CN108513275B

CN108513275B - Zigbee wireless sensing node capable of being connected with field indicating instrument

Info

Publication number: CN108513275B
Application number: CN201810207023.8A
Authority: CN
Inventors: 谢少伟
Original assignee: Zhejiang University of Water Resources and Electric Power
Current assignee: Misensor Tech Shanghai Co ltd
Priority date: 2018-03-13
Filing date: 2018-03-13
Publication date: 2020-08-25
Anticipated expiration: 2038-03-13
Also published as: CN108513275A

Abstract

The invention relates to a Zigbee wireless sensing node capable of being matched with an on-site indicating instrument, which comprises a multi-path signal selection unit, a V-level voltage signal conditioning unit, a mV-level voltage and mA-level current signal conditioning unit, a thermocouple temperature compensation unit and a resistance signal conditioning unit, wherein the V-level voltage signal conditioning unit, the mV-level voltage and mA-level current signal conditioning unit, the thermocouple temperature compensation unit and the resistance signal conditioning unit are respectively connected with the input end of the multi-path signal selection unit, the output end of the multi-path signal selection unit is connected with the input end of an AD conversion unit, the multi-path signal selection unit and the AD conversion unit are respectively connected with a Zigbee system-on-chip unit, and the Zigbee system-on-chip. The invention integrates measurement, control, display and wireless transmission, has the functions of on-site digital indication or analog indication, can carry out measurement control and wireless transmission on various parameters such as liquid level, temperature, pressure, rotating speed and the like, effectively reduces the system cost and improves the system reliability.

Description

Zigbee wireless sensing node capable of being connected with field indicating instrument

Technical Field

The invention relates to a Zigbee wireless sensing node, in particular to a Zigbee wireless sensing node capable of being matched with an on-site indicating instrument, which can be matched with an on-site analog indicating instrument and an on-site digital indicating instrument and has the characteristic of multiple parameters.

Background

With the development and application popularization of the internet of things and big data technology, key data such as liquid level (water level and oil level), temperature, pressure and the like need to be remotely monitored and data collected through the internet of things besides needing field measurement and control. At present, the parameters are accessed into the Internet of things in a mode that the parameters are collected through a special Internet of things data acquisition module on the basis of the existing measurement and control instrument, so that the cost of the system is increased, and the reliability of the system is reduced.

Disclosure of Invention

The invention aims to solve the technical problems, provides a Zigbee wireless sensing node capable of being matched with an on-site indicating instrument, is an integrated Zigbee wireless sensing node with the functions of measurement, control, display and wireless transmission, has the functions of on-site digital indication or analog indication, can carry out measurement control and wireless transmission on various parameters such as liquid level, temperature, pressure, rotating speed and the like, effectively reduces the system cost and improves the system reliability.

The technical problem of the invention is mainly solved by the following technical scheme: the invention comprises a V-level voltage signal conditioning unit, a mV-level voltage and mA-level current signal conditioning unit, a thermocouple temperature compensation unit, a resistance signal conditioning unit, a multi-channel signal selection unit, an AD conversion unit, a relay control unit, a Zigbee system-on-chip unit, a radio frequency unit, a resistance signal output unit and a power supply unit for providing working voltage for the whole Zigbee wireless sensing node, the output ends of the V-level voltage signal conditioning unit, the mV-level voltage and mA-level current signal conditioning unit, the thermocouple temperature compensation unit and the resistance signal conditioning unit are respectively connected with the input end of the multi-path signal selection unit, the output end of the multi-path signal selection unit is connected with the input end of the AD conversion unit, and the multi-path signal selection unit, the AD conversion unit, the relay control unit, the radio frequency unit and the resistance signal output unit are respectively connected with the Zigbee system-on-chip unit. Each conditioning unit is connected with a corresponding sensor, output signals of each conditioning unit are selected by the multi-channel signal selection unit, output signals are sent to the AD conversion unit, are subjected to AD conversion and then are sent to the Zigbee system-on-chip unit, PWM signals are output to the resistance signal output unit after being processed by the Zigbee system-on-chip unit, and the resistance signal output unit is connected with the resistance type analog indicating instrument and used for on-site indication. The Zigbee system-on-chip unit sends out the acquired signals through the radio frequency unit, and wireless transmission is realized. Meanwhile, after being analyzed and processed, the Zigbee system-on-chip unit can send a control signal to the relay control unit as required so as to drive the corresponding relay and control the on-off of the related signal. The integrated Zigbee wireless sensing node has the functions of measurement, control, display and wireless transmission, has the functions of on-site digital indication or analog indication, can carry out measurement control and wireless transmission on various parameters such as liquid level, temperature, pressure, rotating speed and the like, effectively reduces the system cost and improves the system reliability.

Preferably, the Zigbee system-on-chip unit includes a Zigbee system-on-chip U81, and the Zigbee system-on-chip U81 adopts a CC2530 system-on-chip; the multi-channel signal selection unit comprises a multi-channel selection analog switch chip U22, and the multi-channel selection analog switch chip U22 adopts a CD4051 switch chip; the AD conversion unit comprises an AD conversion chip U23, and the AD conversion chip U23 adopts a TM7707AD converter; pins 1-4 of a Zigbee system-on-chip U81 are grounded,

pins

7, 6 and 5 of the Zigbee system-on-chip U81 are respectively connected with

pins

11, 10 and 9 of a multi-path selection analog switch chip U22, pin 10 of the Zigbee system-on-chip U81 is grounded through a capacitor C812 after being connected with a voltage VDD, pin 12, pin 13, pin 14 and pin 15 of the Zigbee system-on-chip U81 are respectively connected with pin 12, pin 13, pin 14 and pin 1 of an AD conversion chip U23, pin 21 of the Zigbee system-on-chip U81 is grounded through a capacitor C810 after being connected with the voltage VDD, pin 20 of the Zigbee system-on-chip U81 is grounded through a resistor R82 and a capacitor C811, a crystal oscillator Y81 is connected between pin 22 and pin 23 of the Zigbee system-on-chip U81, two ends of the crystal oscillator Y81 are grounded through a capacitor C88 and a capacitor C89, and a pin 24 of the Zigbee system-on-chip U81 is grounded through a capacitor C3985 and a capacitor C81,

Pins

28 and 29 are both connected with a voltage VDD, a capacitor C85 and a capacitor C86 are connected between the pin 29 of the Zigbee system-on-chip U81 and a grounding end, a pin 30 of the Zigbee system-on-chip U81 is grounded through a resistor R81, a pin 31 of the Zigbee system-on-chip U81 is grounded through a capacitor C84 after being connected with the voltage VDD, a pin 39 of the Zigbee system-on-chip U81 is grounded through a capacitor C83 after being connected with the voltage VDD, and a pin 40 of the Zigbee system-on-chip U81 is grounded through a capacitor C82; the

pins

13, 12 and 1 of the multi-path selection analog switch chip U22 are respectively connected with the output ends of the V-level voltage signal conditioning unit, the thermocouple temperature compensation unit and the resistance signal conditioning unit, the

pins

14 and 15 of the multi-path selection analog switch chip U22 are respectively connected with the two output ends of the mV-level voltage and mA-level current signal conditioning unit, the pins 6 to 8 of the multi-path selection analog switch chip U22 are all grounded, the pin 16 of the multi-path selection analog switch chip U22 is both connected with the +5V voltage and grounded through a capacitor C24, the pin 3 of the multi-path selection analog switch chip U22 is connected with the pin 7 of the AD conversion chip U23, the pin 8 and the pin 9 of the AD conversion chip U23 are connected with the SGND, the pin 15 of the AD conversion chip U23 is both connected with the +5V voltage and grounded through a parallel circuit of a capacitor C25 and a capacitor C26, the pin 16, the pin 10 and the pin 4 of the AD conversion chip U23 are all grounded, the pin 2 of the conversion chip U23 is connected with the Y-oscillator 685, the 5 pin of the AD conversion chip U23 is connected with +5V voltage. Reasonable structure, convenient realization, flexible control and high reliability.

