Display of transaction error code 057 indicates that the transaction failed and the transaction was automatically terminated by the system. This situation mainly occurs in the use of pos machines. The main reasons include too many password errors, system maintenance, below the minimum limit, over-limit credit card swiping or intraday trading. POS(Pointofsales), which means "point of sale" in Chinese, is called point of sale information management system. It is a terminal reader equipped with bar code or OCR code technology, which has the function of cashier in cash or barter bank. Its main task is to provide data services and management functions for commodity and media transactions, and to carry out non-cash settlement. POS is a multifunctional terminal. It can be installed in special merchants and acceptance outlets of credit cards, and connected with computers to realize automatic transfer of electronic funds. It has the functions of supporting consumption, pre-authorization, balance inquiry and transfer, and is safe, fast and reliable to use.