How is ladder logic executed by the PLC?
Left → Right, Top → Bottom, repeatedly (scan cycle).
How should humans read ladder logic to understand it?
Start from the output (right side) and read right → left.
What does a ladder rung represent logically?
One boolean expression (one IF statement).
What does a Normally Open (NO) contact mean in ladder logic?
The condition is TRUE when the variable is TRUE.
What does a Normally Closed (NC) contact mean in ladder logic?
The condition is TRUE when the variable is FALSE.
How do you translate an NC contact to pseudo-code?
As a NOT condition ( !variable ).
How do you translate a NO contact to pseudo-code?
As the variable itself ( variable ).
What does a coil ( ) represent?
An assignment to a variable (output or flag).
What does a parallel branch mean logically?
OR (||).
What does a series connection mean logically?
AND (&&).
What is an M (marker) variable?
An internal boolean memory flag (no physical hardware).
One sentence that summarizes ladder logic
Ladder logic evaluates conditions — it does not react to triggers.