Preferably, the radio frequency unit comprises an inductor L82, an inductor L83 and an interface SMB 1; a26 pin of the Zigbee system-on-chip U81 is connected with one end of an inductor L82 through a capacitor C813, a 25 pin of the Zigbee system-on-chip U81 is connected with one end of the capacitor C816 through the capacitor C814, the other end of the inductor L82 is connected with the other end of the capacitor C816 and is connected with an interface SMB1 through the capacitor C817, the interface SMB1 is externally connected with a monopole antenna, the connection point of the capacitor C813 and the inductor L82 is grounded through the capacitor C815, and the connection point of the capacitor C814 and the capacitor C816 is grounded through the inductor L83. The inductor L82, the capacitor C815, the inductor L83, and the capacitor C816 implement a differential signal to single-ended (i.e., balun) function.

Preferably, the radio frequency unit comprises an inductor L82, an inductor L83, a radio frequency chip U82 and an interface SMB2, wherein the radio frequency chip U82 adopts an RFX2401 radio frequency chip; a 26 pin of the Zigbee on-chip system chip U81 is connected to one end of an inductor L82 through a capacitor C813, a 25 pin of the Zigbee on-chip system chip U81 is connected to one end of a capacitor C814 and a capacitor C816 through a capacitor C814, the other end of the inductor L82 is connected to the other end of the capacitor C816 and is connected to a 4 pin of the radio frequency chip U82 through a capacitor C817, a connection point of the capacitor C813 and the inductor L82 is grounded through a capacitor C815, a connection point of the capacitor C814 and the capacitor C816 is grounded through an inductor L83, a 5 pin and a 6 pin of the radio frequency chip U82 are respectively connected to a 33 pin and a 32 pin of the Zigbee on-chip system chip U81, a 1 pin, a 2 pin, a 3 pin, and a 7 pin, the

pins

8, 9, 11, 12 and 15 are all grounded, the pin 14 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C819, the pin 16 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C818, the pin 10 of the radio frequency chip U82 is connected with the interface SMB2, and the interface SMB2 is externally connected with a monopole antenna. The RFX2401 radio frequency chip plays a power amplification role, and is externally connected with a monopole antenna through an interface SMB2 so as to increase the communication distance.

Preferably, the Zigbee wireless sensing node capable of being connected with the field indication instrument comprises a 2.5V reference voltage unit, the 2.5V reference voltage unit comprises a regulated power supply U21, the regulated power supply U21 adopts a TL431 regulated power supply, a K pin of the regulated power supply U21 is connected to +5V voltage through a resistor R27 and is connected to one end of a capacitor C23 through a resistor R28, the other end of the capacitor C23 is grounded, a pin a of the regulated power supply U21 is grounded, a pin R of the regulated power supply U21 is connected to a pin K, a capacitor C22 is connected in parallel between the pin K and the pin a of the regulated power supply U21, and a connection point of the resistor R28 and the capacitor C23 is an SGND end;

the V-level voltage signal conditioning unit comprises a resistor R21 and a resistor R22, one end CN1 of a voltage signal input end is connected with the other end CN2 of the voltage signal input end through a series circuit of the resistor R21 and the resistor R22, the other end CN2 of the voltage signal input end is connected with an SGND end, a connecting point of the resistor R21 and the resistor R22 is connected with a pin 13 of a multi-path selection analog switch chip U22, and the other end CN2 of the voltage signal input end is connected with a pin 5 of the multi-path selection analog switch chip U22;

the mV level voltage and mA level current signal conditioning unit comprises an inductor L21, a resistor R23, a resistor R24 and a diode D21, wherein one end CN3 of a voltage signal input end is connected with a 14 pin of a multi-path selection analog switch chip U22 through an inductor L21, the other path is grounded through a resistor R23, the other path is connected with the anode of the diode D21, the cathode of the diode D21 is connected with a 15 pin of the multi-path selection analog switch chip U22 and is connected with the other end CN2 of the voltage signal input end through a resistor R24;

the thermocouple temperature compensation unit comprises a thermistor Rt21 for measuring the temperature of a cold end of the thermocouple, one end of a thermistor Rt21 is grounded, the other end of the thermistor Rt21 is connected with an SGND end through a resistor R25, and a connecting point of the thermistor Rt21 and a resistor R25 is connected with a pin 12 of a multi-path selection analog switch chip U22;

the resistance signal conditioning unit comprises an inductor L22, a resistor R26 and a capacitor C21, and is of a three-wire structure and comprises a current lead L1, a current lead L3 and a voltage lead L2, one end of a resistor RX to be tested is connected with a current lead L1, the resistor RX to be tested is connected with one end of the inductor L22 and one end of a resistor R26 through the current lead L1, the other end of the resistor R26 is grounded, the other end of the inductor L22 is connected with a pin 1 of a circuit selection analog switch chip U22 and is grounded through the capacitor C21, the other end of the resistor RX to be tested is connected with the current lead L3 and the voltage lead L2, the voltage lead L2 is connected with a mV voltage input end, and the current lead L3 is connected with an SGND end.

The V-level voltage signal conditioning unit is suitable for data acquisition of sensors with V-level voltage signal output of 1-5V, 0-10V and the like, and the voltage signals are input through two ends of CN1 and CN 2. The mV and mA signals of the mV level voltage and mA level current signal conditioning unit are input into the same input end through two ends of CN3 and CN2, and are divided into two channels of mV and mA. The thermocouple temperature compensation unit is an internal circuit and has no external input end. The cold end temperature of the thermocouple was measured using thermistor Rt 21. The resistance signal conditioning unit is suitable for three standard resistance forms of a PT100 thermal resistor, a Cu50 thermal resistor and a 0-375Q pressure sensor.

Preferably, the relay control unit comprises a relay J41, a relay J42, a triode Q41 and a triode Q42, wherein pins 37 and 38 of a Zigbee soc chip U81 are respectively connected with bases of the triode Q41 and the triode Q42, emitters of the triode Q41 and the triode Q42 are both grounded, collectors of the triode Q41 and the triode Q42 are respectively connected with negative terminals of driving ends of the relay J41 and the relay J42, positive terminals of driving ends of the relay J41 and the relay J42 are both connected with +12V voltage, two driving ends of the relay J41 are connected with a diode D41 in an anti-parallel mode, and two driving ends of the relay J42 are connected with a diode D42 in an anti-parallel mode.

Preferably, the resistance signal output unit comprises a PWM shaping circuit, a filter circuit, a synthesized resistance output circuit, and a follower; the PWM shaping circuit comprises a resistor R56, a resistor R56 and a triode Q52; the filter circuit comprises a resistor R54, a resistor R55, a capacitor C53 and a capacitor C54; the synthetic resistor output circuit comprises an operational amplifier U52B, a triode Q51 and a resistor R51; the follower comprises an operational amplifier U51A and an operational amplifier U51C; the PWM signal output by the Zigbee system-on-chip unit is connected with the base of a triode Q52 through a resistor R56, the collector of the triode Q52 is connected with the output end of an operational amplifier U51A through a resistor R53, the other path is connected with the non-inverting input end of the operational amplifier U51C through a series circuit of a resistor R54 and a resistor R55, two ends of a resistor R55 are respectively connected with the ground through a capacitor C53 and a capacitor C54, the inverting input end of the operational amplifier U51A is connected with the output end of the operational amplifier U51A, the non-inverting input end of the operational amplifier U51A is connected with the collector of the triode Q51, the inverting input end of the operational amplifier U51C is connected with the output end of the operational amplifier U51C, the output end of the operational amplifier U51C is connected with the non-inverting input end of the operational amplifier U52C through a resistor R C, the non-inverting input end of the operational amplifier U52C is connected with the parallel circuit of the transistor Q C, and the output end of the transistor Q C are connected with the base C, the emitter of the triode Q51 is grounded through a resistor R51, the collector of the triode Q51 is connected with the cathode of the diode D51 and the anode of the electrolytic capacitor C56, the anode of the diode D51 and the cathode of the electrolytic capacitor C56 are connected with the emitter of the triode Q51, and the collector of the triode Q51 outputs a signal Rout which is connected with the resistance type analog indicating instrument. The resistance signal output unit is used for being connected with the resistance type analog indicating instrument. Input signals of sensors such as a reed switch resistance type liquid level sensor, a slide wire resistance type liquid level sensor, a thermistor and the like are converted into corresponding PWM signals after being conditioned, subjected to AD conversion and collected and processed by a CC2530 system-on-chip, output by a Zigbee system-on-chip unit and added to a base electrode of a triode Q52 through a resistor R56. The synthesized resistor is output to the resistance type analog indicating instrument from a signal Rout end.

