CN104155891B - I＜2＞C-based networked transmitter and communication implementation method thereof - Google Patents

Abstract

The invention discloses an I ² C-based networked transmitter and a communication realization method thereof. The transmitter includes a microcontroller circuit, a human-computer interaction module, a transmitter power circuit, a sensor power circuit, an I ² C Communication circuit, analog input circuit, 4~20mA signal output circuit, relay output circuit, Modbus/RS485 communication circuit and wiring terminal block, in which the external analog sensor and the intelligent sensor with I ² C interface are connected to the network transmission through the terminal block The sensor connection, the sensor power supply circuit and the I ² C communication circuit provide corresponding power supply voltage and communication connection according to different requirements of the sensor. The present invention proposes an NTSSP protocol. The NTSSP protocol comprehensively applies the broadcast communication mode of the transmitter, the request-response communication mode and the publish ^- subscribe communication mode, which improves the communication efficiency, and can conveniently and automatically assign the I2C address of the smart sensor, which is convenient use. The invention has the advantages of low cost and plug and play.

Description

I2C-based networked transmitter and its communication implementation method

technical field

The invention relates to the field of automatic instrument research, in particular to an I2C ^- based networked transmitter and a communication realization method thereof.

Background technique

Transmitter is a kind of basic automation equipment, which is used to convert physical quantity signals sent by different sensors into measurement signals of standard signal format. At present, the signal connection between the transmitter and the sensor is mainly an analog signal. Because the conversion circuits of different physical quantities are different, the transmitter can generally only realize the transmission function for one physical quantity, and the transmitter needs to be redesigned for different physical quantities. . In addition, when replacing the sensor, it is often necessary to recalibrate the transmitter. Since this process is carried out on the application site and requires a standard sample (such as 3.5% methane gas), the calibration is very inconvenient and the workload of the calibration process is very large. In order to make the transmitter universal, the IEEE Association has formulated the intelligent sensor interface standard IEEE1451, but the standard is complicated, the module division is unreasonable, the interface between the modules is too special, and the rapid development of microprocessor technology and communication technology is not considered. , has not been accepted by the industry for nearly 20 years.

In practical applications, it is best for the new transmitter to be compatible with existing transmitter types, so as to reduce user investment and facilitate promotion. The standard signal output by existing transmitters is generally a 4-20mADC current signal. In order to facilitate the formation of an automation network with other automation instruments, some transmitters also provide Modbus/RS485 communication interfaces.

Digitization and networking are the development direction of automation instruments. Digitization and networking can not only improve the measurement accuracy of transmitters, but also provide new functions that analog transmitters do not have, such as remote diagnosis, calibration and configuration. In addition, in order for the transmitter to be used alone, it is necessary to have an alarm output, and to be able to configure parameters and functions on site through a handheld operator.

Contents of the invention

The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art, and provide a networked transmitter based on I ² C (Inter-Integrated Circuit), which is compatible with most of the functions of existing transmitters. Multiple smart sensors can be connected without on-site calibration, plug and play, easy to use and replace.

Another object of the present invention is to provide a communication implementation method based on the above-mentioned networked transmitter, which comprehensively applies the transmitter broadcast communication mode, request-response communication mode and publish-subscribe communication mode, and improves communication efficiency , can conveniently and automatically assign the I ² C address of the smart sensor, which is convenient to use.

The purpose of the present invention is achieved through the following technical solutions: an I ² C-based network transmitter, including a microcontroller circuit, a human-computer interaction module, a transmitter power circuit, a sensor power circuit, an I ² C communication circuit, an analog Input circuit, 4 ~ 20mA signal output circuit, relay output circuit, Modbus/RS485 communication circuit and wiring terminal block, in which the external analog sensor and the intelligent sensor with I ² C interface are connected to the networked transmitter through the terminal block, and at the same time The terminal block is also connected with 24V power line, relay output line, 4-20mA signal line and Modbus/RS485 communication line; the sensor power supply circuit is used to output the voltage required by each smart sensor under the control of the microcontroller circuit, I The ² C communication circuit is connected with the external smart sensor through the I ² C bus.

