To provide a system and a method of control capable of reducing the number of data signal lines between a higher order control device and a lower order control device and also capable of simplifying communication procedures.

The system comprises a lower order control device 103 having plural rotary encoders 113-1 to 113-6 to detect position data, time information and temperature information of controlled targets and a higher order control device 101 to be connected to the device 103 via a data signal line 151 and to control the device 103, and so detected data is transmitted in series by a send/receive means 111 of the device 103 that the numbers is allowed to be reduced and also the communication procedures are allowed to be simplified between the device 101 and the device 103 in no need of address settings for each encoder 113-1 to 113-6 because of broadcasting at every period.