Preferably, the Zigbee wireless sensing node capable of being connected with the field indicating instrument includes a pulse signal conditioning unit, the pulse signal conditioning unit includes a triode Q31, a dc pulse input terminal CN5, one path is connected with +5V voltage through a resistor R31, the other path is connected with the anode of a diode D31, the other path is grounded through a capacitor C31, an ac pulse input terminal CN6, one path is connected with the cathode of a diode D31, the other path is grounded through a capacitor C32, the anode of the diode D31 is connected with the anode of a diode D32 through a resistor R32, the cathode of the diode D32 is connected with the base of the triode Q31, the base of the triode Q31 is grounded through a capacitor C33 and the cathode of the diode D33, the anode of the diode D33 is grounded, the emitter of the triode Q31 is grounded, the collector of the triode Q31, the other path is connected with +3.3V voltage through a resistor R33, the other path is grounded through a capacitor C34, and the other path is connected with the system-on-. The direct current pulse input end CN5 can be connected with a Hall sensor and a photoelectric speed measuring sensor with open-drain output. The alternating current pulse input end CN6 can be connected with a magnetoelectric speed measuring sensor.

Preferably, the Zigbee wireless sensing node capable of being connected with the field indicating instrument comprises a keyboard display circuit, wherein the keyboard display circuit comprises an LED driving chip U63, a four-in-one totally-negative nixie tube U61, a three-in-one totally-negative nixie tube U62, seven LED light-emitting tubes D61-D67 and four keys K61-K64, and the LED driving chip U63 adopts a TM1628 driving chip; the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 9 pin and the 8 pin of the Zigbee system-on-chip U81, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with +3.3V voltage through a resistor R61, a resistor R62 and a resistor R63, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the ground through a capacitor C61, a capacitor C62 and a capacitor C63, the 5 pin of the LED driving chip U63 is connected with one ends of keys K61 to K64, the other ends of the keys K61 to K64 are respectively connected with the 8 pin to 11 pin of the LED driving chip U63, the 8 pin to 15 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 7 pin, the 4 pin, the 2 pin, the 1 pin, the 10 pin, the 5 pin and the 3 pin of the four-bit common-negative nixie tube U61, the driving chip U4626 pin, the common nixie 20 pin, 20, The

pins

9, 8 and 6 and the

pins

12, 9 and 8 of the trinity common-cathode nixie tube U62 are connected, the

pins

27, 26, 24, 23, 20, 19 and 18 of the LED driving chip U63 are respectively connected with the cathodes of the LED luminescent tubes D61-D67, the anodes of the LED luminescent tubes D61-D67 are connected with the pin 16 of the LED driving chip U63, the

pins

7 and 21 of the LED driving chip U63 are connected with +3.3V voltage, and the

pins

22, 25 and 28 of the LED driving chip U63 are grounded. The keyboard display circuit is used for field setting and display, and the TM1628 driving chip is a special chip for driving and controlling an LED (light emitting diode display) with a keyboard scanning interface. The 7 nixie tubes and the 7 LED luminous tubes adopt a dynamic scanning circuit form. The 4 keys are used for setting field parameters and are respectively 'setting, shifting, plus 1 and minus 1'. If the analog instrument indication mode is selected, the 'keyboard display circuit' can be omitted, and related parameters can be set through a wireless network.

Preferably, the Zigbee wireless sensing node capable of being connected with the field indicating instrument comprises an RS485 interface circuit, and the RS485 interface circuit is connected with the Zigbee system-on-chip unit. The RS485 interface circuit is mainly used for data acquisition of various sensors with RS485 interfaces, and the wireless sensing node can be accessed to a field RS485 bus to wirelessly transmit sensor data, so that remote data acquisition of the sensor data is realized.

The invention has the beneficial effects that: the integrated Zigbee wireless sensing node has the functions of measurement, control, display and wireless transmission, has the functions of on-site digital indication or analog indication, can carry out measurement control and wireless transmission on various parameters such as liquid level, temperature, pressure, rotating speed and the like, effectively reduces the system cost and improves the system reliability.

Drawings

Fig. 1 is a block diagram of a circuit schematic connection structure of the present invention.

Fig. 2 is a schematic circuit diagram of the power supply unit of the present invention.

FIG. 3 is a schematic circuit diagram of the signal conditioning units, the multi-channel signal selection unit, and the AD conversion unit of the present invention.

Fig. 4 is a schematic circuit diagram of a Zigbee system-on-chip unit and a radio frequency unit according to the present invention.

Fig. 5 is a schematic circuit diagram of a pulse signal conditioning unit according to the present invention.

Fig. 6 is a schematic circuit diagram of a relay control unit according to the present invention.

Fig. 7 is a schematic circuit diagram of the resistance signal output unit of the present invention.

Fig. 8 is a circuit schematic of the keyboard display circuit of the present invention.

Fig. 9 is another circuit schematic of the rf unit of the present invention.

In the figure, 1, a V-level voltage signal conditioning unit, 2, a mV-level voltage and mA-level current signal conditioning unit, 3, a thermocouple temperature compensation unit, 4, a resistance signal conditioning unit, 5.2.5V reference voltage unit, 6, a multi-path signal selection unit, 7, an AD conversion unit, 8, a pulse signal conditioning unit, 9, a relay control unit, 10, a Zigbee system-on-chip unit, 11, a radio frequency unit, 12, an RS485 interface circuit, 13, a resistance signal output unit, 14, a power supply unit and 15, a keyboard display circuit are adopted.

Detailed Description

The technical scheme of the invention is further specifically described by the following embodiments and the accompanying drawings.

Example 1: as shown in fig. 1, the Zigbee wireless sensing node capable of being connected with a field indicating instrument of this embodiment includes a V-level voltage signal conditioning unit 1, a mV-level voltage and mA-level current signal conditioning unit 2, a thermocouple temperature compensation unit 3, a resistance signal conditioning unit 4, a 2.5V reference voltage unit 5, a multi-path signal selection unit 6, an AD conversion unit 7, a pulse signal conditioning unit 8, a relay control unit 9, a Zigbee on-chip system unit 10, a radio frequency unit 11, a keyboard display circuit 15, an RS485 interface circuit 12, a resistance signal output unit 13, a power supply unit 14 for supplying a working voltage to the whole Zigbee wireless sensing node, output ends of the V-level voltage signal conditioning unit, the mV-level voltage and mA-level current signal conditioning unit, the thermocouple temperature compensation unit, and the resistance signal conditioning unit are respectively connected with input ends of the multi-path signal selection unit, the output end of the multi-channel signal selection unit is connected with the input end of the AD conversion unit, and the multi-channel signal selection unit, the AD conversion unit, the pulse signal conditioning unit, the relay control unit, the radio frequency unit, the keyboard display circuit, the RS485 interface circuit and the resistance signal output unit are respectively connected with the Zigbee system-on-chip unit.