Preferably, the microcontroller in the microcontroller circuit uses a STM32L151R8T6 single-chip microcomputer, the transmitter operating parameters are stored in the EEPROM inside the single-chip microcomputer, and the single-chip microcomputer is externally connected to a Flash memory. The low-address storage space of the Flash memory is used to store the 16-dot matrix Chinese character library for LCD Chinese display, and the high-address storage space is used to store the data collected by the sensor due to Modbus communication failure or when the transmitter is used alone. Thereby improving the reliability of data collection.

Preferably, all circuits of the networked transmitter are sealed in the explosion-proof metal shell except for the terminal block, and several metal holes are arranged on the explosion-proof metal shell, and the connecting wires inside the transmitter are connected to the terminal block through the metal holes. , the metal hole is sealed with a sealant.

Preferably, the human-computer interaction module includes an infrared interface circuit of a handheld operator and a liquid crystal display module, and the infrared interface circuit of the handheld operator and the liquid crystal display module are respectively connected to a microcontroller circuit.

Further, the head of the explosion-proof metal shell is made of transparent organic glass. Therefore, the man-machine interface of infrared hand operation and LCD display can be realized through the plexiglass window.

Preferably, the infrared interface circuit of the handheld operator includes a UART and an IrDA transceiver for receiving operation commands and data input of the handheld operator.

Preferably, the liquid crystal display module includes a dot-matrix black-and-white liquid crystal screen with LED backlight.

Preferably, the transmitter power supply circuit is connected to an external 24V power supply through a terminal block, the transmitter power supply circuit includes a DC/DC converter and an LDO voltage regulator, and the DC/DC converter is used to convert the 24V power supply to 5V , The LDO voltage regulator is used to convert the 5V power supply to 3.3V power supply, the 5V power supply output by the transmitter power circuit is used for the operation of the liquid crystal display module and the relay output circuit, and the 3.3V power supply is used for other circuits of the transmitter.

Specifically, the sensor power supply circuit includes a DC/DC forward channel circuit, an analog feedback circuit, a voltage addition circuit and a sensor working power measurement circuit, wherein the DC/DC forward channel circuit is used to change the 24V input voltage into the sensor required The working voltage of the analog feedback circuit is connected in series with the voltage addition circuit, the analog feedback circuit collects the output signal of the DC/DC forward channel circuit, one end of the voltage addition circuit is connected to the microcontroller circuit, and is used to receive the feedback control from the microcontroller circuit The other end is connected to the DC/DC forward channel circuit; the sensor working power measurement circuit is used to send the output signal of the DC/DC forward channel circuit to the microcontroller circuit. According to the use requirements of analog sensors and smart sensors, the user can input the corresponding voltage value through the hand-held device, and the power supply circuit of the transmitter and the microcontroller circuit work together to provide variable output power supply voltage to the external analog sensors and smart sensors. .

Furthermore, both the analog feedback circuit and the sensor working power measurement circuit are resistor divider circuits.

Specifically, the I ² C communication circuit includes two I ² C bus pull-up resistors.

A communication implementation method based on the above-mentioned networked transmitter, comprising steps:

(1) After the smart sensor with I ² C interface is powered on, according to the NTSSP protocol (communication protocol between the transmitter and the smart sensor), it first sends an NTSSP address request to the transmitter; the NTSSP protocol consists of physical layer, data link The physical layer and the data link layer of NTSSP are consistent with the I ² C standard. The application layer in the NTSSP protocol has the following packet structure: address, function number, data length, variable name, variable Value and check code, where the function number is used to indicate the function of the data packet, and different function numbers represent the application for NTSSP address, allocation of NTSSP address, read request data, write request data, subscribe data, and publish data;

(2) The transmitter registers the smart sensor ID according to the smart sensor information table and selects the unassigned NTSSP address (i.e. I ² C address), and then sends the assigned NTSSP address to the smart sensor with the ID number by broadcasting;

(3) The smart sensor reports its working parameters and measurement parameters to the transmitter through the NTSSP address;

(4) After the transmitter registers the attribute parameters of the smart sensor, the transmitter adopts the subscription mode to set the working parameters of the smart sensor;

(5) The smart sensor works according to these working parameters, and adopts the release mode to actively report the measured value and alarm situation to the transmitter.

