Design Of A Portable Non-paper Recorder For The Cooling System

The collection,recording and analysis of the data from industrial field takes a very important place in a control system.The old recorders usually use paper-axis driven by special mechanism,with marker on paper.The disadvantage that the accuracy was low,the response was slow,and the data was not easy to keep is obvious.The system uses "Data Acquisition - Mass Storage - Wireless Communication" option to achieve industrial data records,and it is of flexible operation,high accuracy,high speed and convenience of data analysis.It has been used in large cooling systems.The system uses the STM32 microcontrollers with the ARM Cortex-M3 core.It is divided into analog acquisition module,digital acquisition module and the main control module.In addition to main control module,the acquisition module can be achieved flexibly combined and expanded.The digital acquisition module uses STM32 on-chip pulse input capture unit,and the analog acquisition module uses STM32 on-chip 12-bit A/D converter.In the process channel of the system,digital signal through the isolation circuit and plastic circuit craters the pulse capture unit of the microcontroller for the frequency measurement,and the analog signal through the signal conversion circuit and amplification circuit enters the microcontroller's A/D conversion device.Meanwhile,the analog signal acquisition module is also designed to achieve cold junction compensation and linearization for the thermocouple sensor with nonlinear signal.The mass storage function of the system is implemented by SD card and FAT file system. SD Card is a large-capacity storage medium based on FLASH memory technology,with high speed in the large amount of data read and written,which is fit for large amounts of data acquisition systems.FAT file system ensure that the data collected is written to the specified file which can be read and processed by the host computer software.Communication betwecn the main control module and the host computer uses wireless communication manner,in which nRF2401 single wireless communication chip is selected.It transmits the command and data down to the main control module through the serial communication control to set the argument of the acquisition module.To sum up,the system gets high accuracy.It can works in large industrial cooling systems.