As shown in FIG. 2, the power supply unit is powered by DC12V, the load capacity is greater than 500mA, and the diode D11 is a 12V power supply reverse connection protection diode. The voltage stabilizing chip U11 adopts a TEL42666 voltage stabilizing chip, is a 5V/150mA low-voltage difference and low-power consumption power supply voltage stabilizing chip and mainly provides +5V working voltage for each signal conditioning unit. The voltage stabilizing chip U12 adopts a 78L09 voltage stabilizing chip, is a 9V/100MA voltage stabilizing chip and mainly provides +9V working voltage for a resistance signal output unit connected with an analog indicating instrument. The voltage stabilizing chip U13 adopts an MP1470 voltage stabilizing chip, is a 3.3V/2A high-efficiency synchronous voltage-reducing DC-DC voltage stabilizing chip and mainly provides +3.3V working voltage for circuits such as Zigbee system units on a chip.

As shown in fig. 3 and 4, the Zigbee system-on-chip unit includes a Zigbee system-on-chip U81, and the Zigbee system-on-chip U81 adopts a CC2530 system-on-chip; the multi-channel signal selection unit comprises a multi-channel selection analog switch chip U22, and the multi-channel selection analog switch chip U22 adopts a CD4051 switch chip; the AD conversion unit comprises an AD conversion chip U23, and the AD conversion chip U23 adopts a TM7707AD converter.

The 2.5V reference voltage unit comprises a stabilized voltage power supply U21, a TL431 stabilized voltage power supply is adopted as a stabilized voltage power supply U21, a K pin of a stabilized voltage power supply U21 is connected with +5V voltage through a resistor R27 and is connected with one end of a capacitor C23 through the resistor R28, the other end of the capacitor C23 is grounded, an A pin of the stabilized voltage power supply U21 is grounded, an R pin and a K pin of the stabilized voltage power supply U21 are connected, a capacitor C22 is connected between the K pin and the A pin of the stabilized voltage power supply U21 in parallel, and the connection point of the resistor R28 and the capacitor C23.

The V-stage voltage signal conditioning unit comprises a resistor R21 and a resistor R22, one end CN1 of a voltage signal input end is connected with the other end CN2 of the voltage signal input end through a series circuit of the resistor R21 and the resistor R22, the other end CN2 of the voltage signal input end is connected with an SGND end, a connecting point of the resistor R21 and the resistor R22 is connected with a pin 13 of a multi-path selection analog switch chip U22, and the other end CN2 of the voltage signal input end is connected with a pin 5 of the multi-path selection analog switch chip U22.

The mV level voltage and mA level current signal conditioning unit comprises an inductor L21, a resistor R23, a resistor R24 and a diode D21, wherein one end CN3 of a voltage signal input end is connected with a 14 pin of a multi-path selection analog switch chip U22 through an inductor L21, the other end is grounded through a resistor R23, the other end is connected with the anode of the diode D21, the cathode of the diode D21 is connected with a 15 pin of the multi-path selection analog switch chip U22 and is connected with the other end CN2 of the voltage signal input end through a resistor R24.

The thermocouple temperature compensation unit comprises a thermistor Rt21 for measuring the temperature of the cold end of the thermocouple, one end of a thermistor Rt21 is grounded, the other end of the thermistor Rt21 is connected with the SGND end through a resistor R25, and the connecting point of the thermistor Rt21 and a resistor R25 is connected with a pin 12 of the multi-path selection analog switch chip U22.

The resistance signal conditioning unit comprises an inductor L22, a resistor R26 and a capacitor C21, a three-wire structure is adopted, the resistance signal conditioning unit comprises a current lead L1, a current lead L3 and a voltage lead L2, one end of a resistor RX to be tested is connected with a current lead L1, the current lead L1 is connected with one end of the inductor L22 and one end of a resistor R26, the other end of the resistor R26 is grounded, the other end of the inductor L22 is connected with a pin 1 of a circuit selection analog switch chip U22 and is grounded through a capacitor C21, the other end of the resistor RX to be tested is connected with the current lead L3 and the voltage lead L2, the voltage lead L2 is connected with a mV voltage input end, and the current lead L3 is connected with an SGND end.

11 pins, 10 pins and 9 pins of a multi-path selection analog switch chip U22 are respectively connected with 7 pins, 6 pins and 5 pins of a Zigbee system-on-chip U81, 6 pins-8 pins of a multi-path selection analog switch chip U22 are all grounded, 16 pins of a multi-path selection analog switch chip U22 are grounded through a +5V voltage and a capacitor C24, 3 pins of a multi-path selection analog switch chip U22 are connected with 7 pins of an AD conversion chip U23, 8 pins and 9 pins of an AD conversion chip U23 are connected with SGND, 15 pins of an AD conversion chip U23 are grounded through a +5V voltage and a parallel circuit of a capacitor C25 and a capacitor C26, 16 pins, 10 pins and 4 pins of an AD conversion chip U23 are grounded, a crystal oscillator Y21 is connected between a 2 pin and a 3 pin of the AD conversion chip U23, 5 pins of the AD conversion chip U23 are connected with the +5V voltage, and 12 pins, 13 pins, 14 pins, 1 pins, 12 pins of the AD conversion chip U23, 12 pins of the Zigbee system-on-chip U81 and the Zigbee system-on, The 14 feet and the 15 feet are connected.

1-4 pins of a Zigbee system-on-chip U81 are grounded, 10 pins of a Zigbee system-on-chip U81 are grounded through a capacitor C812 and a voltage VDD, 21 pins of a Zigbee system-on-chip U81 are grounded through a capacitor C810 and a voltage VDD, 20 pins of a Zigbee system-on-chip U81 are grounded through a resistor R82 and a capacitor C811, a crystal oscillator Y81 is connected between 22 pins and 23 pins of a Zigbee system-on-chip U81, two ends of the crystal oscillator Y81 are grounded through a capacitor C88 and a capacitor C89 respectively, 24 pins of a Zigbee system-on-chip U81 are grounded through a capacitor C87 and a voltage VDD, 27 pins, 28 pins and 29 pins of the Zigbee system-on-chip U81 are all grounded through a voltage VDD, a capacitor C85 and a capacitor C42 are connected between the ground terminal of the Zigbee system-on-chip U81 pin and a ground terminal, 30 pins of the Zigbee system-on-chip U81 are grounded through a resistor R81 and a capacitor C585 pin is grounded through a capacitor C84 and a capacitor C84, the pin 40 of the Zigbee system-on-chip U81 is grounded via the capacitor C82. The radio frequency unit comprises an inductor L82, an inductor L83 and an interface SMB 1; a26 pin of a Zigbee system-on-chip U81 is connected with one end of an inductor L82 through a capacitor C813, a 25 pin of a Zigbee system-on-chip U81 is connected with one end of a capacitor C816 through a capacitor C814, the other end of the inductor L82 is connected with the other end of the capacitor C816 and is connected with an interface SMB1 through a capacitor C817, the interface SMB1 is externally connected with a monopole antenna, the connection point of the capacitor C813 and the inductor L82 is grounded through a capacitor C815, and the connection point of the capacitor C814 and the capacitor C816 is grounded through an inductor L83.