The present invention proposes an I2C ^- based network transmitter and smart sensor protocol (Network Transmitter and Smart Sensor Protocol, referred to as NTSSP protocol) in the above-mentioned implementation method. The NTSSP protocol is based ^on the existing I2C bus protocol Add application layer. The NTSSP protocol comprehensively applies the transmitter broadcast communication mode, request-response communication mode and publish-subscribe communication mode, which can improve communication efficiency and give full play to the multi-master communication capability of I ² C. By adding this application layer, the transmitter can automatically obtain the information of each smart sensor, so as to realize plug-and-play and easy to use.

Preferably, the data link layer in the NTSSP agreement in the described step (1) has only adopted Slave Receiver and Master Transmitter two kinds of mechanisms, is the subset of I ² C data link layer, when needing to send in communication process The master mode is adopted for the data, and the slave mode is adopted after sending, waiting for the data to be received.

Preferably, when the smart sensor is working normally, the DC/DC forward channel circuit in the sensor power supply circuit in the transmitter changes the 24V input voltage into the working voltage required by the sensor, and the analog feedback circuit collects the DC/DC forward channel circuit The output signal is input to the voltage addition circuit, and the sensor working power measurement circuit also collects the output signal of the DC/DC forward channel circuit and sends the signal to the microcontroller circuit. The microcontroller circuit is set according to the working voltage of the smart sensor. value, the current measurement value to obtain the voltage difference, and input the voltage difference into the voltage addition circuit, and the voltage addition circuit outputs a feedback signal to the DC/DC forward channel circuit according to the voltage difference and the current measurement value. Realize the working voltage of the intelligent sensor can change between 2.5- 5.0V.

Preferably, in the step ( ⁵ ), when the smart sensor reports the measured value and the alarm situation to the transmitter, the I2C reception in the transmitter is an address matching interrupt reception, specifically as follows:

(5-1) When an interrupt occurs, the received data packet is temporarily stored in the input buffer, and the data number counter is increased by 1 at the same time;

(5-2) compare the byte of the data length in the data packet with the data number counter, judge whether the data packet ends, if end then execute step (5-3), otherwise, execute step (5-7);

(5-3) Calculate the check code of the data packet;

(5-4) Judging whether the check code is correct, if correct, then perform step (5-5); if not, then this reception is invalid, and perform step (5-6);

(5-5) Save the current data packet in the receiving buffer of the transmitter, process the data packet, and simultaneously reset the number of data to prepare for the next data packet reception; perform step (5-7);

(5-6) The data number counter is cleared; Execute steps (5-7);

(5-7) Interrupt return.

Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. The transmitter of the present invention adopts the I ² C bus instead of the IEEE1541 standard, so the communication is not only standardized, but also very easy to implement on an ordinary microcontroller, and can realize a multi-master communication mechanism. In addition to being able to connect an analog sensor, it can also A variety of smart sensors with I ² C interfaces can be connected, making full use of the general I ² C standard and reducing the cost of implementation.

2. The transmitter of the present invention also has 4-20mADC analog standard, Modbus/RS485 communication interface and relay switch output, so the output can be compatible with existing transmitters.

3. The human-computer interaction module is set in the present invention, so it has a good Chinese LCD human-machine interface, and at the same time, the working mode and working parameters of the transmitter can be configured through the infrared hand operator. In addition, the microcontroller circuit in the transmitter also has a memory module, so it has data retention capabilities.

4, the NTSSP agreement that the present invention proposes is to increase application layer on the basis of existing I ² C bus protocol, because most microprocessors are integrated with I ² C interface, even do not contain the single-chip microcomputer of hardware I ² C on-chip peripherals, It can also be realized through the I/O pin of open-collector output and software, so this realization method has the advantages of low cost and easy realization.

5. The NTSSP protocol in the present invention comprehensively applies the broadcast communication mode of the transmitter, the request-response communication mode and the publish-subscribe communication mode, which improves the communication efficiency and can conveniently and automatically assign the I ² C address of the smart sensor, so as not to On-site calibration of the transmitter and smart sensor is required, and the sensor is plug-and-play, which is very convenient.

Description of drawings

Fig. 1 is a schematic diagram of the working principle of the present invention.

Fig. 2 is a schematic diagram of the working principle of the sensor power supply circuit in the present invention.

Fig. 3 is the structure of NTSSP agreement of the present invention.

Fig. 4 is the application layer data packet structure in Fig. 3 .

