Host Engineering Forum

General Category => General Discussion => Topic started by: eman5oh on July 14, 2021, 11:28:27 AM

Title: Run Mode Edits Allowed
Post by: eman5oh on July 14, 2021, 11:28:27 AM

Does a list exist with what is and is not allowed to be done with run mode edit? If I recall adding things like PID loops or new programs require the PLC be taken out of run mode, I am sure there are others as well.

Title: Re: Run Mode Edits Allowed
Post by: franji1 on July 14, 2021, 11:40:59 AM

Basically any change to the System Configuration.  When you create a code block, that creates a new heap-item in the System Configuration, hence requires a transition to Program mode.  Same with a PID instruction - it automagically creates a new PID structure heap item.

The System Configuration changes the structure of everything ladder logic does, possibly changing the actual low level ladder logic opcodes written to the PLC.  Hence, the Program ladder opcodes must be re-generated with the new System Configuration, and the System Configuration itself must be updated in Program mode.