Could you have a look at the barcode Interface script such as $BSE/lib/barcode/<your Printer type>/type<your number> (eg. $BSE/lib/barcode/hp/type01)?
PCL printers such as HP have two font sets (primary, secondary). That allows to change font settings Independent of each other.
\016 = <so> shift out - select secondary font to print subsequent characters
\017 = <si> shift in - select primary font to print subsequent characters
So, our type01 looks like this:
Hope that helps!