A CRUM chip mountable on a consumables unit of an image processing unit includes an interface unit configured to receive a first signal including first data and first integrity monitoring data for the first data from a main body of the image forming apparatus, a monitoring unit configured to separate the first integrity monitoring data from the first signal and monitor integrity of the first signal, a data processing unit configured to generate second data to be transmitted to the main body of the image processing unit, a generating unit configured to generate second integrity monitoring data using the second data and the first integrity monitoring data, and a control unit configured to control the interface unit to transmit a second signal including the second data and the second integrity monitoring data to the main body of the image forming apparatus. Therefore, stability of communication is improved.