As shown in fig. 5, the pulse signal conditioning unit includes a triode Q31 and a dc pulse input terminal CN5, one of which is connected to +5V through a resistor R31, the other of which is connected to the anode of a diode D31, and the other of which is connected to ground through a capacitor C31, and an ac pulse input terminal CN6, one of which is connected to the cathode of the diode D31, the other of which is connected to ground through a capacitor C32, the anode of a diode D68692 is connected to the anode of a diode D32 through a resistor R8, the cathode of a diode D32 is connected to the base of a triode Q31, the base of the triode Q31 is connected to ground through a capacitor C33 and the cathode of a diode D33, the anode of a diode D33 is connected to ground, the emitter of a triode Q31 is connected to ground, the collector of the triode Q31, one of which is connected to +3.3V through a resistor R33, and the other of which is connected to ground through a capacitor C.

As shown in fig. 6, the relay control unit includes a relay J41, a relay J42, a triode Q41 and a triode Q42, pins 37 and 38 of a Zigbee soc chip U81 are respectively connected with bases of the triode Q41 and the triode Q42, emitters of the triode Q41 and the triode Q42 are both grounded, collectors of the triode Q41 and the triode Q42 are respectively connected with negative terminals of driving terminals of the relay J41 and the relay J42, positive terminals of driving terminals of the relay J41 and the relay J42 are both connected with +12V voltage, two driving terminals of the relay J41 are connected in anti-parallel with a diode D41, and two driving terminals of the relay J42 are connected in anti-parallel with a diode D42.

As shown in fig. 7, the resistance signal output unit includes a PWM shaping circuit, a filter circuit, a synthesized resistance output circuit, and a follower; the PWM shaping circuit comprises a resistor R56, a resistor R56 and a triode Q52; the filter circuit comprises a resistor R54, a resistor R55, a capacitor C53 and a capacitor C54; the synthetic resistor output circuit comprises an operational amplifier U52B, a triode Q51 and a resistor R51; the follower comprises an operational amplifier U51A and an operational amplifier U51C. A PWM signal output from the 36 pin of the Zigbee soc U81 is connected to the base of the transistor Q52 via the resistor R56, the collector of the transistor Q52, one path is connected to the output terminal of the operational amplifier U51A via the resistor R53, the other path is connected to the non-inverting input terminal of the operational amplifier U51C via the series circuit of the resistor R54 and the resistor R55, both ends of the resistor R55 are respectively connected to ground via the capacitor C53 and the capacitor C54, the inverting input terminal of the operational amplifier U51A is connected to the output terminal of the operational amplifier U51A, the non-inverting input terminal of the operational amplifier U51A is connected to the collector of the transistor Q A, the inverting input terminal of the operational amplifier U51A is connected to the output terminal of the operational amplifier U51A, the output terminal of the operational amplifier U51A is connected to the non-inverting input terminal of the operational amplifier U52A via the parallel circuit of the resistor R A and the emitter of the transistor Q A, the transistor Q A is connected to the emitter of the operational amplifier U A via the transistor Q A and the emitter of the transistor Q A. The emitter of the triode Q51 is grounded through a resistor R51, the collector of the triode Q51 is connected with the cathode of the diode D51 and the anode of the electrolytic capacitor C56, the anode of the diode D51 and the cathode of the electrolytic capacitor C56 are connected with the emitter of the triode Q51, and the collector of the triode Q51 outputs a signal Rout which is connected with a field resistance type analog indicating instrument.

As shown in fig. 8, the keyboard display circuit includes an LED driving chip U63, a four-in-one common-cathode nixie tube U61, a three-in-one common-cathode nixie tube U62, seven LED tubes D61-D67, and four keys K61-K64, and the LED driving chip U63 adopts a TM1628 driving chip; the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 9 pin and the 8 pin of the Zigbee system-on-chip U81, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with +3.3V voltage through a resistor R61, a resistor R62 and a resistor R63, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the ground through a capacitor C61, a capacitor C62 and a capacitor C63, the 5 pin of the LED driving chip U63 is connected with one ends of keys K61 to K64, the other ends of the keys K61 to K64 are respectively connected with the 8 pin to 11 pin of the LED driving chip U63, the 8 pin to 15 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 7 pin, the 4 pin, the 2 pin, the 1 pin, the 10 pin, the 5 pin and the 3 pin of the four-bit common-negative nixie tube U61, the driving chip U4626 pin, the common nixie 20 pin, 20, The pins 9, 8 and 6 and the pins 12, 9 and 8 of the trinity common-cathode nixie tube U62 are connected, the pins 27, 26, 24, 23, 20, 19 and 18 of the LED driving chip U63 are respectively connected with the cathodes of the LED luminescent tubes D61-D67, the anodes of the LED luminescent tubes D61-D67 are connected with the pin 16 of the LED driving chip U63, the pins 7 and 21 of the LED driving chip U63 are connected with +3.3V voltage, and the pins 22, 25 and 28 of the LED driving chip U63 are grounded.

The working process is as follows:

v level voltage signal conditioning unit: the sensor is suitable for data acquisition of sensors outputting voltage signals of V levels such as 1-5V, 0-5V and 0-10V. The voltage signal is input through two ends of CN1 and CN2(SGND), is divided by a resistor R21 and a resistor R22, is added to a channel 0 input end (13 pins of a CD4051 chip) of a multi-channel selection analog switch chip U22, is selected by the CD4051 chip and is added to AIN + and AIN of an AD conversion chip U23 (7 pins and 8 pins of a TM7707 chip).

mV level voltage and mA level current signal conditioning unit: the mV and mA signals are input from two ends of CN3 and CN2(SGND) at the same input end, and two channels of mV and mA are divided.

(1) And (3) mV signal conditioning: when the mV signal is inputted to both terminals CN3 and CN2, the input voltage of the mV channel is lower than the forward-direction on-state voltage of the diode D21, so that the diode D21 is turned off. The mV signal is filtered by an inductor L21 and then directly applied to the channel 1 input end (14 pins of a CD4051 chip) of the multi-channel selection analog switch chip U22, and is selected by the CD4051 chip and then applied to AIN + and AIN of an AD conversion chip U23 (7 pins and 8 pins of a TM7707 chip). The maximum value of the mV signal does not exceed the forward conducting voltage of the diode D21, such as 600mV, and does not exceed the A/D measurement range of the TM7707 chip, and if the TM7707 selects 16 times of gain, the maximum value of the mV signal cannot exceed 2.5V/16 by about 150 mV. The mV signal is suitable for acquiring a negative voltage signal of the thermocouple, when the thermocouple inputs the negative voltage signal below 0 ℃, namely the input signal is a negative voltage signal relative to SGND, and because the SGND end is higher than the GND end by 2.5V, the negative mV signal is a positive voltage signal relative to GND, the negative mV signal can still pass through the mV voltage signal conditioning circuit and the rear-stage CD4051 electronic switch. The mV signal is connected to GND through a resistor R23(M omega level), so when the mV signal is open-circuited, a-2.5V signal is provided at two ends of CN3 and CN2, and the voltage signal can be used as an open-circuit signal at the mV end, such as being used for thermocouple disconnection detection.

(2) And (3) mA signal conditioning: is suitable for mA signals of 4-20 mA or more. The mA signal and the mV signal are the same input end, a loop is formed by a diode D21 and a resistor R24 to CN2(SGND), the mA signal is converted into a voltage signal by a resistor R24 and is added to a channel 2 input end (15 pins of a CD4051 chip) of the multi-channel selection analog switch chip U22, and the voltage signal is added to AIN + of the AD conversion chip U23 and 7 pins and 8 pins of an AIN- (TM7707 chip) after being selected by the CD4051 chip.

Thermocouple temperature compensation unit: is an internal circuit without external input terminals. The cold end temperature of the thermocouple is measured by adopting a thermistor Rt21, and after voltage of SGND to ground (2.5V reference voltage) is divided by a thermistor Rt21 and a resistor R25 (negative voltage input relative to SGND), the voltage is added to the channel 3 input end (12 pins of a CD4051 chip) of a multi-way selection analog switch chip U22, and is added to AIN + of an AD conversion chip U23 and AIN (7 pins and 8 pins of a TM7707 chip) after being selected by the CD4051 chip. When the thermocouple signal is selected as an input signal, the CD4051 chip selects the channel 1 and the channel 3 to switch at intervals, secondary voltage measurement is carried out, temperature compensation is carried out, and the switching period is preferably 400 mS.

