SCL Postive Edge detection in Dword

MOeZ · Jan 22, 2013

Dear Expert,

SCL Newbie question

, i want to set POS_EDGE Detection output if any of bits changes in DWORD ? i been thinking and still not have correct answer yet.

Currently, i called "POSTIVE_EDGE" Detect Function block 32 times in STAT area of Main FB and check couples of bool one by one and is worked. But i wanted to improve performance in this FB and Hope somebody can help me with better
way of SCL? Thanks in adv.

kour · Jan 22, 2013

MOeZ said:
Dear Expert,

SCL Newbie question , i want to set POS_EDGE Detection output if any of bits changes in DWORD ? i been thinking and still not have correct answer yet.

Currently, i called "POSTIVE_EDGE" Detect Function block 32 times in STAT area of Main FB and check couples of bool one by one and is worked. But i wanted to improve performance in this FB and Hope somebody can help me with better
way of SCL? Thanks in adv.

Hi
I can give you an idea, the implementation of SCL it gets easier.
consider using the famous XOR, and here is the XOR function.

at the beginning and at the first execution, you double your word "EDGE" initializes a word "MD0" for example 0.puis you enter a boucle.Si MD0 XOR front is equal to 0, otherwise you a front and you will have the same posistion. 1: bit 1, 3: two front in the bit 1 and 2 .....

JesperMP · Jan 22, 2013

// the bits in oneshotword will be oneshots of the bits in sourceword formatted as WORD or DWORD
"oneshotword" := "sourceword" AND NOT "memword" ;
"memword" := "sourceword" ;

edit:
(deleted .. I made the mistake thinking that logical word operations have to be made on INTs or DINTs).

MOeZ · Jan 23, 2013

Many Thanks Jesper and Kour! will try it out Jesper Method

and Still have no idea yet Kour's Idea to use Famous XOR!

SCL Postive Edge detection in Dword

MOeZ

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kour

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MOeZ

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