Fig. 5 is a working flow diagram of the transmitter in Embodiment 1.

Fig. 6 is a flow chart of the interrupt routine in the first embodiment.

detailed description

The present invention will be further described in detail below in conjunction with the embodiments and the accompanying drawings, but the embodiments of the present invention are not limited thereto.

Example 1

See Figure 1, the I2C ^- based networked transmitter includes STM32L single-chip microcomputer circuit, handheld operator infrared interface circuit, liquid crystal display module, relay output circuit, 4~20mA signal output circuit, analog input circuit, transmitter power supply circuit , Modbus/RS485 communication circuit, sensor power supply circuit, I ² C communication circuit, terminal blocks. The analog sensor and multiple smart sensors on the right side of the terminal block are sensor modules selected according to the actual measured variable type, and are connected to the transmitter through the terminal block, among which the smart sensor has an I ² C interface. In addition, the external wires of the transmitter are also connected through the terminal block, and the external wires include 24V power wires, relay output wires, 4-20mA signal wires, and Modbus/RS485 communication wires. In this embodiment, the hardware structure of the transmitter is all sealed in the explosion-proof metal shell, and the connecting wires inside the transmitter are connected to the terminal block through the metal hole, and the metal hole is sealed by the sealant. The head of the explosion-proof metal casing is sealed with transparent plexiglass, and the man-machine interface of infrared manual operation and LCD display is realized through the plexiglass window.

In this embodiment, the STM32L single-chip microcomputer circuit adopts STM32L151R8T6 single-chip microcomputer as the core control chip. The working parameters of the transmitter are stored in the 4KB EEPROM inside the single-chip microcomputer. The single-chip microcomputer is externally connected to the 512KB Flash memory AT25DF041A. The font library is used for LCD Chinese display, and the high address 240KB is used to store the data collected by the sensor due to Modbus communication failure or when the transmitter is used alone, so as to improve the reliability of data collection.

The infrared interface circuit of the handheld operator and the liquid crystal display module constitute the human-computer interaction module. The infrared interface circuit of the handheld operator is composed of the on-chip peripheral UART and IrDA transceiver TFDU4101 and related circuits, and receives the operation command and data input of the handheld operator. The liquid crystal display module is composed of 128×64 dot matrix black and white LCD screen LM6059BCW with LED backlight and its related circuits. The single-chip microcomputer uses PWM to adjust the brightness of the LCD LED backlight.

The transmitter power supply circuit converts the external 24V power supply into a 5V power supply through the DC/DC converter CS51412, and then through the LDO voltage regulator SPX1117 into a 3.3V power supply. The 5V power supply is used for LCD backlight and relay output circuits, and the 3.3V power supply It is used for other circuit work of the system.

The analog input circuit and 4-20mA signal output circuit are mainly used to be compatible with existing analog transmitters. The analog input circuit is used to amplify a certain type of sensor signal (such as temperature, etc.), and then connect to the on-chip ADC of the microcontroller. The 4-20mA signal output circuit converts the measured variable into a current signal output, which is composed of DAC, XTR111 and its peripheral circuits on the single-chip microcomputer. The relay output circuit provides relay alarm output, which is composed of driver chip ULN2003 and two relays ATX209. The Modbus/RS485 communication circuit is composed of the on-chip UART of the single-chip microcomputer and the low-power RS485 chip SP3075E, which realizes the Modbus/RS485 communication of the transmitter.

The sensor power supply circuit provides a variable output power supply voltage for the smart sensor to work. The working principle is shown in Figure 2. The sensor power supply circuit includes a DC/DC forward channel circuit, an analog feedback circuit, a voltage addition circuit and a sensor working power measurement circuit. Among them, The DC/DC forward channel circuit is composed of the core control chip CS51412 and its peripheral circuits. It is used to change the 24V input voltage into the working voltage required by the sensor. The output voltage feedback circuit is based on the original analog feedback circuit. A voltage addition circuit is connected in series. The circuit changes the original feedback voltage VFB through the DAC output voltage EsControl of the microcontroller, thereby adjusting Es. Both the analog feedback circuit and the sensor working power measurement circuit are resistor divider circuits, the output EsMeasure of the sensor working power measurement circuit is connected to the on-chip ADC of the single chip microcomputer, and the single chip microcomputer is based on the set value of the sensor working voltage (when there are multiple sensors, take the maximum value) The measured value is compared to find the error, and the size of EsControl is controlled according to the voltage difference to realize the change of Es from 2.5 to 5.0V.

