DATA TRANSFER DEVICE, DATA TRANSFER SYSTEM AND DATA TRANSFER METHOD

摘要

PROBLEM TO BE SOLVED: To prevent the lowering of effective data transfer rate by garbled data. SOLUTION: A transfer start/end detecting part 24 detects timing that a DMARQ signal becomes H, L levels, a transfer time counting part 25 counts transfer time during which data transfer is actually performed among periods in which the preset prescribed number of data blocks are transferred, a number of transferred bytes measuring part 26 measures the number of transferred bytes of pieces of data that can be exactly transferred and an effective transfer rate calculating part 27 calculates the effective data transfer rate by dividing the number of transfer bytes by the transfer time. A transfer rate comparing part 30 compares the effective data transfer rate with transfer rate slower than the one at the present moment by one stage to be outputted from a selectable transfer rate storage part 29 and when the former is slower, a transfer rate switching part 31 switches the transfer rate to the one slower by one stage.