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.

logi.CAD 3 provides the following action qualifiers (AQ):

AC

Description

Short explanation on the effect (1)

Duration(2)

(none)

Non-stored

such as N

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

N

Non-stored

action is active (= delivering TRUE) as long as the internal input is set

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

R

overriding Reset

resetting or interlocking the action; has priority over other action qualifiers

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

S

Set (or Stored)

delivering TRUE; stored

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

L

time Limited

delivering TRUE until the end of the set time or until the internal input is deactivated (depending on what occurs first)

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

D

time Delayed

delivering TRUE after the set time has elapsed until the internal input is deactivated

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

P

Pulse

delivering TRUE exactly with a FALSETRUE transition (edge recognition)

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

SD

Stored and time Delayed

delivering TRUE after the set time has elapsed, also if the internal input is not active any more

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

DS

Delayed and Stored

setting action (stored) after the set time has elapsed but only if the internal input has been continuously active

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

SL

Stored and time Limited

delivering TRUE until the end of the set time

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

P0

Pulse, falling edge

such as block F_TRIG ( detecting a falling edge)

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

P1

Pulse, rising edge

such as P

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg

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.

images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg

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 images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/check.svg , 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 images/s/b2ic8e/9012/1ca6q62/_/images/icons/emoticons/error.svg , a duration literal is not required for this action qualifier.