Data transfer via communication ports
748
Part III FP Instructions
Incoming data is stored in the receive buffer. Start and end codes are not stored in the receive
buffer. The storage area for the data received starts with the second word of the receive buffer
(offset 1). Offset 0 contains the number of bytes received. The initial value of offset 0 is 0.
1
Storage area for the number of bytes received
2
Storage area for the data received
0
1
2
n
Offset
2
1
3
4
2n 2n-1
Bold numbers indicate the order of reception.
When the end code is received, the "reception done" flag turns to TRUE. Reception of any further
data is prohibited. The "reception done" flag only turns to TRUE if an end code, e.g. CR, has been
selected in the system registers.
3. Processing the data in the receive buffer
Verify the end of reception.
Copy the data in the receive buffer to a target area defined in the program using a transfer
instruction, e.g. F10_BKMV (see page 819).
NOTE
For details on the operation of the "reception done" flag, see page 757
4. Preparing the system for the reception of further data
In order to receive the next data, reset the receive buffer. This is done automatically when sending the next data
with F159_MTRN:
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. (The
receive buffer is not cleared).
The "reception done" flag turns to FALSE.
To reset the receive buffer without sending further data, execute F159_MTRN (see page 741) with n_Num
ber =
0.
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