| 摘要 |
PURPOSE:To reduce one set of transmission buffers from two sets by using a reception buffer as a virtual transmission buffer so as to send a test response in the test response transmission to a test command reception in a loop line communication. CONSTITUTION:When a command is received from a primary station via a loop line 4 by a loop line control section 1, a line control section 14 generates a reception interruption from a reception interruption line 182 to a processing section 11. The processing section 11 selects an idle reception buffer according to the reception program stored in a storage section 12, sets a reception address pointer to, e.g., a reception buffer 152, writes a reception data one by one byte in the reception buffer 152 and counts the reception data length. After the final byte is written, the processing section 11 analyzes a command code, and when it is a test command, the section 11 sends the test response being the similar data as the information part of the test command.
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