FX Series Programmable Controllers STL Programming 3
3-16
3.11 Programming Examples
3.11.1 A Simple STL Flow
This simple example is an excerpt from a semi-automatic loadin
-unloadin
ore truck pro
ram.
This example pro
ram has a built in, initialization routine which occurs onl
when the PLC is
powered from OFF to ON. This is achieved b
usin
the special auxiliar
rela
M8002.
This activates a Zone ReSeT (ZRST is applied
instruction 40) instruction which ensures all of
the operational STL states within the pro
ram
are reset. The pro
ram example opposite
shows an M8002/ZRST example.
The push button X0 acts as a start button and a mode selection button. The STL state S0 is
initialized with the ZRST instruction. The s
stem waits until inputs X0 and X2 are
iven and Y
13 is not active. In the scenario this means the ore truck is positioned at the ore dischar
e
point, i.e. above the position sensor X2. The ore truck is not currentl
dischar
in
its load, i.e.
the si
nal to open the trucks unloadin
doors (Y13) is not active and the start button (X0) has
been
iven. Once all of the points have been met the pro
ram steps on to state S21.
On this state the ore cart is moved (Y10) and positioned (X1) at the loadin
hopper. If the start
button (X0) is pressed durin
this sta
e the ore cart will be set into a repeat mode (M2 is reset)
where the ore truck is immediatel
returned to the loadin
hopper after dischar
in
its current
load. This repeat mode must be selected on ever
return to the loadin
station.
Once at the loadin
point the pro
ram steps onto state S22. This state opens the hoppers
doors (Y11) and fills the truck with ore. After a timed duration, state S23 is activated and the
truck returns (Y12) to the dischar
e point (X2).
Y13
X0
Y10
Y12
X2 X1
Y11
Loading hopper
Ore truck
Ore dischange point
Start button
