A method for transmitting a program and parameter to a programmable logic controller, PLC which method is for use in an adapter, the method comprising the steps of: the adapter establishing a connection with the PLC and a connection with a mobile terminal; the adapter reading a state of the PLC from the PLC; the adapter converting data on the state of the PLC into data that a dedicated application program on the mobile terminal is capable of recognizing and transmitting the data that the dedicated application program is capable of recognizing to the mobile terminal; the adapter receiving a program and/or parameter that the mobile terminal has downloaded from a cloud server and that corresponds to the state of the PLC; and the adapter converting the program and/or parameter into data that conforms to a communications protocol exclusive to the PLC and transmitting to the PLC the data that conforms to the communications protocol exclusive to the PLC, the establishing of the connection with the PLC by the adapter including: detecting whether a port and protocol have been set; in a case where the port and protocol have been set, establishing a wired connection with the PLC on a basis of the port and protocol set; and in a case where the port and protocol have not been set, selecting a protocol from a protocol list stored in advance, selecting a port from a port list stored in advance, selecting a port setting from a port setting list stored in advance, and establishing a wired connection with the PLC with use of the protocol selected, the port selected, and the port setting selected. the adapter establishing a connection with the PLC and a connection with a mobile terminal; the adapter reading a state of the PLC from the PLC; the adapter converting data on the state of the PLC into data that a dedicated application program on the mobile terminal is capable of recognizing and transmitting the data that the dedicated application program is capable of recognizing to the mobile terminal; the adapter receiving a program and/or parameter that the mobile terminal has downloaded from a cloud server and that corresponds to the state of the PLC; and the adapter converting the program and/or parameter into data that conforms to a communications protocol exclusive to the PLC and transmitting to the PLC the data that conforms to the communications protocol exclusive to the PLC, the establishing of the connection with the PLC by the adapter including: detecting whether a port and protocol have been set; in a case where the port and protocol have been set, establishing a wired connection with the PLC on a basis of the port and protocol set; and in a case where the port and protocol have not been set, selecting a protocol from a protocol list stored in advance, selecting a port from a port list stored in advance, selecting a port setting from a port setting list stored in advance, and establishing a wired connection with the PLC with use of the protocol selected, the port selected, and the port setting selected. detecting whether a port and protocol have been set; in a case where the port and protocol have been set, establishing a wired connection with the PLC on a basis of the port and protocol set; and in a case where the port and protocol have not been set, selecting a protocol from a protocol list stored in advance, selecting a port from a port list stored in advance, selecting a port setting from a port setting list stored in advance, and establishing a wired connection with the PLC with use of the protocol selected, the port selected, and the port setting selected.