Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrat...Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.展开更多
该文设计了一种高精度4~20 m A恒流输出和检测系统。由STM32控制电流环数模转换芯片DAC161和模数采样芯片ADS1246来完成设计,电流输出采用单线隔离通讯方式,软件算法采用卡尔曼滤波技术来提高采集精度,充分利用STM32的DMA数据传输技术...该文设计了一种高精度4~20 m A恒流输出和检测系统。由STM32控制电流环数模转换芯片DAC161和模数采样芯片ADS1246来完成设计,电流输出采用单线隔离通讯方式,软件算法采用卡尔曼滤波技术来提高采集精度,充分利用STM32的DMA数据传输技术快速处理采集数据。此外通过电源控制、环路检测以及自动休眠等方法降低系统功耗。经测试,此便携式恒流源能够模拟恒流输出、电流输出和检测精度高,且系统功耗低。展开更多
文摘Instrument calibration is vital to a successful control system because signal inputs to the system controllers come from such instruments. This paper presents a method for actualizing a standard low-cost loop calibrator for the famous 4-20 mA electrical signaling scheme. The loop calibrator generates a linear current signal from 4 to 20 mA over a 250 ? typical process instrument load for calibration. The realization of the loop calibrator relies on a voltage-to-current converter to build a constant current source. The voltage controlled constant current source is built from discrete components and an op-amp to keep the cost low. Results from simulations and the prototype demonstrate the performance of the 4-20 mA loop calibrator which utilizes a greatly reduced number of components. The cost of these components is approximately 34% of the least expensive calibrator sampled, though other production costs are not included. This conclusion reinforces the fact that loop calibrators can be cheaper.
文摘该文设计了一种高精度4~20 m A恒流输出和检测系统。由STM32控制电流环数模转换芯片DAC161和模数采样芯片ADS1246来完成设计,电流输出采用单线隔离通讯方式,软件算法采用卡尔曼滤波技术来提高采集精度,充分利用STM32的DMA数据传输技术快速处理采集数据。此外通过电源控制、环路检测以及自动休眠等方法降低系统功耗。经测试,此便携式恒流源能够模拟恒流输出、电流输出和检测精度高,且系统功耗低。
