1. A programmable logic controller (PLC) system connected to a memory card, wherein the PLC system comprises: a data log module, which when executed by a microprocessor in the PLC system, executes a data log function execution mode; a web server module, which when executed by the microprocessor, executes a web server function execution mode; and a file system, which when executed by the microprocessor, controls the memory card to be divided into a plurality of regions corresponding to a plurality of functions, respectively, when the file system is initialized, wherein the plurality of regions obtained through the division comprises: a first storage region storing log data of the PLC system; and a second storage region storing a hyper text markup language (HTML) file, wherein the file system is configured to: transmit the log data to store the log data into the first storage region of the memory card when the data log function execution mode is sensed, and read the HTML file from the second storage region of the memory card when the web server function execution mode is sensed.