How To Start And End An Stl Program; Embedded Stl Programs; Activating New States - Mitsubishi FX1S Series Programming Manual

FX Series Programmable Controllers
Combined SFC Ladder representation
Sometimes STL programs will be written in hard copy as a combination of both flow diagram
and internal sub-program. (example shown below).
Identification of contact states
• Please note the following convention
is used:
Common alternatives are 'a' and 'b'
i d e n t i f i e r s f o r N o r m a l l y O p e n ,
Normally Closed states or often a line
drawn over the top of the Normally
Closed contact name is used, e.g.
X000.
3.3

How To Start And End An STL Program

Before any complex programming can be undertaken the basics of how to start and more
importantly how to finish an STL program need to be examined.
3.3.1

Embedded STL programs

An STL style program does not have to
entirely replace a standard ladder logic
program. In fact it might be very difficult to do
so. Instead small or even large section of STL
program can be entered at any point in a
p r o g r a m . O n c e t h e S T L ta s k h a s b e e n
completed the program must go back to
processing standard program instructions until
the next STL program block. Therefore,
iden tifying the s ta rt a nd en d of a n ST L
program is very important.
3.3.2

Activating new states

Once an STL step has been selected, how is it used and how is the program 'driven'?
This is not so difficult, if it is considered that for an STL step to be active its associated state
coil must be ON. Hence, to start an STL sequence all that has to be done is to drive the
relevant state ON.
There are many different methods to drive a
state, for example the initial state coils could
be pulsed, SET or just included in an OUT
instruction. However, within Mitsubishi's STL
programming language an STL coil which is
SET has a different meaning than one that is
included in an OUT instruction.
Note: For normal STL operation it is recommended that the states are selected using the
SET instruction. To activate an STL step its state coil is SET ON.
¡ Normally Open contact
l Normally Closed contact
M8002
S 0
Y20
X0
X1
S 22 Y22
T0
K20
T0
S 27 Y27
T7
T7
K20
LD X000
Normal Ladder Program
OUT Y004
LD X002
SET S009
STL S009
OUT Y010
LDI X003
Embedded STL Program
OUT Y006
RET
LD X005
OUT Y007
RST M080
STL
S 22
T0
STL
S 27
STL Programming 3
X0
X1
S 26
Y26
X15
Y22
K20
T0
SET S 27
3-3