allow digital state to store a number

Our system PMD Honeywell is a bit random for digital values. A digital value can be 0 or 1 but can also be 254 or 255. I want to do time weighted average for the digitals so I need the value to be a number. If I specify that the digital is digital then I can convert the 254 and 255 to 0 and 1 but that is stored as text not a number so the time weighted average does not work. If I specify it as a float 32 then I can adjust the calculation by subtracting 254 if it is larger than 1 but occaisionally the Honeywell system mixes these choices on the same tag so it will change from 255 to 1 and back again even so that completely screws up my averages. Only solution is to add a block i the PMD that checks the state of the tag and outputs to another tag as floating point 1 or 0. Messy and annoying.If your system had a choicve for the digitsl state to store a number instead of text then the problem would go away. :-)