2-52
Section 2 Programming Languages
(5) Action/action qualifier
An action is a real program which is assigned to the initial, normal, and termination steps and which is executed on the object to
be controlled. In an action, the programmer can assign a BOOL variable, or a program in IL, ST, LD, or FBD language.
Action qualifier
An action qualifier specifies the timing of execution or suppression of an action according to the active or inactive state of the
step. There are nine types of action qualifiers.
1) N (non-stored)
The action is repeated while the step is active. (Note)
S001
T001
ACT1
2) P (Pulse)
The action is executed only once when the step is activated.
S001
T001
ACT1
1 task
Notes:
IEC standard stipulates, “Action instruction statement or network must finally be executed at the trailing edge of action
qualifier.” Therefore, the action of P qualifier is executed twice when the step becomes active.
To make it executed only once, use
“action flag”
as an interlock.
Example of increment:
ADD
EN
ACT1.X
1
INC_DATA
ENO
INC_DATA
* For more information about action flag, refer to “2-6-3
Automatically generated SFC variables.”
