Here is a list of the printers that R&D has tested on the Expression and Express consoles.
Digital, DEC colorwriter 120ic
Cannon BJC 4000 Bubble Jet
Please verify pinout and printer settings.
These printer ports do not work with true serial cables (also called a null modem cable).
If you have difficulty getting things to print, please try to cycle the power on the console so that it "rebinds" with the unit.