As shown in Figure 3, the NTSSP protocol consists of a physical layer M301, a data link layer M302 and an application layer M303. The physical layer and data link layer of NTSSP are consistent with the I ² C standard, with low cost and few connections. The data link layer of NTSSP only uses two mechanisms of Slave Receiver and Master Transmitter, which is a subset of the I ² C data link layer. The difference is that it needs to switch between the two modes during the communication process. When sending data Change to Master mode, and change to Slave mode after sending, waiting for data reception. In order to improve the communication efficiency and give full play to the multi-master communication capability of I ² C, the NTSSP protocol comprehensively applies the transmitter broadcast communication mode, request-response communication mode and publish-subscribe communication mode. The application layer data packet of the NTSSP protocol is shown in Figure 4. It is composed of address, function number, data length, variable name, variable value and check code. The function number indicates the function of the data packet. Number 1 is to allocate NTSSP address, function number 2 is to read request data, function number 3 is to write request data, function number 12 is to subscribe data, and function number 13 is to publish data.

The above-mentioned networked transmitter based on I ² C is implemented as follows: According to the NTSSP protocol, the NTSSP address of the transmitter node (that is, the I ² C address) is fixed at 1, the broadcast address is 0, and the NTSSP address of the smart sensor is Temporarily assigned between 2 and 127, but each smart sensor includes a unique 12-byte ID number. The transmitter keeps a table of information for each sensor in its internal EEPROM and is maintained by the transmitter. When the smart sensor is powered on, it first sends an NTSSP address request to the transmitter, and the transmitter registers the smart sensor ID according to the smart sensor information table and selects an unassigned NTSSP address, and then sends an allocation to the smart sensor with the ID number by broadcasting NTSSP address for the smart sensor to communicate with the transmitter thereafter. After the address is assigned, the smart sensor reports its operating voltage, measurement type of physical quantity and other parameters to the transmitter. After the transmitter registers the sensor’s attribute parameters, the transmitter adopts the subscription mode to set the sensor’s sampling period, alarm value, etc. After that, the sensor works according to these working parameters, and adopts the release mode to actively report the measured value and alarm situation to the transmitter.

The transmitter in this embodiment is controlled by a main program and multiple interrupt programs when it is working. The interrupt program is mainly a communication receiving interrupt program with a similar structure. Figure 6 shows the I ² C receiving data interrupt program. Configure I ² C receiving in the main program as address matching interrupt receiving. When an interrupt occurs, enter M411 to start the I ² C interrupt program. In M412, temporarily save the received data in the input buffer, and at the same time, the data number counter plus 1. In M413, compare the data length byte in the data packet (need to add 3, including the function number and check code, and the address is not counted) with the data number counter to determine whether the data packet is over, if not Then enter M418 to interrupt and return, and if it ends, enter M414 to calculate the check code of the data packet. M415 judges whether the check code is correct, if it is wrong, this reception is invalid, enter M417, and the data number counter is cleared; if the check code is correct, enter M416 to save the data packet in the receiving buffer of the main program, in the main program In the process, the number of data is cleared at the same time to prepare for the next data packet reception.

In addition to completing the communication sending work, the main program also completes the transmitter working parameter configuration according to the man-machine interface or Modbus communication data, and updates the 4-20mA output and relay alarm processing and output according to the received sensor data. See Figure 5, including the following steps:

M400: After the main program is powered on, enter M401;

M401: Complete the initialization of I/O, on-chip peripherals, and buffer memory units (such as I ² C received data counters, etc.), start RTC timing, start UART (infrared), UART (RS485) and I ² C communication interruption. After initialization, it enters an infinite loop and completes each function module in sequence.

M402: Complete the infrared communication processing with the handheld device, and complete the configuration of the transmitter's working parameters according to the user's requirements, so that the transmitter can be used alone without Modbus/RS485 networking.

M403: realize the Chinese man-machine interface, display the measurement data or set the working parameters according to the working status of the transmitter.

M404: Complete the data acquisition of the analog sensor, first read the on-chip ADC output, and then convert it into measurement data according to the configured working parameters.

