Good day, my friend!
Can you help me in one question.
In ST language if you write S= or R= is function like Set and Reset Relay in LD language.
May be for rising and falling edge in ST exist specific symbol, for example : If <Contact THEN ... "<" - like Rising edge.
I ask you, because not comfortable create another variable, remember mean at the end of cycle, and compare in next cycle, like this: If lastContact<Contact THEN... like Rising edge.
If you know about this some interesting information, please, answer me.
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I don't think this is possible because one is kind of an operator and the other is a function block that needs to remember the old value in order to detect a change.
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Zitat:
Ok, but how it is realizΡ in ladder diagram? program remember all variable old value ?
Yes, in LD the variable of type R_TRIG or F_TRIG (from Standard.library) is declared implicitly (automatically and invisible for user).
ST has no such "service", you have to declare them implicitly.
Regards,
Roman
If you would like to refer to this comment somewhere else in this project, copy and paste the following link:
Good day, my friend!
Can you help me in one question.
In ST language if you write S= or R= is function like Set and Reset Relay in LD language.
May be for rising and falling edge in ST exist specific symbol, for example : If <Contact THEN ... "<" - like Rising edge.
I ask you, because not comfortable create another variable, remember mean at the end of cycle, and compare in next cycle, like this: If lastContact<Contact THEN... like Rising edge.
If you know about this some interesting information, please, answer me.
I don't think this is possible because one is kind of an operator and the other is a function block that needs to remember the old value in order to detect a change.
Sent from my SM-G935F using Tapatalk
Ok, but how it is realizΡ in ladder diagram? program remember all variable old value ?
Hi BIZON,
Yes, in LD the variable of type R_TRIG or F_TRIG (from Standard.library) is declared implicitly (automatically and invisible for user).
ST has no such "service", you have to declare them implicitly.
Regards,
Roman