Specifying Bits with Arrays
There's a technique that's actually in the RSLogix Help files that may do what you want.
Back in the PLC5/SLC days, we could reference a B3 address either by Word/Bit (B3:2.5) or by straight bit (B3/37). Very handy when you had alarms number 37, and you wanted to reference bit 37.
But short of BOOL arrays (ugh!), you can't do that in RSLogix. Or can you?
If you create an array ("MyArray") of DInts, then bit 37 is MyArray[1].5
If you have a tag ("Pointer") with value of 37, then the following:
MyArray[(Pointer AND NOT 31) / 32].[Pointer AND 31]
will, believe it or not, reference MyArray[1].5 when you do all the bitwise math.
Change the value in Pointer to something else, and now you are referencing a different bit. And, yes, you can have an instruction XIC MyArray[(Pointer AND NOT 31) / 32].[Pointer AND 31] in a line of ladder. You can also use OTE, although I would advise against it: when Pointer changes, the OTE won't be pointing to the old register anymore. So the bit that was set when Pointer was a different value won't get reset if the OTE drops out. It's a powerful technique, but "with great power comes great irresponsibility" (which is what happens at first in all the movies).
And because you are using DInts, you can do all the bitwise logic on your array (like XOR to clear particular bits) using the FAL instruction. Or FBC which might find the first set bit in your array, to give you a value for "Pointer".
I don't know if this is the sort of thing you're looking for or not (you haven't been very clear). But it's a useful tool in the toolbelt regardless.
Cheers,
