Panasonic FP-E Programming Manual page 522

High−level Instructions
The reading pointer is stored in the upper eight bits of the third word of the FIFO buffer area, and is indicated
by an address in the data storage area.
The actual address is the value of the leading address in the FIFO buffer area specified by S, plus 3, plus the
value of reading pointer (the value of which only the first byte is a decimal value).
When the reading is executed, 1 is subtracted from the number of stored data items, and the reading pointer is
incremented by 1.
Notes
An error occurs if this is executed when the number of stored
data items is 0.
No data is set for D.
Reading is only carried out when the reading pointer is not
equal to the writing pointer.
If this is executed when the reading pointer is indicating the
final address in the FIFO buffer (the n defined by the FIFO
instruction minus 1), the reading pointer is set to 0.
Flag conditions
・Error flag (R9007):
・Error flag (R9008):
3 − 258
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Turns on and stays on when:
Turns on for an instant when:
− The area specified using the index modifier exceeds the limit.
− The size (n) of the FIFO specified by S is n = 0, or when n > 256.
− The number of stored data items of the FIFO = 0.
− The number of stored data items of the FIFO >FIFO size (n).
− The final address of the FIFO based on the FIFO size (n) exceeds the area.
− The FIFO reading pointer > FIFO size (n).
− The FIFO reading pointer is K256 (H100) or higher after the data has been
read.