Control system having isolated user computing unit and control method therefor

A control system having an isolated user computing unit, comprising:

• a user computing unit including a first central processing unit (CPU) and peripheral circuits, and configured to execute a control program for controlling a device to be controlled using input information received from the device to be controlled to generate control information;
• a security computing unit including a second CPU and peripheral circuits, and configured to generate system check information using the input information received from the device to be controlled, a control program, system state information, and the control information provided from the user computing unit, compare the system check information with system state determination standard information, output the control information to the device to be controlled when it is determined that an operation state of the device to be controlled is within a normal range, and take a security action when it is determined that the operation state of the device to be controlled is out of the normal range;
• and
• a control input/output unit connected to the device to be controlled,
• wherein the control input/output unit is connected only to the security computing unit, and the input information is read by the security computing unit from the control input/output unit and provided to the user computing unit.