Hello,
Recently I have been experimenting with the TIME, TIME_TO_STR, and STR_TO_TIME functions. As you know the STR_TO_TIME functions convert a time (string) to an integer which represents seconds. My goal has been to convert a time to an integer, add a value to it, and then convert it back to a time (string).
Curiously, I am having issues doing the addition. As an example: I convert the time "2016-01-10T14:05:00" using STR_TO_TIME and the result is 1389362700 (one billion). So far, so good. Next, I add 14400 to it and receive 1389377024. Unfortunately Excel tells me that I should be getting 1389377100, which is a difference of 76.
DeltaV1389362700 + 14400 = 1389377024
Excel1389362700 + 14400 = 1389377100
Various values give me various differences in answers. It seems as though the issue is related to a number in the billions - either an operand or the result.
I started out using 32-bit Signed Integers (range of +/- 2 billion) as my data type. I have also tried using 32-bit Unsigned Integers (range of +4 billion). I have performed this calculation using an ADD function block as well as structured text in a CALC block, both give me the same result. I am using DeltaV v 13.3 with an SX controller.
Is DeltaV not capable of calculating numbers with accuracy at that size of value? Is there another way I should have approached this?
Thank you,
Dave
In reply to Matt Stoner:
Hi Istvan and Matt,
I found the issue. I was performing a calculation to determine the value of Period Add above. The calculation involved division and a TRUNC() command. I finally realized that DeltaV was having to do a conversion from the result of the division to the UINT32 that occurs after the ACT block executes (http://www.emersonexchange365.com/operateandmanage/deltav/f/50/t/3158).
Once I moved the addition into an ACT block that executed after the ACT block with the TRUNC(), I got the correct result.
Thank you for the help!