M405: Complete I ² C communication processing, save the measurement data of the smart sensor.

M406: Complete the communication processing of Modbus/RS485, send the measurement data, and perform external Flash backup of the measurement data. The 240KB data storage area of the external Flash is composed of ring data tables in succession to realize the backup of the latest data, which is convenient for the handheld operator to read Or the host computer reads historical data through the Modbus/RS485 network.

M407: Change the measurement data into 4~20mA analog output through the on-chip DAC, and at the same time carry out alarm processing and corresponding relay output according to the set alarm parameters (including multi-sensor linkage), and then enter the next cycle.

The above-mentioned embodiment is a preferred embodiment of the present invention, but the embodiment of the present invention is not limited by the above-mentioned embodiment, and any other changes, modifications, substitutions, combinations, Simplifications should be equivalent replacement methods, and all are included in the protection scope of the present invention.

Claims (10)

1. it is based on i²The networking transmitter of c is it is characterised in that include microcontroller circuit, human-computer interaction module, transmitter electricity Source circuit, probe power circuit, i²C telecommunication circuit, analog input circuit, 4～20ma signal output apparatus, relay output Circuit, modbus/rs485 telecommunication circuit and connecting terminal block, wherein external analog sensors and there is i²The intelligence of c interface passes Sensor is connected with networking transmitter by connecting terminal block, and connecting terminal block is also connected with 24v power line, relay output simultaneously Line, 4～20ma holding wire and modbus/rs485 order wire；Described probe power circuit is used in microcontroller circuit control The lower voltage exporting required for each intelligence sensor, i²C telecommunication circuit passes through i²C bus is connected with external smart sensor；

Described have i²Between the intelligence sensor of c interface and networking transmitter adopt ntssp agreement, described ntssp agreement by Physical layer, data link layer and application layer composition, the physical layer data link layer of ntssp and i²C standard is consistent, ntssp's Data link layer, only with slave receiver and two kinds of mechanism of master transmitter, is i²C data link layer Subset, need in communication process send data when be changed into master transmitter pattern, be changed into slave after having sent Receiver pattern, waits data receiver；Ntssp protocol synthesis applies transmitter broadcast communication mode, request-reply communication Pattern and distribution subscription communication pattern；Application layer in described ntssp agreement, its packet structure is as follows: address, function number, Data length, variable name, variable value and check code, wherein function number are used for representing the function of packet, different function number Represent application ntssp address, distribution ntssp address, read request data, write request data respectively, subscribe to data, issue data.

2. according to claim 1 based on i²The networking transmitter of c is it is characterised in that in described microcontroller circuit Microcontroller adopts stm32l151r8t6 single-chip microcomputer, and transmitter running parameter is saved in the eeprom within single-chip microcomputer, monolithic The external flash memory of machine.

3. according to claim 1 based on i²The networking transmitter of c it is characterised in that described networking transmitter except Binding post is exclusive, and other all circuit are all sealed in explosion-proof metal shell, and explosion-proof metal shell arranges several grommet, becomes The connecting line within device is sent to connect connecting terminal block by grommet, grommet is by sealant sealing；

The head of described explosion-proof metal shell is using transparent with machine glass.

4. according to claim 1 based on i²The networking transmitter of c is it is characterised in that described human-computer interaction module includes Manual operator infrared interface circuit and LCD MODULE, manual operator infrared interface circuit and LCD MODULE respectively with microcontroller Device circuit connects；

Described manual operator infrared interface circuit includes uart and irda transceiver, for receiving the operational order data of manual operator Input；

Described LCD MODULE includes the dot matrix black-and-white crystal screen with led backlight.

5. according to claim 4 based on i²The networking transmitter of c is it is characterised in that described transmitter power circuit leads to Cross connecting terminal block to be connected with outside 24v power supply, transmitter power circuit includes dc/dc transducer and ldo manostat, dc/ It is 5v that dc transducer is used for 24v Power convert, and it is 3.3v power supply that ldo manostat is used for 5v Power convert, transmitter power supply The 5v power supply of circuit output be used for for LCD MODULE and outputting circuit for relay work, 3.3v power supply be used for for transmitter its Its circuit work.

