As a metering device, prepaid meters are widely used in energy fields such as water, electricity, gas, and heat, and the characteristics of paying first and using later effectively solve the problem of difficult charging. The STS (Standard Transfer Specification) standard transmission specification is currently the only globally recognized open standard for prepaid systems. The STS Association was officially established in 1997 and standardized to IEC62055 by the International Electrotechnical Commission in 2005. The association is mainly responsible for the formulation of technical standards and the maintenance of the standard system of STS prepaid meters, and promotes the international development of technology.