Hydrolab HL4 is a new generation multi parameter water quality analyzer launched by OTT Hydromet company. Compared to the DS5 series analyzer, the Yu DS5 series analyzer is more compact and can be seen as a compact version of the DS5 series sensor. It can monitor pH, temperature ORP、 Conductivity, dissolved oxygen, turbidity, and depth are seven common parameters. Meet the requirement of HL4 to connect with ADCON's RTU through SDI12 protocol, and meet the online monitoring of water quality for different water bodies such as surface water, groundwater, source water, drinking water, sewage discharge outlets, and oceans.