Rockwell Automation AutoMax Enhanced Ladder Editor - Manual (Page 81)

EĆ1
Appendix E
Rung Execution Order
In a ladder logic program, the rungs are executed from the top to the bottom.
Within a rung, instructions are executed left to right until a branch is
encountered. Therefore, in a program without branches, the instructions are
executed left to right in a rung, with the first rung being executed first and the
last rung executed last.
Keep in mind that using JMP instructions within a ladder program changes the
rung execution sequence. For more information about using the JMP and LBL
instructions, see the AutoMax Enhanced Ladder Language Reference manual,
J2Ć3094.
Using branching techniques in a rung changes the sequence in which the
instructions are executed. Parallel branches are executed from the bottom up.
This means that the bottom branch is executed first and the top branch last.
How branches are executed are listed below:
Branching technique #1:
Connecting contacts or block instructions acting as inputs in parallel (OR
condition)
How the branches are executed:
How parallel branches of input instructions execute depend upon whether:
D The relay input instructions use simple variables, bit-indexed integer,
double integer variables, or element-indexed array variables
D Block instructions are used in a parallel branch
This table summarizes how parallel branches of inputs are executed: