D.1 using the pre-defined program scan variables, D.1 using the prećdefined program scan variables – Rockwell Automation AutoMax Enhanced Ladder Language Reference Manual User Manual

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DĆ2

D.1

Using the PreĆDefined Program Scan Variables

Use the following Boolean variables to execute logic based on the Processor's scan.

Only use these variables for input parameters (read only):

D first_scan

Use this variable to execute logic during a program's first scan. This variable is

true during the initial scan of the ladder rung and false during all other scans.

D second_scan

Use this variable to execute logic during a program's second scan. This

variable is true during the second scan of the ladder rung and false during all

others.

D last_scan

Use this variable to execute logic during a program's last scan. This variable is

true on the final pass of the ladder rung after you have selected TASK STOP.

This variable is not set when a STOPĆALL error occurs.
To use the last_scan variable, your program scan must be less than 0.5 s.
I

MPORTANT:

Do not use the last_scan variable in an eventĆdriven program. Because these

programs are based on the occurrence of an event, the last_scan variable may

never be executed when used in an eventĆdriven program.