I've done a fair amount of getting computers to talk to old pieces of metal fabrication equipment (plasma cutters, oxy-fuel torches, mills, lathes, etc.) and you almost certainly need a null modem cable.

Where is hyperterminal in your testing setup? If you're using hyperterminal to read what the barcode reader is putting out, the barcode reader is already "switched".

Try out the $10 null modem cable. If it works great... if it doesn't work, throw it in your junk cable box :)