adccommunitymod (AutomationDirect) asked a question.
Created Date: February 08,2017
Created By: ryangriggs
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I may just be missing it, but I can't find a simple way to get the absolute value of a math operation. I want to set up a deadband for a value: if the value has changed by more than X, then do Y. However, for this to be simple, I need to calculate the absolute value of current process value - previous process value. Yes, I could do SQRT((Current - Prev) ^ 2) but that seems like hugely overkill, plus you could easily hit the integer limits with larger numbers... not to mention the added CPU cycles required for those SQRT and exponent operations. There doesn't appear to be an "ABS " instruction. Any suggestions or pointers welcome! Thanks!
Created Date: February 08,2017
Created by: ryangriggs
I may just be missing it, but I can't find a simple way to get the absolute value of a math operation. I want to set up a deadband for a value: if the value has changed by more than X, then do Y. However, for this to be simple, I need to calculate the absolute value of current process value - previous process value.
Yes, I could do SQRT((Current - Prev) ^ 2) but that seems like hugely overkill, plus you could easily hit the integer limits with larger numbers... not to mention the added CPU cycles required for those SQRT and exponent operations.
There doesn't appear to be an "ABS " instruction.
Any suggestions or pointers welcome!
Thanks!
Created Date: February 08,2017
Created by: bcarlton
Values in DF1 and DF2, result in DF3
Rung 1: If DF1> DF2 then MATH (result in DF3, formula DF1 - DF2) --- in parallel with MATH - OUT C1
Rung 2: If NOT C1 then MATH (result in DF3, formula DF2 - DF1)
(Of course use any registers you wish)
Created Date: February 09,2017
Created by: ryangriggs
Thanks Bernie. That's exactly what I ended up doing... Was just looking for the simplest way to accomplish this, and I was surprised the Math feature didn't include an ABS function.
Created Date: September 26,2017
Created by: JabboGibbs76
Berine,
Could you share the click program using this deadband
Created Date: September 27,2017
Created by: bcarlton
I don't have a program. Just this quick method to derive an absolute value.