Справочник Пользователя для Mitsubishi Electronics FX2NC
FX Series Programmable Controllers
STL Programming 3
3-5
3.4
Moving Between STL Steps
To activate an STL step the user must first drive the state coil. Setting the coil has already
been identified as a way to start an STL program, i.e. drive an initial state. It was also noted
that using an OUT statement to driving a state coil has a different meaning to the SET
instruction. These difference will now be explained:
been identified as a way to start an STL program, i.e. drive an initial state. It was also noted
that using an OUT statement to driving a state coil has a different meaning to the SET
instruction. These difference will now be explained:
3.4.1
Using SET to drive an STL coil
•
SET is used to drive an STL state coil to make the step active. Once the current STL step
activates a second following step, the source STL coil is reset. Hence, although SET is
used to activate a state the resetting is automatic.
activates a second following step, the source STL coil is reset. Hence, although SET is
used to activate a state the resetting is automatic.
However, if an STL state is driven by a
series of standard ladder logic instructions,
i . e . n o t a p r e c e d i n g S T L s t a t e , t h e n
standard programming rules apply.
In the example shown opposite S20 is not
reset even after S30 or S21 have been
driven. In addition, if S20 is turned OFF,
S 3 0 w i l l a l s o s t o p o pe r a t i n g . T h i s i s
because S20 has not been used as an STL
state. The first instruction involving the
status of S20 is a standard LoaD instruction and NOT an STL instruction.
series of standard ladder logic instructions,
i . e . n o t a p r e c e d i n g S T L s t a t e , t h e n
standard programming rules apply.
In the example shown opposite S20 is not
reset even after S30 or S21 have been
driven. In addition, if S20 is turned OFF,
S 3 0 w i l l a l s o s t o p o pe r a t i n g . T h i s i s
because S20 has not been used as an STL
state. The first instruction involving the
status of S20 is a standard LoaD instruction and NOT an STL instruction.
•
SET is used to drive an immediately following STL step which typically will have a larger
STL state number than the current step.
STL state number than the current step.
•
SET is used to drive STL states which occur within the enclosed STL program flow, i.e.
SET is not used to activate a state which appears in an unconnected, second STL flow
diagram.
SET is not used to activate a state which appears in an unconnected, second STL flow
diagram.
X000
SET S021
S040
S020
RST S022
S020
S030
X000
ZRST S21 S28
Note: If a user wishes to forcibly reset an
STL step, using the RST or ZRST (FNC
40) instructions would perform this task.