Rockwell Automation Logix5000 Controllers Ladder Diagram Programming Manual - Manual (Page 13)

Program ladder diagram Chapter 1
Arrange the input instructions
Determine how to arrange the input instructions on the rung, as shown below.
To check multiple input conditions when: Arrange the input instructions:
• All conditions must be met in order to take action.
For example, If condition_1 AND condition_2 AND condition_3…
In series:
• Any one of several conditions must be met in order to take action.
For example, If condition_1 OR condition_2 OR condition_3…
In parallel:
• There is a combination of the above.
For example:
If condition_1 AND condition_2…
OR
If condition_3 AND condition_2…
In combination:
Tip: The controller executes all instructions on a rung regardless of their
rung-condition-in. For optimal performance of a series of instructions, sequence
the instructions from most likely to be false on the left to least likely to be false on
the right.
When the controller finds a false instruction, it executes the remaining instructions
in the series with their rung-condition-in set to false. Typically, an instruction
executes faster when its rung-condition-in (rung) is false rather than true.
Rockwell Automation Publication 1756-PM008E-EN-P - October 2014 13