FSC - Expression Help

[Mispeld]

For comparing a range of Dints, subtract the highest number that you want to find (1115) from 2147483647 (2147482532), then subtract the span (1115-1101+1=15) from 2147483647 (2177483632) and use that for your comparison. Thus your expression would be

(B_Group_1_Found_Array[zFSC.POS].Lane+2147482532)>2177483632

Assuming the '.Lane' element is a DINT, this computation will generate a minor program Arithmetic Overflow fault for Lane values greater than the largest range value. It does seem to work, though.

 

[proof]

Assuming the '.Lane' element is a DINT, this computation will generate a minor program Arithmetic Overflow fault for Lane values greater than the largest range value.

The logic works because the math overflows, but in my tests, the controller properties Minor Faults does not show the fault when the logic runs. Where are you seeing this fault?

 

[Mispeld]

I am testing on a 1756-L61, and under the Controller Properties, Minor Faults tab, I get the following for values over 1115

6/29/2001 4:54:53 PM
(Type 04) Program Fault
(Code 04) Arithmetic overflow. Result of an arithmetic instruction out of range.
Task: MainTask
Program: MainProgram
Routine: MainRoutine
Location: Rung 16

(Also, in testing I noticed a typo on the greater than test...2147...instead of 2177)

 

[proof]

I am testing on a 1756-L61, and under the Controller Properties, Minor Faults tab, I get the following for values over 1115

OK, I got the 'fault'. I found when I tested the logic that I found the match in the middle of the array. When I added high number to the beginning of the array, reset the .in bit and restarted the logic, the FSC was not starting at 0, but where I found the last match.

I don't like the idea of having code that gives 'faults', but I'd probably use it (with comments on where the numbers come from and the 'fault side effect') over the other methods suggested, since it has less calculations. I am curious as to what other opinionated people here that think they write good code, would choose for a solution, and why.

(Also, in testing I noticed a typo on the greater than test...2147...instead of 2177)

Oops. That's why I explained the math. When I proofread, I am very good at seeing what I wanted to write instead of what I wrote.

 

[JosephMont]

I did not see the warning and it works perfectly.