CN202994311U

CN202994311U - RS-485-bus-based wireless temperature sensor

Info

Publication number: CN202994311U
Application number: CN 201220641116
Authority: CN
Inventors: 王雨秋; 李志鑫; 张振超; 许士锦; 王博; 杨德玉; 祁俊雄; 邓朝晖
Original assignee: North China Electric Power University
Current assignee: North China Electric Power University
Priority date: 2012-11-29
Filing date: 2012-11-29
Publication date: 2013-06-12
Anticipated expiration: 2022-11-29

Abstract

The utility model discloses a RS-485-bus-based wireless temperature sensor. The RS-485-bus-based wireless temperature sensor comprises a temperature sensor, a transmission module composed of a first single-chip microcomputer and a wireless transmitter, a reception module composed of a wireless receiver and a second single-chip microcomputer, and an RS485 interface circuit, wherein the temperature sensor converts a detected temperature signal into an electric signal and transmits the electric signal to the first single-chip microcomputer, the first single-chip microcomputer transmits the electric signal to the second single-chip microcomputer sequentially via the wireless transmitter and the wireless receiver, and an output terminal of the second single-chip microcomputer is connected to an RS485RS232 converter at a PC terminal through the RS485 interface circuit. According to the utility model, the RS-485 bus technology is used to realize the long-distance arrangement of the sensor, improving the transmission distance and the communication capacity and providing convenience for people to obtain and analyze signals at a remote position. The RS-485-bus-based wireless temperature sensor can be used for the temperature measurement of electric contacts, such as contacts and busbars, of high-voltage equipment, such as high-voltage switch cabinets, transformers, and high-voltage cables.

Description

A kind of radio temperature sensor based on the RS-485 bus

Technical field

The utility model relates to a kind of temperature sensor, and is especially a kind of based on RS-485 bus radio temperature sensor.

Background technology

Along with TT﹠C system robotization, intelligentized development, require sensor to have more accuracy and the reliability of Gao Gengqiang, and possess certain data-handling capacity, can self check, self-correcting, self compensation.But traditional sensor can't satisfy these requirements.Existing sensor technology progressively develops into the more powerful intelligence sensor of function in conjunction with singlechip technology, Digital Signal Processing and ICT (information and communication technology).Only with RS-232 interface, the transmission range maximum also only has 20 meters due to PC, long Distance Transmission that can't settling signal.

The utility model content

The technical problems to be solved in the utility model is that a kind of radio temperature sensor based on the RS-485 bus that can realize the temperature signal long-distance transmissions is provided.

For solving the problems of the technologies described above, technical solution adopted in the utility model is:

A kind of radio temperature sensor based on the RS-485 bus, the sending module that comprises temperature sensor, formed by the first single-chip microcomputer and wireless launcher, the receiver module and the RS485 interface circuit that are formed by wireless receiver and second singlechip; Described temperature sensor is sent to the first single-chip microcomputer after converting the temperature signal that detects to electric signal, the first single-chip microcomputer is sent to second singlechip through wireless launcher, wireless receiver successively with this electric signal, and the output terminal of second singlechip is connected to the RS485/RS232 converter of PC end by the RS485 interface circuit.

Wherein, described temperature sensor is monolithic temperature integrated circuit LM92CIM.

Wherein, the circuit structure of described sending module and receiver module is identical, and wherein, the first single-chip microcomputer and second singlechip all adopt AT89C2051, and radio transmitters and wireless receiver all adopt radio transmitting and receiving chip nRF403; The data input/output line SDA of monolithic temperature integrated circuit LM92CIM, serial clock signal line SCL, excess temperature interrupt INT are connected with P1.4, P1.5, the P3.2 of single chip computer AT 89C2051 respectively; The digital signal input Din of radio transmitting and receiving chip nRF403, digital signal output Dout, frequency select Freq, transmitting-receiving to enable Txen, power switch is controlled Pwr_up and is connected with P3.1, P3.0, P3.3, P3.4, the P3.5 of single chip computer AT 89C2051 respectively.

Wherein, described 485 interface circuits adopt the MAX485 chip; The RO of MAX485 chip and DI end is connected with TXD with the RXD of second singlechip AT89C2051 respectively, the MAX485 chip /RE is connected with DE and connects afterwards and be connected with the P1.7 of second singlechip AT89C2051.

