage at the input terminal 10 through the voltage detection point 40 for a duration of a system preset detection cycle (e.g., 100ms) to ensure the reliability of signal type identification.
[0070] Step S2: Determine the signal type based on the voltage value; further, this includes the following steps:
[0071] Step S21: Perform analog-to-digital conversion on the analog voltage at voltage detection point 40 to obtain a digital voltage value;
[0072] Step S22: Perform digital filtering on the digital voltage value to obtain the voltage detection result; in one embodiment, the operation of monitoring the voltage through the voltage detection point 40 is automatically executed every time the system is powered on, and the monitoring duration is the system's preset detection cycle;
[0073] Step S23: Based on the comparison between the voltage detection value and the preset threshold, determine the signal type of the external signal connected to the circuit input terminal; if the voltage detection value is higher than the preset threshold, it is determined to be a wet contact signal; if the voltage detection value is lower than or equal to the preset threshold, it is determined to be a dry contact signal. The preset threshold is determined comprehensively based on the system power supply voltage, signal characteristics, and anti-interference requirements in the circuit design, aiming to reliably distinguish between active signals and passive switch states. For example, it can be set as a reasonable percentage of the typical wet contact voltage (e.g., 24V) after voltage division sampling, such as 50%-70% of the scaled voltage value, while allowing sufficient noise margin.
[0074] Step S3A: If a wet contact signal is identified, maintain the default state of the relay module 20 and directly acquire the input signal; more specifically, after a wet contact signal is identified, the processor 50 controls the relay module 20 to maintain its default contact connection state (such as A2-A3, B2-B3 and C2-C3 contacts are connected), so that the external wet contact signal can directly form a complete acquisition circuit through the input terminal 10 and the relay contacts, and signal acquisition can be completed without the intervention of the system power supply 30.
[0075] Step S3B: If a dry contact signal is identified, control the relay module 20 to switch to the switching state, so that the system power supply 30 is connected to the input circuit to collect the signal; more specifically, when a dry contact signal is identified, the processor 50 controls the output of the relay drive circuit (such as LS2) to switch the contacts of the relay module 20 (such as LS3) from the default connection state to the working state (such as A2-A1, B2-B1, C2-C1 contacts are connected). At this time, the system power supply 30 (such as System_24V) is connected to the input circuit to provide working voltage for the external dry contact signal, thereby forming a complete acquisition path to realize signal acquisition.
[0076] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.
Claims
1. A signal acquisition circuit compatible with both dry and wet contacts, characterized in that, include: The input terminals include a first input terminal and a second input terminal that are connected to each other, for receiving external signals; The relay module contains multiple sets of contacts and drive circuitry; The system power supply is connected to the relay module to provide operating voltage to the circuit. The voltage detection point is located in the input circuit between the first input terminal and the relay module, forming a detection connection with the processor. The processor is connected to the drive circuits of the voltage detection point and the relay module respectively, and monitors the voltage signal in the input circuit in real time through the voltage detection point; When an effective voltage is detected, it is identified as a wet contact signal, and the control relay module is kept in the default connection state, so that the input signal forms a complete acquisition loop through the first input terminal and the second terminal. When no effective voltage is detected, it is identified as a dry contact signal. The drive circuit controls the relay module to switch the contact state, so that the system power supply is connected to the input circuit, providing working voltage for the external dry contact signal and forming a collection circuit.
2. The signal acquisition circuit compatible with dry and wet contacts as described in claim 1, characterized in that, The voltage detection point is connected to a voltage acquisition circuit, which includes voltage divider resistors and filter components.
3. The signal acquisition circuit compatible with dry and wet contacts as described in claim 2, characterized in that, The voltage divider resistors in the voltage acquisition circuit are configured to convert the input voltage into a safe voltage range that the processor can recognize.
4. The signal acquisition circuit compatible with dry and wet contacts as described in claim 1, characterized in that, The default connection state of the relay module is the wet contact signal direct acquisition circuit connection state.
5. The signal acquisition circuit compatible with dry and wet contacts as described in claim 1, characterized in that, The switching state of the relay module is the connection state of the power supply circuit of the dry contact signal system.
6. The signal acquisition circuit compatible with dry and wet contacts as described in claim 1, characterized in that, It also includes an optocoupler isolation element, which is placed between the input terminal and the processor for signal isolation.
7. A signal acquisition method compatible with dry and wet contacts, applied in the signal acquisition circuit compatible with dry and wet contacts as described in any one of claims 1-6, characterized in that, Includes the following steps: After the system is powered on, the voltage at the input terminals is monitored through voltage detection points; Signal type is determined based on voltage value; If the signal is identified as a wet contact, maintain the default state of the relay module and directly acquire the input signal; If the signal is identified as a dry contact signal, the control relay module switches to the switching state, allowing the system power supply to be connected to the input circuit before the signal is acquired.
8. The signal acquisition method compatible with dry and wet contacts as described in claim 7, characterized in that, The method of determining the signal type based on voltage value includes the following steps: The analog voltage at the voltage detection point is converted from analog to digital to obtain a digital voltage value; The digital voltage value is digitally filtered to obtain the voltage detection result; The signal type of the external signal connected to the circuit input terminal is determined based on the comparison result between the voltage detection value and the preset threshold.
9. The signal acquisition method compatible with dry and wet contacts as described in claim 7, characterized in that, When the system is not powered on, the contacts of the relay module are in the default connected state.
10. The signal acquisition method compatible with dry and wet contacts as described in claim 7, characterized in that, The operation of monitoring voltage through voltage detection points is performed automatically every time the system is powered on, and the monitoring duration is the system's preset detection cycle.