Patent ID: 8122316

Claim:
An error detecting system comprising: a central processing unit; a storing apparatus; and an error detecting apparatus detecting an error of data string which transmitted from the central processing unit to the storing apparatus and is stored in the storing apparatus, wherein the error detecting apparatus comprises; a diagnosis data generating part adding diagnosis data to the data string before stored in the data storing apparatus in order to detect an error of the data string, an error detecting part determining an error of the data string read out from the storing apparatus with reference to the diagnosis data added to the data string; and a data switching unit selecting first diagnosis data generated by the diagnosis data generating part or second diagnosis data transmitted from the central processing unit, adding selected diagnosis data to the data string transmitted from the central processing unit to the storing apparatus, wherein the first diagnosis data includes generated first diagnosis data which is generated by the diagnosis data generating part and read out first diagnosis data which added to the data string by the data switching unit, is stored in the data storing apparatus, and then read out from the data storing apparatus by the central processing unit, wherein the second diagnosis data includes transmitted second diagnosis data which is transmitted from the central processing unit to the data switching unit and read out second diagnosis data which added to the data string by the data switching unit, is stored in the data storing apparatus, and then read out from the data storing apparatus by the central processing unit, wherein the central processing unit determines an abnormal fixation of the data switching unit based on results of a first determination and a second determination, wherein the first determination is executed to determine whether or not the transmitted second diagnosis data which is stored in the central processing unit and the read out second diagnosis data are matched each other when the central processing unit transmits to the data switching unit a signal which instruct the data switching unit to select the second diagnosis data, wherein the second determination is executed to determine whether or not the transmitted second diagnosis data which the central processing unit transmits to the data switching unit and being stored in the central processing unit and the read out first diagnosis data are matched each other when the central processing unit transmits to the data switching unit a signal which instruct the data switching unit to select the first diagnosis data.