Abstract: A CRUM apparatus includes a power extraction circuit that extracts power from a high value of a clock signal received from an image forming apparatus, and a control circuit activated by the power extracted by the power extraction circuit. The clock signal has high and low values alternately repeated in a first period in a data section and the high and low values alternately repeated in a second period different from the first period in a pause section. When the second period is changed to a fourth period in an idle section in which data transmission is prepared, the control circuit determines transmission and reception of a data signal to and from the image forming apparatus is to be performed at a third period different from the first period for a second data section after the idle section.

Abstract: A CRUM apparatus includes a power extraction circuit that extracts power from a high value of a clock signal received from an image forming apparatus, and a control circuit activated by the power extracted by the power extraction circuit. The clock signal has high and low values alternately repeated in a first period in a data section and the high and low values alternately repeated in a second period different from the first period in a pause section. When the second period is changed to a fourth period in an idle section in which data transmission is prepared, the control circuit determines transmission and reception of a data signal to and from the image forming apparatus is to be performed at a third period different from the first period for a second data section after the idle section.