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Is there a 'first scan' bit?

markus506markus506
edited March 2021 in PLCnext Engineer
I was wondering if there is a 'first scan' bit that is set on startup for only 1 cycle (similar to other PLC's). Since we are able to select what variables can be retained on power up, this may not be as necessary, but it could be useful in certain circumstances. Does the PLCNext have something like this?

Comments

  • Martin [PLCnext Technology Team]Martin [PLCnext Technology Team]
    No, unfortunately this type of system value is not available in PLCnext Engineer.
    Of course you can set your own bit(s) at the end of the first "scan" ( however you define a "scan" ), and if the value is FALSE then obviously that code has not executed yet.
    You will need to think about how many of these bits you will need. Many PLCs run everything from one "Idle" task, but PLCnext Engineer also allows you to define other cyclic and event-based tasks in addition to the Idle task. So you will probably want one "first scan" bit for each task in your application.
    ~ Martin.
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