if you've got the Keyspan adapter, it usually DOES work with the autoconfigure ...
one thing that the autoconfigure will NOT do, is try different serial ports ... in other words, you might have to manually change from COM1 to COM2, etc. to find where your computor has "landed" the USB adaptor ...
if that doesn't get it working, consider that the SLC's Channel 0 might have been reconfigured for DH-485 or ASCII or something other than just plain-vanilla DF1 ...
do you have an existing (and current) copy of the SLC's .RSS program? ... if so, check under "Channel Configuration" and see how the serial port has been configured ...