| Level detection technology plays an important role in the process control of the chemical industry.The commonly used level measurement methods include static pressure type,buoyancy type,electric type,acoustic type and ray type,which are widely used in various fields of chemical production.This project designs a multi-protocol digital RF admittance level meter,which is developed on the basis of capacitive level meter and combined with RF admittance technology,which can effectively solve the problem of false level interference caused by electrode hanging material in chemical production.The level meter is composed of two parts: a detection module and a transmitter.The detection module detects the level signal in the chemical tank,the sinusoidal signal generation circuit generates a high frequency signal of 100 KHz,and is sent to a bridge circuit formed by the probe and the isolation coil,and the signal is amplified and chopped integration to obtain the voltage signal,and after V-I conversion,the current signal proportional to the level is output;the transmitter receives the current signal outputted by the detection module,after I-V conversion,send it to 24 bit high precision AD,it is sent to the ARM processor for data processing.The transmitter has a liquid crystal display module and a matrix keyboard module,which realizes multi-level menu function,which can perform parameter setting,linear calibration and local display.It has a 4-20 mA standard current output interface,after calibration outputs a current signal linearly related to the level.It also has an Ethernet communication interface,from which the collected level data can be sent to the remote server.There are still some shortcomings in this topic.The Hart protocol has done some theoretical research.The protocol transplantation function is incomplete,the function menu needs to be strengthened,and the robustness of the program needs to be improved.It needs to be further improved in the future. |
