Please tell us which SLC you have. SLC5/01 ,5/02, 5/03, 5/04, 5/05.
For a serial port...
1747-CP3 cable ( null-modem cable)
You may need a USB to serial adapter if you don't have a serial on your PC. ( see link below to get one)
For a DH485 port..
1747-UIC ( USB to DH485 converter)
For a DH+ port....
1784-U2DHP ( USB to DH+ cable)
For a Ethernet port...
For direct connection use a crossover cable.
If using a switch or hub then a patch cord ( straight thru cable)