Abstract: An electronic control apparatus is designed to perform an engine control program in an object-oriented programming manner. A first type message, which does not contain a count value generated as a result of execution of a method of an object, is stored in a message storage unit. At the time that execution of the method is completed, the stored first type message is read out and a method of the object corresponding to the destination of the message is executed. A timer message, which contains a count value generated as a result of execution of the method of the object, is stored in another storage unit. The count value (timer counter) of the timer message in the other storage unit is reduced one by one as a result of the process being performed every predetermined time. When the count value of the timer message reaches 0 in the message storage unit the message is re-stored as a first type message.

Abstract: An ECU is provided with a microcomputer for performing arithmetic operation for controlling a control target by executing a program stored in a ROM and for performing the process to transmit the control data calculated by means of the arithmetic operation to a communication target. The program comprises independent program modules, that is, a program (application unit) for performing the arithmetic operation, a program (communication conversion unit) for extracting the control data to be transmitted from among the control data calculated by the application unit and for performing the process to convert the extracted control data to the communication data string corresponding to the communication protocol of the communication target, and a program (communication driver unit) for performing the process to transmit the data string according to the communication protocol.