Fifo Variable $Ac_Fifo1[N] - Siemens SINUMERIK 840D sl Programming Manual

10.3.10 FIFO variable $AC_FIFO1[n] ... $AC_FIFO10[n]
Function
10 FIFO variables (circulating buffer store) are available to store associated data sequences.
Data type: REAL
Application:
• Cyclical measurement
• Pass execution
Each element can be accessed in read or write
FIFO variables
The number of available FIFO variables is programmed in machine data
MD 28260: NUM_AC_FIFO.
The number of values that can be entered in a FIFO variable is defined via machine data
MD 28264: LEN_AC_FIFO. All FIFO variables are equal in length.
The sum of all FIFO elements is only formed if bit 0 is set in MD 28266 MODE_AC_FIFO.
Indices 0 to 5 have a special significance:
n=0:While writing: New value is stored in the FIFO
While reading: the oldest element will be read and removed from the FIFO
n=1:Access to oldest stored element
n=2:Access to latest stored element
n=3:Sum of all FIFO elements
n=4:Number of elements available in FIFO.
Every element in the FIFO can be read and write-accessed. 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 beginning of FIFO
n=6 to 6+nmax:Access to nth FIFO element:
Job planning
Programming Manual, 03/2006 Edition, 6FC5398-2BP10-1BA0
Motion synchronous actions
10.3 Main run variables for synchronized actions
10-19