You will need an RS-232 port on your computer.
Almost no modern PCs have these built in. I prefer a USB/RS-232 converter made by Keyspan/Tripp-Lite, the USA-19HS.
It's a few bucks more expensive than the cheap devices on the market, but the utility included with it and the overall stability have saved me thousands of dollars in time and hassle.
It's compatible with most A-B and other RS-232 based protocols and devices except for Data Highway 485 (which needs a special purpose protocol converter, the 1747-UIC).