Rockwell Automation AutoMax Enhanced Ladder Language Reference Manual - Manual (Page 290)

AĆ18
A.6.2 About the User Specified Initialization Method
When a variable is configured to use a User Specified value, the value defined as the
initial value is written to the variable at the start of the first scan. If the variable's initial
value is changed via inline editing, forcing, setting, or a program's execution, this new
value is not retained when the program is stopped and rerun. The value written to the
variable each time the program is placed into run is always that specified in the Initial
Value field of the Variable's property sheet. Choose User Specified initialization when
you want a variable to use the initial value you defined every time the program is placed
into run.
IMPORTANT
Do not use userĆspecified initialization for a global I/O variable being used as an input. If
you do, a bus error (error 31) occurs when you try to run the task.
A.6.3 About the Retained Value Initialization Method
When a variable is configured to use a Retained Value, the value defined as the initial
value is written to the variable at the start of the first scan. If the variable's initial value is
changed via inline editing, forcing, setting, or through the Variable Properties dialog
box, the value the variable contains when program execution stops is the one that is
written to the variable when the program is rerun. Retained Value initialization is the
default initialization type for timers and counters. An initial value of a variable configured
to use Retained Value initialization can be changed by any ladder program. For
example, you can change a timer or counter preset value by using ladder logic. Initial
values changed online can be permanently installed only by saving the program from
the Processor. Choose Retained Value initialization when you want a variable to be
initialized with the value it had at the time the program was stopped. Make sure that you
specify global variables using Retained Value initialization as nonĆvolatile variables.
IMPORTANT
Do not use retainedĆvalue initialization for global I/O variables. Doing so causes an error
when the program is verified.