FX Series Programmable Controllers STL Programming 3
3-10
3.6 Restrictions Of Some Instructions When Used With STL
Althou
h STL can operate with most basic and applied instructions there are a few exceptions.
As a
eneral rule STL and MC-MCR pro
rammin
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
eneral
states
Branch-
in
and
mer
in
states
Output
processin
Transfer
processin
STL
S**SET
STL
S**SET
STL
STL
STL
S**SET
• Most applied instructions can be used within STL pro
rams. Attention must be paid to
the wa
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
ram blocks.
- Subroutines and interrupts can not contain STL pro
ram blocks.
-STL pro
ram blocks can not be written after an FEND instruction.
- FOR - NEXT instructions are allowed within an STL pro
ram with a nestin
of up to 4
levels.
For more details please see the operational compatibilit
listed in the two tables on
pa
es 7-12,7-13.
Using ‘jump’ operations with STL
• Althou
h it is possible to use the pro
ram
ump operations (CJ instruction) within STL
pro
ram flows, this causes additional and often unnecessar
pro
ram flow
complications. To ensure eas
maintenance and quick error findin
it is recommended
that users do not write
ump instructions into their STL pro
rams.
