Seeking advice on Allen-Bradley module programming issues
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During data configuration, the initial value of DV is FALSE; how can it be changed so that the initial input value is TRUE? In a non-mandatory state, compare as shown in the figure
Is this DV signal being sent in from the scene? If it’s from the site, just select the normally open and normally closed ones there
The valve inspection shutdown feedback signal, right? First, you need to make sure the signal coming in is correct If it’s a shutdown signal, is it normally closed or normally open? If there’s no problem, I’ll make the changes. If it is changed, what kind of signal is the valve check? For NAMUR signals, the value can be inverted at the isolator; in the case of dry contacts, inverting it in the program will suffice
Simply invert it directly, or add a NOT function block after DV
This is valve feedback; in the end, it’s still necessary to rely on the actual signals from the field. Worrying about this during configuration is pointless
Understood, thank you:handshake
Actually, when you add this variable, the default value is FALSE; of course, it’s also possible to set this initial default value to TRUE. This has nothing to do with the actual application scenario – default values can be set for both channel variables and intermediate point variables. It’s just my personal opinion that if control needs to be handled by recommending the opposite approach, it will differ quite significantly from everyone’s usual programming habits; this will make it difficult to troubleshoot errors later on. These are just my humble thoughts – please let me know if there are any mistakes in them.