Is there some kind of standard of modbus input register?
As stated in another answer:


  There are no guaranteed addresses or registers with ModBus; that's one
  of its biggest failings (or one if it's greatest strengths, depending
  on how (in)experienced you are in the field). There have been numerous
  attempts to generate some kind of standard for common devices but
  ultimately there is no way to do this since there is no standards body
  oversight for such a thing to succeed.