Siemens SINUMERIK 828D Programming Manual page 570

Motion synchronous actions
10.3 Main run variables for synchronized actions
Example: Circulating memory
During a production run, a conveyor belt is used to transport products of different lengths
(a, b, c, d). The conveyor belt of transport length therefore carries a varying number of
products depending on the lengths of individual products involved in the process. With a
constant speed of transport, the function for removing the products from the belt must be
adapted to the variable arrival times of the products.
Program code
DEF REAL INTV=2.5
DEF REAL TOTAL=270
EVERY $A_IN[1]==1 DO $AC_FIFO1[4]=0
EVERY $A_IN[2]==1 DO $AC_TIMER[0]=0
EVERY $A_IN[2]==0 DO $AC_FIFO1[0]=$AC_TIMER[0]*$AA_VACTM[B]
EVERY $AC_FIFO1[3]+$AC_FIFO1[4]*ZWI>=GESAMT DO POS[Y]=-30
$R1=$AC_FIFO1[0]
570
Comments
; Constant distance between products
that are placed down.
; Distance between the length
measurement and removal position.
; At the start of the process, reset
FIFO
; If a product interrupts the light
barrier, start the time measure-
ment.
; If the product leaves the light
barrier, calculate the product
length from the measured time and
transport speed and save in FIFO.
; As soon as the sum of all product
lengths and intermediate distances
are greater than/equal to the
length between the position where
the product is placed down and
where it is removed, remove the
product from the conveyor belt at
the removal position, read-out the
associated product length from
FIFO.
Programming Manual, 07/2010, 6FC5398-2BP40-0BA0
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