Filter
Top Products
FX Series Programmable Controllers STL Programming 3
3-18
3.11.2 A Selective Branch/ First State Merge Example Program
The followin
g
example depicts an automatic sortin
g
robot. The robot sorts two sizes of ball
bearin
g
s from a mixed ‘source pool’ into individual stora
g
e buckets containin
g
onl
y
one t
y
pe of
ball bearin
g
.
The sequence of ph
y
sical events (from initial power On) are:
1) The pickup arm is moved to its zero-point when the start button (X12) is pressed. When the
pickup arm reaches the zero-point the zero-point lamp (Y7) is lit.
2) The pickup arm is lowered (Y0) until a ball is collected (Y1). If the lower limit switch (X2) is
made a small ball bearin
g
has been collected; consequentl
y
no lower limit switch si
g
nal
means a lar
g
e ball bearin
g
has been collected. Note, a proximit
y
switch (X0) within the
‘source pool’ identifies the availabilit
y
of ball bearin
g
s.
3) Dependin
g
on the collected ball, the pickup arm retracts (output Y2 is operated until X3 is
received) and moves to the ri
g
ht (Y3) where it will stop at the limit switch (X4 or X5)
indicatin
g
the container required for stora
g
e.
4) The pro
g
ram continues b
y
lowerin
g
the pickup arm (Y0) until the lower limit switch (X2) is
reached.
5) The collected ball bein
g
is released (Y1 is reset).
6) The pickup arm is retracted (Y2) once more.
7) The pickup arm is traversed back (Y4) to the zero-point (X1).
Y3
Y4
X12 Y7
X1
X3
X4 X5
X2
X0
Y1
Y2
Y0
Points to note
• The Selective Branch is used to choose the deliver
y
pro
g
ram for either small ball
bearin
g
s or lar
g
e ball bearin
g
s. Once the destination has been reached (i.e. step S24
or S27 has been executed) the two independent pro
g
ram flows are re
j
oined at step
S30.
• The example pro
g
ram shown works on a sin
g
le c
y
cle, i.e. ever
y
time a ball is to be
retrieved the start button (X12) must be pressed to initiate the c
y
cle.