Find most significant bit.

L D[AR2 said:

...also returns location 0 if no bits are set.

Click to expand...

Oops, hadn't spotted that ...

Perhaps we need an AOI developed to do this ?


Logix500 processors (most of them) had an ENC instruction which would tell you the first bit set, but this was from lowest to highest bit.

So perhaps an AOI should have a parameter for which way to go, lowest to highest, or contra ....

L D[AR2 said:

...also returns location 0 if no bits are set.

Click to expand...

Usually the LSB is bit zero so if no bit is set then a -1 is returned.

Back when I hated myself and didn't leave space between step numbers, I would do 2 exponent step number and transfer that in a DINT, then I'd make a rung schematic of the sequence above the actual sequence to visualize, as well as for general usage because an EQU is bulky and you can put comments on individual DINT bits.

I've tried a bunch of methods to represent the step number via bits but there's none I like quite as much as that one. Unfortunately it's nowhere as good if you leave space between steps because then the link between step number and bit position is muddled.