Backwards with grouping seems to be off (or I'm just not getting what grouping/null is supposed to do)
14 node string with 1 null node and grouping of 2
I would expect on channel 1,2,3 the 3rd and 4th nodes from the end to light up but at channels 25,26,27 the 1st and 2nd from the end light up and so on groups of 2 nodes light as I go up.
14 node string with 0 null nodes and grouping of 2
nothing happens until channels 22,23,24
14 node string with 0 null nodes and grouping of 1
works perfect at channels 1,2,3
Forward using the same as above works great nulls and grouping