DIAGNOSTIC SYSTEM FOR VEHICLE

摘要

PURPOSE:To positively transmit a control data corresponding to a required address value to a diagnostic apparatus. CONSTITUTION:A main CPU and a subject CPU mutually send and receive control data by means of a DMA(direct memory access) when a read request for RAM value is output. When a read request for RAM value is detected to be sent from the main CPU to the subject CPU, in steps 1710-1730, it is checked whether a required address value from the main CPU to the subject CPU agrees with a transmitted address value from the subject CPU to the main CPU. If both address values are detected to agree, a flag XA4ANS is set. A predetermined time later (16ms) after the flag is set, a RAM value corresponding to the required address value is sent to a diagnosing apparatus in steps 1740-1760. Accordingly, an erroneous data is positively prevented from being sent to the diagnosing apparatus.