It's a Rosewill RC-300 1 Port serial PCI adapter. From http://www.newegg.com/Product/Product.aspx?Item=N82E16815166003, it says "The Rosewill RC-300 features a 9-pin RS232 serial port to add..." so I assume it only supports RS-232? Sorry for the ignorant question; I tried looking up differences between the specifications but it's pretty complicated for me.
Unless you've bought a card that specifically supports RS485, no, you don't have it.
RS232 uses at a minimumum, three wires. A transmit, a receive and signal ground. The signal is a swing of around +-15VDC on the receive and transmit wires and is referenced to the ground wire.
RS485 is a differential balanced signal (one wire swings positive while the other swings negative) over twisted pair, similar to what Ethernet uses and typically is used for CSU/DSU units, process control, etc. Full Duplex requires two twisted pairs.
There's nothing in the manual to suggest the RC-300 supports RS-485
Other vendor's product descriptions generally do say if they support RS-485.
RS-485 is a more specialised comms standard than RS-232, mainly used in industrial systems