PURPOSE: To easily change or manage control data inherent in each programmable controller(PC) in a system constituted of linking data among plural slave station PCs and one main PC.

CONSTITUTION: A ladder program for each of plural slave stations includes a common ladder describing data inherent in each slave station as a parameter and an operation data table 11 for storing inherent data to be applied to the parameter of a common ladder and a monitor data table 12 are set up in a register area 20 in a main PC through a computer. At the time of turning on a power supply, corresponding data table parts in these tables 11, 12 are transferred to a corresponding slave station, which enters data tables (e.g. data tables 111, 121 for a slave station PC 1) for the slave station itself and applies the tables to the parameter of its command ladder.