A system including a programmable logic controller control data generation device, a PLC including a function block and a control object device, the PLC control data generation device comprising: a setting data generator configured to generate a setting data file that is to be referred to by the function block in the PLC; and a transmitter configured to transmit the setting data file generated by the setting data generator to the PLC, wherein: the setting data file generated by the setting data generator is usable by the FB that is configured to change an operation setting value of the control object device controlled by the PLC, the FB is configured to transmit the setting data file to the control object device, and the control object device is configured to rewrite the operation setting value of the control object device based on the setting data file, characterized in that the FB is configured to change the operation setting value during actual operation of the control object device controlled by the PLC, the setting data generator comprises a display input controller that is configured to display at least one item in the setting data file on a display screen and to control setting of a value of the item by input from a user, the control object device is an IO-Link device, the setting data generator further comprises an Input-Output Device Description (IODD) file acquisition processor configured to acquire, from an outside, an IODD file which is related to the control object device and in which, for each functional item of the control object device, a value settable for that functional item and a default operation setting value for that functional item are indicated, and the display input controller is further configured to produce the setting data file from the IODD file acquired by the file acquisition processor based on the input from the user. a setting data generator configured to generate a setting data file that is to be referred to by the function block in the PLC; and a transmitter configured to transmit the setting data file generated by the setting data generator to the PLC, the setting data file generated by the setting data generator is usable by the FB that is configured to change an operation setting value of the control object device controlled by the PLC, the FB is configured to transmit the setting data file to the control object device, and the control object device is configured to rewrite the operation setting value of the control object device based on the setting data file, characterized in that the FB is configured to change the operation setting value during actual operation of the control object device controlled by the PLC, the setting data generator comprises a display input controller that is configured to display at least one item in the setting data file on a display screen and to control setting of a value of the item by input from a user, the control object device is an IO-Link device, the setting data generator further comprises an Input-Output Device Description (IODD) file acquisition processor configured to acquire, from an outside, an IODD file which is related to the control object device and in which, for each functional item of the control object device, a value settable for that functional item and a default operation setting value for that functional item are indicated, and the display input controller is further configured to produce the setting data file from the IODD file acquired by the file acquisition processor based on the input from the user.