Abstract: Even in a case where a master-CPU of an image forming section and a slave-CPU of a sheet transportation section are driven by respective oscillation circuits with different oscillation accuracies, a large difference in accuracy is not caused in transfer sheet transportation speed driven by clock signals formed by the respective oscillation circuits. In the master-CPU and the slave-CPU that are cascadingly connected to each other, in order to calculate a clock frequency of an oscillation circuit of the target-CPU, a predetermined time transmitted from the other CPU connected to the target-CPU is counted by the clock signal of the target-CPU. With reference to the predetermined time, an operating process, such as division of an acquired counter value by the predetermined time, acquires an error of the clock frequency of the oscillation circuit driving the slave-CPU, and corrects the error, thereby improving the accuracy thereof.

Abstract: Even in a case where a master-CPU of an image forming section and a slave-CPU of a sheet transportation section are driven by respective oscillation circuits with different oscillation accuracies, a large difference in accuracy is not caused in transfer sheet transportation speed driven by clock signals formed by the respective oscillation circuits. In the master-CPU and the slave-CPU that are cascadingly connected to each other, in order to calculate a clock frequency of an oscillation circuit of the target-CPU, a predetermined time transmitted from the other CPU connected to the target-CPU is counted by the clock signal of the target-CPU. With reference to the predetermined time, an operating process, such as division of an acquired counter value by the predetermined time, acquires an error of the clock frequency of the oscillation circuit driving the slave-CPU, and corrects the error, thereby improving the accuracy thereof.