The correct usage method of SJ-210 Sanfeng roughness meter: When measuring the surface roughness of the workpiece, the sensor is placed on the measured surface of the workpiece, and the internal driving mechanism of the instrument drives the sensor to slide along the measured surface at a constant speed. The sensor senses the roughness of the measured surface through the built-in sharp stylus. At this time, the roughness of the measured surface of the workpiece causes displacement of the stylus, which changes the inductance of the sensor inductor coil. As a result, an analog signal proportional to the roughness of the measured surface is generated at the output end of the phase-sensitive rectifier. After amplification and level conversion, the signal enters the data acquisition system, and the DSP chip performs digital filtering and parameter calculation on the collected data. The measurement results of SJ-210 Sanfeng roughness meter are displayed in the LCD. It can be read on the monitor, output on the printer, and communicate with a PC.