In order to configure in which way the actions should be associated to the IEC steps, some qualifiers are available, which are to be inserted in the qualifier field of an action element.
These qualifiers are handled by the SFCActionControl function block of the IecSfc.library, which automatically is included in a project by the SFC plug-ins.
The available qualifiers:
|
N |
Non-stored |
The action is active as long as the step is active. |
|
R0 |
overriding Reset |
The action gets deactivated. |
|
S0 |
Set (Stored) |
The action will be started when the step becomes active and will be continued after the step is deactivated, until the action gets reset. |
|
L |
time Limited |
The action will be started when the step becomes active and it will continue until the step goes inactive or a set time has passed. |
|
D |
time Delayed |
A delay timer will be started when the step becomes active. If the step is still active after the time delay, the action will start and continue until it gets deactivated |
|
P |
Pulse |
The action will be started when the step becomes active/deactive and will be executed once. |
|
SD |
Stored and time Delayed |
The action will be started after the set time delay and it will continue until it gets reset. |
|
DS |
Delayed and Stored |
If the step is still active after the specified time delay, the action will start and it will continue until it gets reset |
|
SL |
Stored and time limited |
The action will be started when the step becomes active and it will continue for the specified time or until a reset. |
The qualifiers L, D, SD, DS and SL need a time value in the TIME constant format.
以上内容摘自Codesys的Help文档。
原文：http://www.cnblogs.com/zaishuiyifang006/p/4789660.html