Resistance signal conditioning unit: the resistor is suitable for three standard resistor forms of a PT100 thermal resistor, a Cu50 thermal resistor and a 0-375 omega pressure sensor. The adjusting resistor R26 can be used for other resistance sensors such as reed pipe resistance type liquid level, slide wire resistance type liquid level, thermistor and the like. The current lead L1, the current lead L3 and the voltage lead L2 can adopt leads with the same specification and the same length. Through CN4, CN3 and CN2(SGND) three-terminal input, wherein CN3 terminal is mV signal input channel, through multichannel selection analog switch chip U22 channel 1 input (14 feet of CD4051 chip), through measuring mV value of CN3, CN2 terminal, can measure the lead voltage drop of current lead L3 (the lead voltage drop of current lead L1 and current lead L3 is equal when the specification, the same length), alright eliminate the lead resistance influence of current lead L1 and current lead L3. The tested resistor RX and the resistor R26 form a serial voltage dividing line, 2.5V reference voltage between an SGND end and GND is divided, filtered by an inductor L22 and a capacitor C21 and then added to an input end (pin 1 of a CD4051 chip) of a channel 4 of a multi-way selection analog switch chip U22, selected by the CD4051 chip and then added to AIN + of an AD conversion chip U23 and AIN (pin 7 and pin 8 of a TM7707 chip), and measurement conversion from the resistor to the voltage is achieved. During measurement, the CD4051 chip selects the channel 4 and the channel 1 to switch at intervals, secondary voltage measurement is carried out, lead voltage compensation is carried out, and the switching period is preferably 400 mS.

2.5V reference voltage unit: the +5V voltage is applied to regulated power supply U21 through resistor R27, regulated TL431 power supply is in a fixed voltage output mode, and the voltage at two ends of A, K is 2.5V. The CN2 terminal, which is the SGND signal ground, is connected to the K terminal of the TL431 regulated power supply through a small resistor R28 (with a narrow current path, which takes 1 Ω and can effectively limit the loop current and suppress noise). The voltage between the SGND and the GND is 2.5V reference voltage, so that the electronic switch can conveniently transmit +/-mV signals of the thermocouple. The 2.5V voltage between SGND and GND can be used as the A/D reference voltage. The sensor working power supply of the input signal with the SGND as a reference end needs to be isolated from GND.

A multipath signal selection unit: the multi-channel modulation/selection analog switch controlled by a CD4051 digital signal has low on-resistance and low off-state leakage current, is powered by +5V voltage, the voltage range of a digital control signal is 3-15V, the A, B, C selection signal of the multi-channel modulation/selection analog switch is controlled by the 3.3V level of a CC2530 on-chip system, and the output of the selection signal (pin 3 of a CD4051 chip) is connected with an AD conversion chip U23. The AD conversion chip U23 adopts a TM7707 dual-channel fully differential analog input AD converter.

A pulse signal conditioning unit: the direct current pulse input end CN5 can be connected with a Hall sensor and a photoelectric speed measuring sensor with open-drain output. The direct current pulse signal is added to the base electrode of a triode Q31 through a resistor R32 and a diode D32, the collector electrode of the triode Q31 is connected with a +3.3V level through a resistor R33 in an upward pulling mode, the 3.3V level is shaped through a triode Q31, and the collector electrode of the triode Q31 outputs a pulse signal with the 3.3V level to be added to a pin 19 of a CC2530 on-chip system. The alternating current pulse input end CN6 can be connected with a magnetoelectric speed measuring sensor. When the AC pulse is positive pulse and the amplitude is lower than 5V, the diode D31 is conducted, and when the level of the point A is higher than the voltage drop of the diode D32 and the triode Q31, the triode Q31 is conducted. When the positive pulse amplitude is high, the transistor D31 is turned off, and the +5V voltage can still turn on the diode D32 and the transistor Q31. When the ac pulse is negative, the diode D31 is turned on, the point a is low, and the diode D32 and the transistor Q31 are turned off. After the alternating current pulse is shaped by a transistor Q31, a pulse signal with 3.3V level is output by the collector of the alternating current pulse and is applied to a pin 19 of a CC2530 system on chip. The diode D32 and the diode D33 are used for preventing the BE terminal of the transistor Q31 from being broken down reversely during the negative pulse. The power ground of the pulse signal sensor may be common to the GND terminal.

A relay control unit: relay J41 and relay J42 each output a pair of normally open and normally closed contacts. Control signals are output by pins 37 and 38 of a CC2530 system-on-chip, the relay is driven after power amplification of a triode Q41 and a triode Q42, and a diode D41 and a diode D42 are used for absorbing counter potential of the relay.

A resistance signal output unit: is used for being matched with a resistance type analog indicating instrument. The input signals of the sensors such as the reed pipe resistance type liquid level, the slide wire resistance type liquid level, the thermistor and the like are converted into corresponding PWM signals after being conditioned, AD converted and collected and processed by the CC2530 on-chip system, and the PWM signals are output by a pin 36 of the CC2530 on-chip system and are added to a base electrode of a triode Q52 through a resistor R56. After being shaped by a triode Q52, the PWM signal is filtered by a secondary filter circuit consisting of a resistor R54, a resistor R55, a capacitor C53 and a capacitor C54 and then is used as a control signal of the resistor to be added into a synthetic resistor control circuit consisting of an operational amplifier U51A. In the synthesized resistor output circuit, the resistor R51 is a reference resistor, and different values can be output to different synthesized circuit ranges. The diode D51 is used for simulating counter potential absorption generated by the instrument, and the electrolytic capacitor C56 is a filter capacitor. The operational amplifier U51A and the operational amplifier U51C form a follower, wherein, the signal filtered by the PWM shaping circuit is output by the operational amplifier U51C, and then is output after voltage division by the resistor R57 and the resistor R58, the voltage division ratio of the resistor R57 and the resistor R58 is changed, and the output range of the synthesized resistor can be adjusted. The combined resistance is output by the signal Rout terminal. When the duty ratio of the PWM signal is a constant value, the ratio of the voltage and the current at the terminal of the signal Rout is kept constant, and a constant resistance value is output. The power ground of the latter stage analog meter may be common to the GND terminal.

Keyboard display circuit: the TM1628 driving chip is a chip special for driving and controlling an LED (light emitting diode display) with a keyboard scanning interface. The 7 nixie tubes and the 7 LED luminous tubes adopt a dynamic scanning circuit form, 8 pen segments of each nixie tube are respectively driven by SEG 1-SEG 8 ends of TM1628, and the 7 LED luminous tubes are equivalent to the 9 th pen segment of the 7 nixie tubes and are driven by an SEG9 end of the TM 1628. The 4 keys are used for setting field parameters and are respectively 'setting, shifting, plus 1 and minus 1'. If the analog instrument indication mode is selected, the 'keyboard display circuit' can be omitted, and related parameters can be set through a wireless network.

RS485 interface circuit: the wireless sensor node is mainly used for data acquisition of various sensors with RS485 interfaces, the wireless sensor node can be accessed to a field RS485 bus, wireless transparent transmission of sensor data is carried out (an upper computer directly communicates with a sensor with the RS485 interface through the wireless sensor node, the wireless sensor node can be configured to have a data transparent transmission function at the moment), remote data acquisition of the sensor data is realized, and the wireless sensor node is only accessed to the field RS485 bus and does not participate in field control at the moment. The RS485 interface circuit can adopt an RS485 low-power-consumption transceiver (such as a MAX3485 chip), wherein a pin R, D of the MAX3485 is connected to a pin 16 and a pin 17 of the CC2530 system on chip, and the level of serial ports TXD and RXD of the CC2530 system on chip is converted into the level of RS 485.

