Thank you. Just what I needed.

Busy integrating into final design now.

Well here is my FBD used in the end.

Makes use of the mathmatical instruction to both calculate the next value as well as hold the value (when en = "0").

Output of this is fed to a "limiter" that stops the output value going above start and end values.

The inputs to the mathmatical instruction are from analog MUX's that select what the mathmatical instruction will process, either increment, decrement or load with value.

Operation is as follows:

1. Upon reset, with I3=0, the "start" value is loaded into the counter, note that the "start" value may be greater or less than the "end" value.
2. Setting I3 =1, will allow I2 to step the counter to the "end" value in number of steps set by "steps" value. Stepping may be +V or -V depending on the "start" and "end" values.
3. Counter stops counting when "end" value reached.
4. Setting i3=0, will allow I2 to step the counter to the "start" value.
5. Counter stops counting when "start" value reached.
6. Upon reset, with I3=1 works the opposite way with "end" value (instead of "start") being loaded into the counter.

Enjoy.