The Digital RS485 suspended solid sensor is based on the infrared absorption scattered light method and combined with the application of ISO7027 method, can guarantee the continuous and accurate detection of suspended solids and sludge concentration. Based on ISO7027, infrared double scattering light technology will not be affected by chroma for the measurement of suspended solids and sludge concentration value. According to the usage environment, self-cleaning function can be equipped with. It assures the stability of data and reliability of performance; with the built-in self-diagnosis function, it can make sure the accurate data be delivered; besides, the installation and calibration is quite simple. The product is widely used in sewage plant, water plant, water station, surface water, farming, industry and other fields.