Hi,
that read out is made for a particular linear encoder. You will have to match the linear distance travelled per count to one count of your rotary encoder.
If for instance one linear scale count is 0.01mm then you will have to arrange a rotary encoder to match... lets say you have a 5mm pitch ballscrew
direct coupled to your stepper then the stepper will rotate (0.01/5)*360 which is .72 degree. Thus your one count is 0.72 degree or (360/0.72)= 500 count per rev,
therefore your rotary encoder must have 500/4=125 lines. I don't recall seeing an encoder with that unusual number of lines.
It may be some of the 'programmable' magnetic line encoders could offer the flexibility to specify some unusual number of lines. The only ones I've seen locally
have been worth BIG BUCKS, like $800 each!
To be honest I think trying to match a linear scale to a rotary encoder is going to be a real battle.
Perhaps ask the manufacturer of the readout if it is possible to 'reprogram' the readout , that I suspect would be a lot easier than the reverse.
Craig