using linux ubuntu to dnc or upload files to fanuc 21i-TA

I have a Fanuc 21i-TA which can only use stupid money 3.3v SRAM cards, £832 for a 4mb card. It does have RS232 connection, but I only have access to PC's which have physical serial ports that are running Linuxmint which is basically tweaked and slightly modded Ubuntu. I have OneCNC DNC software but under Wine it will not see serial ports.
From research I believe that DNC software is basically the likes of Hyperterminal. And that any console software should be capable of firing files down a serial cable at 4800bps, 7bits, 2stop bits, even parity, software handshake as my panel requires. Surely this cannot be so difficult, but it is proving so!

Is there anyone who knows how to send and receive files via direct RS232 to a fanuc panel from linux. i am not interested in drip feeding DNC, but need a mechanism for getting NC files onto the controller.

Thanks in advance for any help given.

John