High-stability 485 data acquisition system based on multipath switching

Abstract

The high-stability 485 data acquisition system comprises a plurality of 485 modules, an analog switch RX, an analog switch TX and an MCU module, each 485 module comprises a 485 sensor, a 485 interface, a protection module and an isolation module which are connected in sequence, each 485 module is connected with the analog switch RX and the analog switch TX, the analog switch RX and the analog switch TX are connected with the MCU module, and the MCU module is connected with the 485 sensor. The analog switch TX controls signal sending, the analog switch RX controls signal receiving, the two analog switches control switching access 485 sensors, the protection module protects a circuit from overvoltage impact, the isolation module carries out isolation processing on the signals, noise interference is reduced, electrical isolation among all parts of the system is kept, the MCU module receives information of the 485 module, and the MCU module receives the information of the 485 module. Therefore, operation of the whole system is controlled, extra-long-distance 485 sensor deployment is achieved, other sensors are not affected by faults of a single sensor, and one device can be connected to multiple paths of sensors.

Description

Technical Field

[0001] The present application relates to the technical field of 485 data acquisition systems, and in particular to a high-stability 485 data acquisition system based on multi-channel switching. Background Art

[0002] 485 sensor refers to a sensor that uses the RS-485 communication interface. RS-485 is a standard interface for serial data transmission, especially suitable for industrial environments because of its long-distance transmission capability and good noise suppression characteristics. This interface allows multiple devices to be connected on a single twisted pair to form a multi-point communication network, which is very suitable for collecting data in decentralized industrial field applications.

[0003] 485 sensors can measure a variety of physical quantities, including but not limited to temperature, humidity, pressure, current, voltage, gas concentration, etc. Their working principles usually involve the following components:

[0004] Sensing element: The sensing element is the core of the sensor and is used to detect changes in specific physical quantities, such as thermistors or thermocouples in temperature sensors.

[0005] Signal conditioning circuit: The signal conditioning circuit converts the output signal of the sensing element into a signal form suitable for further processing.

[0006] Analog to Digital Converter: Analog to digital converter converts analog signals into digital signals to facilitate digital communication.

[0007] Microcontroller or signal processor: Processes the digital signal, performs the necessary calculations and prepares the data for transmission.

[0008] RS-485 transceiver: It converts the data prepared by the microcontroller into signals suitable for the RS-485 bus, and also converts the signals received from the bus into a format that the microcontroller can understand.

[0009] Power management: Providing the power required for sensor operation, which may include battery supply, external power supply, or energy harvesting mechanisms.

[0010] Advantages of the 485 sensor include:

[0011] Long-distance communication: communication distances of hundreds of meters or even thousands of meters can be achieved.

[0012] Multi-point communication: allows multiple sensors to be connected to the same bus, simplifying wiring and reducing costs.

[0013] Anti-interference: RS-485 interface has good anti-electromagnetic interference performance.

[0014] Reliability: Due to the use of differential signals, the RS-485 interface can effectively suppress common-mode noise.

[0015] Flexibility: Devices on the network can be easily added or removed without affecting the operation of other devices.

[0016] 485 sensors are often used in industrial automation, environmental monitoring, building automation, agriculture and scientific research. Through the integrated RS-485 interface, they can easily communicate with various control systems and data acquisition systems. For example, Modbus RTU protocol is often used as the communication protocol between 485 sensors and master control equipment.

