How to give a physical input a speed reference value

[PLC_N00B_5 0]

Is it possible to give a physical proximity switch or photo eye input a value to change a vfd's speed. Speed up or slow down when it has been triggered. 

[Crossbow 295]

You would have to provide a lot more detail.  Like how is the VFD being controlled?  Analog?  Network?

You can certainly write logic so that when an input is triggered, a new speed can be set.  

[PLC_N00B_5 0]

the speed ref is being sent to the VFD from a DA3605 or a DA3603 depending on the VFD

[Crossbow 295]

So based on a physical input, you can move a numeric value into the variable you attach to the analog output.