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根据远程网络应用环境下的温度测量需求,设计出一种基于以太网的远程多通道高精度温度数据采集系统。系统由下位机和远程主机构成,下位机硬件主要由温度传感器PT1000、仪用放大器INA128构成的调理电路、A/D转换器Max1300、32位微控器PIC32MX795以及物理网卡芯片构成,上位机为远程PC机。在恒流源的激励下,PT100电压的变化依赖温度的变化,经信号调理、16bitA/D转换后由PIC32MX795求解出高次方程的数值根即温度值,然后通过以太网发送给远程主机进行处理。系统充分利用PIC32MX795的计算性能,利用牛顿法直接寻找高次方程的数值根即为温度值,其测量精度优于0.1℃。系统长期工作稳定。
According to the demand of temperature measurement in the remote network application environment, a remote multi-channel high-precision temperature data acquisition system based on Ethernet is designed. The system consists of a lower computer and a remote host computer. The hardware of the lower computer is mainly composed of the temperature sensor PT1000 and the instrumentation amplifier INA128 conditioning circuit, the A / D converter Max1300, the 32-bit microcontroller PIC32MX795 and the physical network card chip. The host computer is a remote PC machine. Under the excitation of constant current source, the change of PT100 voltage depends on the change of temperature. After signal conditioning, 16-bit A / D conversion, PIC32MX795 solves the value root of the high-order equation, which is then sent to the remote host through Ethernet . The system takes full advantage of the computational performance of the PIC32MX795. Using Newton’s method, the numerical root of the higher-order equation is directly searched for the temperature value, and the measurement accuracy is better than 0.1 ° C. Long-term system stability.