[0017] The 485 data acquisition system is used to collect data from sensors based on the 485 interface and upload it in the form of a network port. It can also be expanded to other types of sensors in the future. It is a universal sensor data acquisition system. Sensors are one of the ways for machines to sense the environment and have a wide range of uses. Among the many sensors, the 485 interface type is the most common, and the overall cost of sensors is low and the penetration rate is high. The construction and installation of 485 is mostly in the form of a bus. All sensors are mounted on the bus and the host computer performs collection. The length of the field bus depends on the scope of the on-site implementation. The longest bus is several kilometers long. After the sensor is mounted on the bus, the signal transmission stability is poor and the data transmission is wrong due to the long distance. The error of a sensor affects the subsequent sensor data collection, and in extreme cases affects the online sensors behind. There are also some solutions on the market that use 485 repeaters to make star connections for a relatively concentrated block of sensors, and connect blocks hand in hand. Although the sensors in the block do not affect each other, the sensors between blocks still have the above problems. When the bus length is lengthened, the power supply voltage and signal transmission become unstable, resulting in occasional data collection failures on site. This problem is difficult to troubleshoot and has a great impact on the stability of the entire system. Utility Model Content

[0018] The purpose of this application is to provide a high-stability 485 data acquisition system based on multi-channel switching to solve the technical problems in the above-mentioned background technology.

[0019] To achieve the above-mentioned purpose, the present application provides the following technical solutions: a high-stability 485 data acquisition system based on multi-channel switching, comprising: a plurality of 485 modules, an analog switch RX, an analog switch TX and an MCU module, the 485 module comprising a 485 sensor, a 485 interface, a protection module and an isolation module connected in sequence, each 485 module is respectively connected to the analog switch RX and the analog switch TX, the analog switch RX and the analog switch TX are connected to the MCU module, the analog switch TX controls the sending signal, the analog switch RX controls the receiving signal, the two analog switches control the switching of the connected 485 sensors, the protection module protects the circuit from overvoltage shock, the isolation module isolates the signal to reduce noise interference and maintain electrical isolation between the various parts of the system, the MCU module receives the information of the 485 module, thereby controlling the operation of the entire system.

[0020] This system realizes the ultra-long-distance deployment of 485 sensors. The sensors do not affect each other and are completely isolated. The failure of a single sensor does not affect other sensors. One device can connect to multiple sensors. The switching of sensors is changed from the original address to analog switch, which has higher reliability.

[0021] Preferably, the analog switch RX includes a chip U13 for realizing bidirectional communication, the sixteenth end of the chip U13 is connected to the power supply VCC3.3 and the capacitor C41, the ninth end of the chip U13 is connected to the first end of the resistor R61, the tenth end of the chip U13 is connected to the first end of the resistor R62, the eleventh end of the chip U13 is connected to the first end of the resistor R63, the second ends of the resistors R61, R62 and R63 are commonly connected to the power supply VCC3.3, the sixth end of the chip U13 is connected to the first end of the resistor R66, and the second end of the resistor R66 is grounded.

[0022] Preferably, the analog switch TX includes a chip U12, a sixteenth terminal of the chip U12 is connected to a power source VCC3.3 and a capacitor C39, a sixth terminal of the chip U12 is connected to a first terminal of a resistor R65, and a second terminal of the resistor R65 is grounded.

[0023] Preferably, the RX1 end of the analog switch RX is connected to the RO end of the chip U15, the TX1 end of the analog switch TX is connected to the DI end of the chip U15, the DE end of the chip U15 is the drive enable end, the RE end of the chip U15 is the receive enable end, the A end and the B end of the chip U15 are connected to the inductor L7, and the VCC end of the chip U15 is connected to the power supply and the capacitor C43.

[0024] Preferably, inductor L7 connects the first ends of diodes D14 and D17, the second end of D14 is connected to the second end of D17, diode D15 is connected between the first end of diode D14 and the first end of D17, the first end of diode D14 is connected to fuse F6, the first end of diode D17 is connected to fuse F8, fuse F6 and fuse F8 are connected between resistor R68, and resistor R68 connects switch SW4 and diode D16.

[0025] Preferably, the switch SW4 and the diode D16 are connected to the third end and the second end of the connector P2 respectively, the fourth end of the connector P2 is grounded, the first end of the connector P2 is connected to the fuse F5, and the fuse F5 is connected to the 12V power supply.

