Panasonic FP-X0 L14R User Manual page 88

6.5.5 Flag Operation in Serial Communication
Header: No-STX, Terminator: CR
Receiving data:
The "reception done" flag, the "transmission done" flag, and the F159 (MTRN) instruction are
related as follows:
For general-purpose serial communication, half-duplex transmission must be used.
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Reception is disabled when the "reception done" flag R9038 is on.
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When F159 (MTRN) is executed, the number of bytes received is cleared, and the address (write
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pointer) in the receive buffer is reset to the initial address.
Also, when F159 (MTRN) is executed, the error flag R9037, the "reception done" flag R9038 and the
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"transmission done" flag R9039 goes off.
Duplex transmission is disabled while F159 (MTRN) is being executed. The "transmission done" flag
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R9039 must be observed.
Reception stops if the error flag R9037 goes on. To resume reception, execute the F159 (MTRN)
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instruction, which turns off the error flag.
Note:
Be aware that the "reception done" flag R9038 changes even while a scan is in progress (e.g., if the
"reception done" flag is used multiple times as an input condition, there is a possibility of different
statuses existing within the same scan.) To prevent multiple read access to the special internal relay you
should generate a copy of it at the beginning of the program.
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