The beneficial effect that adopts technique scheme to produce is:

The utility model is on the basis of existing sensor, adopt the RS-485 bussing technique, realized the remote layout of sensor, improved transmission range and communication capacity, maximum transmission distance can reach 3000 meters, is easy to people and obtains a long way off signal and make analyzing and processing.Also adopt simultaneously balance to send and difference acceptance, can suppress the common mode interference ability, not only can effectively solve the transmission range of signal, and improved the transfer efficiency of signal and save cost, realized the intellectuality of sensor.The utility model can be used for the temperature detection of the electric contacts such as the contact, busbar of the high-tension apparatuses such as high-tension switch cabinet, transformer, high-tension cable.

Description of drawings

Fig. 1 is structural principle block diagram of the present utility model;

Fig. 2 is the utility model temperature detection and transtation mission circuit schematic diagram;

Fig. 3 is the utility model wireless transceiver circuit schematic diagram;

Fig. 4 is 485 interface circuit schematic diagrams of the utility model second singlechip;

Fig. 5 is the utility model RS-485/RS-232 level shifting circuit schematic diagram.

Embodiment

Below in conjunction with the drawings and specific embodiments, the utility model is described in further detail.

Be illustrated in figure 1 as structural principle block diagram of the present utility model.Of the present utility model is a kind of radio temperature sensor based on the RS-485 bus, the sending module 1 that it comprises temperature sensor, be comprised of the first single-chip microcomputer and wireless launcher, the receiver module 2 and the RS485 interface circuit that are comprised of wireless receiver and second singlechip; Temperature sensor is sent to the first single-chip microcomputer after converting the temperature signal T that detects to electric signal, the first single-chip microcomputer is sent to second singlechip through wireless launcher, wireless receiver successively with this electric signal, and the output terminal of second singlechip is connected to the RS485/RS232 converter of PC end by the RS485 interface circuit.Described sending module 1 is identical with the circuit structure of receiver module 2, and wherein, the first single-chip microcomputer and second singlechip all adopt AT89C2051, and radio transmitters and wireless receiver all adopt radio transmitting and receiving chip nRF403.

Be illustrated in figure 2 as temperature detection of the present utility model and transtation mission circuit schematic diagram.In Fig. 2, temperature sensor U1 adopts the monolithic temperature integrated circuit LM92CIM of National Semiconductor, this chip internal comprises temperature sensor and 13 integrated A/D converters (most significant digit is-symbol position), environment temperature can be converted to the digital signal of l3 position, the excess temperature deixis is provided simultaneously, and the IC serial bus interface is provided.By LM92CIM collecting temperature signal, section carries out A/D conversion within it, with digital signal transfers to the first single-chip microcomputer U2.In Fig. 2, the data input/output line SDA of chip LM92CIM, serial clock signal line SCL, excess temperature interrupt INT are connected with P1.4, P1.5, the P3.2 of single chip computer AT 89C2051 respectively.When SCL keeps high level, SDA is from the high level to the low transition, the transmission of beginning data-signal, send into subsequently 7 of LM92CIM from address and read/write operation information: 10010A2A1 R/W, the read/write control bit is 1 o'clock, expression is to the LM92CIM read operation, and the read/write control bit is 0 o'clock, and expression is to the LM92CIM write operation; When each byte transmits end. must just can carry out next step operation after receiving the confirmation signal (ACK) of LM92CIM, send into again pointer register address and data, it is last in the situation that SCL keeps high level, when SDA is high level from low transition, stop the transmission operation of data.

Be illustrated in figure 3 as wireless transceiver circuit schematic diagram of the present utility model.In Fig. 3, nRF403 monolithic wireless receiving and dispatching one chip U3, U4 that radio transmitters and wireless receiver all adopt Norway Nordic company to produce, integrated radio-frequency transmissions, radio frequency reception in this chip, the functions such as PLL is synthetic, FSK modulation, FSK demodulation, multi-frequency switching have that peripheral components is few, a low-power consumption, the advantage such as easy to use.The digital signal input Din (9) of nRF403 chip, digital signal output Dout (10), frequency select Freq (12), transmitting-receiving to enable Txen (19), power switch is controlled Pwr_up (18) and is connected with TXD (P3.1), RXD (P3.0), P3.3, P3.4, the P3.5 of single chip computer AT 89C2051 respectively; The Anti of nRF403 chip (16) and Ant2 (15) are connected to ring-shaped P CB antenna (ANTENNA).When holding state, not receive data and transmitting data.

