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Arithmetic instructions
F117_FIFW
F/P117 writes the data specified by s into the FIFO buffer specified by d1.
Description
How to use the FIFO buffer (see page 483)
The specified data is written to the address indicated by the writing pointer when the instruction is
executed.
15
d1
d1+1
d1+2
d1+3
Writing
pointer
d1+n+1
d1+n+2
(0), (n-2) and (n-1) are addresses assigned to the data storage area.
n is the value specified by the F115_FIFT (see page 483) instruction.
The writing pointer is stored in the lower eight bits of the third word of the FIFO buffer area, and is
indicated by a relative position in the data storage area. The actual address to which data is being
written is specified by d1 plus the offset 3 plus the value of the writing pointer (the value of which
only the lower byte is a decimal value).
When the writing is executed, 1 is added to the number of stored data items, and the writing pointer
is incremented by 1, or reset to zero if the writing pointer pointed to the final element.
This instruction also exists as a P instruction (for FP2/2SH, FP3/5, FP10/10SH PLC types), which
is only executed at the rising edge of the EN trigger. Select [Insert P instruction] from the
"Instructions" pane if you require a P instruction. To facilitate reuse, the instruction then appears
under "Recently used" in the pop-up menu. Press <Ctrl>+<Shift>+<v> within the programming
area to open the list of recently used elements.
PLC types
Availability of F117_FIFW (see page 1320)
Data types
Variable
Data type
s
ANY16
d1
The variables s and d1 have to be of the same data type.
492
Write to FIFO buffer
0
Memory size of FIFO buffer (n)
Number of stored data items (words), written
and not read
Writing pointer in lower byte
Data [0]
[s]
Data [n-2]
Data [n-1]
Function
16-bit area or equivalent constant for storing data to write in
the FIFO buffer
starting 16-bit area of FIFO buffer
Data storage area
(n words)
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