6. according to claim 1 based on i²The networking transmitter of c is it is characterised in that described probe power circuit bag Include dc/dc forward path circuit, analog feedback circuit, voltage adder circuit and working sensor power measurement circuit, wherein dc/ Dc forward path circuit is added with voltage for 24v input voltage is changed into the running voltage needed for sensor, analog feedback circuit Method circuit connected in series, analog feedback circuit gathers output signal, voltage adder circuit one end and the micro-control of dc/dc forward path circuit Device circuit processed is connected, for receiving the feedback control signal that microcontroller circuit sends, the other end and dc/dc forward path circuit It is connected；Working sensor power measurement circuit is used for for the output signal of dc/dc forward path circuit being sent to microcontroller electricity Road.

7. according to claim 6 based on i²The networking transmitter of c is it is characterised in that described analog feedback circuit and biography Sense device working power measurement circuit is resistor voltage divider circuit；

Described i²C telecommunication circuit includes two i²C bus pull-up resistor.

8. a kind of based on described in claim 1 based on i²The Realization Method of Communication of the networking transmitter of c is it is characterised in that wrap Include step:

(1) there is i²After electricity on the intelligence sensor of c interface, according to ntssp agreement, first sending ntssp address to transmitter please Ask；Described ntssp agreement is made up of physical layer, data link layer and application layer, the physical layer data link layer of ntssp with i²C standard is consistent, and the data link layer of ntssp is only with slave receiver and two kinds of machines of master transmitter System, is i²The subset of c data link layer, needs to be changed into master transmitter mould when sending data in communication process Formula, is changed into slavereceiver pattern after having sent, wait data receiver；It is logical that ntssp protocol synthesis applies transmitter broadcast Letter pattern, request-reply communication pattern and distribution subscription communication pattern；Application layer in described ntssp agreement, its packet Structure is as follows: address, function number, data length, variable name, variable value and check code, wherein function number are used for representing data The function of bag, different functions number represents application ntssp address, distribution ntssp address, read request data, write request number respectively According to, subscribe to data, issue data；

(2) transmitter carries out intelligence sensor id according to intelligence sensor information table and registers and select unappropriated ntssp address, Then pass through the ntssp address that broadcast mode sends distribution to this No. id intelligence sensor；

(3) intelligence sensor is reported oneself running parameter, measurement parameter to transmitter by this ntssp address；

(4), after transmitter has registered the property parameters of intelligence sensor, transmitter adopts subscribing mode to set intelligence sensor Running parameter；

(5) intelligence sensor works according to these running parameters, and using release model active to transmitter reporting measurements and Alarm condition.

9. Realization Method of Communication according to claim 8 is it is characterised in that in intelligence sensor normal work, pick-up 24v input voltage is changed into the running voltage needed for sensor by the dc/dc forward path circuit in probe power circuit in device, It is input in voltage adder circuit after the output signal of analog feedback circuit collection dc/dc forward path circuit, sensor simultaneously The output signal that working power measuring circuit also gathers dc/dc forward path circuit sends signal to microcontroller circuit, micro- Controller circuitry asks for voltage difference according to the setting value of intelligence sensor running voltage, current measured value, will be defeated for this voltage difference Enter in voltage adder circuit, voltage adder circuit is according to this voltage difference, current measured value output feedback signal to before dc/dc To channel circuit.

10. Realization Method of Communication according to claim 8 is it is characterised in that in described step (5), in intelligence sensor During to transmitter reporting measurements and alarm condition, i in transmitter²C is received as address coupling to interrupt receiving, specific as follows:

(5-1) have no progeny in occurring, the packet receiving is stored temporarily in input block, data amount check enumerator simultaneously Plus 1；

(5-2) byte of the data length in packet is compared with data amount check enumerator, judges whether packet is tied Bundle, if terminated, execution step (5-3), otherwise, execution step (5-7)；

(5-3) calculate the check code of packet；

(5-4) judge whether check code is correct, if correctly, execution step (5-5)；If incorrect, this reception is invalid, holds Row step (5-6)；

(5-5) current data packet is saved in the reception relief area of transmitter, packet is processed, carry out data simultaneously Number counter O reset, prepares next packet and receives；Execution step (5-7)；

(5-6) data amount check counter O reset；Execution step (5-7)；

(5-7) interrupt returning.