RSlogix 5000, odd or even?

Hi, guys, how’s going?

In RSlogix 5000, if the integer in tag “number” (DINT) is odd, then the output “ODD.1” is ON. How can we program it?

Thanks a lot.

Actually the first bit of any integer is odd/even. So number.0 = 0 (even), number.0 = 1 (odd). In other words, XIC number.0. If it's false your DINT is even, of it's true, your DINT is odd.

As @dmroeder notes, the low bit is ODD.0, not ODD.1.

My answer was going to be a CMP instruction with the expression ...which will evaluate true if the number is even, and false if it is odd

But I guess an XIC is simpler :site:

I would do it dmroder's way.
If were doing assembly language programming I would rotate the word right through carry and jump or not jump if carry.
This way I don't need to load the constant 1.

isOdd := number & 16#00000001;

?

Peter Nachtwey said:

I would do it dmroder's way.
If were doing assembly language programming I would rotate the word right through carry and jump or not jump if carry.
This way I don't need to load the constant 1.

Click to expand...

Depending on the assembly language instruction set, you may not need to load a 1 at all if the constant is embedded in the instruction word.

dmroeder said:

Actually the first bit of any integer is odd/even. So number.0 = 0 (even), number.0 = 1 (odd). In other words, XIC number.0. If it's false your DINT is even, of it's true, your DINT is odd.

Click to expand...

Amazing! Thanks a lot.

You can address to the bit level in DINT tags in RS/Studio5000.

Bit 0 is the least significant bit, and has a binary "weighting" of 1, which is Odd. All the binary weightings of all the other bits are Even (except the sign bit, of course)

All "odd" numbers will have bit 0 turned on, so it is simply a case of inspecting bit 0 of your DINT tag, if it's on, then DINT tag has an "ODD" value, if it is off, the DINT tag holds an "EVEN" value, or more simply "Not ODD".

And you do not even need to write any code to test for this... If you make a new tag "My_Value_Is_Odd", and ALIAS it to "MyValue.0", where MyValue is your DINT tag.

"My_Value_Is_Odd" will inherit the BOOL data-type of the base tag, i.e. bit 0 of "MyValue"

XIC MyValue_Is_Odd : True if MyValue is Odd

XIO MyValue_Is_Odd : False if MyValue is Even (Not Odd)

Use your own tag-names as appropriate...

Using an alias with a descriptive moniker like ".....is_odd" may be preferable to just addressing bit 0 in MyValue directly, which of course is always a contender.