Action qualifiers for SFC elements

The action qualifier (maybe also known as qualifier) controls an →action with the →SFC network. Hence, the action qualifier determines

• when the statements of an action should be executed or

• which value the enclosed Boolean variable (Boolean action) receives.

The usage of the action qualifier depends on the used programming language:

• Within the ST-editor, the action qualifier is specified when associating the action within the step or initial step. The statements of the action are specified within the action.

• Within the FBD-editor, the action qualifier is entered within an action block. The statements for the action follow this action block.

Neuron Power Engineer provides the following action qualifiers (AQ):

AC	Description	Short explanation on the effect (1)	Duration(2)
(none)	Non-stored	such as N
N	Non-stored	action is active (= delivering TRUE) as long as the internal input is set
R	overriding Reset	resetting or interlocking the action; has priority over other action qualifiers
S	Set (or Stored)	delivering TRUE; stored
L	time Limited	delivering TRUE until the end of the set time or until the internal input is deactivated (depending on what occurs first)
D	time Delayed	delivering TRUE after the set time has elapsed until the internal input is deactivated
P	Pulse	delivering TRUE exactly with a FALSE → TRUE transition (edge recognition)
SD	Stored and time Delayed	delivering TRUE after the set time has elapsed, also if the internal input is not active any more
DS	Delayed and Stored	setting action (stored) after the set time has elapsed but only if the internal input has been continuously active
SL	Stored and time Limited	delivering TRUE until the end of the set time
P0	Pulse, falling edge	such as block F_TRIG ( detecting a falling edge)
P1	Pulse, rising edge	such as P
PN	Pulse, Non-stored	delivering TRUE as long as the internal input is set but at least until the end of the set time Enhancement to IEC-standard PN is an enhancement for the →IEC-standard.

Legend:
⁽¹⁾ ... See "Evaluating SFC elements" and "Behavior of the action qualifiers for SFC elements" for a better understanding how one/several action qualifiers affect the evaluation of the ST-code or the FBD-logic.
⁽²⁾ ... In case of , you have to specify a duration literal of data type TIME or a variable of data type TIME for this action qualifier (see →Time literal for examples on duration literals). In case of , a duration literal is not required for this action qualifier.