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Sequential control system
A control system executed in a strict sequence from one programmed step to the
next depending on satisfied conditions.
Start point
The start point is the defined beginning of a program cycle. At the start, the process
image input table (PII) is read; in other words the plant status is queried.
Status
The status refers to the signal state of the bits of an address on the PLC.
Status display
The status display is the display of the signal state of an address on the screen or
display of a programming device connected online to the PLC.
Step
The control task is divided into single steps. Actions are formulated in the steps
that are executed by the controller in a certain status (for example for controlling
the outputs or activating/deactivating steps).
Step Comment
A step comment is a text for a step and can have up to 2048 characters.
Step enabling condition
A step enabling condition is a Boolean logic operation which specifies the
conditions under which the predecessor step is deactivated and the successor step
activated.
It is part of the transitions.
Supervision
A supervision is a programmable condition within a step. A supervision influences
how the sequencer progresses from one step to the next.
S7-GRAPH for S7-300/400 Programming Sequential Control Systems
C79000-G7076-C526-01
Glossary
Glossary-3
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