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FX Series Programmable Controllers STL Programming 3
3-10
3.6 Restrictions Of Some Instructions When Used With STL
Althou
g
h STL can operate with most basic and applied instructions there are a few exceptions.
As a
g
eneral rule STL and MC-MCR pro
g
rammin
g
formats should not be combined. Other
instruction restrictions are listed in the table below.
Restrictions on using applied instructions
Operational State
Basic Instructions
LD, LDI, AND,
ANI, OR,ORI,
NOP, OUT,
SET, RST,
PLS,PLF
ANB, ORB,
MPS,MRD,
MPP
MC, MCR
Initial and
g
eneral
states
Branch-
in
g
and
mer
g
in
g
states
Output
processin
g
Transfer
processin
g
STL
S**SET
STL
S**SET
STL
STL
STL
S**SET
• Most applied instructions can be used within STL pro
g
rams. Attention must be paid to
the wa
y
STL isolates each non-active step. It is recommended that when applied
instructions are used their operation is completed before the active STL step transfers to
the next step.
Other restrictions are as follows:
- FOR - NEXT structures can not contain STL pro
g
ram blocks.
- Subroutines and interrupts can not contain STL pro
g
ram blocks.
-STL pro
g
ram blocks can not be written after an FEND instruction.
- FOR - NEXT instructions are allowed within an STL pro
g
ram with a nestin
g
of up to 4
levels.
For more details please see the operational compatibilit
y
listed in the two tables on
pa
g
es 7-12,7-13.
Using ‘jump’ operations with STL
• Althou
g
h it is possible to use the pro
g
ram
j
ump operations (CJ instruction) within STL
pro
g
ram flows, this causes additional and often unnecessar
y
pro
g
ram flow
complications. To ensure eas
y
maintenance and quick error findin
g
it is recommended
that users do not write
j
ump instructions into their STL pro
g
rams.