[0026] Compared with the prior art, the beneficial effects of this application are:

[0027] 1. This application collects 485 data based on network transmission data, and solves the limitation that the serial port server can only access a single-channel 485 device. It uses an analog switch to switch to realize the access of multiple sensors to the serial port, and has a certain degree of stability and reliability, while isolating the influence between each sensor;

[0028] 2. This application realizes the ultra-long-distance 485 sensor deployment. The sensors do not affect each other and are completely isolated. The failure of a single sensor does not affect other sensors. One device can access multiple sensors. The switching of sensors is changed from the original address to an analog switch, which is more reliable.

[0029] 3. This application no longer needs to configure and modify the sensor address, and the acquisition end can send data request frames in a broadcast manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a structural diagram of a high-stability 485 data acquisition system based on multi-channel switching according to the first embodiment of the present application;

[0031] Figure 2 This is a circuit connection diagram of the analog switch RX and the analog switch TX of the core component of the high-stability 485 data acquisition system based on multi-channel switching according to the first embodiment of the present application;

[0032] Figure 3 This is a circuit connection diagram of the protection module and the isolation module of the high-stability 485 data acquisition system based on multi-channel switching according to the first embodiment of the present application. DETAILED DESCRIPTION

[0033] 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.

[0034] Embodiment 1

[0035] like Figures 1 to 3 As shown, a high-stability 485 data acquisition system based on multi-channel switching includes: three 485 modules, an analog switch RX, an analog switch TX and an MCU module. The 485 module includes a 485 sensor, a 485 interface, a protection module and an isolation module connected in sequence. Each 485 module is connected to the analog switch RX and the analog switch TX respectively. The analog switch RX and the analog switch TX are connected to the MCU module. The analog switch TX controls the sending signal, and the analog switch RX controls the receiving signal. The two analog switches control the switching of the connected 485 sensors. The protection module protects the circuit from overvoltage shock. The isolation module isolates the signal to reduce noise interference and maintain electrical isolation between the various parts of the system. The three 485 sensors are connected to the system through the 485 interfaces respectively, and are responsible for collecting environmental information and converting it into digital signals for transmission to the system. The MCU module receives the information of the 485 modules, thereby controlling the operation of the entire system.

[0036] The analog switch RX includes a chip U13, which is used to realize bidirectional communication. The sixteenth end of the chip U13 is connected to the power supply VCC3.3 and the capacitor C41, and the capacitor C41 is used for filtering. The ninth end of the chip U13 is connected to the first end of the resistor R61, the tenth end of the chip U13 is connected to the first end of the resistor R62, and the eleventh end of the chip U13 is connected to the first end of the resistor R63. The second ends of the resistors R61, R62 and R63 are commonly connected to the power supply VCC3.3. The sixth end of the chip U13 is connected to the first end of the resistor R66, and the second end of the resistor R66 is grounded.

[0037] The analog switch TX includes a chip U12 for realizing bidirectional communication. The sixteenth terminal of the chip U12 is connected to the power supply VCC3.3 and the capacitor C39. The sixth terminal of the chip U12 is connected to the first terminal of the resistor R65. The second terminal of the resistor R65 is grounded.

[0038] The RX1 end of the analog switch RX is connected to the RO end of the chip U15. The chip U15 is an RS-485 transceiver chip for realizing bidirectional communication. The TX1 end of the analog switch TX is connected to the DI end of the chip U15. The DE end of the chip U15 is the drive enable end. The RE end of the chip U15 is the receive enable end. The A end and the B end of the chip U15 are connected to the inductor L7. The VCC end of the chip U15 is connected to the power supply and the capacitor C43. The capacitor C43 is a filter capacitor. The inductor L7 is connected to the first end of the diode D14 and the second end of D17. The second end of D14 is connected to the second end of D17. The diode D15 is connected between the first end of the diode D14 and the first end of D17. The first end of the diode D14 Fuse F6 is connected, the first end of diode D17 is connected to fuse F8, fuse F6 and fuse F8 are connected between resistor R68, resistor R68 is connected to switch SW4 and diode D16, switch SW4 and diode D16 are respectively connected to the third end and the second end of connector P2, diode D15 is a transient voltage suppression diode, used to protect the circuit from overvoltage shock, inductor L7 is used to filter high-frequency noise, resistor R68 is a terminal matching resistor, used to reduce signal reflection, diode D16 is a rectifier diode, which may be used for reverse current protection, switch SW4 is a manual switch, used to select the working mode (send or receive) of RS-485 interface. The fourth end of connector P2 is grounded, the first end of connector P2 is connected to fuse F5, fuse F5 is connected to 12V power supply, and is protected by fuse F5 and transient voltage suppression diode D14.

