Difference between Shift Register(SN) and Feedback Nodes(FN)

Shift Register(SN ) and Feedback Nodes(FN ) are different implementations of the same thing. The feedback node was introduced later (in LV 7 or so) to clean up the diagram a bit, so you don’t have to route wires from one end of the diagram to the other. They Pass a data item from iteration of a loop to the next. The main difference is in how they are wired and the fact that a feedback node can’t be expanded to get items from more than the previous iteration of the loop.

If you only have one history terminal, they are the same and you can covert between the two by right-click "Replace with feedback node/Repace with shift register". Feedback nodes have the advantage of less clutter, especially if you have wide loops (short localized wire loops instead of telephone lines across). Personally, I always prefer shift registers. Feedback nodes always seem to make the diagram less clear.

Both Shift Registers (SR) and Feedback Nodes (FN) can pass data from one iteration of a loop to the next.
Both can be initialized to a value before the loop starts (although this is hidden by default for FNs).

The main differences are:

1. Getting values from previous iterations
   • SR = can expand input terminal to get multiple previous iteration values
   • FN = can only get the most recent iteration
2. Getting last value when loop ends
   • SR = value is available at output terminal
   • FN = value is not available without additional programming
3. Block diagram space
   • SR = wires must be run to both sides of the loop
   • FN = wires can be very short

So, in situations where you only need the last value and you don’t need to pass the final value out of the loop, the FN provides a less cluttered option.

HOWEVER, the FN is currently SLOWER than the SR.
If We run following 2 program, the one using SR takes only 9728ms, while the other one using FN takes 12796