Siemens SINUMERIK 840D

10
12.97 Motion-Synchronous Action
10.3 S
p
ecial real-time variables for s
y
nchronized actions
10
840D
NCU 572
NCU 573
810D
CCU2
840Di

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SINUMERIK 840D/840Di/810D/FM-NC Programming Guide Advanced (PGA) – 04.00 Edition
10-357
10.3.6 FIFO variable $AC_FIFO1[n] … $AC_FIFO10[n], SW 4 and higher
Function
Data type REAL
10 FIFO variables (circulating buffer store) are available
to store associated data sequences.
Application:
•
Cyclic measurement
•
Pass execution
Each element can be accessed in read or write
mode.
The number of available FIFO variables is defined
using machine data MD 28260: NUM_AC_FIFO.
The number of values that can be written into an FIFO
variable is defined using the machine data
MD 28264: LEN_AC_FIFO. All FIFO variables are of
the same length.
Indices 0 to 5 have a special significance:
n=0: While writing: New value is stored in FIFO
While reading: Oldest element is read and
removed from FIFO
n=1: Accessing the oldest stored element
n=2: Accessing the most recently stored element
n=3: Sum of all FIFO elements
n=4: Number of elements available in FIFO.
Read and write access to each element
is possible.
FIFO variables are reset by resetting the
number of elements, e.g.for the first FIFO
variable: $AC_FIFO1[4]=0
n=5: Current write index relative to
start of FIFO
n=6 to 6+n
max
:
Access to nth FIFO element