Today, I will introduce a national invention authorized patent-a temperature transmitter. The patent was applied by Fujian Shunchang Hongrun Precision Instrument Co., Ltd., and was granted an authorization announcement on June 1, 2018.
Description of contentThe invention relates to the field of industrial data collection and transmission output, in particular to a temperature transmitter.
Background of the inventionAs a kind of temperature signal conversion instrument, the temperature transmitter is installed in the primary instrument shell at the top of the temperature sensor. It is mainly used to receive the temperature signal collected by the temperature sensor and convert the temperature signal collected by the temperature sensor into a standard analog signal such as 4 -20mA signal. The temperature sensor and the temperature transmitter fixed at the top mostly work in a high temperature environment, and it is generally difficult for the operator to get close, which brings great trouble to the later debugging work, and most of the existing temperature transmitters use the temperature sensor The bridge sampling circuit is composed of, but the bridge sampling circuit is not related to other signal sampling circuits. Therefore, the bridge sampling circuit of the temperature transmitter cannot achieve the access of multiple signals, and the single signal can be accessed. The temperature signal of the temperature transmitter is easily interfered by strong industrial electricity, which eventually causes the measured temperature to deviate or jump.
Summary of the inventionThe purpose of the invention is to provide a temperature transmitter.
The figure is a functional block diagram of the present invention.
A temperature transmitter includes an acquisition circuit, an ADC analog-to-digital conversion circuit, a photoelectric isolation circuit, a room temperature detection circuit, a processor, a 4-20mA loop current circuit, and a HART communication circuit. The acquisition circuit is a voltage-dividing acquisition circuit and an acquisition circuit Including temperature sensor R1 and grounding resistance R2 connected in series, the free end of temperature sensor R1 is connected to a fixed voltage, the intermediate point voltage of temperature sensor R1 and grounding resistance R2 is used as the output voltage of the acquisition circuit, and the voltage-divided acquisition circuit is sequentially converted to ADC Circuit, photoelectric isolation circuit communication connection, photoelectric isolation circuit, room temperature detection circuit and 4-20mA loop current circuit are all connected to the processor communication, HART communication circuit and processor bidirectional communication connection, 4-20mA loop current circuit is also connected to HART The communication circuit is connected to form a circuit loop.
Among them: the acquisition circuit is used to convert the temperature sensor's induction value that changes with temperature into a voltage value; the ADC analog-to-digital conversion circuit is used to convert the analog signal of the voltage value collected by the acquisition circuit into a digital signal; the photoelectric isolation circuit is used to The digital signal output from the ADC analog-to-digital conversion circuit is isolated and transmitted to reduce interference signals; the room temperature detection circuit is used to detect the ambient temperature signal at the connection point of the temperature sensor. When the temperature sensor is a thermocouple, it is used as the cold junction compensation temperature value of the thermocouple , Used in the calculation of the final temperature value; the processor is used to receive the signal sent by the photoelectric isolation circuit and the room temperature detection circuit and perform calculation processing, and send related signals to the 4-20mA loop current circuit according to the calculation result. The external equipment communicates; the 4-20mA loop current circuit receives the relevant signal sent by the processor and converts the relevant signal into an analog signal to generate a loop current signal that changes linearly with the detected temperature change within 4-20mA, And the loop current signal flows through HART communication circuit; HART communication circuit is used to loop 4-20mA Loop current circuit generates the signaling flow out, and to realize mutual transmission between the processor and an external device a digital signal.
The temperature transmitter according to the present invention has the following advantages: 1) The acquisition circuit uses a voltage-dividing acquisition circuit, which has a simple structure, and compared with the bridge acquisition circuit, because the voltage at the free end of the temperature sensor R1 is fixed, the thermocouple signal and heat The resistance signals can all share the fixed voltage. Therefore, the present invention has a shared resource of different signals, which can support the access of more signals; 2) A room temperature detection circuit is provided to constantly detect the ambient temperature signal at the connection point of the temperature sensor. When the connected temperature sensor is a thermocouple, it is used as the cold junction compensation temperature of the thermocouple. The ambient temperature value detected by the room temperature detection circuit is used in the calculation of the final temperature value. When the connected temperature sensor is a thermal resistance, the room temperature detection The ambient temperature value detected by the circuit will not be used by the processor in the calculation of the final temperature value. Compared with the existing room temperature detection circuit, the temperature sensor can only be a thermal resistance temperature transmitter. The temperature sensor can be a thermal resistance, a thermocouple, or a linear resistance used to measure the liquid level, so it can adapt to more different signals Access; 3) A HART communication circuit is set up, which can communicate with external devices through the HART communication circuit, so that remote debugging can be carried out to modify parameters, and at the same time, the loop current generated on the 4-20mA loop current circuit can be The signal (that is, the signal representing the final temperature value) is transmitted. In this way, the embarrassment that the existing temperature transmitter cannot be scheduled online and can only be read at close range is avoided, and the detection work, especially the later debugging work, is more convenient; 4) There is a temperature transmitter, a photoelectric isolation circuit is added to strengthen the anti-interference ability, weaken the industrial strong electrical interference, and make the final detected temperature value more accurate.
Thick Film Resistor is one of the fixed resistors made of thick film, which with the max working voltage up to 45KV and the max related power up to 50W.
Thick Film Resistor,Hv Thick Film Resistor, High Power Resistor, High Voltage Tubular Resistor
XIAN STATE IMPORT & EXPORT CORP. , https://www.shvcomponents.com