| 摘要 |
A 2-wire, loop-powered shaft rotational speed sensor device that outputs a 4-20 mA current in response to the shaft rotational speed. The device is comprised of a sensor (e.g., magnetic, optical) that senses an output from a sensor disk (e.g., magnetic, optical) and outputs a series of voltage pulses whose frequency varies with the shaft rotational speed. A microcontroller measures this pulse frequency and generates a digital code representative of that frequency. A digital-to-analog converter generates an analog waveform in response to the digital code. A loop-powered, voltage-to-current circuit generates the output current in response to the analog waveform. |
