Panasonic FP0R User Manual page 141

Communication
When receiving data, operation is as follows:
1. Characters A, B, and C received from the external device are stored in the receive
buffer.
2. When the end code is received, the "reception done" flag turns to TRUE. Reception of
any further data is prohibited. (Character D is not stored.)
3. F159_MTRN is executed to send response data to the external device. When
F159_MTRN is executed:
- The receive buffer is reset.
- The "reception done" flag turns to FALSE.
- The "transmission done" flag turns to FALSE.
- The communication error flag turns to FALSE.
- Characters 1, 2, and 3 are sent to the external device.
- The end code is automatically added to the data sent.
- While F159_MTRN is being executed, no data can be received. (The
"transmission done" flag is FALSE.)
4. When the specified number of bytes has been sent, the "transmission done" flag turns
to TRUE.
5. Characters E, F, and G received from the external device are stored in the receive
buffer.
NOTE
Resetting the receive buffer sets the number of bytes received in offset 0 to 0
and moves the write pointer back to offset 1. Subsequent data will be stored in
the receive buffer starting at offset 1.
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