DATA RECEPTION CONTROL SYSTEM

摘要

PURPOSE:To attain transmission of a transmitting text of variable length with us of a DMA control circuit by adding the fixed text length information to a fixing position of a data frame to be transmitted and also adding an end code to the end of the frame. CONSTITUTION:The text length information 2 shows the byte length of a subsequent text 3 and is set at the fixing position of a data frame. The text 3 has the transmission properties that can include an optional bit pattern and the variable length properties for optional length. A serial/parallel converter 7 converts the serial data received from a device at the remote side into a parallel form. This parallel data is transferred automatically to a memory 6 by a DMA control circuit 8. The number of bytes received actually is compared with the number of bytes received finally. If the former bytes are smaller than the latter ones, the receiving action is continued to wait for the report of detection of the next end code. Then the end of reception of a data frame is decided when the coincidence is secured between said two numbers of bytes. Thus it is possible to receive a transmitting text of optional length.