Added info:
The fractional conversion precision you have set in SU will affect what SU shows in say the entity info dialog. Take your 21 9/16, enter as decimal 21.5625 and set precision at 1/16, entity info reports 21 9/16, but set to say 1/2 and it will report with a different number with tilda showing only approximation. That precision basically controls the size of the denominator so you no not get cases where you have ie 100 /500 which would be use less to user. ( reason you can only set up to 1/64) If you see a case with the tilda you want to increase precision. For what you are trying to do I would never use that format
I am more convinced part of the issue maybe you are violating the interface to the printer, the manual gives specs . BTW the maintenance manual is on thier site. I would have both near by! The print heads are basically same as in many small format printers. It converts the post script to raster via the included RPI I mention above and prints as raster so you need to make sure you have the correct inter face. When you feed it raster and the printer expects vector ?? Note there are also windows and auto CAD drivers what are you using?