[0039] It is obvious to those skilled in the art that the present application is not limited to the details of the exemplary embodiments described above, and that the present application can be implemented in other specific forms without departing from the spirit or essential features of the present application. Therefore, the embodiments should be regarded as exemplary and non-limiting in all respects, and the scope of the present application is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present application. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

Claims

1. A high-stability 485 data acquisition system based on multi-channel switching, characterized in that: include: Several 485 modules, analog switch RX, analog switch TX and MCU module. The 485 module includes a 485 sensor, a 485 interface, a protection module and an isolation module connected in sequence. Each 485 module is connected to the analog switch RX and the analog switch TX respectively. The analog switch RX and the analog switch TX are connected to the MCU module. The analog switch TX controls the sending signal, and the analog switch RX controls the receiving signal. The two analog switches control the switching of the connected 485 sensors. The protection module protects the circuit from overvoltage shock. The isolation module isolates the signal to reduce noise interference and maintain electrical isolation between various parts of the system. The MCU module receives the information of the 485 module to control the operation of the entire system.

2. A high-stability 485 data acquisition system based on multi-channel switching according to claim 1, characterized in that: The analog switch RX includes a chip U13, which is used to realize bidirectional communication. The sixteenth end of the chip U13 is connected to the power supply VCC3.3 and the capacitor C41, the ninth end of the chip U13 is connected to the first end of the resistor R61, the tenth end of the chip U13 is connected to the first end of the resistor R62, the eleventh end of the chip U13 is connected to the first end of the resistor R63, the second ends of the resistors R61, R62 and R63 are commonly connected to the power supply VCC3.3, the sixth end of the chip U13 is connected to the first end of the resistor R66, and the second end of the resistor R66 is grounded.

3. A high stability 485 data acquisition system based on multi-channel switching according to claim 2, characterized in that: The analog switch TX includes a chip U12, a sixteenth terminal of the chip U12 is connected to a power source VCC3.3 and a capacitor C39, a sixth terminal of the chip U12 is connected to a first terminal of a resistor R65, and a second terminal of the resistor R65 is grounded.

4. A high-stability 485 data acquisition system based on multi-channel switching according to claim 3, characterized in that: The RX1 end of the analog switch RX is connected to the RO end of the chip U15, the TX1 end of the analog switch TX is connected to the DI end of the chip U15, the DE end of the chip U15 is the drive enable end, the RE end of the chip U15 is the receive enable end, the A end and the B end of the chip U15 are connected to the inductor L7, and the VCC end of the chip U15 is connected to the power supply and the capacitor C43.

5. A high stability 485 data acquisition system based on multi-channel switching according to claim 4, characterized in that: Inductor L7 is connected to the first ends of diodes D14 and D17, the second end of D14 is connected to the second end of D17, diode D15 is connected between the first end of diode D14 and the first end of D17, the first end of diode D14 is connected to fuse F6, the first end of diode D17 is connected to fuse F8, fuse F6 and fuse F8 are connected between resistor R68, and resistor R68 is connected to switch SW4 and diode D16.

6. A high-stability 485 data acquisition system based on multi-channel switching according to claim 5, characterized in that: The switch SW4 and the diode D16 are connected to the third end and the second end of the connector P2 respectively. The fourth end of the connector P2 is grounded. The first end of the connector P2 is connected to the fuse F5. The fuse F5 is connected to the 12V power supply.

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