PURPOSE: To minimize damage on a plant, by a method wherein deviation of tracking during failure in operation of a tracking device is adjusted to zero, and regarding an item, which is to be backup-outputted even if its preset timing pasts, preset output is practicable.
CONSTITUTION: When a tracking device is brought into a trouble state, a trouble signal is outputted to a moving amount measuring device 10. When the device 4 is in a normal operating condition, the device 10 outputs a moving amount of a steel strip to the device 4 at a specified period, but during failure in operation, counting of pulses from a pulse generating circuit 6 are accumulated until the device is recovered from the failure in operation. The moving amount of the steel strip during failure in operation is neither calculated nor outputted to the device 4 before a trouble recovery signal is inputted. The device 4 searches a preset tape, and regarding an item, the preset timing of which pasts, starting is applied on a preset value calculating device 7 in relation to an unset item out of items which are within an allowable range set at each preset item, and after a preset value is calculated, the result is outputted to a set device 8.
SUZUKI YASUYUKI
TOGASHI NOBUYUKI
