6-16
Header: STX, Terminator: ETX
Receiving data:
The “reception done” flag, the “transmission done” flag, and the MTRN instruction are related as follows:
• The data is stored in the receive buffer within MCU in sequential order. When the header is received,
the receive pointer is initialized.
• Receiving data still continues after the “reception done” flag turned on. There are 8 receive buffers of
2048 bytes each internally, therefore, data for the amount of these 8 sets can be received.
• If there are two headers, data following the second header overwrites the data in the receive buffer.
• The “reception done” flag X4 (X5) is turned off when no data is received after executing F159 (MTRN)
instruction. (It does not turn off right after the execution of MTRN insruction. It will be turned off at the
beginning of the next scan or later.)
Key Point:
There is no relevance between the operation of transmission by F159 (MTRN) instruction and the
operation of reception by F161 (MRCV) instruction. MCU can always receive data.
• In case of transmission, a request to send is given to MCU using F159 (MTRN) instruction.
• In case of reception, received data are copied from MCU using F161 (MRCV) instruction.
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