Be illustrated in figure 4 as 485 interface circuit figure of second singlechip.In Fig. 4, adopted MAX485 interface chip U5 to realize the RS485 interface circuit.The MAX485 chip is a kind of RS-485 chip of Maxim company, adopts single power supply+5 V work, and rated current is 300 μ A, adopts the half duplex communication mode.It completes the function that Transistor-Transistor Logic level is converted to the RS-485 level.The RO(1 pin of MAX485 chip U5) and the DI(4 pin) end meets respectively RXD and the TXD of second singlechip; MAX485 chip U5 /the RE(2 pin) and the DE(3 pin) be respectively the Enable Pin that receives and send, bipod and connect after connect the P1.7 pin of second singlechip; When/when RE was logical zero, device was in accepting state; When DE was logical one, device was in the transmission state; Side a and b is respectively the differential signal end that receives and send, and during higher than B, the data that representative sends are 1 when the level of A pin; When the level of A was held lower than B, the data that representative sends were 0.Add build-out resistor R9, the resistance of general optional 120 Ω simultaneously between A and B end.Like this, just can complete the input and output operation of relevant serial data.

Be illustrated in figure 5 as RS-485/RS-232 level shifting circuit schematic diagram.In Fig. 5, this circuit has used three photo-coupler TLP-521, has realized the electrical isolation between PC side MAX485 chip U6 and PC, has effectively suppressed interference each other, has improved the reliability of entire system work.When the RTS of RS-232 end for logic level 1 (12V) time, the light emitting diode of photoelectrical coupler is not luminous, not conducting of phototriode, output TTL logic level 1 (+5V), choose the DE end of RS-485 this moment, allow RS-485 to accept, like this, the TXD of RS-232 end just can send data (work-based logic is similar to RTS).When the RTS of RS-232 end for logical zero (+12V) time. the lumination of light emitting diode of photoelectrical coupler.Phototriode conducting, output terminal be logic level 0 (+12V), choose this moment RS-485 /RE end, allow to send.When the R of RS-485 end was output as logic level 1, the light emitting diode of photoelectrical coupler was not luminous, not conducting of phototriode, when RS-232 output stopped, its TXD level was-12V that electric capacity is charged to-12V like this, its output is also become-12V, and namely logic level 1; When its output logic level 0. the lumination of light emitting diode of photoelectrical coupler, the phototriode conducting, at this moment, it is output as+5V, also in the scope of RS-232 logic level 0, is logic level 0.

Claims

1. radio temperature sensor based on the RS-485 bus is characterized in that: the sending module (1) that comprises temperature sensor, is comprised of the first single-chip microcomputer and wireless launcher, the receiver module (2) and the RS485 interface circuit that are comprised of wireless receiver and second singlechip; Described temperature sensor is sent to the first single-chip microcomputer after converting the temperature signal that detects to electric signal, the first single-chip microcomputer is sent to second singlechip through wireless launcher, wireless receiver successively with this electric signal, and the output terminal of second singlechip is connected to the RS485/RS232 converter of PC end by the RS485 interface circuit.

2. a kind of radio temperature sensor based on the RS-485 bus according to claim 1, it is characterized in that: described temperature sensor is monolithic temperature integrated circuit LM92CIM.

3. a kind of radio temperature sensor based on the RS-485 bus according to claim 2, it is characterized in that: described sending module (1) is identical with the circuit structure of receiver module (2), wherein, the first single-chip microcomputer and second singlechip all adopt AT89C2051, and radio transmitters and wireless receiver all adopt radio transmitting and receiving chip nRF403; The data input/output line SDA of monolithic temperature integrated circuit LM92CIM, serial clock signal line SCL, excess temperature interrupt INT are connected with P1.4, P1.5, the P3.2 of single chip computer AT 89C2051 respectively; The digital signal input Din of radio transmitting and receiving chip nRF403, digital signal output Dout, frequency select Freq, transmitting-receiving to enable Txen, power switch is controlled Pwr_up and is connected with P3.1, P3.0, P3.3, P3.4, the P3.5 of single chip computer AT 89C2051 respectively.

4. a kind of radio temperature sensor based on the RS-485 bus according to claim 3, is characterized in that: described 485 interface circuits employing MAX485 chips; The RO of MAX485 chip and DI end is connected with TXD with the RXD of second singlechip AT89C2051 respectively, the MAX485 chip /RE is connected with DE and connects afterwards and be connected with the P1.7 of second singlechip AT89C2051.