To solve a problem such that the processing related to transmission completion is required and the processing load on a CPU is increased by this processing in a system where the CPU confirms transmission completion at each time of data transmission in communication control operation between the CPU and a CCP.
A transmission completion predicting timer is managed by a prescribed period, and data transmission control processing is automatically performed in a data storage part on the basis of a line status signal, and thus confirmation processing of transmission completion is performed. Therefore, sending of data from a communication controller via a normal transmission line, storage of transmission data on the occurrence of a line fault, and sending of stored data in the restoration from the line fault are all performed without transitting the operation part of the CPU not only to reduce the processing load on the CPU but also to improve the performance and the function of the communication controller by this reduction of the processing load on the CPU.
OZAKI KAZUMASA
TAHIRA MITSUHIRO
HITACHI ENG CO LTD