Example 2: in the Zigbee wireless sensing node capable of being connected with an on-site indicator instrument according to this embodiment, as shown in fig. 9, the radio frequency unit includes an inductor L82, an inductor L83, a radio frequency chip U82, and an interface SMB2, where the radio frequency chip U82 adopts an RFX2401 radio frequency chip; a 26 pin of the Zigbee on-chip system chip U81 is connected to one end of an inductor L82 through a capacitor C813, a 25 pin of the Zigbee on-chip system chip U81 is connected to one end of a capacitor C814 and a capacitor C816 through a capacitor C814, the other end of the inductor L82 is connected to the other end of the capacitor C816 and is connected to a 4 pin of the radio frequency chip U82 through a capacitor C817, a connection point of the capacitor C813 and the inductor L82 is grounded through a capacitor C815, a connection point of the capacitor C814 and the capacitor C816 is grounded through an inductor L83, a 5 pin and a 6 pin of the radio frequency chip U82 are respectively connected to a 33 pin and a 32 pin of the Zigbee on-chip system chip U81, a 1 pin, a 2 pin, a 3 pin, and a 7 pin, the pins 8, 9, 11, 12 and 15 are all grounded, the pin 14 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C819, the pin 16 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C818, the pin 10 of the radio frequency chip U82 is connected with the interface SMB2, and the interface SMB2 is externally connected with a monopole antenna. The rest of the structure is the same as that of example 1. The RFX2401 radio frequency chip plays a power amplification role, and is externally connected with a monopole antenna through an interface SMB2 so as to increase the communication distance.

The invention has the following characteristics:

1. and 2.4GHz radio frequency is adopted, and IEEE 802.15.4 and Zigbee RF4CE wireless transmission standards are supported.

2. Adaptation: resistance output (such as reed pipe resistance type liquid level, slide wire resistance type liquid level, thermal resistance, thermistor sensor); mV output (sensors such as thermocouples, piezoresistive pressure, 75mV current sampling resistors, etc.); outputting standard voltage of 1-5V and the like; outputting standard 4-20 mA and other currents; outputting the pulse frequency; and sensors for liquid level, temperature, pressure, large current, rotating speed and the like output by the RS485 bus.

3. Besides wireless transmission, the collected parameters can be indicated on site, and analog or digital indication modes can be selected. The analog indication is output in a synthetic resistance mode and is matched with an indicating instrument matched with the existing resistance type sensor, such as an analog water level and oil level indicating instrument matched with a resistance type water level and oil level sensor, and an analog temperature instrument matched with a thermistor sensor.

4. The two-way relay passive contact output is provided, and two-position or PTD control can be performed, such as control of oven temperature, water tank level and the like.

5. The system has the functions of setting relevant parameters on site or remotely through a wireless network, such as matched sensor model selection, 2-bit control, alarm value, PTD (packet transport device) adjustment and the like.

6. The power supply is provided by a DC12V power supply, and most sensors connected with the power supply need to be electrically isolated.

Claims

1. A Zigbee wireless sensing node capable of being matched with an on-site indicating instrument is characterized by comprising a V-level voltage signal conditioning unit, a mV-level voltage and mA-level current signal conditioning unit, a thermocouple temperature compensation unit, a resistance signal conditioning unit, a multi-path signal selection unit, an AD conversion unit, a relay control unit, a Zigbee on-chip system unit, a radio frequency unit, a resistance signal output unit and a power supply unit for providing working voltage for the whole Zigbee wireless sensing node, wherein the output ends of the V-level voltage signal conditioning unit, the mV-level voltage and mA-level current signal conditioning unit, the thermocouple temperature compensation unit and the resistance signal conditioning unit are respectively connected with the input end of the multi-path signal selection unit, the output end of the multi-path signal selection unit is connected with the input end of the AD conversion unit, and the multi-path signal selection unit, the AD conversion unit, the radio frequency unit and the resistance signal output unit are respectively connected with a Zigbee system-on-chip unit, the Zigbee system-on-chip unit comprises a Zigbee system-on-chip U81, and the Zigbee system-on-chip U81 adopts a CC2530 system-on-chip; the multi-channel signal selection unit comprises a multi-channel selection analog switch chip U22, and the multi-channel selection analog switch chip U22 adopts a CD4051 switch chip; the AD conversion unit comprises an AD conversion chip U23, and the AD conversion chip U23 adopts a TM7707AD converter; pins 1-4 of a Zigbee system-on-chip U81 are grounded, pins 7, 6 and 5 of the Zigbee system-on-chip U81 are respectively connected with pins 11, 10 and 9 of a multi-path selection analog switch chip U22, pin 10 of the Zigbee system-on-chip U81 is grounded through a capacitor C812 after being connected with a voltage VDD, pin 12, pin 13, pin 14 and pin 15 of the Zigbee system-on-chip U81 are respectively connected with pin 12, pin 13, pin 14 and pin 1 of an AD conversion chip U23, pin 21 of the Zigbee system-on-chip U81 is grounded through a capacitor C810 after being connected with the voltage VDD, pin 20 of the Zigbee system-on-chip U81 is grounded through a resistor R82 and a capacitor C811, a crystal oscillator Y81 is connected between pin 22 and pin 23 of the Zigbee system-on-chip U81, two ends of the crystal oscillator Y81 are grounded through a capacitor C88 and a capacitor C89, and a pin 24 of the Zigbee system-on-chip U81 is grounded through a capacitor C3985 and a capacitor C81, Pins 28 and 29 are both connected with a voltage VDD, a capacitor C85 and a capacitor C86 are connected between the pin 29 of the Zigbee system-on-chip U81 and a grounding end, a pin 30 of the Zigbee system-on-chip U81 is grounded through a resistor R81, a pin 31 of the Zigbee system-on-chip U81 is grounded through a capacitor C84 after being connected with the voltage VDD, a pin 39 of the Zigbee system-on-chip U81 is grounded through a capacitor C83 after being connected with the voltage VDD, and a pin 40 of the Zigbee system-on-chip U81 is grounded through a capacitor C82; the pins 13, 12 and 1 of the multi-path selection analog switch chip U22 are respectively connected with the output ends of the V-level voltage signal conditioning unit, the thermocouple temperature compensation unit and the resistance signal conditioning unit, the pins 14 and 15 of the multi-path selection analog switch chip U22 are respectively connected with the two output ends of the mV-level voltage and mA-level current signal conditioning unit, the pins 6 to 8 of the multi-path selection analog switch chip U22 are all grounded, the pin 16 of the multi-path selection analog switch chip U22 is both connected with the +5V voltage and grounded through a capacitor C24, the pin 3 of the multi-path selection analog switch chip U22 is connected with the pin 7 of the AD conversion chip U23, the pin 8 and the pin 9 of the AD conversion chip U23 are connected with the SGND, the pin 15 of the AD conversion chip U23 is both connected with the +5V voltage and grounded through a parallel circuit of a capacitor C25 and a capacitor C26, the pin 16, the pin 10 and the pin 4 of the AD conversion chip U23 are all grounded, the pin 2 of the conversion chip U23 is connected with the Y-oscillator 685, the 5 pin of the AD conversion chip U23 is connected with +5V voltage.

2. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, wherein the radio frequency unit comprises an inductor L82, an inductor L83 and an interface SMB 1; a26 pin of the Zigbee system-on-chip U81 is connected with one end of an inductor L82 through a capacitor C813, a 25 pin of the Zigbee system-on-chip U81 is connected with one end of the capacitor C816 through the capacitor C814, the other end of the inductor L82 is connected with the other end of the capacitor C816 and is connected with an interface SMB1 through the capacitor C817, the interface SMB1 is externally connected with a monopole antenna, the connection point of the capacitor C813 and the inductor L82 is grounded through the capacitor C815, and the connection point of the capacitor C814 and the capacitor C816 is grounded through the inductor L83.

3. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, wherein the radio frequency unit comprises an inductor L82, an inductor L83, a radio frequency chip U82 and an interface SMB2, and the radio frequency chip U82 adopts an RFX2401 radio frequency chip; a 26 pin of the Zigbee on-chip system chip U81 is connected to one end of an inductor L82 through a capacitor C813, a 25 pin of the Zigbee on-chip system chip U81 is connected to one end of a capacitor C814 and a capacitor C816 through a capacitor C814, the other end of the inductor L82 is connected to the other end of the capacitor C816 and is connected to a 4 pin of the radio frequency chip U82 through a capacitor C817, a connection point of the capacitor C813 and the inductor L82 is grounded through a capacitor C815, a connection point of the capacitor C814 and the capacitor C816 is grounded through an inductor L83, a 5 pin and a 6 pin of the radio frequency chip U82 are respectively connected to a 33 pin and a 32 pin of the Zigbee on-chip system chip U81, a 1 pin, a 2 pin, a 3 pin, and a 7 pin, the pins 8, 9, 11, 12 and 15 are all grounded, the pin 14 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C819, the pin 16 of the radio frequency chip U82 is connected with the voltage VDD and grounded through the capacitor C818, the pin 10 of the radio frequency chip U82 is connected with the interface SMB2, and the interface SMB2 is externally connected with a monopole antenna.

4. The Zigbee wireless sensing node capable of being matched with the field indicating instrument according to claim 1, 2 or 3, characterized by comprising a 2.5V reference voltage unit, wherein the 2.5V reference voltage unit comprises a regulated power supply U21, a TL431 regulated power supply is adopted as the regulated power supply U21, a K pin of the regulated power supply U21 is connected with +5V voltage through a resistor R27 and is connected with one end of a capacitor C23 through a resistor R28, the other end of the capacitor C23 is grounded, an A pin of the regulated power supply U21 is grounded, an R pin of the regulated power supply U21 is connected with the K pin, a capacitor C22 is connected between the K pin and the A pin of the regulated power supply U21 in parallel, and the connection point of the resistor R28 and the capacitor C23 is an SGND end;

5. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, wherein the relay control unit comprises a relay J41, a relay J42, a triode Q41 and a triode Q42, wherein pins 37 and 38 of a Zigbee system-on-chip U81 are respectively connected with bases of the triode Q41 and the triode Q42, emitters of the triode Q41 and the triode Q42 are grounded, collectors of the triode Q41 and the triode Q42 are respectively connected with negative driving ends of the relay J41 and the relay J42, positive ends of driving ends of the relay J41 and the relay J42 are respectively connected with +12V voltage, two driving ends of the relay J41 are connected with a diode D41 in an anti-parallel mode, and two driving ends of the relay J42 are connected with a diode D42 in an anti-parallel mode.

6. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, wherein the resistance signal output unit comprises a PWM shaping circuit, a filter circuit, a synthesized resistance output circuit and a follower; the PWM shaping circuit comprises a resistor R56, a resistor R56 and a triode Q52; the filter circuit comprises a resistor R54, a resistor R55, a capacitor C53 and a capacitor C54; the synthetic resistor output circuit comprises an operational amplifier U52B, a triode Q51 and a resistor R51; the follower comprises an operational amplifier U51A and an operational amplifier U51C; the PWM signal output by the Zigbee system-on-chip unit is connected with the base of a triode Q52 through a resistor R56, the collector of the triode Q52 is connected with the output end of an operational amplifier U51A through a resistor R53, the other path is connected with the non-inverting input end of the operational amplifier U51C through a series circuit of a resistor R54 and a resistor R55, two ends of a resistor R55 are respectively connected with the ground through a capacitor C53 and a capacitor C54, the inverting input end of the operational amplifier U51A is connected with the output end of the operational amplifier U51A, the non-inverting input end of the operational amplifier U51A is connected with the collector of the triode Q51, the inverting input end of the operational amplifier U51C is connected with the output end of the operational amplifier U51C, the output end of the operational amplifier U51C is connected with the non-inverting input end of the operational amplifier U52C through a resistor R C, the non-inverting input end of the operational amplifier U52C is connected with the parallel circuit of the transistor Q C, and the output end of the transistor Q C are connected with the base C, the emitter of the triode Q51 is grounded through a resistor R51, the collector of the triode Q51 is connected with the cathode of the diode D51 and the anode of the electrolytic capacitor C56, the anode of the diode D51 and the cathode of the electrolytic capacitor C56 are connected with the emitter of the triode Q51, and the collector of the triode Q51 outputs a signal Rout which is connected with the resistance type analog indicating instrument.

7. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, which comprises a pulse signal conditioning unit, wherein the pulse signal conditioning unit comprises a triode Q31 and a direct current pulse input end CN5, one path is connected with +5V voltage through a resistor R31, the other path is connected with the anode of a diode D31, the other path is grounded through a capacitor C31, an alternating current pulse input end CN6, one path is connected with the cathode of a diode D31, the other path is grounded through a capacitor C32, the anode of the diode D31 is connected with the anode of the diode D32 through a resistor R32, the cathode of a diode D32 is connected with the base of the triode Q31, the base of a triode Q31 is grounded through a capacitor C33 and the cathode of a diode D33, the anode of a diode D33 is grounded, the emitter of the triode Q31 is grounded, the collector of a triode Q31 is connected with +3.3V voltage through a resistor R33, and the other path is grounded through a capacitor C6767 34, and the other path is connected with the Zigbee system-on-chip unit.

8. The Zigbee wireless sensing node capable of being connected with a field indicating instrument in a matching manner as claimed in claim 1, which is characterized by comprising a keyboard display circuit, wherein the keyboard display circuit comprises an LED driving chip U63, a four-in-one totally-negative nixie tube U61, a three-in-one totally-negative nixie tube U62, seven LED luminescent tubes D61-D67 and four keys K61-K64, and the LED driving chip U63 adopts a TM1628 driving chip; the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 9 pin and the 8 pin of the Zigbee system-on-chip U81, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with +3.3V voltage through a resistor R61, a resistor R62 and a resistor R63, the 2 pin, the 3 pin and the 4 pin of the LED driving chip U63 are respectively connected with the ground through a capacitor C61, a capacitor C62 and a capacitor C63, the 5 pin of the LED driving chip U63 is connected with one ends of keys K61 to K64, the other ends of the keys K61 to K64 are respectively connected with the 8 pin to 11 pin of the LED driving chip U63, the 8 pin to 15 pin of the LED driving chip U63 are respectively connected with the 11 pin, the 7 pin, the 4 pin, the 2 pin, the 1 pin, the 10 pin, the 5 pin and the 3 pin of the four-bit common-negative nixie tube U61, the driving chip U4626 pin, the common nixie 20 pin, 20, The pins 9, 8 and 6 and the pins 12, 9 and 8 of the trinity common-cathode nixie tube U62 are connected, the pins 27, 26, 24, 23, 20, 19 and 18 of the LED driving chip U63 are respectively connected with the cathodes of the LED luminescent tubes D61-D67, the anodes of the LED luminescent tubes D61-D67 are connected with the pin 16 of the LED driving chip U63, the pins 7 and 21 of the LED driving chip U63 are connected with +3.3V voltage, and the pins 22, 25 and 28 of the LED driving chip U63 are grounded.

9. The Zigbee wireless sensing node capable of being connected with a field indicating instrument according to claim 1, characterized by comprising an RS485 interface circuit, wherein the RS485 interface circuit is connected with the Zigbee system-on-chip unit.