Drivers authoring for Electronic Tax Register

We need someone to write drivers (any language) for our Electronic Tax Register. This is a serial port device that connects to RS232 port of a PC. It is desired to send sales receipt data to this device and obtain a unique signature from this device to be printed on a receipt. Detailed technical document shall be exchanged with the shortlisted candidate. Only those candidates apply who have experience in writing device drivers. Anyone with an experience in this type of project shall be given top priority. Kindly advise your respective project in this field / domain.